Parasympathetic Signaling Research Articles

Melatonin inhibits voltage-gated potassium KV4.2 channels and negatively regulates melatonin secretion in rat pineal glands.

Melatonin is synthesized in and secreted from the pineal glands and regulates circadian rhythms. Although melatonin has been reported to modulate the activity of ion channels in several tissues, its effects on pineal ion channels remain unclear. In the present study, the effects of melatonin on voltage-gated K+ (KV) channels, which play a role in regulating the resting membrane potential, were examined in rat pinealocytes. The application of melatonin reduced pineal KV currents in a concentration-dependent manner (IC50 = 309 µM). An expression analysis revealed that KV4.2 channels were highly expressed in rat pineal glands. Melatonin-sensitive currents were abolished by the small interfering RNA knockdown of KV4.2 channels in rat pinealocytes. In human embryonic kidney 293 (HEK293) cells expressing KV4.2 channels, melatonin decreased outward currents (IC50 = 479 µM). Inhibitory effects were mediated by a shift in the voltage dependence of steady-state inactivation in a hyperpolarizing direction. This inhibition was observed even in the presence of 100 nM luzindole, an antagonist of melatonin receptors. Melatonin also blocked the activity of KV4.3, KV1.1, and KV1.5 channels in reconstituted HEK293 cells. The application of 1 mM melatonin caused membrane depolarization in rat pinealocytes. Furthermore, KV4.2 channel inhibition by 5 mM 4-aminopyridine attenuated melatonin secretion induced by 1 µM noradrenaline in rat pineal glands. These results strongly suggest that melatonin directly inhibited KV4.2 channels and caused membrane depolarization in pinealocytes, resulting in a decrease in melatonin secretion through parasympathetic signaling pathway. This mechanism may function as a negative-feedback mechanism of melatonin secretion in pineal glands. NEW & NOTEWORTHY Melatonin is a hormone that is synthesized in and secreted from the pineal glands, which regulates circadian rhythms. However, the effects of melatonin on pineal ion channels remain unclear. The present study demonstrated that melatonin directly inhibited voltage-gated potassium KV4.2 channels, which are highly expressed in rat pinealocytes, and induced membrane depolarization, resulting in a decrease in melatonin secretion. This mechanism may function as a negative-feedback mechanism of melatonin secretion in pineal glands.

Rita Levi-Montalcini: From Persecution to the Nobel Prize and an Honorary Degree From a Canadian University.

Rita Levi-Montalcini (RLM) is recognized as a prestigious and renowned researcher of her time. She was the fourth woman to earn the Nobel Prize in Physiology and Medicine in 1986 for the discovery of nerve growth factor (NGF). We review her biography and scientific discovery, and provide an example of why her discovery is still important. She had a special relationship with McGill University, Canada, which we describe. We searched for articles and books about her for biographical and scientific material and met with Dr. Claudio Cuello, Former Chair of McGill's Faculty of Medicine. RLM was born in 1909 in Turin, Italy, where she had studied medicine. She started her career in research. Because of the anti-Jewish racial laws in Italy in 1938, she went underground and continued her projects in her bedroom. After the war, she visited St. Louis, USA, and conducted research there. Her experiments confirmed that tumors release a factor that causes nerve growth and cancer proliferation. Initially, scientists responded to this discovery with skepticism, but after its purification in 1959 and determination of its protein structure in 1971, NGF became widely accepted.Currently, crosstalk between cancers and nerves is poorly understood. The example of prostate cancer shows that surgical or chemical denervation of sympathetic nerves prevents the initiation of prostate tumors, whereas inhibition of parasympathetic nerve signaling reduces the spread of prostate cancer. McGill University awarded RLMa doctoral degree in 2011. It was the first time in itshistory that the University awarded an honorary doctorate outside of Canada, and the second one outside of Quebec.Through her discovery of NGF, RLM exemplified the power of passion and determination despite the obstacles she faced. Her relentless dedication has led to remarkable achievements.

Cholinergic Neurotransmission Controls Orexigenic Endocannabinoid Signaling in the Gut in Diet-Induced Obesity.

