Animals ; Gallbladder ; physiology ; Rabbits ; Solitary Nucleus ; drug effects ; Thyrotropin-Releasing Hormone ; pharmacology ; Vagus Nerve ; drug effects ; physiology

The effects of administration of motilin into the lateral hypothalamic area (LHA) on gastric antrum motility in conscious rats and on gastric distention (GD) sensitive neurons in dorsal vagal complex (DVC) in anesthetized rats were studied. Microinjection of motilin (0.37 nmol/0.5 microl) into the LHA increased the gastric antrum motility index by 76.29 +/- 4.09% (P<0.01). In 60 GD sensitive neurons, firing rate increased in 39 neurons (65%) and decreased in 21 neurons (35%), which were classified as GD-excitatory and GD-inhibitory neurons, respectively. Firing rate by 7.17 +/- 7.89% within 1.5 min in 15 of 24 GD-excitatory neurons, and firing rate increased by 44.35 +/- 7.89% in 12 of 14 GD-inhibitory neurons after motilin microinjection into the LHA. The results suggest that exogenous motilin in LHA plays a role in the regulation of gastric antrum motility possibly via the vagal pathway from LHA-DVC to the stomach.
Animals ; Hypothalamic Area, Lateral ; drug effects ; Microinjections ; Motilin ; pharmacology ; Neurons ; drug effects ; physiology ; Pyloric Antrum ; drug effects ; physiology ; Rats ; Rats, Wistar ; Vagus Nerve ; drug effects ; physiology

The glutamatergic innervations and the GABAergic innervations are respectively the major excitatory and inhibitory inputs of preganglionic cardiac vagal neurons (CVNs). Whether and how these two kinds of innervations interact in the regulation of CVNs is unknown. Using retrograde fluorescent labeling of CVNs and voltage patch-clamp technique, we demonstrated that mixed global application of glutamatergic NMDA and non-NMDA antagonists AP(5) and CNQX, while had no effect on the GABAergic synaptic events of the CVNs in the nucleus ambiguus (NA), significantly decreased the GABAergic synaptic events of the CVNs in the dorsal motor nucleus of the vagus (DMNX). These results suggest that the GABAergic neurons preceding the CVNs in the DMNX receive tonic glutamatergic control, whereas the GABAergic neurons preceding the CVNs in the NA receive little, if any, glutamatergic innervations. This differential central regulation of the CVNs in the DMNX from those in the NA might be a possible mechanism that enables the CVNs in the DMNX play different roles from those in the NA in the parasympathetic control of heart rate and cardiac functions.
Animals ; Animals, Newborn ; Brain Stem ; physiology ; GABAergic Neurons ; physiology ; Glutamates ; physiology ; Heart ; physiology ; Heart Rate ; physiology ; Motor Neurons ; drug effects ; Rats ; Rats, Sprague-Dawley ; Vagus Nerve ; physiology

Ouabain, a Na(+)/K(+)-ATPase inhibitor, induces slowly adapting pulmonary stretch receptors (SARs) to discharge paradoxically. Paradoxical discharge is characterized by increased SAR activity during lung deflation coupled with silence during lung inflation. We hypothesized that over-excitation silences the SARs. Accordingly, if cyclic inflation pressure was reduced so as to lower SAR stimulation, paradoxical discharge would be prevented. In the present study, single-unit activity of SARs was recorded in anesthetized, open-chest and mechanically ventilated rabbits with positive-end-expiratory pressure (PEEP). After microinjection of ouabain into the receptive field, SAR activity initially increased and then gradually became paradoxical. During paradoxical cycling, SAR activity started and stopped abruptly, oscillating between high frequency discharge during lung deflation and silence during peak inflation. Removing PEEP reduced basal cyclic stimulation and returned the discharge pattern to normal, that is, SAR activity was highest at peak inflation pressure but silent during deflation. It is speculated that stretching SARs causes Na(+) influx, producing generator potential (GP). Normally, GP recovers by Na(+) extrusion via Na(+)/K(+)-ATPase. Ouabain inhibits the ATPase, which limits Na(+) extrusion, and thus sustains the GP. Therefore, after ouabain microinjection, lung inflation will further increase GP, causing over-excitation to silence the SARs.
Action Potentials ; physiology ; Adaptation, Physiological ; drug effects ; Animals ; Lung ; drug effects ; physiology ; Male ; Mechanoreceptors ; physiology ; Ouabain ; pharmacology ; Pulmonary Stretch Receptors ; drug effects ; physiology ; Pulmonary Ventilation ; drug effects ; physiology ; Rabbits ; Sodium-Potassium-Exchanging ATPase ; antagonists & inhibitors ; physiology ; Vagus Nerve ; physiology

