Postganglionic Research Articles

Serotonergic Paracrine Targets in the Intestinal Mucosa.

Serotonin functions as a neurotransmitter in the enteric nervous system. Aside from its neurotransmitter role, serotonin also is a paracrine mediatorial signal in the digestive tract. It is a major paracrine signaling molecule in the integrated physiology of several classes of cells in the intestinal mucosa. Paracrine action can be initiation or suppression of activity in populations of cells that make up divergent phenotypic classes. This underlies phenotypic plasticity in single classes and links single classes to other neighboring phenotypic classes, thereby forming a single and higher-order organization in which different categories of function are integrated to work in harmony as a single homeostatic entity at higher levels of physiological organization. Phenotypic classes of cells that are linked by serotonergic paracrine signaling at upper levels of functional organization in the small intestine are (1) enterochromaffin cells; (2) enteric mast cells; (3) spinal sensory afferents; (4) sympathetic postganglionic neurons; (5) enteric neurons.

Pineal Gland Culture.

Pineal gland secretes the hormone melatonin at night with a circadian rhythm. The synthesis and secretion of melatonin are stimulated at night by norepinephrine released by sympathetic postganglionic neurons projecting from the superior cervical ganglia. Norepinephrine simultaneously activates α- and β-adrenoceptors, triggering melatonin synthesis.To study the regulation of melatonin production and secretion, it is very convenient to use an ex vivo preparation. Thus, it is possible to keep intact pineal glands in culture and to study the actions of agonists, antagonists, modulators, toxic agents, etc., in melatonin synthesis. Artificial melatonin synthesis stimulation in vitro is usually achieved by using a β-adrenergic agonist alone or in association with an α-adrenergic agonist. In this chapter, the methodology of cultured pineal glands will be described. Several papers were published by our group using this methodology, approaching the role played in melatonin synthesis control by angiotensin II and IV, insulin, glutamate, voltage-gated calcium channels, anhydroecgonine methyl ester (AEME, crack-cocaine product), monosodium glutamate (MSG), signaling pathways like NFkB, pathophysiological conditions like diabetes, etc.

Osteopathic Manipulation of the Sphenopalatine Ganglia Versus Sham Manipulation, in Obstructive Sleep Apnoea Syndrom: A Randomised Controlled Trial.

(1) Background: osteopathic manipulation of the sphenopalatine ganglia (SPG) blocks the action of postganglionic sensory fibres. This neuromodulation can reduce nasal obstruction and enhance upper airway stability. We investigated the manipulation of the SPG in 31 patients with obstructive sleep apnoea syndrome (OSAS); (2) Methods: Randomised, controlled, double-blind, crossover study. Participants received active (AM), then sham manipulation (SM), or vice versa. The primary endpoint was apnoea-hypopnoea index (AHI). Secondary endpoints were variation of nasal obstruction evaluated by peak nasal inspiratory flow (PNIF) and upper airways stability evaluated by awake critical closing pressure [awake Pcrit]), at 30 min and 24 h. Schirmer’s test and pain were assessed immediately post-manipulation. Tactile/gustatory/olfactory/auditory/nociceptive/visual sensations were recorded. Adverse events were collected throughout. (3) Results: SPG manipulation did not reduce AHI (p = 0.670). PNIF increased post-AM but not post-SM at 30 min (AM-SM: 18 [10; 38] L/min, p = 0.0001) and 24 h (23 [10; 30] L/min, p = 0.001). There was no significant difference on awake Pcrit (AM-SM) at 30 min or 24 h). Sensations were more commonly reported post-AM (100% of patients) than post-SM (37%). Few adverse events and no serious adverse events were reported. (4) Conclusions: SPG manipulation is not supported as a treatment for OSAS but reduced nasal obstruction. This effect remains to be confirmed in a larger sample before using this approach to reduce nasal congestion in CPAP-treated patients or in mild OSAS.

Frey's Syndrome: A Review of Aetiology and Treatment.