The brain bidirectionally communicates with the gut to control food intake and energy balance, which becomes dysregulated in obesity. For example, endocannabinoid (eCB) signaling in the small-intestinal (SI) epithelium is upregulated in diet-induced obese (DIO) mice and promotes overeating by a mechanism that includes inhibiting gut-brain satiation signaling. Upstream neural and molecular mechanism(s) involved in overproduction of orexigenic gut eCBs in DIO, however, are unknown. We tested the hypothesis that overactive parasympathetic signaling at the muscarinic acetylcholine receptors (mAChRs) in the SI increases biosynthesis of the eCB, 2-arachidonoyl-sn-glycerol (2-AG), which drives hyperphagia via local CB1Rs in DIO. Male mice were maintained on a high-fat/high-sucrose Western-style diet for 60 d, then administered several mAChR antagonists 30 min prior to tissue harvest or a food intake test. Levels of 2-AG and the activity of its metabolic enzymes in the SI were quantitated. DIO mice, when compared to those fed a low-fat/no-sucrose diet, displayed increased expression of cFos protein in the dorsal motor nucleus of the vagus, which suggests an increased activity of efferent cholinergic neurotransmission. These mice exhibited elevated levels of 2-AG biosynthesis in the SI, that was reduced to control levels by mAChR antagonists. Moreover, the peripherally restricted mAChR antagonist, methylhomatropine bromide, and the peripherally restricted CB1R antagonist, AM6545, reduced food intake in DIO mice for up to 24 h but had no effect in mice conditionally deficient in SI CB1Rs. These results suggest that hyperactivity at mAChRs in the periphery increases formation of 2-AG in the SI and activates local CB1Rs, which drives hyperphagia in DIO.

Activation of ChAT+ neuron in dorsal motor vagus (DMV) increases blood glucose through the regulation of hepatic gene expression in mice

The brain and peripheral organs communicate through hormones and neural connections. Proper communication is required to maintain normal whole-body energy homeostasis. In addition to endocrine system, from the perspective of neural connections for metabolic homeostasis, the role of the sympathetic nervous system has been extensively studied, but understanding of the parasympathetic nervous system is limited. The liver plays a central role in glucose and lipid metabolism. This study aimed to clarify the innervation of parasympathetic nervous system in the liver and its functional roles in metabolic homeostasis. The liver-specific parasympathetic nervous system innervation (PNS) was shown by tissue clearing, immunofluorescence and transgenic mice at the three-dimensional histological level. The parasympathetic efferent signals were manipulated using a chemogenetic technique and the activation of ChAT+ parasympathetic neurons in dorsal motor vagus (DMV) results in the increased blood glucose through the elevated hepatic gluconeogenic and lipogenic gene expression in the liver. Thus, our study showed the evidence of ChAT+ parasympathetic neurons in the liver and its role for hepatic parasympathetic nervous signaling in glucose homeostasis through the regulation of hepatic gene expression.

Abstract 13924: Combined Gene Therapy Approach Targets Parasympathetic Signaling and Oxidative Stress to Reverse Pre-Existing Persistent Atrial Fibrillation in a Canine Model

Introduction: Atrial fibrillation (AF) is a multifactorial disease, with oxidative stress (NADPH oxidase 2, NOX2) and autonomic remodeling (hyperinnervation and parasympathetic signaling) playing an important role. Disrupting both mechanisms simultaneously with gene-based therapy may allow for reversal of established remodeling in AF. Hypothesis: Gene therapy aimed at attenuation of parasympathetic signaling (Gαi/o inhibitory peptides, GiGo_ct) and prevention of nerve sprouting (nerve growth factor short hairpin RNA, NGF shRNA) combined with reduction of oxidative stress (NOX2 shRNA) can reverse AF in a large animal chronic AF model. Methods: Chronic AF model was created by rapid atrial pacing (RAP) at 600bpm in 5 dogs, followed by gene therapy treatment (Panel A). A combination of NOX2 shRNA and GiGo_ct plasmids with (n=2) or without (n=3) NGF shRNA was injected in both atria followed by electroporation to facilitate gene delivery. Control RAP dogs did not receive gene (n=5) or underwent scrambled gene injection (n=6). AF burden was assessed over time and residual AF was recorded at terminal EP study. NOX2 and NGF knockdown and GiGo_ct expression were evaluated by PCR. Results: After 3.3±1.3 weeks of RAP, all 11 animals reached >80% AF burden. Combined (NOX2+GiGo±NGF) gene therapy significantly reduced AF burden by 66% (p<0.05) compared to scramble controls and by 38% (p<0.05) compared to pre-treatment AF burden (Panel B). Residual AF after the treatment was slower and more organized than in controls (panel C). PCR analysis showed NOX2 and NGF downregulation and evidence of GiGo_ct expression. Conclusions: Gene-based attenuation of autonomic remodeling through inhibition of parasympathetic signaling and nerve sprouting, and reduction of oxidative stress by NOX2 downregulation may be effective at reversing AF. Development of optimized gene therapy to target multiple AF mechanisms simultaneously may lead to more effective treatments for persistent AF.