The effects of paraventricular nucleus (PVN) stimulation and vasopressin on gastric ischemia-reperfusion injury (GI-RI) were investigated in male SD rats of which the celiac artery was clamped for 30 min and reperfused for 1 h by removal of the clamp. The results were as follows. Both electrical and chemical stimulation of the PVN obviously attenuated the GI-RI. Bilateral electrolytic lesion of the nucleus tractus solitarius (NTS) or microinjection of AVP-V(1) receptor antagonist into the NTS could eliminate the protective effect of electrical stimulation of the PVN on GI-RI. Hypophysectomy did not influence the effect of electrical stimulation of the PVN. Both vagotomy and sympathectomy could increase the effect of stimulating PVN on GI-RI. Microinjection of arginine-vasopressin (AVP) into the PVN also attenuated the effect on GI-RI. These results suggest that the PVN and AVP participate in the regulation of GI-RI and play an important role in protection against GI-RI. This protective effect of PVN on GI-RI might be mediated by activation of AVP-ergic neurons in the PVN, which release AVP from the descending projection fibers and activate the AVP-V(1) receptors on the NTS neurons. The vagus and sympathetic nerves are involved in the efferent pathway exerting their effects on GI-RI. Hypophysis does not seem to be involved in the protective effect of PVN stimulation.
Afferent Pathways ; physiology ; Animals ; Electric Stimulation ; Male ; Paraventricular Hypothalamic Nucleus ; drug effects ; physiology ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; physiopathology ; therapy ; Stimulation, Chemical ; Stomach ; blood supply ; Sympathetic Nervous System ; physiology ; Vagus Nerve ; physiology ; Vasopressins ; pharmacology

To study the possibility of activation of vagus afferent in response to lipopolysaccharide (LPS) through interleukin-1 (IL-1), Wistar rats were randomly divided into LPS group and saline (NS) group. The expression of c-Fos, CD14 and Mac-1 were detected by immunohistochemistry staining. IL-1 bioactivity was determined by L929 cell proliferation. The expression of IL-1R I mRNA was detected by in situ hybridization. Our results showed that there were some c-Fos protein expression positive neurons in the nodose ganglion in LPS group, but no c-Fos protein expression positive neurons in the nodose ganglion in control group. The number of macrophages (M phi) in the connective tissue surrounding the abdominal vagus increased significantly in response to LPS i.p. Forty-five minutes after the application of LPS, the IL-1 bioactivity in the supernatant of M phi was increased. Positive IL-1R mRNA neurons were also observed in the nodose ganglion in the LPS group. The results indicate that vagus afferent is activated in response to LPS and that IL-1 production might be involved in the activation of vagus afferent.
Animals ; Cells, Cultured ; Interleukin-1 ; biosynthesis ; physiology ; Lipopolysaccharides ; pharmacology ; Macrophages ; drug effects ; metabolism ; Male ; Neurons, Afferent ; drug effects ; metabolism ; Proto-Oncogene Proteins c-fos ; biosynthesis ; Rats ; Rats, Wistar ; Vagus Nerve ; drug effects ; metabolism

OBJECTIVETo confirm the effect of Er'bao granule (EBG) on the sensitivity to peripheral afferent signal of neurons in lateral hypothalamic area (LHA) to illustrate the central mechanism of EBG in promoting ingestion behavior.

