Serotonin (5-HT) is crucial molecule in animal kingdom. It is involved in control of multiple processes. It might act via transmembrane receptors or via postranslational protein modification (serotonylation). D. gyrociliatus is a marine worm-like invertebrate with quite short lifespan. In this study lifetime experiments were performed. We incubated freshly laid eggs, adult females lifelong in HTP, PCPA and cystamine. Every week we monitored the survived individuals. This was lifelong (about 5 moth) monitoring. The survival analysis demonstrated that PCPA and cystamine reduce lifespan longevity drastically and even in F1 offsprings from mothers with reduced level of serotonin. HTP incubation to the contary extended mean lifespan longevity up to 22 % even in F1 offsprings from mothers with extended levels of serotonin. Thus, our results demonstrated that serotonin impacts lifespan longevity and moreover the level of serotonin in mother organism affects offspring lifespan longevity.

L-17 is a thiadiazine derivative with putative anti-inflammatory, neuroprotective, and antidepressant-like properties. In this study, we applied combined in silico, ex vivo, and in vivo electrophysiology techniques to reveal the potential mechanism of action of L-17. PASS 10.4 Professional Extended software suggested that L-17 might have pro-cognitive, antidepressant, and antipsychotic effects. Docking energy assessment with AutoDockVina predicted that the binding affinities of L-17 to the serotonin transporter (SERT) and serotonin receptors 3 and 1A (5-HT3 and 5-HT1A) receptors are compatible to the selective serotonin reuptake inhibitor (SSRI) fluoxetine and selective antagonists of 5-HT3 and 5-HT1A receptors, granisetron and WAY100135, respectively. Acute pre-treatment with L-17 robustly increased c-Fos immunoreactivity in the amygdala (central nucleus), suggesting increased neuronal excitability in this brain area after L-17 administration. Acute L-17 also dose-dependently inhibited of 5-HT neurons of the dorsal raphe nucleus (DRN). This inhibition was partially reversed by subsequent administration of WAY100135, suggesting the involvement of extracellular 5-HT. Based on in silico predictions, c-Fos immunohistochemistry, and in vivo electrophysiology, we suggest that L-17 is a potent 5-HT reuptake inhibitor and/or partial 5-HT1A receptor antagonist. Thus, L-17 might be a representative of a new class of antidepressant drugs. Since L-17 also possesses neuro- and cardio-protective properties, it can be useful in post-stroke and post-myocardial infarction (MI) depression. In general, combined in silico predictions and ex vivo neurochemical and in vivo electrophysiological assessment might be a useful strategy for early preclinical assessment of the affectivity and neural mechanism in action of the novel CNS drugs.

5-Hydroxytryptamine (5-HT) or serotonin plays a crucial role as a neuromodulator and/or neurotransmitter of several nervous system functions. Its actions are complex and depend on multiple factors, including the type of effector or receptor activated. Briefly, 5-HT can activate: (i) metabotropic (G-protein-coupled) receptors to promote inhibition (5-HT1, 5-HT5) or activation (5-HT4, 5-HT6, 5 HT7) of adenylate cyclase, as well as activation (5-HT2) of phospholipase C; and (ii) ionotropic receptors (5-HT3), which form a ligand-gated Na+/K+ channel. Regarding blood pressure regulation (and beyond the intricacy of central 5-HT effects), this monoamine also exerts direct postjunctional (on vascular smooth muscle and endothelium) or indirect prejunctional (on autonomic and sensory perivascular nerves) effects. At the prejunctional level, 5-HT can facilitate or preclude the release of autonomic (e.g., noradrenaline and acetylcholine) or sensory (e.g., calcitonin gene-related peptide) neurotransmitters facilitating hypertensive or hypotensive effects. Hence, we cannot formulate a specific impact of 5-HT on blood pressure level, since an increase or decrease in neurotransmitter release would be favoured depending on the type of prejunctional receptor involved. This review summarizes and discusses the current knowledge on the prejunctional mechanisms involved in blood pressure regulation by 5-HT and its impact on some vascular-related diseases.

Atypical antipsychotic drugs were introduced in the early 1990th. Unlike typical antipsychotics, which are effective only against positive symptoms of schizophrenia, atypical antipsychotics show effectiveness against negative and cognitive symptoms as well. Furthermore, they are effective not only in psychotic, but also in affective disorders, by their own or as adjuncts to antidepressant drugs. While typical antipsychotics act, almost exclusively, via dopamine-2 (D2) receptors, atypical target serotonin-1A/1B/2A/2C (5-HT1A/1B/2A/2C), α1/2-adrenergic, and/or histamine-1 (H1) receptors as well. Blocking of 5-HT1A/1B autoreceptors, inducing their early desensitization, and/or activation of α1-adrenoceptors, allow some atypical drugs to enhance 5-HT transmission. Blocking of 5-HT2A/2C and/or α2-adrenoceptors enable some atypical antipsychotics to stimulate catecholamine transmission and/or diminish the inhibition of catecholamine neurons induced by some antidepressants. It is possible, that the activation of H1 and/or blocking of H3 boost monoamine transmission as well, via a mechanism involving stimulation of firing activity of dopamine neurons. The experimental drugs with antipsychotic potential, acting on adenosine and trace amino associated (TAAR) receptors, might be effective in mood disorders as well, because of the ability to modulate the excitability of monoamine-secreting neurons and to potentiate extracellular concentrations of monoamines in the limbic areas of the brain.

Fear can sometimes paralyze us, and it can sometimes be exciting; for some people, fear is so crippling it can significantly mix up their lifes! We understand a little bit about how the brain acts when we are afraid, mainly by studying the brains of animals. Recently, surprising findings were made using a humble animal, the zebrafish – a small aquarium fish that in the past has helped scientists figure out how our organs develop. Zebrafish are useful because they develop quickly, reproduce richly, and have brains which are similar to ours. They also produce what we call an “alarm substance” that alerts shoalmates when one of them has been injured; when they smell this substance in the water they act as if they are very scared. When this happens, they release serotonin in their brains, a neurotransmitter that acts as a light switch, making them less afraid but more cautious – as if trying to figure out if a predator is there or not. Hopefully, finding more about how the zebrafish brains process this serotonin signal can help scientists develop better treatments for mental disorders that are associated with fear.