Induction of tetraspanin 13 contributes to the synergistic anti-inflammatory effects of parasympathetic and sympathetic stimulation in macrophages

The autonomic nervous system plays an important role in the regulation of peripheral inflammation. Sympathetic nervous activation stimulates inflammatory gene expression and cytokines, whereas parasympathetic nervous activation suppresses the production of inflammatory cytokines by immune cells. However, most studies on the relationship between the autonomic nervous system and immune processes have analyzed a single branch of the autonomic nerves in isolation. Therefore, this study aimed to examine the effects of sympathetic and parasympathetic stimulation on macrophages, which are controlled by autonomic regulation.Macrophages were stimulated with lipopolysaccharide (LPS) to induce TNF-α. Then, the effects of β2 adrenergic receptor and α7 nicotinic acetylcholine receptor activation on TNF-α production were assessed using concentration-dependent assays. RNA-seq data were also used to identify genes whose expression was enhanced by parasympathetic and sympathetic stimulation.The simultaneous activation of β2 adrenergic receptors and α7 nicotinic acetylcholine receptors suppressed LPS-induced TNF-α production in a concentration-dependent manner. Moreover, simultaneous activation of these receptors had synergistic anti-inflammatory effects and induced Tspan13 expression, thereby contributing to anti-inflammatory mechanisms in macrophages.Our study revealed the synergistic anti-inflammatory effects of the parasympathetic and sympathetic stimulation of macrophages. Our results suggest that targeting both sympathetic and parasympathetic signaling is a promising therapeutic approach for inflammatory diseases.

BS-452758-4 COMBINED GENE THERAPY APPROACH TARGETS PARASYMPATHETIC SIGNALING AND OXIDATIVE STRESS TO ATTENUATE PERSISTENT ATRIAL FIBRILLATION DEVELOPMENT IN A CANINE MODEL

Atrial fibrillation (AF) is the most common arrhythmia, a major risk factor for stroke and is associated with substantial morbidity and mortality. Unfortunately, current pharmacological and interventional treatment approaches are suboptimal. Parasympathetic nervous system (PNS) activity upregulation and oxidative stress (OS), mainly generated by NADPH oxidase 2 (NOX2), have been shown as key players in AF induction and maintenance. A deeper understanding of these molecular mechanisms underlying AF and their interplay will be instrumental to the development of new, mechanism-targeted therapies for AF. To evaluate whether combined gene therapy can inhibit parasympathetic signaling (Gαi and Gαo - GiGo) and reactive oxygen species generation and attenuate AF development and maintenance in a large animal chronic AF model. Combination of plasmids expressing NOX2 (main source of OS in atrial cardiomyocytes) short hairpin RNA and GiGo inhibitory peptides (GiGo_ct) was injected in the canine (n=4) atria followed by electroporation to facilitate gene delivery. Rapid atrial pacing (RAP) was performed for up to 8 weeks. Residual AF was evaluated at terminal EP study. Plasmids expression was evaluated with polymerase chain reaction (PCR). Controls developed persistent AF (≥8 hours) after a median of 14 days. Combined (NOX2+GiGo) gene therapy attenuated development of persistent AF and significantly reduced AF burden by 32% (Panel A). AF at the terminal experiment displayed increased organization in gene therapy animals (panel B), with one animal spontaneously converting to sinus rhythm. PCR analysis showed NOX2 downregulation and evidence of GiGo_ct expression upon >2 months since gene injection. Targeting both parasympathetic nerve signaling and OS significantly attenuated AF development, which proves their important mechanistic role. Gene-based, selective parasympathetic signaling inhibition by GiGo_ct and oxidative stress attenuation by NADPH oxidase 2 downregulation prevents initiation and maintenance AF. Future optimization of gene therapy and developing combined approaches to target several mechanisms of AF pathophysiology simultaneously may lead to novel treatments for AF.

Abstract PR020: Cholinergic modulation of T lymphocytes in pancreatic adenocarcinoma

