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.
REVIEW | doi:10.20944/preprints202208.0278.v1
Subject: Medicine & Pharmacology, Other Keywords: central stress response system; sympathetic activity; HPA axis; SAR-CoV-2; catecholamine; corti-costeriods; clonidine; dexamethasone
Online: 16 August 2022 (05:07:18 CEST)
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.
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.