First described by Polish Neurologist Łucja Frey in 1923, Frey’s syndrome (FS), or auriculotemporal syndrome, is a rare condition characterised by gustatory sweating, typically encountered as sequelae following invasive head and neck surgery. The pathophysiology of FS can be described by aberrant reinnervation of postganglionic parasympathetic neurons to the surrounding denervated sweat glands and cutaneous blood vessels.Multiple invasive procedures have been associated with FS ranging from salivary gland surgery to burn reconstruction and thoracoscopic sympathectomies. Rarely, FS can be secondary to trauma or non-surgical aetiologies, including diabetes and infection.Physical symptoms vary based on the severity and surface area affected by FS and range from mild symptoms to severe psychosocial morbidity for patients. Surgeons operating in the head and neck, including otolaryngologists, maxillofacial surgeons, and plastic surgeons, should be aware of this potential complication and be up to date with diagnosis and treatment strategies for FS.This review article summarises the literature relating to FS focusing on its aetiologies, symptomatology, prevention, and available treatments, aiming to provide an up-to-date review of this condition for surgeons operating in the head and neck region. Although various treatment options have been suggested, these are often limited to topical agents that require life-long administration for symptom control. Further research is recommended to identify the optimal treatment for this condition and the role of surgery as a treatment for severe or refractory cases.

Different phenoconversion pathways in pure autonomic failure with versus without Lewy bodies.

Pure autonomic failure (PAF) is a rare disease in which chronic neurogenic orthostatic hypotension (nOH) dominates the clinical picture. Longitudinal studies have reported that PAF can phenoconvert to a central synucleinopathy with motor or cognitive involvement-i.e., to Parkinson disease (PD), dementia with Lewy bodies (DLB), or multiple system atrophy (MSA). These studies have classified patients clinically as having PAF based on nOH without an identified secondary cause or clinical evidence of motor or cognitive impairment due to central neurodegeneration. This approach lumps together two nOH syndromes that are pathologically and neurochemically distinct. One is characterized by intraneuronal cytoplasmic alpha-synuclein aggregates (i.e., Lewy bodies) and degeneration of postganglionic sympathetic neurons, as in PD and DLB; the other is not, as in MSA. Clinical and postmortem data show that the form of PAF that involves sympathetic intraneuronal synucleinopathy and noradrenergic deficiency can phenoconvert to PD or DLB-but not to MSA. Conversely, PAF without these features leaves open the possibility of premotor MSA.

Endurance training increases ventricular refractoriness and wavelength of the cardiac impulse without participation of parasympathetic postganglionic neurons. A study in isolated rabbit heart

Abstract Background Endurance physical training plays a protective role in against ventricular fibrillation (VF), but the exact underlying mechanisms are not completely understood. It is well-known that modifications in myocardial ventricular properties such as refractoriness, conduction velocity and wavelength are key in the initiation and maintenance of VF; furthermore, vagus nerve stimulation has prophylactic effects on malignant arrhythmias and VF. On the other hand, parasympathetic nervous system activity is increased in trained individuals, which in turn affects different ventricular electrophysiological properties. We hypothesized that physical training increases conduction velocity and wavelength, and that these changes are mediated by myocardial cholinergic neurons. Methods To test this hypothesis, ten rabbits were submitted to a six-week endurance training protocol and twenty controls were not trained (divided in control group, n=10 and sham group n=10). After training, rabbits were euthanized and their hearts excised, isolated and perfused in a Langendorff system. A pacing electrode and a plaque with 240 recoding electrodes acquiring at 1 KHz were positioned on the left ventricle (LV). Extraestimulus test using four different pacing cycle lengths (90% basal cycle length, 250, 200 and 150 ms) was performed before and after atropine (1μM, control and trained groups) or vehicle (tyrode, sham group) infusion. We studied 1) LV effective refractory period (ERP), 2) LV functional refractory period (FRP), 3) LV conduction velocity (CV), and 4) LV wavelength, determined as LV FRP x CV. Factorial ANOVA (mixed model) was used for statistical analysis (p<0.05). Results Before parasympathetic blockade, LV FRP increased in trained animals (Figure, B) whereas no difference was found in LV CV between trained and control animals at any pacing cycle length (Figure, A). In consequence, LV wavelength increased in trained animals (Figure, C). There were no changes in LV ERP, FRP, CV and wavelength when comparisons were made within groups before and after atropine infusion. In sham animals, vehicle infusion or time-course of the experiment did not modify LV FRP, ERP, CV and wavelength. Conclusion Physical training increases LV wavelength, which can be one electrophysiological mechanism by which endurance training could protect against VF. Since modifications of ventricular refractoriness and wavelength do not seem dependent of intrinsic parasympathetic nervous system activity, other intrinsic mechanisms could be implied and warrant further research. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Instituto de Salud Carlos III, Generalitat Valenciana

The sympathetic nervous system in development and disease.