Abstract Immunotherapy, which can produce durable responses in some cancers, has generally proven ineffective in PDAC, partially due to an immunosuppressive tumor immune microenvironment (TIME). Adjunctive therapies to sensitize PDAC to immunotherapy have the potential to greatly improve survival for patients with PDAC. We have shown that parasympathetic signaling via the vagus nerve inhibits PDAC by suppressing cancer stem cells. Cholinergic signaling through the Muscarinic Acetylcholine Receptor 1 (Chrm1) mediates this phenomenon. The effect of cholinergic signaling on the tumor immune microenvironment is unknown. Our objective is to investigate if loss of Chrm1 or cholinergic signaling impairs anti-tumor immune responses. We used two models of PDAC a) the KRasLSL G12D/+;Trp53R172H/+;Pdx1-Cre (KPC) autochthonous mouse model of PDAC crossed with Chrm1 knockout mice (KPCM) and b) orthotopic PDAC transplantation models. The composition of the TIME and tumor kinetics of these models were assessed, and the effect of genetic loss or pharmacological inhibition of CHRM1 on T lymphocytes function was examined. Inflammatory markers were analyzed in plasma samples from PDAC patients enrolled in a Phase 0/window of opportunity study of the cholinergic agonist, bethanechol, prior to surgery. Results show that loss of Chrm1 is associated with decreased T cell infiltration in the TIME of PDAC and increased tumor growth. CD8+ T cells deficient in Chrm1 demonstrate impaired proliferation, activation and suppression of TCF1, a transcription factor with well described roles in T cell development and maintenance of effector T cell function. Analysis of paired plasma samples obtained from patients treated with the cholinergic agonist, bethanechol show increased expression of CCL5, a chemokine with known roles in T cell migration in the TIME as well as suppression of a number of other inflammatory cytokines including TNF-alpha. These data suggest that cholinergic signaling via CHRM1 on T lymphocytes promotes CD8+ T cell infiltration into the TIME and maintenance of anti-tumor immune responses. Citation Format: Ruth A. White, Quin T. Waterbury, Yosuke Ochiai, Leah B. Zamechek, Susan E. Bates, Timothy C. Wang. Cholinergic modulation of T lymphocytes in pancreatic adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr PR020.

Abstract 15072: Targeted Atrial Inhibition of Parasympathetic Signaling With GiGo Inhibitory Peptides Attenuates Electrical Remodeling and Development of Persistent Atrial Fibrillation in a Canine Model

Background: While vagal contribution to paroxysmal atrial fibrillation (AF) is well demonstrated, a role for parasympathetic signaling in persistent AF is less clear. We have shown marked atrial parasympathetic hyperinnervation in a canine rapid atrial pacing (RAP) model of AF. However, the role of these new nerves in AF development is unknown. Hypothesis: RAP-induced parasympathetic hyperinnervation contributes to the onset and maintenance of AF, and a gene therapy approach inhibiting muscarinic M2 signaling (Gα i and Gα o - GiGo) in the atria can prevent persistent AF. Methods: Plasmids expressing GiGo inhibitory peptides (GiGo_ct) were injected in the atria of 7 dogs followed by electroporation to facilitate gene delivery. RAP was performed for up to 12 weeks. At terminal EP study, residual AF was recorded in the posterior left atrium (PLA), left atrial free wall (LAFW) and left atrial appendage (LAA). Regional atrial ERP was measured. Results: Controls developed ≥30 minutes of AF after a median of 4 days, and persistent AF (≥8 hours) after a median of 14 days. GiGo_ct delayed onset of AF of ≥30 minutes, and attenuated development of persistent AF. ERP was markedly shortened in the PLA and LAA of controls, and this was attenuated by GiGo_ct (p<0.001). Residual AF was slower (lower dominant frequency; PLA 9.4±0.6Hz Vs 11.0±0.7Hz; LAFW 7.8±0.3Hz Vs 10.4±0.7Hz; LAA 8.9±0.6Hz Vs 9.9±0.5Hz p<0.01), less fractionated (longer fractionation interval; PLA 70.0.4±5.2ms Vs 68.1±5.2ms; LAFW 98.8±4.1ms Vs 70.9±3.1ms; LAA 88.9±7.8ms Vs 80.3±2.0ms p<0.01) and more organized (lower Shannon's entropy; p<0.05). Conclusion: Newly sprouted atrial parasympathetic nerves play a functional role in development of persistent AF. Gene-based, selective M2 signaling inhibition by GiGo_ct attenuates electrical remodeling and prevents initiation and maintenance AF. Future optimization of gene therapy targeting autonomic remodeling may lead to novel, mechanism-guided treatments for AF.

