OBJECTIVETo investigate the efferent pathway from the dorsal raphe nucleus to the inner ear.

METHODSEleven adult cats weighing 2.0 - 3.0 kg were used. The animals had no middle-ear disease and their auricle reflex was sensitive to sound. They were divided into experimental group (8 cats) and control group (3 cases). The fluorescent tracer cholera toxin subunit-B (CTB) was injected into cat cochlea and the CTB-labelled neurons of dorsal raphe nucleus (DRN) were identified using an immunofluorescence technique after a survival period of 7 days. For studying other fluorescence labelling, the sections containing CTB-labelled neurons were divided into four groups and incubated in antisera directed against tyrosine hydroxylase (TH), serotonin (5-HT), gamma-aminobutyric acid (GABA) and dopamine B-hydroxylase (DBH), respectively. Single-and double-labelled neurons were identified from the DRN.

RESULTS(1) A subpopulation of dorsal raphe nucleus (DRN) neurons were intensely labelled with CTB and these CTB-labelled neurons were densely distributed in a dorsomedial part of the DRN; (2) Four immunolabelling, TH, 5-HT, GABA and DBH were presented throughout the DRN. Of the total population of CTB-labelled neurons, 100% were TH-labelled neurons (double labelling) and no double-stained neuron with 5-HT, GABA and DBH was observed in the DRN.

CONCLUSIONSThere was a projection from DRN to the inner ear and this pathway might be a dopaminergic projection.

Animals ; Cats ; Ear, Inner ; innervation ; metabolism ; Efferent Pathways ; Neurons ; metabolism ; physiology ; Raphe Nuclei ; metabolism ; physiology

AIMTo investigate the roles of serotonergic neurons in dorsal raphe nuclei (DRN) in sleep.

METHODSStereotaxic, microinjection and polysomnography (PSG) were used in the experiment.

RESULTSMicroinjection of L-glutanate (L-Glu) into the DRN decreased slow wave sleep (SWS) and paradoxical sleep (PS), and increased wake (W). Microinjection of kainic acid (KA) and p-chlorophenylalanine (PCPA) respectively into the DRN, SWS and PS were promoted, and W was reduced.

CONCLUSIONSerotonergic neurons in dorsal raphe nuclei involved in the regulation of sleep. Sleep was reduced when the serotonergic neurons were excited, and when the neurons were inhibited. sleep was increased

Action Potentials ; Animals ; Male ; Neurons ; physiology ; Polysomnography ; Raphe Nuclei ; physiology ; Rats ; Rats, Sprague-Dawley ; Serotonin ; physiology ; Sleep ; physiology

OBJECTIVETo explore the interrelationship among dorsal motor nucleus of the vagus (DMV), locus coeruleus (LC) and raphe magnus nucleus (NRM) in the mechanism of the descending regulation on gastric motility, which may constitute a parasympathetic local circuit, work as a neural center of gastric modulation in brainstem.

METHODSUsing nucleus location, electric stimulation and lesion, together with microinjection, and recording the inter-gastric pressure.

RESULTS(1) LC stimulation could inhibit the gastric motility significantly (P < 0.01), DMV lesion weaken this effect, while blocking the a receptor on DMV could reverse the effect. (2) NRM stimulation reduced the amplitude of gastric constriction (P < 0.01), DMV lesion could abolish the effect, but blocking the 5-HT2A receptor on DMV depressed the gastric motility heavily (P < 0.01) like NRM stimulation. While LC lesion could abolish the effect of NRM stimulation, and microinjection of ritanserin into LC could likewise abolish it.

CONCLUSION(1) LC inhibit the gastric motility via a receptor in DMV, and meanwhile may excite it through 5-HT2A receptor in DMV, these two ways work together to keeping the gastric motility amplitude normally. (2) NRM inhibit the gastric motility via 5-HT2A receptor in LC.

Animals ; Brain Stem ; physiology ; Female ; Gastrointestinal Motility ; physiology ; Locus Coeruleus ; physiology ; Male ; Motor Neurons ; physiology ; Raphe Nuclei ; physiology ; Rats ; Rats, Sprague-Dawley ; Vagus Nerve ; physiology