The sympathetic nervous system prepares the body for 'fight or flight' responses and maintains homeostasis during daily activities such as exercise, eating a meal or regulation of body temperature. Sympathetic regulation of bodily functions requires the establishment and refinement of anatomically and functionally precise connections between postganglionic sympathetic neurons and peripheral organs distributed widely throughout the body. Mechanistic studies of key events in the formation of postganglionic sympathetic neurons during embryonic and early postnatal life, including axon growth, target innervation, neuron survival, and dendrite growth and synapse formation, have advanced the understanding of how neuronal development is shaped by interactions with peripheral tissues and organs. Recent progress has also been made in identifying how the cellular and molecular diversity of sympathetic neurons is established to meet the functional demands of peripheral organs. In this Review, we summarize current knowledge of signalling pathways underlying the development of the sympathetic nervous system. These findings have implications for unravelling the contribution of sympathetic dysfunction stemming, in part, from developmental perturbations to the pathophysiology of peripheral neuropathies and cardiovascular and metabolic disorders.

The Frequency-Dependence of Pre- and Postganglionic Nerve Stimulation of Pig and Rat Bladder.

PurposeThe urinary bladder generates phasic contractions via action potentials generated in pre- and then postganglionic neurons. Whilst the frequency-dependence of postganglionic neurons to generate contractions has been quantified, the dynamic range of preganglionic neurons is less clear and if intramural ganglia exert frequency-dependent modulation of transmission between pre- and postganglionic neurons. The phosphodiesterase type 5 inhibitor sildenafil reduces neurotransmitter release from postganglionic fibres to detrusor smooth muscle and an additional question was if there was also a preganglionic action. This study aimed to compare the frequency range of bladder contractile activation by pre- and postganglionic stimulation in pig and rat bladders and if sildenafil exerted additional preganglionic actions.MethodsAn arterially-perfused ex vivo pig bladder preparation was used for preganglionic (pelvic nerve) and mixed pre-and postganglionic (direct bladder wall) stimulation at 36°C and postganglionic mediated contractions achieved by field-stimulation of in vitro isolated detrusor strips. With rats, pelvic nerve stimulation was carried out in vivo and postganglionic stimulation also with isolated detrusor strips.ResultsAll contractions were abolished by 2% lignocaine indicating they are nerve-mediated. Stimulation targets were verified with hexamethonium that completely abolished pelvic nerve responses by had no effect on detrusor strips; responses to mixed bladder wall stimulation were partially reduced. The frequency-dependence of contractile activation was similar whether by pre- or postganglionic stimulation in both pigs and rats. Sildenafil reduced contractions to preganglionic stimulation significantly more than to postganglionic stimulation. Mixed pre- and postganglionic stimulation were reduced by an intermediate extent.ConclusionsIntramural ganglia offer no frequency-dependent modulation under the experimental conditions used here and the sildenafil data are consistent with multiple sites of action underlying generation of bladder contractions. A translational aspect of these findings is discussed in terms of setting stimulation parameters for neuromodulation protocols.

Electrical properties and synaptic transmission in mouse intracardiac ganglion neurons in situ.

The intrinsic cardiac nervous system represents the final site of signal integration for neurotransmission to the myocardium to enable local control of cardiac performance. The electrophysiological characteristics and ganglionic transmission of adult mouse intrinsic cardiac ganglion (ICG) neurons were investigated using a whole‐mount ganglion preparation of the excised right atrial ganglion plexus and intracellular microelectrode recording techniques. The passive and active electrical properties of ICG neurons and synaptic transmission including synaptic response strength and efficacy as a function of stimulation frequency were examined. The resting membrane potential and input resistance of ICG neurons were −47.9 ± 4.0 mV and 197.2 ± 81.5 MΩ, respectively. All neurons had somatic action potentials with overshoots of >+15 mV and after‐hyperpolarizations having an average of 10 mV amplitude and ~45 ms half duration. Phasic discharge activities were recorded from the majority of neurons studied and several types of excitatory synaptic responses were recorded following inputs from the vagus or interganglionic nerve trunk(s). Most postganglionic neurons (>75%) received a strong, suprathreshold synaptic input and reliably followed high‐frequency repetitive nerve stimulation up to at least 50 Hz. Nerve‐evoked synaptic transmission was blocked by extracellular Cd2+, ω‐conotoxin CVIE, or α‐conotoxin RegIIA, a selective α3‐containing nicotinic acetylcholine receptor antagonist. Synaptic transmission and the electrical properties of murine ICG neurons contribute to the pattern of discharge which regulates chronotropic, dromotropic, and inotropic elements of cardiac function.