Abstract P1105: Inflammatory Bowel Disease Induced Autonomic Dysregulation Increases The Risk For Atrial Fibrillation

Introduction: Ulcerative colitis causes inflammation of the innermost lining of the colon and rectum. The disease has a relapsing and remitting course and is accompanied by extraintestinal manifestations such as an increased risk for atrial fibrillation (AF). Here we will test the hypothesis that during active colitis, dysregulation of parasympathetic signaling increases the propensity for atrial arrhythmic events. Methods: Dextran Sulfate Sodium (DSS: 3%, 7days) treated mice (C57BL/6) exhibit disrupted intestinal barrier function that mimics the disease phenotype of active colitis. Changes in atrial electrophysiology was quantified in-vivo (EKG) and in the Langendorff (LD)-perfused heart (atrial electrograms) during peak inflammation (DSS A ) and remission (DSS R ). Results: During peak inflammation, structural remodeling was reflected in a decreased heart weight to tibia length ratio (Control (CTL A ): 9.9±0.4 mg/mm, n=10; DSS A : 8.8±0.3 mg/mm, n=12; p<0.05) whereas electrophysiological atrial remodeling was supported by a prolonged P-wave duration (CTL A : 25.5±0.6 ms, n=10; DSS A : 31.2±0.6 ms, n=24; p<0.0001) and shortened atrial effective refractory period (CTL A : 27.3±1.7 ms, n=4; DSS A : 19.3±0.6 ms, n=4; p<0.01). In comparison to CTL A , DSS A mice exhibited autonomic dysregulation reflected in an attenuated heart rate (HR) variability and a decreased change in HR in response to the muscarinic receptor blocker atropine (CTL A : 7.6±1.8 %, n=5; DSS A : 2.2±0.7 %, n=7; p<0.01). The decreased vagal tone in DSS A coincided with an exaggerated response to the parasympathomimetic carbachol (CCh, 150ng/g) that resulted in a larger decrease in HR (in vivo: CTL A : -12.3±3.1 %, n=10; DSS A : -46.0±5.6 %, n=10; p<0.0001) and increased number of spontaneous arrhythmic events (CTL A : 1.7±0.6 events/min, n=10; DSS A : 9.8±3.8 events/min, n=10; p<0.05) in vivo and in the LD-configuration. The susceptibility for pacing induced AF trended to be increased in DSS A animals. Structural and electrophysiological changes were reversible upon remission. Conclusion: Active colitis induces transient structural and electrophysiological remodeling. We propose that dysregulation of cholinergic signaling drives the increased propensity for atrial arrhythmia.

Autonomic nervous system receptor-mediated regulation of mast cell degranulation modulates the inflammation after corneal epithelial abrasion

Mast cells (MCs) regulate wound healing and are influenced by the autonomic nervous system (ANS). However, the underlying mechanisms affecting wound healing outcomes remain elusive. Here, we explored the specific role of the ANS by regulating MC degranulation following corneal epithelium abrasion. A mouse model of corneal abrasion was established by mechanically removing a 2-mm central epithelium. Wound closure, neutrophil infiltration, and transcription of injured corneas were investigated using whole-mount immunostaining, flow cytometry, and RNA-sequencing analysis, respectively. Inhibition of MC degranulation by the MC stabilizers cromolyn sodium and lodoxamide tromethamine increased the infiltration of neutrophils and delayed healing of abraded corneas. Moreover, transcriptomic profiling analysis showed that purified MCs from the limbus expressed adrenergic and cholinergic receptors. Pharmacological manipulation and sympathectomy with 6-hydroxydopamine confirmed that sympathetic nervous system signaling inhibited MC degranulation after corneal abrasion, whereas parasympathetic nervous system signaling enhanced MC degranulation. We conclude that normal degranulation of MCs in the corneal limbus and crosstalk between the ANS and MCs are crucial for the appropriate control of inflammation and the repair progress of wounded corneas. This suggests a potential approach for improving defective corneal wound healing by the administration of clinically available autonomic activity-modulating agents.

Autonomic Regulation of Nociceptive and Immunologic Changes in a Mouse Model of Complex Regional Pain Syndrome

Chronic pain frequently develops after limb injuries, and its pathogenesis is poorly understood. We explored the hypothesis that the autonomic nervous system regulates adaptive immune system activation and nociceptive sensitization in a mouse model of chronic post-traumatic pain with features of complex regional pain syndrome (CRPS). In studies sympathetic signaling was reduced using 6-hydroxydopamine (6-OHDA) or lofexidine, while parasympathetic signaling was augmented by nicotine administration. Hindpaw allodynia, unweighting, skin temperature, and edema were measured at 3 and 7 weeks after fracture. Hypertrophy of regional lymph nodes and IgM deposition in the skin of injured limbs were followed as indices of adaptive immune system activation. Passive transfer of serum from fracture mice to recipient B cell deficient (muMT) mice was used to assess the formation of pain-related autoantibodies. We observed that 6-OHDA or lofexidine reduced fracture-induced hindpaw nociceptive sensitization and unweighting. Nicotine had similar effects. These treatments also prevented IgM deposition, hypertrophy of popliteal lymph nodes, and the development of pronociceptive serum transfer effects. We conclude that inhibiting sympathetic or augmenting parasympathetic signaling inhibits pro-nociceptive immunological changes accompanying limb fracture. These translational results support the use of similar approaches in trials potentially alleviating persistent post-traumatic pain and, possibly, CRPS. PerspectiveSelective treatments aimed at autonomic nervous system modulation reduce fracture-related nociceptive and functional sequelae. The same treatment strategies limit pain-supporting immune system activation and the production of pro-nociceptive antibodies. Thus, the therapeutic regulation of autonomic activity after limb injury may reduce the incidence of chronic pain.

