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"Nervous System - drug effects"
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ACE2-mediated reduction of oxidative stress in the central nervous system is associated with improvement of autonomic function
Oxidative stress in the central nervous system mediates the increase in sympathetic tone that precedes the development of hypertension. We hypothesized that by transforming Angiotensin-II (AngII) into Ang-(1-7), ACE2 might reduce AngII-mediated oxidative stress in the brain and prevent autonomic dysfunction. To test this hypothesis, a relationship between ACE2 and oxidative stress was first confirmed in a mouse neuroblastoma cell line (Neuro2A cells) treated with AngII and infected with Ad-hACE2. ACE2 overexpression resulted in a reduction of reactive oxygen species (ROS) formation. In vivo, ACE2 knockout (ACE2(-/y)) mice and non-transgenic (NT) littermates were infused with AngII (10 days) and infected with Ad-hACE2 in the paraventricular nucleus (PVN). Baseline blood pressure (BP), AngII and brain ROS levels were not different between young mice (12 weeks). However, cardiac sympathetic tone, brain NADPH oxidase and SOD activities were significantly increased in ACE2(-/y). Post infusion, plasma and brain AngII levels were also significantly higher in ACE2(-/y), although BP was similarly increased in both genotypes. ROS formation in the PVN and RVLM was significantly higher in ACE2(-/y) mice following AngII infusion. Similar phenotypes, i.e. increased oxidative stress, exacerbated dysautonomia and hypertension, were also observed on baseline in mature ACE2(-/y) mice (48 weeks). ACE2 gene therapy to the PVN reduced AngII-mediated increase in NADPH oxidase activity and normalized cardiac dysautonomia in ACE2(-/y) mice. Altogether, these data indicate that ACE2 gene deletion promotes age-dependent oxidative stress, autonomic dysfunction and hypertension, while PVN-targeted ACE2 gene therapy decreases ROS formation via NADPH oxidase inhibition and improves autonomic function. Accordingly, ACE2 could represent a new target for the treatment of hypertension-associated dysautonomia and oxidative stress.
Journal Article
Metabolic and sympathovagal effects of bolus insulin glulisine versus basal insulin glargine therapy in people with type 2 diabetes: A randomized controlled study
Aims/Introduction
This study compares the effects of two different insulin regimens – basal versus bolus insulin – on metabolic and cardiovascular autonomic function in Japanese participants with type 2 diabetes.
Materials and Methods
Participants were randomly assigned to groups for therapy with insulin glulisine (IGlu) or insulin glargine (IGla). The primary efficacy end‐point was glycemic variability, including M‐values, mean of glucose levels, and a blood glucose profile of seven time points before and after the intervention. The secondary end‐points included pleiotropic effects, including endothelial and cardiac autonomic nerve functions.
Results
Blood glucose levels at all time points significantly decreased in both groups. Post‐lunch, post‐dinner, and bedtime blood glucose levels were significantly lower in the IGlu group than in the IGla group. Nadir fasting blood glucose levels at the end‐point were significantly lower in the IGla group than in the IGlu group. The M‐value and mean blood glucose levels were significantly decreased from baseline in both groups, although the former was significantly lower in the IGlu group than in the IGla group. IGla, but not IGlu, was found to elevate 24‐h parasympathetic tone, especially during night‐time, and it decreased 24‐h sympathetic nerve activity, especially at dawn.
Conclusions
Both IGlu and IGla regimens reduced glucose variability, with IGlu bringing a greater reduction in M‐value. IGla, but not IGlu, increased parasympathetic tone during night‐time and decreased sympathetic nerve activity at dawn. These findings shed light on the previously unrecognized role of night‐time basal insulin supplementation on sympathovagal activity in type 2 diabetes patients.
Both insulin glulisine and insulin glargine regimens decrease glucose variability, with a greater decrease in M‐value by insulin glulisine in people with poorly controlled type 2 diabetes. Insulin glargine, but not insulin glulisine, elevated parasympathetic tone at night‐time, and reduced sympathetic nerve activity at dawn.
Journal Article
Cannabinoids mediate analgesia largely via peripheral type 1 cannabinoid receptors in nociceptors
Although endocannabinoids constitute one of the first lines of defense against pain, the anatomical locus and the precise receptor mechanisms underlying cannabinergic modulation of pain are uncertain. Clinical exploitation of the system is severely hindered by the cognitive deficits, memory impairment, motor disturbances and psychotropic effects resulting from the central actions of cannabinoids. We deleted the type 1 cannabinoid receptor (CB1) specifically in nociceptive neurons localized in the peripheral nervous system of mice, preserving its expression in the CNS, and analyzed these genetically modified mice in preclinical models of inflammatory and neuropathic pain. The nociceptor-specific loss of CB1 substantially reduced the analgesia produced by local and systemic, but not intrathecal, delivery of cannabinoids. We conclude that the contribution of CB1-type receptors expressed on the peripheral terminals of nociceptors to cannabinoid-induced analgesia is paramount, which should enable the development of peripherally acting CB1 analgesic agonists without any central side effects.