Mapping afferent and pelvic postganglionic neurons of the urethra from female rats: The L6 DRG is the major primary afferent supplier.

To map sensory and pelvic postganglionic neurons from three different regions of the female rat urethra. The neuronal tracer True Blue (TB) was injected into the pre-pelvic, pelvic, and clitoral regions of the urethra from female Wistar rats. Seven days after TB injection, TB+ cells from the dorsal root ganglia (DRGs) and the major pelvic ganglion (MPG) were examined. The number and morphometry of TB+ cells were determined. TB+ cells were mainly distributed in lumbar 1 (L1), lumbar 2 (L2), lumbar 6 (L6), and sacral 1 (S1) DRGs, and in the MPG. The mean number of sensory neurons was 1200 ± 143. TB injection in pre-pelvic and pelvic urethra labeled neurons in L1, L2, L6, and S1 DRGs. TB injection in clitoral urethra labeled neurons in L6 and S1 DRGs. L6 DRG contained >50% of the total urethral TB+ neurons, and ~80% of the clitoral region. The mean value of the total number of MPG TB+ neurons was 1217 ± 72. DRG and MPG neurons projecting to the urethra presented a somatotopic distribution. The results demonstrated that L6 DRG is the major supplier of afferent innervation to the urethra, and that the distal urethral region is exclusively innervated by lower lumbosacral DRGs. Considering that electrical stimulation of sensory pudendal nerve improves overactive bladder, and that most of the sensory neurons in the distal urethra are from L6 DRG, electrical stimulation of this ganglion may be an innovative and effective neuromodulation therapy for neurogenic urinary dysfunctions.

Reduced Cell Excitability of Cardiac Postganglionic Parasympathetic Neurons Correlates With Myocardial Infarction-Induced Fatal Ventricular Arrhythmias in Type 2 Diabetes Mellitus

ObjectiveWithdrawal of cardiac vagal activity is considered as one of the important triggers for acute myocardial infarction (MI)-induced ventricular arrhythmias in type 2 diabetes mellitus (T2DM). Our previous study demonstrated that cell excitability of cardiac parasympathetic postganglionic (CPP) neurons was reduced in T2DM rats. This study investigated whether cell excitability of CPP neurons is associated with cardiac vagal activity and MI-induced ventricular arrhythmias in T2DM rats.MethodsRat T2DM was induced by a high-fat diet plus streptozotocin injection. MI-evoked ventricular arrhythmia was achieved by surgical ligation of the left anterior descending coronary artery. Twenty-four-hour, continuous ECG recording was used to quantify ventricular arrhythmic events and heart rate variability (HRV) in conscious rats. The power spectral analysis of HRV was used to evaluate autonomic function. Cell excitability of CPP neurons was measured by the whole-cell patch-clamp technique.ResultsTwenty-four-hour ECG data demonstrated that MI-evoked fatal ventricular arrhythmias are more severe in T2DM rats than that in sham rats. In addition, the Kaplan-Meier analysis demonstrated that the survival rate over 2 weeks after MI is significantly lower in T2DM rats (15% in T2DM+MI) compared to sham rats (75% in sham+MI). The susceptibility to ventricular tachyarrhythmia elicited by programmed electrical stimulation was higher in anesthetized T2DM+MI rats than that in rats with MI or T2DM alone (7.0 ± 0.58 in T2DM+MI group vs. 3.5 ± 0.76 in sham+MI). Moreover, as an index for vagal control of ventricular function, changes of left ventricular systolic pressure (LVSP) and the maximum rate of increase of left ventricular pressure (LV dP/dtmax) in response to vagal efferent nerve stimulation were blunted in T2DM rats. Furthermore, T2DM increased heterogeneity of ventricular electrical activities and reduced cardiac parasympathetic activity and cell excitability of CPP neurons (current threshold-inducing action potentials being 62 ± 3.3 pA in T2DM rats without MI vs. 27 ± 1.9 pA in sham rats without MI). However, MI did not alter vagal control of the ventricular function and CPP neuronal excitability, although it also induced cardiac autonomic dysfunction and enhanced heterogeneity of ventricular electrical activities.ConclusionThe reduction of CPP neuron excitability is involved in decreased cardiac vagal function, including cardiac parasympathetic activity and vagal control of ventricular function, which is associated with MI-induced high mortality and malignant ventricular arrhythmias in T2DM.