The human gastrointestinal tract is inhabited by trillions of commensal bacteria collectively known as the gut microbiota. Our recognition of the significance of the complex interaction between the microbiota, and its host has grown dramatically over the past years. A balanced microbial community is a key regulator of the immune response, and metabolism of dietary components, which in turn, modulates several brain processes impacting mood and behavior. Consequently, it is likely that disruptions within the composition of the microbiota would remotely affect the mental state of the host. Here, we discuss how intestinal bacteria and their metabolites can orchestrate gut-associated neuroimmune mechanisms that influence mood and behavior leading to depression. In particular, we focus on microbiota-triggered gut inflammation and its implications in shifting the tryptophan metabolism towards kynurenine biosynthesis while disrupting the serotonergic signaling. We further investigate the gaps to be bridged in this exciting field of research in order to clarify our understanding of the multifaceted crosstalk in the microbiota-gut-brain interphase, bringing about a novel microbiota-targeted therapeutics for mental illnesses.

Long Covid has become a blight, its economic consequences overwhelming. But Long Covid (LC) may represent persistent Covid-19 in those with preexisting Candida overgrowth (CO). The features shared by both are striking. LC may be a growing subset of CO. The altered tryptophan metabolism encountered in LC is driven by IFN-γ in reaction to CO. Females are robust producers of IFN-γ, yet estrogen promotes CO.The consequent decline in serotonin and melatonin triggers the mood swings and sleeplessness respectively in LC. The low serotonin, the primary messenger in the gut brain axis, creates autonomic dysfunction. The CO induced gut dysbiosis and leaky gut initiate an autoimmune path. TNFα seen in both LC and this opportunistic yeast is at the center of the cytokine triad that leads to neurodegeneration. The Western diet, high in carbohydrates, alcohol, and glutamate, is exploited by this commensal turned parasite. Residual SARS CoV2 and Candida generate abundant ROS, inducing mitochondrial dysfunction. Alcohol tastes different for many with LC, because acetaldehyde requires functioning hepatic mitochondria. This article delves into the complex physiology and biochemistry that drive the symptoms of this conspicuous connection. Recent research has revealed innovative approaches that might address this global scourge, including D-mannose for the immune dysfunction and butyrate for the gut dysbiosis created by and seen in both LC and intestinal Candidiasis.

Intestinal microbiota attracts daily attention of a growing number of study which have attempted to link gut dysbiosIs with a variety of disease states: irritable bowel syndrome (IBS), inflamed bowel disease (IBD), Crohn's disease (CD), leaky gut syndrome (LGS), food intolerance, diabetes, metabolic syndrome, cancer, etc.. In our study we analyzed how intestinal dysbiosis may be related to chronic fatigue syndrome (CFS) and depression through the exchange of information through the gut-brain axis (GBA). We studied 33 subjects, 13 males and 20 females, who reported CFS or/and depression: we investigated their salivary cortisol levels, blood serotonin, omega 3/6 ratio, intestinal dysbiosis (calculated on the urinary levels of indoxyl sulfate and skatole), and we looked for the presence of Candida a. or mycetes in the stool; the data accumulated with this research show a correlation between the presence of Candida a./miceti, indoxyl sulfate urine values beyond the physiological and low serotonin levels. In addition, data analysis showed that the EPA/DHA values also show pro-inflammatory levels in case of dysbiosis and low serotonina levels. The relationship, however, with cortisol levels requires further research although this study showed a statistically significant positive correlation between these values, measured at specific times, and serotonin levels. Aims its connections with We investigated the relationship between stress (evaluated through the measurement of salivary cortisol levels) and gastrointestinal efficiency measured as a function of intestinal fermentative and putrefactive dysbiosis, evaluating the levels of urinary indoxyl sulfate in the first case (a possible correlation with the presence of Candida spp or Mycetes in the subjects feces was investigated), urinary skatole levels in the second one, in patients with chronic fatigue syndrome (SFC) and depression. In these patients we also have studied omega 3/6 ratio, and finally we have analized the impact that the alteration of these parameters can have on the serotonin levels. This research attemps to highlight the contact points, in some cases not so obvious, among these topics, contact points that, although they give us interesting indications, show the need to be further deepened by analyzing a larger amount of data.

The soma, dendrites and axon of neurons may display calcium-dependent release of transmitters and peptides. Such release is named extrasynaptic for occurring in the absence of synaptic structures. This review describes cooperative actions of three calcium sources on somatic exocytosis. Emphasis is given to the release of serotonin by the classical serotonergic leech Retzius neuron, which has allowed detailed studies of each step between excitation and exoctytosis. Trains of action potentials induce transmembrane calcium entry through L-type channels. If the frequency of action potentials is above 5 Hz, summation of calcium transients upon individual action potentials increases the intracellular calcium concentration to activate calcium–induced calcium release. The amplified calcium wave activates motochondrial ATP synthesis that fuels the transport of vesicles to the plasma membrane. Serotonin that is released activates autoreceptors coupled to phospholipase C. Production of IP3 produces release of calcium that sustains the large-scale exocytosis. The swiss-clock workings of the release machinery for somatic exocytosis has a striking disadvantage. The essential calcium-releasing endoplasmic reticulum that lays between resting vesicles and the plasma membrane becomes an obstacle for the vesicle transport. Such architecture reduces drastically the thermodynamic efficiency of the vesicle transport and elevates its energy cost..

