ARTICLE | doi:10.20944/preprints202002.0448.v1
Subject: Biology, Physiology Keywords: Stress; Hypertension; Microglia; Neuroinflammation; Sympathetic overactivation
Online: 28 February 2020 (16:30:19 CET)
Background: Hypertension is a cardiovascular syndrome with the highest morbidity and mortality worldwide. Hypertension caused by various stress factors is called stress-induced hypertension (SIH). The rostral ventrolateral medulla (RVLM) "neuroinflammatory-sympathetic overactivation" is involved in SIH formation. Melatonin has anti-inflammatory, anti-oxidant and blood pressure lowering effects. The present study is to explore the antihypertensive effects and mechanism of central melatonin which based on microglia derived neuroinflammation. Methods: Stress-induced hypertension (SIH) was induced by electric foot-shock stressors with noise interventions in rats. Melatonin (0.01，0.1，1 mmol/L) was administered to RVLM and then blood pressure (BP) and serum norepinephrine (NE) were monitored to reflect sympathetic vasomotor activity in SIH rats. Excitatory neurotransmitter (Glutamate) and inhibitory neurotransmitter [γ-aminobutyric acid (GABA)] were measured using ELISA kits. Markers of microglia M1 polarization (CD86) and pro-inflammatory cytokines (PICs (IL-1β, TNF-α)) expression in the RVLM were measured by RT-qPCR. Results: (1) Stress-induced increase in blood pressure and serum NE concentration; RVLM microinjection melatonin attenuated the elevation of blood pressure and increase of plasma NE in SIH rats in a dose-dependent manner. (2) The expression of CD86, PICs (IL-1β, TNF-α) and c-fos were increased in SIH rats; RVLM injection melatonin attenuated RVLM neuroinflammation and its effect is concentration-dependent. (3). Stress-induced increase in glutamate concentration in RVLM; RVLM injection melatonin reduced glutamate level and increased GABA level in SIH rats in a concentration-dependent manner. Conclusion: RVLM injection of melatonin inhibits M1 polarization and has anti-hypertensive effects. Melatonin reduces M1 polarization in microglia might be a novel target and a new strategy for anti-stress induced-hypertension.
ARTICLE | doi:10.20944/preprints202109.0268.v1
Subject: Life Sciences, Endocrinology & Metabolomics Keywords: flavan-3-ols; adipose; browning; catecholamine; sympathetic nerve
Online: 15 September 2021 (15:16:21 CEST)
We previously found increases in uncoupling protein (Ucp)-1 transcription in brown adipose tissue (BAT) of mice following a single oral dose of flavan 3-ols (FL), a fraction of catechins and procyanidins. It was confirmed that these changes were totally reduced by co-treatment of adrenaline blockers. According to these previous results, FL possibly activates sympathetic nervous system (SNS). In this study, we confirmed the marked increase in urinary catecholamine (CA) s projecting SNS activity following a single dose of 50 mg/kg FL. In addition, we examined the impact of the repeated administration of 50 mg/kg FL for 14 days on adipose tissues in mice. In BAT, FL tended to increase the level of Ucp-1 along with thermogenic transcriptome factors, such as peroxisome proliferator-activated receptor γ coactivator (PGC)-1α and PR domain-containing (PRDM)1. Transcription of browning markers, such as CD137 and transmembrane protein (TMEM) 26 in addition to PGC-1α were increased in epididymal adipose (eWAT) by FL. A multilocular morphology with cell size reduction was shown in the inguinal adipose (iWAT), together with increasing the level of Ucp-1 following administration of FL. These results suggest that FL produces browning in adipose through activation of the SNS.