In the present study, changes of the neuronal activity of 5-hydroxytrypamine (5-HT) neurons of dorsal raphe nucleus(DRN) in a rat model of Parkinson's disease (PD) were investigated with glass microelectrode recording. The results showed that the discharge rates of 5-HT neurons in control and PD rats were (1.61+/-0.56) Hz and (2.61+/-1.97) Hz, respectively. The discharge rate of PD rats was significantly increased when compared to that of the control rats. In control rats, 79% of 5-HT neurons discharged regularly and 21% in bursts. In PD rats, however, 36% of 5-HT neurons discharged regularly, 16% irregularly and 47% in bursts. The percentage of 5-HT neurons discharging in bursts was obviously higher than that of the control rats (P<0.05). The data suggest that the discharge rate and bursting pattern of 5-HT neurons in DRN are increased in a rat model of Parkinson's disease.
Animals ; Electrophysiology ; Male ; Microelectrodes ; Neurons ; physiology ; Parkinson Disease ; physiopathology ; Raphe Nuclei ; metabolism ; physiopathology ; Rats ; Rats, Sprague-Dawley ; Serotonin ; metabolism

In this paper the response characteristic of the nerve fiber to the modulation magnetic field induction is studied by using the method of numeric simulation. It is found that the nerve fiber is sensitive to the low frequency modulated signal but not to the high frequency carrier wave. A simulative EEG signal generator is developed according to the change of EEG rhythm during the sleep. The simulative EEG square wave is modulated by high-frequency magnetic impulse. The modulation magnetic field is coupled into the rabbit's brain to study the influence of magnetic stimulation on the discharge of 5-hydroxytryptamine (5-HT) nerve cell. The experiment results demonstrate that discharge frequency of median raphe nuclei related to sleep changes significantly and the discharge becomes slow, which shows that magnetic stimulation can inhibit electrical activity of 5-HT nerve cell and provide a new way to improve insomnia.
Animals ; Brain ; metabolism ; physiology ; Computer Simulation ; Electroencephalography ; Electromagnetic Fields ; Electrophysiology ; Humans ; Neurons ; physiology ; Rabbits ; Raphe Nuclei ; metabolism ; physiology ; Serotonin ; metabolism ; Sleep ; physiology ; Sleep Initiation and Maintenance Disorders ; metabolism ; physiopathology

Animals ; Blood Pressure ; drug effects ; Electric Stimulation ; Female ; Habenula ; physiology ; Lidocaine ; pharmacology ; Male ; Raphe Nuclei ; physiology ; Rats ; Rats, Wistar ; Respiration ; drug effects ; Serotonin ; physiology

In vivo extracellular recordings were made in the subthalamic nucleus (STN) of intact control rats and rats with 5,7-dihydroxytryptamine (5,7-DHT) -produced lesion of dorsal raphe nucleus (DRN). The results showed that the firing rate of STN neurons in control rats and DRN-lesioned rats were (6.93+/-6.55) Hz and (11.27+/-9.31) Hz, respectively, and the firing rate of DRN-lesioned rats significantly increased when compared to the control rats (P<0.01). In control rats, 13% of STN neurons discharged regularly, 46% irregularly and 41% in bursts. In DRN-lesioned rats, 9% of STN neurons discharged regularly, 14% irregularly and 77% in bursts, the percentage of STN neurons firing in bursts was obviously higher than that of the control rats (P<0.01). In addition, the mean interspike interval coefficient of variation of STN neurons in control rats and DRN-lesioned rats were (0.05+/-0.04) and (0.11+/-0.09), respectively. The mean interspike interval coefficient of variation of DRN-lesioned rats was significantly higher than that of the control rats (P<0.001). These results show that the firing rate and the bursting pattern rate of neurons in STN of DRN-lesioned rats increase significantly, suggesting that DRN inhibits the neuronal activity of the subthalamic neurons in the intact rat.
5,7-Dihydroxytryptamine ; pharmacology ; Adrenergic Agents ; pharmacology ; Animals ; Electrophysiological Phenomena ; Male ; Neurons ; physiology ; Random Allocation ; Raphe Nuclei ; drug effects ; pathology ; Rats ; Rats, Sprague-Dawley ; Subthalamic Nucleus ; physiopathology