Nerve-sparing Robot-assisted Retroperitoneal Lymph Node Dissection: The Monoblock Technique

BackgroundRetroperitoneal lymph node dissection (RPLND) is a treatment option for men with stage 1 or 2 testis cancer and the standard of care for men with postchemotherapy retroperitoneal residual disease. Given the morbidity of RPLND, four important surgical modifications have been proposed: minimally invasive access, nerve-sparing resection, template resection, and en-bloc resection. ObjectiveTo describe the surgical steps and perioperative outcomes of robotic nerve-sparing unilateral template RPLND with en-bloc resection (roboRPLND-NS+). Design, setting, and participantsFrom 2017 to 2019, five patients with suspicion of retroperitoneal metastatic testicular cancer on abdominopelvic computed tomography underwent roboRPLND-NS+ at a single referral center. All surgeries were carried out by a single surgeon who has performed more than 500 extended and more than 50 super-extended robot-assisted lymph node dissections. Surgical procedureA lateral transperitoneal robotic approach with a da Vinci Xi Surgical System (Intuitive Surgical, Sunnyvale, CA, USA) in six-arm configuration was used. The sympathetic chains, postganglionic sympathetic fibers, and hypogastric plexus were preserved as much as possible to ensure a nerve-sparing procedure. The template borders consisted of the renal vein cranially, the ureter laterally, the interaortocaval space medially, the common iliac artery caudally, and the psoas muscle dorsally for the right and left modified RPLND templates. Lymph nodes and the surrounding fatty tissue were progressively resected from the common iliac vessels and the abdominal aorta using the split-and-roll technique, and all of the template tissue was resected as a single specimen. Intraoperative and postoperative complications were recorded. MeasurementsLymph node yield and perioperative and postoperative oncological and functional outcomes were measured. Results and limitationsThe median patient age was 38 yr (interquartile range [IQR] 32–41) and the median operative time was 274 min (IQR 238–280). Node metastases were pathologically confirmed in three patients. The median number of lymph nodes removed was 19 (IQR 18–21), and the median number of positive lymph nodes was 2 (IQR 1–3). No patient experienced intraoperative or postoperative complications. The postoperative hospital stay was either 3 or 4 d. Maintenance of antegrade ejaculation was achieved in all patients. After median follow-up of 15 mo (IQR 14–30), all patients were alive and no recurrence was observed. Limitations include the low number of patients and the single surgeon experience. ConclusionsRoboRPLND-NS+ is a safe and feasible technique that allows removal of a high number of lymph nodes with good functional outcomes. Short-term survival outcomes were excellent, with no recurrences or deaths recorded. Patient summaryWe describe a feasible and safe robot-assisted surgical procedure for removal of lymph nodes in patients with testicular cancer. Our technique has potential to decrease the medical problems arising as side effects of the surgery while achieving good cancer control.

Physiology of cholinergic and adrenergic synapses. Role in pharmacology and practical significance

The transmission of signals between cholinergic neurons and from neurons to muscle cells (neuro-neuronal and neuromuscular transduction) occurs through synapses. They are formed by the membranes of two contacting cells, presynaptic and postsynaptic, which are separated by a narrow synaptic gap. The review article provides up-to-date information about the physiological processes in cholinergic and adrenergic synapses. The role of these synapses in pharmacology and their practical significance are presented. The transmission of excitation in cholinergic synapses occurs with the help of acetylcholine. The stages of synthesis, storage and release of acetylcholine are the same in all cholinergic neurons. The specific effects of acetylcholine mediated through cholinergic synapses depend mainly on the type of synaptic cholinergic receptors. In the system of efferent innervation, adrenergic synapses are formed by the endings of postganglionic sympathetic (adrenergic) fibers and cells of effector organs.

Sympathetic innervation of the mouse kidney and liver arising from prevertebral ganglia.