Aged Mice Devoid of the M3 Muscarinic Acetylcholine Receptor Develop Mild Dry Eye Disease.

The parasympathetic nervous system is critically involved in the regulation of tear secretion by activating muscarinic acetylcholine receptors. Hence, various animal models targeting parasympathetic signaling have been developed to induce dry eye disease (DED). However, the muscarinic receptor subtype (M1–M5) mediating tear secretion remains to be determined. This study was conducted to test the hypothesis that the M3 receptor subtype regulates tear secretion and to evaluate the ocular surface phenotype of mice with targeted disruption of the M3 receptor (M3R−/−). The experimental techniques included quantification of tear production, fluorescein staining of the ocular surface, environmental scanning electron microscopy, assessment of proliferating cells in the corneal epithelium and of goblet cells in the conjunctiva, quantification of mRNA for inflammatory cytokines and prooxidant redox enzymes and quantification of reactive oxygen species. Tear volume was reduced in M3R−/− mice compared to age-matched controls at the age of 3 months and 15 months, respectively. This was associated with mild corneal epitheliopathy in the 15-month-old but not in the 3-month-old M3R−/− mice. M3R−/− mice at the age of 15 months also displayed changes in corneal epithelial cell texture, reduced conjunctival goblet cell density, oxidative stress and elevated mRNA expression levels for inflammatory cytokines and prooxidant redox enzymes. The findings suggest that the M3 receptor plays a pivotal role in tear production and its absence leads to ocular surface changes typical for DED at advanced age.

Efficacy and neurophysiological predictors of treatment response of adjunct bifrontal transcranial direct current stimulation (tDCS) in treating unipolar and bipolar depression

BackgroundAlthough add-on transcranial direct current stimulation (tDCS) is a promising intervention for treating unipolar (UD) and bipolar depression (BD), its moderate antidepressant efficacy urges research into biomarkers for predicting therapeutic response and achieving highly targeted applications. MethodsThis open-label trial enrolled UD (N=58) and BD (N=22) patients who had failed 1 or more trials of adequate pharmacologic interventions (ClinicalTrials.gov ID: NCT03287037). Bifrontal tDCS (anode/cathode: F3/F4) was applied using a 2 mA current for 20 min, twice daily, for 5 consecutive weekdays. Depression was measured with Hamilton Depression Rating Scale-17 (HAMD) at baseline, after 10-session stimulation, 1- and 4-week follow-ups. Heart rate (HR) and heart rate variability (HRV) was measured at baseline, during the initial 5 min of the 1st session, after 10-session stimulation, 1- and 4-week follow-ups. Cognitive performance and other outcomes were also assessed. ResultsBifrontal tDCS rapidly and equally improved depression in both groups. The effects persisted until the end of the trial. Both groups had similar improvements in cognitive performance, anxiety, and psychosocial functioning. Compared with baseline, increased vagally-mediated HRV was observed one month after tDCS for both groups. A positive correlation was found between HR deceleration within the 1st session and treatment response after 10-session tDCS only among UD patients, explaining 20% of the variance. ConclusiontDCS as an adjunct therapy is effective for both UD and BD. Data suggest that the greater the increase in parasympathetic signaling during the 1st session, the better the clinical response after 10-session tDCS for UD patients.

Interleukin-1 receptor-induced PGE2 production controls acetylcholine-mediated cardiac dysfunction and mortality during scorpion envenomation

Scorpion envenomation is a leading cause of morbidity and mortality among accidents caused by venomous animals. Major clinical manifestations that precede death after scorpion envenomation include heart failure and pulmonary edema. Here, we demonstrate that cardiac dysfunction and fatal outcomes caused by lethal scorpion envenomation in mice are mediated by a neuro-immune interaction linking IL-1 receptor signaling, prostaglandin E2, and acetylcholine release. IL-1R deficiency, the treatment with a high dose of dexamethasone or blockage of parasympathetic signaling using atropine or vagotomy, abolished heart failure and mortality of envenomed mice. Therefore, we propose the use of dexamethasone administration very early after envenomation, even before antiserum, to inhibit the production of inflammatory mediators and acetylcholine release, and to reduce the risk of death.