Objectives: The mechanism of action of drugs that depress the central nervous system (CNS) was unknown until molecular pharmacology discovered each drug's exact role. The benefit of knowing the mechanism of action is to design a new drug that could have the same efficacy as the prototype drug but with fewer side effects. Some of the available CNS depressant drugs that were abused or illegally used could be modified to make them used medically. Methods: We reviewed various published articles in PubMed and Google Scholar that focused on CNS depressants' molecular pharmacology.Results: It was clear that at specific plasma concentrations of ethyl alcohol showed almost same mode of action of propofol by targeting the extrasynaptic GABA-A receptors, which causes tonic GABAergic inhibition. Besides, the High affinity of some benzodiazepines (e.g., midazolam) to α1 subunit of GABA-A receptor causes sedative, hypnotic, amnesic, and some antiepileptic effects; however, some other benzodiazepines (e.g., diazepam) have high affinity to α3 subunits, which causes anxiolytic, muscle relaxant, and strong antiepileptic effects. The CB1 receptor partial agonism effect of tetrahydrocannabinol has a sedative advantage over full agonism due to desensitization of CB1 receptors. Conclusion: From the molecular pharmacology prospect, it is possible to design new drugs with more specific CNS depressants effect and fewer side effects by targeting particular receptors with a precise reaction.

Vasoreactivity is relatively well documented in terrestrial snakes, but has previously been investigated in only one semi-arboreal snake species. Consequently, the extent to which vasoreactivity is common across snake taxa, or varies by habitat is unclear. The Tokara habu (Protobothrops tokarensis) is a semi-arboreal snake endemic to only two small adjacent Japanese islands, and hence a useful species for further investigation of vasoreactivity. We evaluated responses to known vasoactive substances in thoracic aortas isolated from Tokara habu. Under resting tension, noradrenaline and angiotensin II induced concentration-dependent contraction, but acetylcholine, serotonin (5-hydroxytriptamine; 5-HT), and isoproterenol induced relaxation followed by contraction. Histamine and rattlesnake bradykinin had no effect. Experiments with receptor-specific antagonists suggest that M1 and M3 receptors are involved in the acetylcholine-induced response, 5-HT1, 5-HT2 and 5-HT7 receptors in the serotonin-induced response, and β1 and β2 receptors in isoproterenol-induced relaxation. NO may be involved in acetylcholine-induced relaxation, but not the responses to serotonin or isoproterenol. In contrast to the uniform vasoreactivity observed in terrestrial snakes, the vasoreactivity of semi-arboreal snakes may be governed by diverse regulatory mechanisms.

By using a systems biological perspective and available literature on human social interaction, grouping, and cohesiveness, a new coherent model is proposed that integrates existing social integration and neurobiological research into a theoretical neurobiological framework of personality and social interaction. This model allows for the coherent analysis of complex social systems and interactions within them, and proposes a framework for estimating group cohesiveness and evaluating group structures in order to build and organize optimized social groups. This „Neurobiological-Associative“ model proposes two primary feedback loops, with environmental conditioning (learning) being sorted into an associative model that modulates interaction with the social environment, and which impacts the second feedback loop involving the individuals' neurobiological capacity. In this paper, the concept of neurobiological capacity is developed and based upon contemporary research on intelligence, personality, and social behavior with a focus on the oxytocin, serotonin, and dopamine systems. The basis of social exclusion and group structure is thus, expressed in the very most simple terms, neurobiological compatibility and risk assessment modulated by an internal associative model.

The brain of Drosophila melanogaster is comprised of some 100,00 neurons, 127 and 80 of which are dopaminergic and serotonergic, respectively. Their activity regulates behavioral functions equivalent to those in mammals, e.g. motor activity, reward and aversion, memory formation, feeding, sexual appetite etc. Mammalian dopaminergic and serotonergic neurons are known to be heterogeneous. They differ in their projections and in their gene expression profile. A sophisticated genetic tool box is available, which allows for targeting virtually any gene with amazing precision in Drosophila melanogaster. Similarly, Drosophila genes can be replaced by their human orthologs including disease-associated alleles. Finally, genetic manipulation can be restricted to single fly neurons. This has allowed for addressing the role of individual neurons in circuits, which determine attraction and aversion, sleep and arousal, odor preference etc. Flies harboring mutated human orthologs provide models, which can be interrogated to understand the effect of the mutant protein on cell fate and neuronal connectivity. These models are also useful for proof-of-concept studies to examine the corrective action of therapeutic strategies. Finally, experiments in Drosophila can be readily scaled up to an extent, which allows for drug screening with reasonably high throughput.

L-17 is a thiadiazine derivative with putative anti-inflammatory, neuroprotective, and antidepressant-like properties. In this study, we applied combined in silico and in vivo electrophysiology techniques to reveal the potential mechanism of action of L-17. PASS 10.4 Professional Extended software suggested that L-17 might have pro-cognitive, antidepressant, and antipsychotic effects. Docking energy assessment with AutoDockVina predicted that the binding affinities of L-17 to the serotonin transporter (SERT) and serotonin receptors 3 and 1A (5-HT3 and 5-HT1A) are compatible to the selective serotonin reuptake inhibitor (SSRI) fluoxetine and selective antagonists of 5-HT3 and 5-HT1A receptors, granisetron and WAY100135, respectively. However, while the binding mechanisms of L-17 to the SERT and 5-HT1A receptor were similar to fluoxetine and WAY100135, its interacting with 5-HT3 receptor might be substantially different from this of granisetron. Acute administration of L-17 led to dose-dependent inhibition of firing activity of 5-HT neurons of the dorsal raphe nucleus. This inhibition was partially reversed by subsequent administration of WAY100135. Based on both in silico and in vivo electrophysiology assessments, we suggest that L-17 is a potent 5-HT reuptake inhibitor and a putative partial agonist of 5-HT1A receptors. As such, L-17 in particular and thiadiazine derivatives, in general, might be a representative of a new class of antidepressant drugs. Since L-17 also possesses neuro- and cardioprotective properties, it can be useful in affective illness developing due to the general medical condition, such as post-stroke and post-myocardial infarction (MI) depression.