ARTICLE | doi:10.20944/preprints202301.0001.v1
Subject: Medicine & Pharmacology, Nursing & Health Studies Keywords: light therapy; dementia; heart rate variability; cognitive function; parasympathetic; sympathetic
Online: 3 January 2023 (02:27:06 CET)
Bright morning light (BML) entrains the body clock, modulates circadian rhythm, and improves sleep-wake disturbances. However, its impact on the autonomic nervous system (ANS) at night remains unclear. Hence, we investigated the effects of BML exposure on activities of the parasympathetic nervous system (PSNS) and sympathetic nervous system (SNS) at night. This non-randomized controlled pilot study included participants ≥60 years, diagnosed with a type of dementia or cognitive disorder. We excluded participants with pacemakers. The treatment group received 2500 lx BML, whereas the control group received approximately 200 lx of general lighting. We measured the heart rate variability to quantify ANS activity. The treatment group displayed significantly increased high-frequency (HF) power (Roy's largest root=2.44; P<.01) and insignificantly decreased normalized low-frequency (LF%) power. The corresponding low-frequency/high-frequency ratio (LF/HF), insignificant decrease, and cognitive function were correlated with PSNS activity (Roy's largest root=3.92; P<.01), which is effective for moderate dementia. BML exposure reduced SNS activity and enhanced PSNS activity at night, which consequently affected cognitive function. Furthermore, the light washout intervention markedly increased SNS activity at night. BML therapy may be a useful clinical tool for alleviating the deterioration of cognitive function.
ARTICLE | doi:10.20944/preprints202211.0464.v1
Subject: Life Sciences, Molecular Biology Keywords: NHE3; glomerular filtration rate; bicuculline; PVN of the hypothalamus; sympathetic nerve activity.
Online: 25 November 2022 (02:49:16 CET)
This study aimed to verify the effects of an acute increase in blood pressure (BP) and/or renal sympathetic nerve activity (rSNA) on the renal excretion of sodium and water and its potential effect on the regulation of NHE3 activity. Uninephectomized anesthetized male Wistar rats were divided into three experimental groups: 1) Sham, the rats had their BP and rSNA recorded, and urine was collected for 2 h; 2) bicuculline (Bic) paraventricular nucleus of the hypothalamus (PVN), rat BP, and rSNA were recorded, and urine was collected for 1 h at baseline conditions and 1 h after bicuculline injection into the PVN; 3) RNS + Bicuculine injection into the PVN, BP, and rSNA were recorded, and urine was collected 1h after RNS and 1 h after bicuculline injection into the PVN. Renal nerve stimulation (RNS) decreased sodium and water excretion independent of changes in BP. However, after Bic in the PVN during RNS stimulation, BP and rSNA increased up to 30% and 60%, respectively, increasing diuresis (5-fold) and natriuresis (2.3-fold), accompanied by a significant reduction in the NHE3 activity independent of GFR changes. In conclusion, an acute increase in BP overcomes such effects, generating diuresis, natriuresis, and NHE3 activity inhibition.
REVIEW | doi:10.20944/preprints202208.0278.v2
Subject: Medicine & Pharmacology, General Medical Research Keywords: stress response system; sympathetic activity; HPA(Hypothalamic-Pituitary-Adrenal) axis; SARS-CoV-2; catecholamine; corticosteroids; clonidine; dexamethasone
Online: 30 December 2022 (02:43:54 CET)
We are in amidst of COVID-19 pandemic. Since Dec 2019, severe acute respiratory corona virus (SAR-CoV-2) has infected more than half a billion people killing nearly 7 million people worldwide. Now the BA.5 variant of SARS-CoV-2 is causing mayhem and driving the global surge. Epidemiologist are aware of the fact that this virus is capable of escaping immunity and likely to infect the same person multiple times despite adequate vaccination status. Elderly people of age more than 60 years and those with underlying health conditions are considered as high-risk who are likely to suffer complications and death. While it is tempting to frame complications and mortality from COVID-19 as a simple matter of too much of a virulent virus in too weak of a host, much more is at play here. Framing the pathophysiology of COVID-19 in the context of the Chrousos and Gold model of the central stress response system can shed insight into its complex pathogenesis. Understanding the mechanisms by which pharmacologic modulation of the central stress response system via administration of clonidine and/or dexamethasone may offer an explanation as to why a viral pathogen can be well tolerated and cleared by one host while inflaming and killing another.