Journal Article
Neuroimmunology of Huntington’s Disease: Revisiting Evidence from Human Studies
Huntington’s disease (HD) is a neurodegenerative disorder characterized by selective loss of neurons in the striatum and cortex, which leads to progressive motor dysfunction, cognitive decline, and psychiatric disorders. Although the cause of HD is well described—HD is a genetic disorder caused by a trinucleotide (CAG) repeat expansion in the gene encoding for huntingtin (HTT) on chromosome 4p16.3—the ultimate cause of neuronal death is still uncertain. Apart from impairment in systems for handling abnormal proteins, other metabolic pathways and mechanisms might contribute to neurodegeneration and progression of HD. Among these, inflammation seems to play a role in HD pathogenesis. The current review summarizes the available evidence about immune and/or inflammatory changes in HD. HD is associated with increased inflammatory mediators in both the central nervous system and periphery. Accordingly, there have been some attempts to slow HD progression targeting the immune system.
Journal Article
Physiological Importance of Hydrogen Sulfide: Emerging Potent Neuroprotector and Neuromodulator
Hydrogen sulfide (H2S) is an emerging neuromodulator that is considered to be a gasotransmitter similar to nitrogen oxide (NO) and carbon monoxide (CO). H2S exerts universal cytoprotective effects and acts as a defense mechanism in organisms ranging from bacteria to mammals. It is produced by the enzymes cystathionine β-synthase (CBS), cystathionine ϒ-lyase (CSE), 3-mercaptopyruvate sulfurtransferase (MST), and D-amino acid oxidase (DAO), which are also involved in tissue-specific biochemical pathways for H2S production in the human body. H2S exerts a wide range of pathological and physiological functions in the human body, from endocrine system and cellular longevity to hepatic protection and kidney function. Previous studies have shown that H2S plays important roles in peripheral nerve regeneration and degeneration and has significant value during Schwann cell dedifferentiation and proliferation but it is also associated with axonal degradation and the remyelination of Schwann cells. To date, physiological and toxic levels of H2S in the human body remain unclear and most of the mechanisms of action underlying the effects of H2S have yet to be fully elucidated. The primary purpose of this review was to provide an overview of the role of H2S in the human body and to describe its beneficial effects.
Journal Article
Compared to non-drinkers, individuals who drink alcohol have a more favorable multisystem physiologic risk score as measured by allostatic load
Alcohol use is associated with both positive and negative effects on individual cardiovascular risk factors, depending upon which risk factor is assessed. The present analysis uses a summative multisystem index of biologic risk, known as allostatic load (AL), to evaluate whether the overall balance of alcohol-associated positive and negative cardiovascular risk factors may be favorable or unfavorable.
This analysis included 1255 adults from the Midlife in the United States (MIDUS) biomarker substudy. Participants, average age 54.5 (±11) years, were divided into 6 alcohol-use categories based on self-reported drinking habits. Current non-drinkers were classified as lifelong abstainers and former light drinkers, former moderate drinkers, or former heavy drinkers. Current alcohol users were classified as light, moderate, or heavy drinkers. A total AL score was calculated using 24 biomarkers grouped into 7 physiologic systems including cardiovascular, inflammation, glucose metabolism, lipid metabolism, sympathetic and parasympathetic nervous systems, and the hypothalamic-pituitary-adrenal axis. Mixed-effects regression models were fit to determine the relationship between alcohol use categories and AL with controls for covariates that may influence the relationship between alcohol use and AL.
468 (37.6%) individuals were current non-drinkers while 776 (62.4%) were current drinkers. In adjusted mixed-effects regression models, all 3 groups of current drinkers had significantly lower average AL scores than the lifelong abstainer/former light drinker group (light: -0.23, 95% CI -0.40, -0.07, p < 0.01; moderate: -0.20, 95% CI -0.38, -0.02, p < 0.05; heavy: -0.30, 95% CI -0.57, -0.04, p < 0.05), while the average AL scores of former moderate and former heavy drinkers did not differ from the lifelong abstainer/former light drinker group.
Current alcohol use is associated cross-sectionally with a favorable multisystem physiologic score known to be associated with better long-term health outcomes, providing evidence in support of long-term health benefits related to alcohol consumption.
Journal Article
Distinct functional and temporal requirements for zebrafish Hdac1 during neural crest-derived craniofacial and peripheral neuron development
The regulation of gene expression is accomplished by both genetic and epigenetic means and is required for the precise control of the development of the neural crest. In hdac1(b382) mutants, craniofacial cartilage development is defective in two distinct ways. First, fewer hoxb3a, dlx2 and dlx3-expressing posterior branchial arch precursors are specified and many of those that are consequently undergo apoptosis. Second, in contrast, normal numbers of progenitors are present in the anterior mandibular and hyoid arches, but chondrocyte precursors fail to terminally differentiate. In the peripheral nervous system, there is a disruption of enteric, DRG and sympathetic neuron differentiation in hdac1(b382) mutants compared to wildtype embryos. Specifically, enteric and DRG-precursors differentiate into neurons in the anterior gut and trunk respectively, while enteric and DRG neurons are rarely present in the posterior gut and tail. Sympathetic neuron precursors are specified in hdac1(b382) mutants and they undergo generic neuronal differentiation but fail to undergo noradrenergic differentiation. Using the HDAC inhibitor TSA, we isolated enzyme activity and temporal requirements for HDAC function that reproduce hdac1(b382) defects in craniofacial and sympathetic neuron development. Our study reveals distinct functional and temporal requirements for zebrafish hdac1 during neural crest-derived craniofacial and peripheral neuron development.
Journal Article