Designing a bioelectronic treatment for Type 1 diabetes: targeted parasympathetic modulation of insulin secretion.

The pancreas is a visceral organ with exocrine functions for digestion and endocrine functions for maintenance of blood glucose homeostasis. In pancreatic diseases such as Type 1 diabetes, islets of the endocrine pancreas become dysfunctional and normal regulation of blood glucose concentration ceases. In healthy individuals, parasympathetic signaling to islets via the vagus nerve, triggers release of insulin from pancreatic β-cells and glucagon from α-cells. Using electrical stimulation to augment parasympathetic signaling may provide a way to control pancreatic endocrine functions and ultimately control blood glucose. Historical data suggest that cervical vagus nerve stimulation recruits many visceral organ systems. Simultaneous modulation of liver and digestive function along with pancreatic function provides differential signals that work to both raise and lower blood glucose. Targeted pancreatic vagus nerve stimulation may provide a solution to minimizing off-target effects through careful electrode placement just prior to pancreatic insertion.

Design for a multicenter, randomized, sham-controlled study to evaluate safety and efficacy after treatment with the Nuvaira\xae lung denervation system in subjects with chronic obstructive pulmonary disease (AIRFLOW-3)

BackgroundTargeted lung denervation (TLD) is a bronchoscopically delivered ablation therapy that selectively interrupts pulmonary parasympathetic nerve signaling. The procedure has the potential to alter airway smooth muscle tone and reactivity, decrease mucous secretion, and reduce airway inflammation and reflex airway hyperresponsiveness. Secondary outcome analysis of a previous randomized, sham-controlled trial showed a reduction in moderate-to-severe exacerbations in patients with COPD after TLD treatment. A pivotal trial, AIRFLOW-3 has been designed to evaluate the safety and efficacy of TLD combined with optimal medical therapy to reduce moderate or severe exacerbations throughout 1 year, compared with optimal medical therapy alone.MethodsThe study design is a multicenter, randomized, full sham bronchoscopy controlled, double-blind trial that will enroll 400 patients (1:1 randomization). Key inclusion criteria are FEV1/FVC < 0.7, FEV1 30 to 60% of predicted, post-bronchodilator, ≥ 2 moderate or 1 severe COPD exacerbations in the prior year, and COPD assessment test (CAT) ≥ 10. Primary objective will be the comparison of moderate or severe COPD exacerbations through 12 months of TLD therapy with optimal medical therapy versus optimal medical therapy alone. The sham group will be allowed to cross over at 1 year. Patients will be followed for up to 5 years.DiscussionThe multicenter, randomized, full sham bronchoscopy controlled, double-blind AIRFLOW-3 trial will evaluate the efficacy of TLD to reduce moderate or severe COPD exacerbations beyond optimal medical therapy alone. The target population are patients with COPD, who suffer persistent symptoms and exacerbations despite optimal treatment, defining an unmet medical need requiring novel therapeutic solutions. This trial is registered at clinicaltrials.gov: NCT03639051.

Parasympathetic activity is reduced during slow-wave sleep, but not resting wakefulness, in patients with chronic fatigue syndrome.

Physiological dearousal characterized by an increase in parasympathetic nervous system activity is important for good-quality sleep. Previous research shows that nocturnal parasympathetic activity (reflected by heart rate variability [HRV]) is diminished in individuals with chronic fatigue syndrome (CFS), suggesting hypervigilant sleep. This study investigated differences in nocturnal autonomic activity across sleep stages and explored the association of parasympathetic activity with sleep quality and self-reported physical and psychological wellbeing in individuals with CFS. Twenty-four patients with medically diagnosed CFS, and 24 matched healthy control individuals participated. Electroencephalography and HRV were recorded during sleep in participants' homes using a minimally invasive ambulatory device. Questionnaires were used to measure self-reported wellbeing and sleep quality. Sleep architecture in patients with CFS differed from that of control participants in slower sleep onset, more awakenings, and a larger proportion of time spent in slow-wave sleep (SWS). Linear mixed-model analyses controlling for age revealed that HRV reflecting parasympathetic activity (normalized high frequency power) was reduced in patients with CFS compared to control participants, particularly during deeper stages of sleep. Poorer self-reported wellbeing and sleep quality was associated with reduced parasympathetic signaling during deeper sleep, but not during wake before sleep, rapid eye movement sleep, or with the proportion of time spent in SWS. Autonomic hypervigilance during the deeper, recuperative stages of sleep is associated with poor quality sleep and self-reported wellbeing. Causal links need to be confirmed but provide potential intervention opportunities for the core symptom of unrefreshing sleep in CFS.