The sympathetic nervous system (SNS) plays a crucial role in the regulation of renal and hepatic functions. Although sympathetic nerves to the kidney and liver have been identified in many species, specific details are lacking in the mouse. In the absence of detailed information of sympathetic prevertebral innervation of specific organs, selective manipulation of a specific function will remain challenging. Despite providing major postganglionic inputs to abdominal organs, limited data are available about the mouse celiac-superior mesenteric complex. We used tyrosine hydroxylase (TH) and dopamine β-hydroxylase (DbH) reporter mice to visualize abdominal prevertebral ganglia. We found that both the TH and DbH reporter mice are useful models for identification of ganglia and nerve bundles. We further tested if the celiac-superior mesenteric complex provides differential inputs to the mouse kidney and liver. The retrograde viral tracer, pseudorabies virus (PRV)-152 was injected into the cortex of the left kidney or the main lobe of the liver to identify kidney-projecting and liver-projecting neurons in the celiac-superior mesenteric complex. iDISCO immunostaining and tissue clearing were used to visualize unprecedented anatomical detail of kidney-related and liver-related postganglionic neurons in the celiac-superior mesenteric complex and aorticorenal and suprarenal ganglia compared with TH-positive neurons. Kidney-projecting neurons were restricted to the suprarenal and aorticorenal ganglia, whereas only sparse labeling was observed in the celiac-superior mesenteric complex. In contrast, liver-projecting postganglionic neurons were observed in the celiac-superior mesenteric complex and aorticorenal and suprarenal ganglia, suggesting spatial separation between the sympathetic innervation of the mouse kidney and liver.

Review of the external carotid plexus: anatomy, function, and clinical manifestations.

The external carotid plexus is a combination of postganglionic sympathetic fibers derived from the superior cervical ganglion. This plexus travels along the external carotid artery and continues onto the artery’s branches. The external carotid plexus plays an important role in innervating the mid and lower face. Therefore, implications to the plexus may result in facial abnormalities. Herein, we review the anatomy, function, and review its clinical applications.

Neurodegenerative disorders affecting the autonomic nervous system: Pure autonomic failure and multiple system atrophy

AbstractPure autonomic failure (PAF) and multiple system atrophy (MSA) are representative neurodegerative diseases present with a severe autonomic dysfunction in the urinary, cardiovascular, and pupillary systems, as well as the gastrointestinal tract and skin/sweat glands. Clinically PAF is characterized by chronic progressive pure autonomic dysfunction occasionally associated with parkinsonism or cognitive dysfunction (Lewy body disease), whereas MSA is associated with cerebellar manifestation and/or parkinsonism. Pathology of both PAF and MSA is characterized by α‐synuclein deposition, but in PAF major involvement exists in the sympathetic ganglion and postganglionic autonomic nerve fibers, whereas MSA mainly affects the central autonomic system, such as the vagal nerve lateral nucleus, locus coeruleus, spinal cord medial lateral nucleus, and sacral Onuf's nucleus. Therefore, it is necessary to evaluate whether peripheral or central autonomic function is predominantly affected by the differential diagnosis of PAF and MSA. Autonomic dysfunction is also frequently present in patients with Parkinson's disease, but usually not so severe as in PAF or MSA. This review summarizes features of autonomic dysfunction in PAF and MSA.

Postganglionic Sudomotor Dysfunction and Brain Glucose Hypometabolism in Patients with Multiple System Atrophy.

Sudomotor dysfunction is common in patients with multiple system atrophy (MSA). Postganglionic sudomotor dysfunction in MSA, which can be assessed using quantitative sudomotor axon reflex testing (QSART), results from the degeneration of preganglionic sympathetic neurons and direct loss of postganglionic fibers. We investigate whether abnormal QSART responses in patients with MSA are associated with disease severity. In this retrospective study, patients with probable MSA who underwent both 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) and autonomic function tests were included. Autonomic function test results were integrated divided into three sub-scores, including sudomotor, cardiovagal, and adrenergic sub-scores. The sudomotor sub-score represented postganglionic sudomotor function. Unified Multiple System Atrophy Rating Scale (UMSARS) Part I, Part II, and sum of Part I and II scores (Part I + II) to reflect disease severity and 18F-FDG-PET/CT results were collected. Of 74 patients with MSA, 62.2%demonstrated abnormal QSART results. The UMSARS Part I + II score was significantly higher in the abnormal QSART group than in the normal QSART group (p = 0.037). In the regression analysis, both UMSARS Part I (β= 1.185, p = 0.013) and Part II (β= 1.266, p = 0.021) scores were significantly associated with the sudomotor sub-score. On 18F-FDG-PET/CT, the abnormal QSART group exhibited more severely decreased metabolic activity in the cerebellum and basal ganglia in patients with MSA-P and MSA-C, respectively. The sudomotor sub-score was significantly associated with regional metabolism in these areas. Patients with MSA and postganglionic sudomotor dysfunction may have worse disease severity and greater neuropathological burden than those without.