METHODSThe anorexia rat model was established by feeding special prepared forage for one week, and all the model rats were administrated with EBG by gavage for 3 weeks. The spontaneous discharge of LHA neurons was recorded using electro-physiological extracellular recording method, and its response to electrical stimulus on gastric vagus nerve and intravenous injection of glucose were observed and compared among the normal, model and treated groups.

RESULTSAs compared with the normal group, among the LHA neurons responding to afferent gastric vagal impulse, the proportion of glycemia-sensitive neurons in the model group was significantly decreased (P <0.01), but insignificant difference was shown in comparison between the treated group and the normal group.

CONCLUSIONEBG play a role in regulating the sensitivity of LHA neurons to peripheral afferent signal and thus to influence the multi-afferent information integration of ingestion central neurons.

Afferent Pathways ; drug effects ; Animals ; Anorexia ; drug therapy ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Electrophysiology ; Feeding Behavior ; drug effects ; Hypothalamic Area, Lateral ; physiopathology ; Neurons ; physiology ; Phytotherapy ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Vagus Nerve ; physiopathology

Natural toxic substances have a bitter taste and their ingestion sends signals to the brain leading to aversive oral sensations. In the present study, we investigated chronological changes in c-Fos immunoreactivity in the nucleus tractus solitarius (NTS) to study the bitter taste reaction time of neurons in the NTS. Equal volumes (0.5 mL) of denatonium benzoate (DB), a bitter tastant, or its vehicle (distilled water) were administered to rats intragastrically. The rats were sacrificed at 0, 0.5, 1, 2, 4, 8, or 16 h after treatment. In the vehicle-treated group, the number of c-Fos-positive nuclei started to increase 0.5 h after treatment and peaked 2 h after gavage. In contrast, the number of c-Fos-positive nuclei in the DB-treated group significantly increased 1 h after gavage. Thereafter, the number of c-Fos immunoreactive nuclei decreased over time. The number of c-Fos immunoreactive nuclei in the NTS was also increased in a dose-dependent manner 1 h after gavage. Subdiaphragmatic vagotomy significantly decreased DB-induced neuronal activation in the NTS. These results suggest that intragastric DB increases neuronal c-Fos expression in the NTS 1 h after gavage and this effect is mediated by vagal afferent fibers.
Adjuvants, Immunologic/pharmacology ; Afferent Pathways/physiology ; Animals ; Injections/veterinary ; Ligands ; Male ; Proto-Oncogene Proteins c-fos/*metabolism ; Quaternary Ammonium Compounds/*pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, G-Protein-Coupled/*metabolism ; Solitary Nucleus/*physiology ; Vagus Nerve/*drug effects/*physiology

OBJECTIVETo observe abnormalities in heart rate variability (HRV) in diabetic rats and to explore the effects of treatment with Guizhi Decoction ([symbols; see text]) on cardiac autonomic nervous (CAN) imbalance.

METHODSA radio-telemetry system for monitoring physiological parameters was implanted into rats to record electrocardiac signals and all indictors of HRV [time domain measures: standard deviation of all RR intervals in 24 h (SDNN), root mean square of successive differences (RMSSD), percentage of differences between adjacent RR intervals greater than 50 ms (PNN50), and standard deviation of the averages of RR intervals (SDANN); frequency domain measures: low frequency (LF), high frequency (HF), total power (TP), and LF/HF ratio]. The normal group was randomly selected, and the remaining rats were used to establish streptozocin (STZ)-induced diabetic model. After 4 weeks, the model rats were divided into the model group, the methycobal group, and the Guizhi Decoction group, 9 rats in each group. Four weeks after intragastric administration of the corresponding drugs, the right atria of the rats were collected for immunohistochemical staining of tyrosine hydroxylase (TH) and choline acetyltransferase (CHAT) to observe the distribution of the sympathetic and vagus nerves in the right atrium. The myocardial homogenate from the interventricular septum and the left ventricle was used for determination of TH, CHAT, growth-associated protein 43 (GAP-43), nerve growth factor (NGF), and ciliary neurotrophic factor (CNTF) levels using an enzyme-linked immunosorbent assay.