Although migraine belongs to the main causes of disability worldwide the mechanisms of its pathogenesis are poorly known, which is among the reasons that this disease is underdiagnosed and undertreated. As migraine diagnosis is based on the subjective assessment of symptoms, there is a need to establish objective markers of its occurrence and severity. Tryptophan (TRP) metabolism has been associated with the pathogenesis of neurological and psychiatric disorders. In the present work, we investigated an association between migraine and the urine concentration of TRP and its metabolites 5-hydroxyindoleacetic acid (5-HIAA), kynurenine (KYN), kynurenic acid (KYNA) and quinolinic acid (QA) in 21 low-frequency episodic migraine patients and 32 controls. Migraine patients displayed lower urinary levels of 5-HIAA and KYNA, but KYN and QA were enhanced as compared with the controls. Consequently, the patients were characterized by different values of the 5-HIAA/TRP, KYN/TRP, KYNA/KYN, and KYNA/QA ratios. Furthermore, urinary concentration of 5-HIAA was negatively correlated with Migraine Disability Assessment score, monthly migraine, and monthly headache days. A negative correlation between Patient Health Questionnaire 9 scores assessing depression. In conclusion, the urinary 5-HIAA level may be an easy-to-determine marker of migraine occurrence and severity and may contribute to the identification of migraine patients with depression.

Aims: Anxiety, major depressive disorder and accelerated cognitive decline frequently complicate traumatic brain injury. Obesity and type 2 diabetes mellitus drive peripheral inflammation which can accelerate traumatic brain injury-associated neurodegeneration. The Zucker rat harbors G-protein coupled receptor agonist IgG autoantibodies and in vitro neurotoxicity caused by these autoantibodies was prevented by a novel synthetic fragment of the serotonin 2A receptor. The aim of the present study was to test whether genetic obesity manifested in Zucker diabetic fatty rat is associated with anxiety, depression and spatial memory impairment induced by mild traumatic brain injury. Furthermore, we investigated whether these neurobehavioral or neurodegenerative complications can be lessened by administration of a novel putative neuroprotective peptide. Methods: Age-matched lean and fatty diabetic Zucker rats were tested in the sucrose preference test (anhedonia), open field test in bright light (anxiety measure) and the Morris water maze (spatial memory) prior to receiving a sham-injury or lateral fluid percussion (LFP) mild traumatic brain injury. Behavioral testing was repeated at 1-week, 1-month, and 3-month intervals following injury. A synthetic peptide consisting of a portion of the 5- hydroxytryptamine (serotonin) 2A receptor (2 mg/kg) (or vehicle) was administered via intraperitoneal route every other day for 7 days after sham or LFP injury to lean rats or 7 days before and after sham or LFP injury to fatty rats. Results: Sucrose preference decreased transiently (one week after mild traumatic brain injury) in Zucker lean rats indicative of anhedonia. Baseline anxiety-like behavior (bright light, open field test) was lower in fatty vs. lean Zucker rats, and anxiety behavior increased significantly in fatty rats but not lean rats following mild traumatic brain injury. Mild traumatic brain injury impaired recall of spatial memory in fatty and lean rats, and the effect was longer-lasting in fatty rats. A synthetic peptide fragment of the 5-hydroxytryptamine 2A receptor enhanced recall of spatial learning one-week after sham injury in Zucker rats and it may have prevented ‘anhedonia’ one-week after TBI (LFP) in a subset of Zucker fatty and lean rats expressing near-normal baseline sucrose preference. Mean plasma 5-hydroxytryptamine 2A receptor autoantibody level (determined 2 weeks after injury) was 2.5-fold higher than background, but did not differ significantly in (sham- vs TBI) Zucker lean rats. Conclusions: These are the first data to suggest reduced baseline anxiety-like behavior in Zucker fatty (vs. lean) rats. The pronounced increases in anxiety , and spatial memory impairment experienced by Zucker fatty (vs lean) rats following mild traumatic brain injury may have accounted in part for absence of a 5-hydroxytryptamine 2A receptor peptide neuroprotective effect in brain- injured Zucker fatty rats.

Personality disorders (PD) are described as enduring patterns of markedly deviant and pervasive inner experiences and behaviors, with onset in adolescence, which lead to severe distress or impairment. Patients suffering with major depressive disorder (MDD) display higher rates of comorbidity with personality disorders, often complicating the treatment, and worsening the outcome. Borderline personality disorder (BPD) is the most common of PD and is frequently associated with MDD, with which shares several features. The most part of research agrees on the fact that comorbid BPD in MDD patients quite double the poor response to treatments. Moreover, no treatment strategy stands out currently to emerge as more effective in these cases, thus urging the call for the need of a new approach. Herein, we revise the current literature on BPD, its neurobiology and comorbidity with MDD, as well as the more recent treatment strategies used. Then, based on its pharmacology, we propose a possible role of trazodone as a valuable tool to approach underlying BPD in MDD

The current systematic review examines whether there is an association between the genetic 5-HTTPLR pol-ymorphism and parenting and the mechanisms by which this association operates. The literature was searched in various databases such as PubMed, Scopus and ScienceDirect. In line with our inclusion criteria, nine articles were eligible out of 22. Most of the studies, analysed in this review, found an association between 5HTTLPR and parenting. Four studies found a direct association between 5-HTTLPR and parenting with conflicting findings: two studies found that mothers carrying the short variant were more sensitive to their infants, while two studies found that parents carrying the S allele were less sensitive. In addition, several studies found strong interaction between genetic and environmental factors, such as childhood stress and disruptive child behaviour, quality of early care experiences, poor parenting environment, and quality of environment. Only one study found an association between children’s 5HTTLPR and parenting. Parenting can be described as a highly complex construct influenced by multiple factors, including environmental, parenting and child charac-teristics. According to the studies, maternal 5-HTTLPR polymorphism is most likely associated with sensitive parenting.