Conceptualization of a Parasympathetic Endocrine System.

We here propose a parasympathetic endocrine system (PES) comprised of circulating peptides released from secretory cells in the gut, significantly modulated by vagal projections from the dorsal motor nucleus of the vagus (DMV). While most of these gut peptides mediate well-described satiety and digestive effects that increase parasympathetic control of digestion (Lee et al., 1994; Gutzwiller et al., 1999; Klok et al., 2007), they also have actions that are far-reaching and increase parasympathetic signaling broadly throughout the body. The actions beyond satiety that peptides like somatostatin, cholecystokinin, glucagon-like peptide 1, and vasoactive intestinal peptide have been well-examined, but not in a systematic way. Consideration has been given to the idea that these and other gut-derived peptides are part of an endocrine system has been partially considered (Rehfeld, 2012; Drucker, 2016), but that it is coordinated through parasympathetic control and may act to increase the actions of parasympathetic projections has not been formalized before. Here only gut-derived hormones are included although there are potentially other parasympathetically mediated factors released from other sites like lung and liver (Drucker, 2016). The case for the existence of the PES with the DMV as its integrative controller will be made through examination of an anatomical substrate and evidence of physiological control mechanisms as well as direct examples of PES antagonism of sympathetic signaling in mammals, including humans. The implications for this conceptual understanding of a PES reframe diseases like metabolic syndrome and may help underscore the role of the autonomic nervous system in the associated symptoms.

Chronic allopregnanolone treatment enhances glucose tolerance through parasympathetic activity

It is estimated that one and a half million Americans are diagnosed with diabetes each year. A startling statistic given that diabetes is considered the 7th leading cause of death making diabetes a significant health burden to the United States. It is imperative than that we develop new treatments and regulators of glucose metabolism. The ability of the central nervous system to regulate whole body glucose metabolism is one such treatment avenue. We are particularly interested in the role of the parasympathetic nervous system on glucose homeostasis since stimulation of the vagus nerve alters insulin and glucagon release from the pancreas. Previous work demonstrated that GABAergic signaling to parasympathetic motor neurons is critical to normal parasympathetic function, including the regulation of pancreatic secretions. Recent work from other brain regions identified that allopregnanolone (ALLO) is an endogenous ligand to GABAA receptors and can have positive effects on brain related disorders, such as anxiety, depression, and stroke. There is even evidence that it can improve diabetic neuropathic pain. Therefore, we aimed to determine if ALLO could alter glucose metabolism. We hypothesized that ALLO improves glucose tolerance through improved parasympathetic signaling. In initial experiments, female mice were ovariectomized (OVX), to normalize hormone concentrations, and implanted with subcutaneous silastic capsules (20mm) containing either ALLO (20mg) or vehicle (sesame oil; 0.1% alcohol). After 10 days, mice were administrated an intraperitoneal (i.p.) glucose tolerance test (GTT; 2g/kg) and blood glucose was monitored at intervals of 0, 15, 30, 60, and 120 minutes during the GTT. Mice given ALLO for 10–14 days had a significant improvement in glucose tolerance compared to vehicle (213 ± 12 mg/dL vs 325 ± 37 mg/dL). To determine if the parasympathetic nervous system was involved in the improvement in glucose tolerance after chronic ALLO exposure, a GTT was repeated after a pre‐treatment with atropine methyl nitrate (0.5mg/kg; i.p.). After atropine pre‐treatment mice exposed to ALLO did not demonstrate a significant difference in GTT compared to atropine treated mice exposed to vehicle (351 ± 35 mg/dL vs 362 ± 29 mg/dL), indicating that parasympathetic nervous system function is required for ALLO‐induced improvements in GTT. Follow‐up experiments used interventricular cannula (IVC) administration for ALLO. Again, in OVX females, IVC ALLO improved GTT (265 ± 15 mg/dL vs 346 ± 49 mg/dL), further indicating the important role of the brain in regulating the ability of ALLO to modulate glucose tolerance. On‐going studies will probe the end organ mechanism(s) responsible for this improvement. As well as how ALLO works centrally to modulate vagal motor drive. Interestingly, systematic administration of ALLO to males (20mg) did not demonstrate significant improvements in GTT (423 ± 15 mg/dL vs 410 ± 56 mg/dL). Taken together, these data suggest that ALLO is a novel, modulator of glucose metabolism, particularly in females. By understanding the role of ALLO on vagal drive and glucose homeostasis, we hope to development new therapies to treat diabetes and its complications.Support or Funding InformationAHA 16SDG26590000This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.