Hydrogen peroxide accelerates ventricular arrhythmogenesis by inactivating N‐type calcium channels in cardiac vagal postganglionic neurons in type 2 diabetic rats

Withdrawal of cardiac vagal activity is a common complication in patients with type 2 diabetes mellitus (T2DM), and is associated with arrhythmia-related sudden cardiac death and high mortality in T2DM patients. Although our recent study has demonstrated that reduction of N-type calcium (Cav2.2) currents and cell excitability of cardiac vagal postganglionic (CVP) neurons exacerbates myocardial infarction-evoked ventricular arrhythmias and mortality in T2DM rats, the mechanisms responsible for T2DM-reduced Cav2.2 channel activity in CVP neurons remain unclear. Since reactive oxygen species (ROS) has been reported to modulate calcium channel activity in peripheral postganglionic neurons, here we tested if hydrogen peroxide (H2O2, a type of ROS) overproduction inactivates Cav2.2 channels and further contributes to ventricular vagal dysfunction and ventricular arrhythmogenesis in T2DM. Rat T2DM was induced by a high-fat diet plus streptozotocin injection. Adenoviral catalase gene (Ad.CAT, 2 µl, 1 x 1010 pfu/ml) was microinjected into CVP neurons to scavenge local H2O2 production. Reduced catalase expression accompanied by overproduction of H2O2 was detected in the CVP neurons in T2DM rats. In vivo transfection of Ad.CAT not only increased protein expression of catalase but also attenuated H2O2 production in CVP neurons in T2DM rats. Data from reverse-phase protein array also demonstrated that overexpression of catalase by transfection of Ad.CAT into CVP neurons markedly increased T2DM-reduced protein expression of Cav2.2 in CVP neurons. Local microinjection of Ad.CAT into CVP neurons also significantly restored T2DM-blunted ventricular vagal activity, as demonstrated by an improvement in the response of left ventricular systolic pressure to left vagal efferent nerve stimulation. Additionally, in the power spectral analysis of heart rate variability (HRV), transfection of Ad.CAT into CVP neurons increased the T2DM-attenuated high frequency power (an index of vagal activity), leading to further restoration of the low frequency to high frequency ratio. Moreover, the inducibility of ventricular arrhythmia measured in anesthetized condition was significantly reduced in T2DM rats transfected with Ad.CAT, compared with T2DM rats (0.75±0.48 in T2DM+Ad.CAT group vs. 3.0±1.38 in T2DM group). Transfection of Ad. vector into CVP neurons had no effects on protein expression of catalase and Cav2.2, ventricular vagal activity, HRV, as well as susceptibility to ventricular arrhythmias in T2DM. Based on above data, we conclude that H2O2 overproduction inactivates Cav2.2 channels and further contributes to ventricular vagal dysfunction and ventricular arrhythmogenesis in T2DM, suggesting that H2O2 signaling pathway might be an effective therapeutic target to suppress ventricular arrhythmias in patients with T2DM.

Macrophage depletion in stellate ganglia attenuates cardiac sympathetic overactivation and ventricular arrhythmogenesis by inhibiting neuroinflammation in heart failure