Cannabidiol, is the first cannabis-derived drug approved for the treatment of Lennox-Gastaut syndrome (LGS), Dravet syndrome (DS), and Tuberous Sclerosis Complex (TSC). The current study performed a descriptive analysis followed by a disproportionality analysis of potential adverse events caused by CBD extracted from the database VigiBase®. Further, biological plausibility of the association between CBD and the serotonin 5-HT1A receptor, as possible cause of adverse events was analyzed and discussed. Data were extracted from VigiBase® database using VigiLyze® signal detection and signal management tool. Adverse events in VigiBase® reports were coded using MedDRA, version 19 of Preferred Terms (PTs). Data were uploaded into SPSS software and analyzed via disproportionality analysis. Statistically significant disproportionality signals for CBD were found for “weight decreased” 5.19 (95% CI: 4.54 - 5.70), “hypophagia” 3.68 (95% CI: 3.22 - 5.27), and “insomnia” 1.6 (95% CI: 1.40 - 1.83). Positive IC025 values were found for “weight decreased” (2.2), “hypophagia” (1.3), and “insomnia” (0.5), indicating a surplus of reported cases. CBD’s interactions with 5-HT1A serotonin receptors may offer a potential biological explanation for the occurrence of insomnia in patients. It is noteworthy that the risk profiles mentioned in the prescribing information for CBD as antiepileptic agent by regulatory agencies showed disparities specifically related to the adverse event “insomnia”.

Depression is estimated to be a leading contributor to the global mental health-related burden. The determinants of this huge prevalence lie in the fact that depressive symptoms may be comorbid in a wide variety of disorders, thus complicating and exacerbating their clinical pictures. This makes the treatment of depressive symptoms even more difficult since many pharmacological and pharmacokinetic interactions should be considered by physicians approaching the therapy. Hence, depression still represents a challenge for both psychiatrists and the other clinicians, in terms of its high rates of relapse and resistance despite well-established protocols. It is also complicated by the well-known latency in its complete response to current antidepressant treatments. In this context, the search for new strategies in antidepressant treatment is mandatory; even including revising the use of “old” pharmacotherapies by considering their specific features may help to perfecting the treatment of depression, both in its standalone psychiatric manifestation and in the framework of other clinical conditions. The results of a consensus of experts regarding the possible use of trazodone as a valuable strategy for addressing the “real world” unmet needs of depression treatment is herein reported. This is based on the unique characteristics of this drug possibly delivering a rapid antidepressant action as compared to other selective serotonin reuptake inhibitors (SSRIs) as well as on its pharmacodynamic malleability and pharmacokinetic tolerability when used in the milieu of other drugs in treating comorbid depressive symptoms.

Serotonin (5-HT) show important relations to stress, and this relationship is crucial to understanding the psychobiology of common mental disorders. Environmental stressors regulate phasic and tonic serotonin levels, which are related to valence and outcome probabilities. This regulation takes place at smaller timescales, but also at the level of gene expression regulation. Moreover, genes related to the synthesis, metabolism, and transport of 5-HT are also involved in this regulation. Genetic variations in these genes modulate how stressors can lead to mental distress, but stressors also modulate gene expression in a genotype-dependent manner. As a result, the relationship between psychosocial stress and the regulation of the expression of 5-HTergic genes is bidirectional. This suggests a “circular causality” in which gene variations control tonic and phasic 5-HT signals (“upward causality”), while configurations and functions of the entire organism determine which genes are up- or downregulated, or which gene products are actually relevant in each situation (“downward causality”). The highly important role of social factors in human psychopathology is highlighted, and factors such as attachment and socioeconomic status modulate how the circular vertical causality between genes, neurotransmitters, and behavior is organized, representing circular horizontal causality. These complex interrelationships also suggest that more refined epistemologies are needed to fully grasp the relationship between 5-HT and common mental disorders.

Brucellosis infection induces fever, chills, sweats, headache, myalgia, arthralgia, anorexia, fa-tigue, and mood disorders. In mice, it causes a rise in IL-6, TNF-, and IFN-; and reduces sero-tonin and dopamine levels in hippocampus. There is loss in muscle strength and equilibrium and increased anxiety and hopelessness. Imipramine (ImiP) is a tricyclic antidepressant that increases the capacity of macrophages to destroy intracellular microorganisms in vivo. The effect of ImiP was evaluated in Balb/c mice infected with Brucella abortus 2308. Serum levels were determined in IFN-, IL-6, TNF-, IL-12, MCP-1, and IL-10 by FACS; the bacterial count in the spleen, by CFU; the serotonin concentration in the hippocampus, by HPLC; and strength, equilibrium, and mood by behavioral tests. Our results showed that infected vs. control mice had a significant rise in lev-els of IFN-, IL-6, TNF-, and IL-12 with a low IFN-/IL-6 ratio, elevated bacterial-counts, alter-ations in serotonin concentration at hippocampus, and decreased muscular strength, equilibrium, and mood. Infected mice treated with ImiP vs. infected mice showed: 1) improved mood; 2) in-creased hippocampal serotonin availability, splenic dendritic cells, and macrophage phagocytic activity; and 3) upturn inflammation and reduced CFU ability. Our results support that ImiP fa-vors positive outcomes in subjects handling Brucella infections likely by improving psychoim-mune resilience.