RESULTS(1) STZ rats had elevated blood glucose levels, reduced body weight, and decreased heart rate; there was no difference between the model group and the drug treated groups. (2) Compared with the model group, only RMSSD and TP increased in the methycobal group significantly (P<0.05); SDNN, RMSSD, PNN50, LF, HF, and TP increased, LF/HF decreased (P<0.05), and SDANN just showed a decreasing trend in the Guizhi Decoction group (P>0.05). TH increased, CHAT decreased, and TH/CHAT increased in the myocardial homogenate of the model group (P<0.05). Compared with the model group, left ventricular TH reduced in the methycobal group; and in the Guizhi Decoction group CHAT increased, while TH and TH/CHAT decreased (P<0.05). Compared with the model group, CNTF in the interventricular septum increased in the methycobal group (P<0.05); GAP-43 increased, NGF decreased, and CNTF increased (P<0.05) in the Guizhi Decoction group. There were significant differences in the reduction of NGF and elevation of CNTF between the Guizhi Decoction group and the methycobal group (P<0.05). (3) Immunohistochemical results showed that TH expression significantly increased and CHAT expression significantly decreased in the myocardia of the model group, whereas TH expression decreased and CHAT expression increased in the Guizhi Decoction group (P<0.05).

CONCLUSIONGuizhi Decoction was effective in improving the function of the vagus nerve, and it could alleviate autonomic nerve damage.

Animals ; Autonomic Nervous System ; drug effects ; physiopathology ; Choline O-Acetyltransferase ; metabolism ; Diabetes Mellitus, Experimental ; drug therapy ; physiopathology ; Diabetic Neuropathies ; drug therapy ; physiopathology ; Disease Models, Animal ; Drugs, Chinese Herbal ; pharmacology ; Heart ; innervation ; physiopathology ; Heart Rate ; drug effects ; physiology ; Male ; Monitoring, Physiologic ; methods ; Rats, Wistar ; Telemetry ; methods ; Treatment Outcome ; Tyrosine 3-Monooxygenase ; metabolism ; Vagus Nerve ; drug effects ; physiopathology

OBJECTIVEOur previous work suggested that sensitivity of hippocampal neurons is changed in process of epileptic activities, and closely parallel to the dynamic characteristic of epileptic activity of the neurons. This study investigated the sensitivity of epileptic brain to vagal nerve stimulation (VNS) in epileptic process.

METHODSEpileptic model was evoked by penicillin. Left vagal nerves were stimulated to inhibit the seizures induced by penicillin. The electrocorticography (ECoG) and electromyography (EMG) were recorded to analyze inhibiting effect of VNS in epileptic process.

RESULTSIt was found that VNS could inhibit the seizures caused by penicillin, and the inhibiting effect of VNS to seizures increased as the vagal nerve stimulating time prolonged. It was also found that the inhibiting effect of VNS to seizures decreased in epileptic process.

CONCLUSIONThe results suggested that the sensitivity of epileptic brain to VNS was different in epileptic process. The inhibiting effect of VNS to seizure decreased as the development of seizures.

Action Potentials ; physiology ; Animals ; Electric Stimulation ; Electroencephalography ; Electromyography ; Epilepsy ; chemically induced ; prevention & control ; Frontal Lobe ; physiopathology ; Male ; Motor Cortex ; drug effects ; physiopathology ; Neural Inhibition ; physiology ; Nonlinear Dynamics ; Parietal Lobe ; physiopathology ; Penicillins ; Rats ; Rats, Sprague-Dawley ; Seizures ; chemically induced ; prevention & control ; Vagus Nerve ; physiology