Cardiac sympathetic overactivation is a key trigger for ventricular arrhythmogenesis in patients with chronic heart failure (CHF). Inflammatory infiltration in the stellate ganglion (SG) is a critical factor for cardiac sympathetic hyperactivation in patients with ventricular arrhythmias. This study aims to investigate if macrophage depletion in SG decreases cardiac sympathetic overactivation and ventricular arrhythmogenesis by reducing neuroinflammation in CHF. RatCHF was induced by surgical ligation of left anterior descending coronary artery (LAD). Clodronate liposomes (2µl, 20mg/ml) was microinjected into bilateral SGs in CHF rats. CHF rats treated with PBS liposomes served as control. Final experiments were performed at 1 week after drug treatment (13 weeks of LAD ligation). Data from cytokine protein array demonstrated that nine inflammatory cytokines were detectable, among which the levels of only proinflammatory cytokines including TNFα and IL-1β were elevated in SGs from CHF rats. Using immunofluorescence staining and western blot analysis, we found that macrophage infiltration and expression of TNFα and IL-1β in SG were markedly increased in CHF rats, compared with age matched sham rats. Flow cytometry data further confirmed that percentage of macrophages (defined as CD45+/CD11b+ cells) in SG was much higher in CHF rats than sham rats. Treatment with clodronate liposomes significantly reduced CHF-elevated expression of TNFα and IL-1β as well as macrophage expansion in SGs. Our patch-clamp data demonstrated that clodronate liposomes treatment in SGs significantly reduced N-type (Cav2.2) Ca2+ currents (28.6±2.6 pA/pF in CHF+Clodronate liposomes group vs. 49.1±1.9 pA/pF in CHF group) and excitability of cardiac sympathetic postganglionic (CSP) neurons in CHF rats. In addition, CHF-induced increase in cardiac sympathetic nerve activity (CSNA) was markedly inhibited by clodronate liposomes treatment. ECG data obtained from 24-hour continuous telemetry recording in conscious rats demonstrated that treatment with clodronate liposomes in SGs not only restored CHF-increased heterogeneity of ventricular electical activities, but also reduced the incidence and duration of ventricular tachycardia/fibrillation in CHF. However, clodronate liposomes failed to improve CHF-induced cardiac contractile dysfunction. PBS liposomes had no effects on expression of TNFα and IL-1β and macrophage expansion in SG, Cav2.2 currents and cell excitability of CSP neurons, CSNA, and ventricular arrhythmogenesis in CHF rats. These data suggested that macrophage depletion with clodronate liposomes attenuated CHF-induced cardiac sympathetic overactivation and ventricular arrhythmias through reduction of macrophage expansion and proinflammatory cytokine levels in SGs. The present study suggests that macrophage depletion or anti-inflammatory treatment in SGs might be an effective therapeutic strategy to suppress lethal ventricular arrhythmia in patients with CHF.

Loss of Cervical Sympathetic Chain Input to the Superior Cervical Ganglia Affects the Ventilatory Responses to Hypoxic Challenge in Freely-Moving C57BL6 Mice.

The cervical sympathetic chain (CSC) innervates post-ganglionic sympathetic neurons within the ipsilateral superior cervical ganglion (SCG) of all mammalian species studied to date. The post-ganglionic neurons within the SCG project to a wide variety of structures, including the brain (parenchyma and cerebral arteries), upper airway (e.g., nasopharynx and tongue) and submandibular glands. The SCG also sends post-ganglionic fibers to the carotid body (e.g., chemosensitive glomus cells and microcirculation), however, the function of these connections are not established in the mouse. In addition, nothing is known about the functional importance of the CSC-SCG complex (including input to the carotid body) in the mouse. The objective of this study was to determine the effects of bilateral transection of the CSC on the ventilatory responses [e.g., increases in frequency of breathing (Freq), tidal volume (TV) and minute ventilation (MV)] that occur during and following exposure to a hypoxic gas challenge (10% O2 and 90% N2) in freely-moving sham-operated (SHAM) adult male C57BL6 mice, and in mice in which both CSC were transected (CSCX). Resting ventilatory parameters (19 directly recorded or calculated parameters) were similar in the SHAM and CSCX mice. There were numerous important differences in the responses of CSCX and SHAM mice to the hypoxic challenge. For example, the increases in Freq (and associated decreases in inspiratory and expiratory times, end expiratory pause, and relaxation time), and the increases in MV, expiratory drive, and expiratory flow at 50% exhaled TV (EF50) occurred more quickly in the CSCX mice than in the SHAM mice, although the overall responses were similar in both groups. Moreover, the initial and total increases in peak inspiratory flow were higher in the CSCX mice. Additionally, the overall increases in TV during the latter half of the hypoxic challenge were greater in the CSCX mice. The ventilatory responses that occurred upon return to room-air were essentially similar in the SHAM and CSCX mice. Overall, this novel data suggest that the CSC may normally provide inhibitory input to peripheral (e.g., carotid bodies) and central (e.g., brainstem) structures that are involved in the ventilatory responses to hypoxic gas challenge in C57BL6 mice.