Pathophysiology of depression is related with reduced volume of the hippocampus and amygdala and hypertrophy of the nucleus accumbens. The mechanism of these changes is not well under-stood, but clinical studies have shown that administration of the fast-acting antidepressant keta-mine reversed the decrease in hippocampus and amygdala volume in depressed patients, and the magnitude of this effect correlated with the reduction of depressive symptoms. In the present study, we attempted to find out whether the psychedelic substance psilocybin affects neurotransmission in the limbic system in comparison to ketamine. Psilocybin and ketamine increased the release of dopamine (DA) and serotonin (5-HT) in the nucleus accumbens of naive rats as demonstrated using microdialysis. Both drugs influenced glutamate and GABA release in the nucleus accumbens, hippocampus and amygdala and increased ACh levels in the hippocampus. The changes in D2, 5-HT1A and 5-HT2A receptor density in the nucleus accumbens and hippocampus was observed as a long-lasting effect. A marked anxiolytic effect of psilocybin in acute phase and 24 h post-treatment was shown in the open field test. These data provide the neurobiological background for psilocybin effect on stress, anxiety and structural changes in the limbic system and translate into antidepres-sant effect of psilocybin in depressed patients.

All living cells maintain a charge distribution across their cell membrane (membrane potential) by carefully controlled ion fluxes. These bioelectric signals regulate cell behavior (such as migration, proliferation, differentiation) as well as higher-level tissue and organ patterning. Thus, voltage gradients represent an important parameter for diagnostics as well as a promising target for therapeutic interventions in birth defects, injury, and cancer. However, despite much progress in cell and molecular biology, little is known about bioelectric states in human stem cells. Here, we present simple methods to simultaneously track ion dynamics, membrane voltage, cell morphology, and cell activity (pH and ROS), using fluorescent reporter dyes in living human neurons derived from induced neural stem cells (hiNSC). We developed and tested functional protocols for manipulating ion fluxes, membrane potential, and cell activity, and tracking neural responses to wounding and re-innervation in vitro. Finally, using morphology sensor, we tested and quantified the ability of physiological actuators (neurotransmitters and pH) to manipulate nerve wound re-innervation. These methods are not specific to a particular cell type and should be broadly applicable to the study of bioelectrical controls across a wide range of combinations of models and endpoints.

Suicidal behaviour is a public health problem whose magnitude is both substantial and increasing. Since many individuals seek medical treatment following a suicide attempt, strategies aimed at reducing further attempts in this population are a valid and feasible secondary prevention approach. An evaluation of the available evidence suggests that existing treatment approaches have limited efficacy in this setting, highlighting the need for innovative approaches to suicide prevention. Existing research on the neurobiology of social pain has highlighted the importance of this phenomenon as a risk factor for suicide, and has also yielded several attractive targets for pharmacological preventive strategies. In this paper, the available evidence related to these targets is synthesized and critically evaluated. The way in which social pain is related to the “anti-suicidal” properties of recently approved treatments, such as ketamine and psilocybin, is also examined. Such strategies may be effective for the short-term reduction of suicidal ideation and behaviour in individuals who have made a suicide attempt suicide prevention, particularly in cases where social pain is identified as a contributory factor. These pharmacological approaches may be effective regardless of the presence or absence of a specific psychiatric diagnosis.

Several studies suggests that ghrelin (GHRL) has neurobiological effects that extend beyond control of food intake. Our previous results confirmed that GHRL modulates the secretory activity of the pineal gland (PG) through nocturnal melatonin (MEL) secretion in sheep, the seasonally reproductive animals. Here we investigated the effects of GHRL (10 ng/ml) on the expression of enzymes limiting synthesis of MEL, including tryptophan 5-hydroxylase 1 (TPH1), serotonin N-acetyltransferase (AA-NAT) and its phosphorylated form p31T-AA-NAT in sheep PG explants (n = 72) during the 4-hour incubation in a gas-liquid interface, at a short (SD) and long (LD) photoperiods. After each hour of incubation selected explants were frozen in liquid nitrogen and stored at -80°C for subsequent analysis (real-time PCR, western-blotting, ELISA). Results show that GHRL regulates nightly MEL secretion in a TPH1-independent manner. The factor modulating GHRL activity was photoperiod. During SD photoperiod GHRL significantly reduced the expression of p31T-AA-NAT, AA-NAT and inhibited MEL secretion from PG explants. Whereas, during LD photoperiod no effect of GHRL on MEL secretion and expression of examined enzymes was noted. Studies indicate that GHRL directly affects PG under in vitro conditions and causes MEL secretion in animals which exhibit seasonality in reproductive and metabolic processes.

Introduction: Carcinoid heart disease is a rare cause of right-sided valvular dysfunction, an important complication in patients with carcinoid syndrome. Objectives: We aim to present our own experience regarding early myocardial dysfunction in patients with carcinoid syndrome. Methods: 64 patients (35-90 year old, 62,5% female, 37,5% male patients) with carcinoid syndrome were evaluated be-tween October 2017 and June 2021. All patients underwent two-dimensional echocardiography with additional tissue Doppler and speckle-tracking techniques. For all patients there were measured urinary level of 5- hydroxyindolacetic acid, serotonin and NT-proBNP values. Results: The following echocardiographic features: global longitudinal strain of both ventricles, mean systolic velocity of the left ventricle, systolic velocity of the free wall of right ventricle, correlated with high values of specific biomarkers: serotonin, and urinary 5-hydroxyindolacetic acid, and also with the presence of hepatic metastases and poorly differentiated tumors. Discussion: In this study we identified several patients with early myocardial dysfunction due to carcinoid syndrome, representing a predictive model of poor prognosis, requiring further investigations. Conclusion: Echocardiographic assessment based on the measurement of systolic velocities, as well as the global longitudinal strain of both ventricles, together with specific biomarkers may contribute to better recognition of carcinoid heart disease in clinical practice, but this needs validation through further studies enrolling larger number of patients.