ARTICLE | doi:10.20944/preprints202102.0031.v1
Subject: Life Sciences, Biochemistry Keywords: primary cilium; ciliogenesis; neural circuits formation; neural crest cells; DRG; boundary cap cells; sympathetic ganglia; PNS
Online: 1 February 2021 (13:26:06 CET)
The primary cilium plays a pivotal role during embryonic development of vertebrates. It acts as a somatic signaling hub for specific pathways, such as sonic hedgehog signaling. In humans, mutations in genes that cause dysregulation of ciliogenesis or ciliary function lead to severe developmental disorders called ciliopathies. Beyond its obvious role in early morphogenesis, growing evidence points towards an essential function of the primary cilium in neural circuit formation in the central nervous system. However, very little is known about a potential role in the formation of the peripheral nervous system. Here, we investigated the presence of the primary cilium in neural crest cells and their derivatives in the trunk of the developing chicken embryo in vivo. We found that neural crest cells, sensory neurons, and boundary cap cells all bear a primary cilium during key stages of early peripheral nervous system formation. Moreover, we described differences in the ciliation of neuronal cultures of different populations from the peripheral and central nervous system. Our results offer a framework for further in vivo and in vitro investigations on specific roles that the primary cilium might play during peripheral nervous system formation.
ARTICLE | doi:10.20944/preprints202211.0171.v1
Subject: Medicine & Pharmacology, Behavioral Neuroscience Keywords: brain clearance; Qdots; nasal turbinates; subarachnoid space; cervical lymphatics; sympathetic ganglia; cervical spinal cord; thoracic spinal cord
Online: 9 November 2022 (08:57:11 CET)
Unwanted proteins and metabolic waste in cerebral spinal fluid are cleared from the brain by meningeal and nasal lymphatics, and perineural sheath of cranial nerves; however, the distribution and clearance of CSF along the subarachnoid space of the entire spinal cord is not fully understood. It was hypothesized that the anatomical resolution of Cryo-Fluorescence Tomography (CFT) could provide the visual evidence of clearance across the spinal cord at each level of the vertebral column. To that end, isoflurane anesthetized mice were infused into the lateral cerebroventricle with 5.0 µl of quantum dots [QdotR 605 ITKTM amino (PEG)] over two mins. Mice were allowed to recover (ca 2-3 min) and remained awake and ambulatory for 5, 15, 30, 60 and 120 minutes after which they were euthanized, and the entire intact body frozen at -800. The entire mouse was sectioned and imaged to produce an isotropic voxel resolution of 35 µm. Both white light and fluorescent images were captured after each slice to produce high resolution three-dimensional volumes for each mouse. CFT highlighted the circulation of tracer throughout the ventricular system and central canal of the spinal cord and the entire subarachnoid space of the CNS. Signal could be visualized in the nasal cavity, deep cervical lymph nodes, thoracic lymph nodes and more superficial submandibular lymph nodes as early as 15 min post infusion. Fluorescent signal could be visualized along the dorsal root ganglia and down the proximal extension of the spinal nerves of the thoracic and lumbar segments at 30 min. There was significant accumulation of tracer in the lumbar and sacral lymph nodes between 15- 60 min. The dense fluorescent signal in the thoracic vertebrae noted at 5- and 15-mins post infusion was significantly reduced by 30 min. Indeed, all signal in the spinal cord was ostensibly absent by 120 min except for trace amounts in the coccyx. The brain still had some residual signal at 120 min. These data show that Qdots with a hydrodynamic diameter of 16-20 nm rapidly clear from the brain of awake mice. These data also clearly demonstrate the rapid distribution and efflux of trace along a major length of the vertebral column and the potential contribution of the spinal cord in the clearance of brain waste.
REVIEW | doi:10.20944/preprints202212.0030.v1
Subject: Medicine & Pharmacology, General Medical Research Keywords: Blood Pressure; Cardiovascular Disorder; Hypertension; Hypotension; Hypoxia; Baroreflex; Hemorrhagic Shock; Hypovolemic Shock; Vasopressure; Resuscitation; Centhaquine (Lyfaquin); Sympathetic System; Parasympathetic System; Adrenoreceptors
Online: 2 December 2022 (02:00:06 CET)
The pressure exerted on the heart and blood vessels because of blood flow is considered as an important parameter for the cardiovascular function. It determines sufficient blood perfusion as well as transportation of nutrition, oxygen and other essential factors to every organ. Pressure in the primary arteries located near the heart and the brain, known as central blood pressure (CBP), while in peripheral arteries, known as peripheral blood pressure (PBP). Normally, CBP and PBP are correlated; however, cardiovascular disorders interfere their regulation and affect the blood flow in vital organs and accessory organs, differently. Therefore, understanding each of them in normal and disease conditions is essential for managing various cardiovascular disorders and increasing their treatment outcomes. In this review, we have described the control systems (neural, hormonal, osmotic and cellular) of the blood pressure and its regulation in hypovolemic shock using centhaquine (Lyfaquin®) as a resuscitative agent.