Anxiety disorders are among the most common mental disorders worldwide, and often respond incompletely to existing treatments. Selenium, a micronutrient that is a component of several biologically active selenoproteins, is also involved in several aspects of brain functioning, and may exert antidepressant and anxiolytic effects through multiple pathways. The current paper is a scoping review of translational, observational and interventional evidence on the potential role of selenium and its compounds in the management of anxiety and related disorders. Evidence from animal models suggests that this approach may be promising. Though evidence from observational studies in humans is inconsistent and affected by several confounding factors, the available evidence from randomized controlled trials suggests that selenium supplementation may be beneficial in the management of certain anxiety-related conditions, such as anxiety in medically ill patients, prevention of anxiety following exposure to traumatic stress, and obsessive-compulsive disorder. This paper provides a critical evaluation of the existing evidence base, including unanswered questions that could serve as the focus of further research, and outlines the potential benefits and risks associated with the use of selenium in anxiety disorders.

Exposure to predator scent (PS) has been used as a model of stress associated with danger to life and body integrity. We tested the hypothesis that repeated PS exposure alters the excitability of serotonin (5-HT) neurons of the dorsal raphe nucleus. To study the mechanisms involved, we approached serum and adrenal corticosterone and aldosterone concentrations, as well as cortical brain-derived neurotrophic factor (BDNF) expression. Adult male Sprague-Dawley rats were exposed to PS for ten minutes daily for ten consecutive days. Two weeks after the last exposure, electrophysiological and biochemical assessments were performed. Measurements by in vivo electrophysiology showed increased spontaneous firing activity of 5-HT neurons in rats exposed to PS. PS exposure resulted in reduced serum corticosterone and aldosterone concentrations. Concentrations of both corticosteroids in the adrenal glands, as well as the relative weight of the adrenals, were unaffected. The gene expression of hippocampal BDNF of rats exposed to PS remained unaltered. In conclusion, repeated exposure of rats to PS leads to enhanced firing activity of 5-HT neurons accompanied by reduced serum, but not adrenal aldosterone and corticosterone concentrations. Reduced corticosteroid concentrations in the blood appear to be the result of increased metabolism and/or tissue uptake rather than altered steroidogenesis. The decrease in circulating corticosterone in rats experienced repeated PS may represent part of the mechanisms leading to increased excitability of 5-HT neurons. The increase in 5-HT neuronal firing activity might be an important compensatory mechanism designated to diminish the harmful effects of the repeated PS exposure on the brain.

Emerging autologous cellular therapies that utilize platelet-rich plasma (PRP) applications have the potential to play adjunctive roles in a variety of regenerative medicine treatment plans. There is a global unmet need for tissue repair strategies to treat musculoskeletal (MSK) and spinal disorders, osteoarthritis (OA), and patients with chronic complex and recalcitrant wounds. PRP therapy is based on the fact that platelet growth factors (PGFs) support the three phases of wound healing and repair cascade (inflammation, proliferation, remodeling). Many different PRP formulations have been evaluated, originating from human, in vitro, and animal studies. However, recommendations from in vitro and animal research often lead to different clinical outcomes because it is difficult to translate non-clinical study outcomes and methodology recommendations to human clinical treatment protocols. In recent years, progress has been made in understanding PRP technology and the concepts for bioformulation, and new research directives and new indications have been suggested. In this review, we will discuss recent developments regarding PRP preparation and composition regarding platelet dosing, leukocyte activities concerning innate and adaptive immunomodulation, serotonin (5-HT) effects and pain killing. Furthermore, we discuss PRP mechanisms related to inflammation and angiogenesis in tissue repair and regenerative processes. Lastly, we will review the effect of certain drugs on PRP activity, and the combination of PRP and rehabilitation protocols.

Memory and emotion, fundamental components of our mental existence, are highly vulnerable to psychiatric disorders like post-traumatic stress disorder (PTSD). This condition has been linked to serotonin (5-HT) metabolism disruptions. Over 95% of the 5-HT precursor tryptophan (Trp) is metabolized through the Trp-kynurenine (KYN) metabolic pathway, but little is known about its role in behavior. Kynurenine aminotransferases are responsible for the production of the Trp-KYN metabolite kynurenic acid. The gene aadat codes for mitochondrial kynurenine aminotransferase isotype 2. We generated CRISPR/Cas9-induced aadat knockout (kat2−/−) mice to examine the consequence of the gene deletion on negative valence in emotion, memory, and motor function in males 8 weeks of age and compared them to their wild-type counterparts. The forced swim test showed increased depression-like behaviors in transgenic mice. Anxiety and memory tests showed no significant differences. The transgenic mice had fewer center field and corner entries, shorter ambulation distances, and fewer jumping counts in the open field test. Overall, the transgenic mice exhibit depression-like behavior in a learned helplessness model, emotional indifference, and motor deficits. Here we present the first evidence that the deletion of the aadat gene triggers depression-like behaviors, uniquely associated with despair experience rather than adverse-conditioned memory. These findings have profound implications, opening avenues for further exploration into the main causes of experience-based depression linked to despair. This investigation has the potential to advance our understanding of these complex conditions and pave the way for improved therapeutic strategies by elucidating the relationship between Trp metabolism and the pathogenesis of PTSD.

Recent research has identified the gut-brain axis as a key mechanistic pathway and potential therapeutic target in depression. In this paper, the potential role of gut hormones as potential treatments or predictors of response in depression is examined, with specific reference to the peptide hormone motilin. This possibility is explored through two methods: (a) a conceptual review of the possible links between motilin and depression, including evidence from animal and human research as well as clinical trials, and (b) an analysis of the relationship between a functional polymorphism (rs2281820) of the motilin (MLN) gene and cross-national variations in the prevalence of depression. It was observed that (a) there are several plausible mechanisms, including interactions with diet, monoamine, and neuroendocrine pathways, to suggest that motilin may be relevant to the pathophysiology and treatment of depression, and (b) there was a significant correlation between rs2281820 allele frequencies and the prevalence of depression after correcting for multiple confounding factors. These results suggest that further evaluation of the utility of motilin and related gut peptides as markers of antidepressant response is required, and that these molecular pathways represent potential future mechanisms for antidepressant drug development.

Humans are evolutionary-driven to adult mating and conceive social expectations on the quality of their affiliations. The genetic susceptibility to adverse environments in critical periods can alter close relationships. The current research investigates how the promoter region of the Serotonin Transporter Gene (5-HTTLPR) and perceived caregiving behavior in childhood could influence the social expectations on close adult relationships. For this purpose, 5-HTTLPR data was collected from the buccal mucosa of 65 Italian individuals (33 males). The participants filled a) the Parental Bonding Instrument (PBI) to provide the levels of care and overprotection from mother and father, and b) the Experience in Close Relationships-Revised (ECR-R) to report the social expectations on the intimate relationship assessed in terms of anxiety and avoidance from the partner. An interaction effect between 5-HTTLPR and PBI dimensions on the ECR-R scores was hypothesized. Results confirmed that the interplay between the genetic groups and history of maternal overprotection predicted avoidance experienced in romantic relationships in adulthood. Moreover, both adult anxiety and avoidance felt in an intimate relationship were found to covary as a function of maternal overprotection. The present work proposes further evidence of the genetic and parental mechanisms regulating social expectations involved in close relationships.

Our knowledge on the plastic functions of the serotonin (5-HT) receptor subtype 7 (5-HT7R) in the brain physiology and pathology considerably advanced in the last few years. A wealth of data show that the 5-HT7R is a key player in the establishment and remodeling of neuronal cytoarchitecture during development and in the mature brain, and its dysfunction is linked to neuropsychiatric and neurodevelopmental diseases. The involvement of this receptor in synaptic plasticity is further demonstrated by data showing that its activation allows to rescue long term potentiation (LTP) and long term depression (LTD) deficits in various animal models of neurodevelopmental diseases. In addition, it is becoming clear that the 5-HT7R is involved in inflammatory intestinal diseases, possibly playing a role in the gut-brain axis, and modulates the function of immune cells. In this review, we will mainly focus on recent findings on this receptor’s role in the structural and synaptic plasticity of the mammalian brain, although we will also illustrate novel aspects highlighted in gut and immune system.

Environmental studies, metabolic research, and state of the art neurobiology point towards the reduced amount of natural day and sunlight exposure of the developing child’s organism as the consequence of increasingly long hours spent indoors online as the single unifying source of a whole set of health risks identified worldwide, as is made clear in this review of the current literature. Over exposure to digital environments, from abuse to addiction, now concerns even the youngest (ages 0 to 2), and triggers, as argued on the basis of clear examples herein, a chain of interdependent negative and potentially long-term metabolic changes. This leads to a deregulation of the serotonin and dopamine neurotransmitter pathways in the developing brain, currently associated with online activity abuse and/or internet addiction, and akin to that found in severe substance abuse syndromes. A general functional working model is proposed under the light of evidence brought to the forefront in this review.

Understanding brain function is one of the most important open problems in science today. At present, there is no concrete theory for how the brain works. Here, a theory is presented that provides a detailed mechanistic biological account of the brain’s capacities. Brain function is managed by a response (R) process that is structurally similar to the immune response, and shows anatomical and molecular specificity. Different R process stages utilize different cortical layers, hippocampus fields, basal ganglia paths, GABAergic interneurons, cerebellum paths, and molecular agents such as dopamine, serotonin and opioids. We show how the R process supports hierarchical action sequences, language and thought. The theory is supported by a large body of experimental evidence in many modalities, and accounts for virtually all of the major facts known about the brain at the system level.

The connective tissue mast cell (MC), a sentinel tissue-residing secretory immune cell, is preserved in all vertebrate classes since approximately 500 million years. No physiological role of the MCs has yet been established. Considering the power of natural selection of cells during evolution, it is likely that the MCs exert essential yet unidentified life-promoting actions. All vertebrates feature a circulatory system, and the MCs interact readily with the vasculature. It is notable that embryonic MC progenitors are generated from endothelial cells. The MC hosts many surface receptors enabling its activation by a vast variety of potentially harmful exogenous and endogenous molecules, and by reproductive hormones in the female sex organs. Activated MCs release a unique composition of pre-formed and newly synthesized bioactive molecules, like heparin, histamine, serotonin, proteolytic enzymes, cytokines, chemokines, and growth factors. MCs play important roles in immune responses, tissue remodeling, cell proliferation, angiogenesis, inflammation, wound healing, tissue homeostasis, health, and reproduction. As recently suggested, MCs enable perpetuation of the vertebrates because of key effects—spanning generations—in ovulation and pregnancy, as in life-preserving activities in inflammation and wound healing from birth till reproductive age, thus creating a permanent life-sustaining loop. Here, we present recent advances that further indicate that the MC is a specific life-supporting and progeny-safeguarding cell

Understanding brain function is one of the most important problems in human history. At present, there is no concrete theory for how the brain works. Here, a theory is presented that provides a detailed mechanistic biological account of the brain's capacities, including motor control, functional states, language, and thinking. Brain function is managed by a well-defined response (R) process that is generally similar to the process underlying the immune system. The R process is strongly reflected in the brain's anatomy, physiology, and external interactions. Different R process stages are supported by distinct excitatory networks located in different cortical layers, hippocampal fields, and bagal ganglia paths, by distinct coordination networks comprised of GABAergic interneurons, and by distinct molecular agents. The roles of norepinephrine, serotonin, dopamine and acetylcholine is to promote the alert, planning, goal-setting and execution R process modes, respectively. Opioids and oxytocin promote termination by success, failure, fight or run, while glucocorticoids and cannabinoids suppress acute responses to protect cells. The R process has two instances occurring at different time scales. The millisecond-scale Quax process implements the execution of hierarchical sequences of movements and thoughts, in which the selection of the next action is determined via interaction between top-down predictions and sensory inputs. The slower Need process controls the satisfaction of internal and external needs. The theory differs from the existing standard accounts in many of the major topics (e.g., the basal ganglia, dopamine, language), and shows how cognition results from biological processes.