ARTICLE | doi:10.20944/preprints202211.0491.v1
Subject: Life Sciences, Immunology Keywords: COVID-19; SARS-CoV-2; exercise; autonomic nervous system; sympathetic nervous system; parasympathetic nervous system; COVID-19 vaccination; post-acute sequelae of COVID-19; communicable diseases
Online: 28 November 2022 (03:39:10 CET)
Coronavirus disease 2019 (COVID-19) has detrimental multi-system consequences. Symptoms may appear during the acute phase of infection, but literature on long-term recovery of young adults after mild-to-moderate infection is lacking. Heart rate variability (HRV) allows observation of autonomic nervous system (ANS) modulation post SARS-CoV-2 infection. Additionally, physical activity (PA) helps improve ANS modulation, where investigation of PA influence on ANS recovery is vital to reduce risk and severity of symptoms. Clinicians may use this research to aid development of non-medication interventions. At baseline, 18 control (CT) and 20 post-COVID-19 (PCOV) participants were observed where general amnamnesis was performed, followed by HRV and PA assessment. 10 CT and 7 PCOV subjects returned for follow-up (FU) evaluation 6 weeks after complete immunization (2 doses) and assessments were repeated. Over the follow-up period, decrease in sympathetic (SNS) activity (mean heart rate: p=0.0024, CI=-24.67- -3.26; SNS index: p=0.0068, CI=-2.50- -0.32) and increase in parasympathetic (PNS) activity (mean RR:p=0.0097, CI=33.72-225.51; PNS index: p=0.0091, CI=-0.20-1.47) were observed. At follow-up, HRV was not different between groups (p>0.05). Additionally, no differences were observed in PA between moments and groups. This study provides evidence of ANS recovery after SARS-CoV-2 insult in young adults over a follow-up period, independent of changes in PA.
REVIEW | doi:10.20944/preprints202009.0593.v1
Subject: Keywords: gut inflammation; neuroinflammation; inflammatory bowel disease; Crohn’s disease; ulcerative colitis; irritable bowel syndrome; Celiac disease; functional dyspepsia; anterior cingulate cortex; microglia; sympathetic nervous system; mood disorders; depression; anxiety; cognition
Online: 25 September 2020 (03:45:08 CEST)
The brain reciprocally communicates with the rest of the body via neural, endocrine, immune, and other systems. This is crucial for coordinating the complex behavioral and physiological responses needed to cope with the many challenges of life. The Anterior Cingulate Cortex (ACC) is a key brain structure involved in assessing rewards and threats, as well as activating appropriate responses. This is a dynamic process that depends on evolving needs and challenges. Important challenges include illness or injury. These typically involve inflammation and pain, which evoke neuroinflammatory processes in the brain to drive sickness behaviours. In the short term, sickness behaviours are considered adaptive, as they promote convalescence (e.g. low mood; lethargy, fatigue, social withdrawal), and enhanced threat appraisal (e.g. anxiety) to combat increased risk/vulnerability associated with sickness. Chronic inflammation, however, appears to remodel the system to inappropriately activate threat-coping responses, resulting in depressive and/or anxious phenotypes. These mood disorders are particularly pronounced in diseases and disorders associated with gut dysfunction, which feature chronic inflammation and altered ACC function. We propose that chronic inflammation remodels ACC physiology such that it errantly predicts heightened danger based on a mental model (a.k.a ‘schema’) of the world. This evokes chronic activation of threat-coping systems, including endocrine signaling (e.g. adrenaline), and anxiety. Inflammation can be driven by brain systems involving ACC, leading to a feedback-cycle that self-reinforces pathological states. This theory accounts for a wealth of clinical and preclinical data that implicate the ACC in disorders of mood and gastrointestinal function, and reveals a key player in the gut-brain axis that may represent a novel therapeutic target.