Initially, when periaqueductal gray (PAG) is electrically stimulated, analgesia is induced, and this phenomenon is called stimulation-produced analgesia. Nucleus raphe magnus (NRM) as well as PAG are known to be the potent analgesic centers. NRM could modulate the nociceptive response of spinal cord neurons through spinally projecting fibers. However, as well as the above analgesic effects have been confined to the somatic pain, it was variable according to species, and the analgesic effect by NRM stimulation on the visceral pain was not yet clarified. In this study the analgesic effect by NRM stimulation on the visceral pain was examined through recording the activities of the dorsal horn neurons with renal input and renal pain, as a type of visceral pain. The renal pain was induced by ureteral occlusion or renal arterial occlusion, which in turn activated the renal mechanoreceptor or chemoreceptor. These cells had concomitant somatic input. In order to compare the effects of NRM stimulation on the renal pain with somatic pain, the somatic stimulation such as squeezing was conducted on the peripheral receptive field. The main results are summarized as follows: 1) After an electrical stimulation of NRM, spontaneous activities of dorsal horn neurons with renal input were reduced to 73.3 +/- 9.7% of the control value. 2) After an electrical stimulation of NRM, activities of dorsal horn neurons with renal input evoked by a brush, a type of non-noxious stimuli, did not change significantly. But the activities by a squeeze, a type of noxious stimuli, the activities were reduced to 63.2 +/- 7.2% of the control value. 3) After an electrical stimulation of NRM, activities of dorsal horn neurons with renal input evoked by occlusion of ureter or renal artery were reduced to 46.7 +/- 8.8% and 49.0 +/- 8.0% of the control value respectively. 4) The inhibitory effect of NRM on the dorsal horn neurons with renal input did not show any difference between renal A delta fiber and C fiber group. 5) By the electrical stimulation of NRM, the activities evoked by ureteral occlusion showed more reduction in the high threshold cell group than in the wide dynamic range cell group. These results suggest that activation of NRM can alleviate the renal pain as well as the somatic pain by modulating the dorsal horn neurons activities.
Afferent Pathways/cytology/physiology ; Animal ; Cats ; Electric Stimulation ; Female ; Kidney/innervation/*physiopathology ; Male ; Nervous System/cytology ; Nervous System Physiology ; Neurons/physiology ; *Pain Threshold ; Raphe Nuclei/*physiology ; Spinal Cord/cytology/physiology ; Support, Non-U.S. Gov't

By means of Fos immunocytochemistry, nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry and microinjection methods, the role of nitric oxide synthase (NOS) of dorsal raphe (DR) neurons in the modulation of rats sigmoid pain was studied. The results showed: (1) Rats exhibited aversive behavioral responses related to visceral pain after injecting formalin into the sigmoid wall. NOS neurons in DR were up-regulated, in addition, about 8% of NOS-labeled neurons were Fos positive. By contrast, there were no Fos/NOS double-labeled neurons in the control group. (2) Formalin-induced sigmoid pain scores and the expression of Fos in the spinal cord at S1 segment were decreased after microinjecting L-NAME into the DR. These findings suggest that NOS neurons are involved in the modulation of formalin-induced sigmoid pain and that NO may play an important role in the transmission of visceral nociceptive message in the midbrain.
Analgesics ; pharmacology ; Animals ; Genes, fos ; Microinjections ; NG-Nitroarginine Methyl Ester ; pharmacology ; Neurons ; physiology ; Nitric Oxide Synthase ; metabolism ; Nociceptors ; physiology ; Pain ; chemically induced ; physiopathology ; Pain Measurement ; Raphe Nuclei ; physiology ; Rats ; Rats, Sprague-Dawley ; Sigmoid Diseases ; chemically induced ; physiopathology

In the present study, changes in the neuronal activity of serotonergic neurons in the dorsal raphe nucleus (DRN) and the effect of the selective 5-HT(1A) receptor antagonist WAY-100635 in a rat model of Parkinson's disease (PD) were investigated by using extracellular single unit recording. Rat model of PD was produced by microinjection of 6-hydroxydopamine (6-OHDA) into the substantia nigra pars compacta on the right side of the brain. The results showed that the mean spontaneous firing rate of DRN serotonergic neurons in the control and 6-OHDA-lesioned rats were (1.76+/-0.11) spikes/s (n=24) and (2.43+/-0.17) spikes/s (n=21), respectively. The firing rate of serotonergic neurons in 6-OHDA-lesioned rats was significantly higher than that in the control rats (P<0.001). In the control rats, 92% (22/24) of the neurons fired regularly and 8% (2/24) fired in bursts. In rats with 6-OHDA lesions, 9% (2/21) of neurons fired regularly, 43% (9/21) exhibited irregular pattern and 48% (10/21) fired in bursts. The percentage of DRN serotonergic neurons firing in bursts was obviously higher in 6-OHDA-lesioned rats than that in the control rats (P<0.001). Local injection of WAY-100635 (3 microg in 200 nL) into the DRN significantly increased the firing rate of serotonergic neurons with no change in firing pattern in the control rats (n=19, P<0.002), but did not change the firing rate and firing pattern of serotonergic neurons in 6-OHDA-lesioned rats (n=17, P>0.05). These results suggest the dysfunction of 5-HT(1A) receptor in 6-OHDA-lesioned rats and the involvement of the DRN in the pathophysiological mechanism of PD.
Action Potentials ; physiology ; Animals ; Disease Models, Animal ; Male ; Neurons ; physiology ; Oxidopamine ; Parkinsonian Disorders ; chemically induced ; physiopathology ; Piperazines ; pharmacology ; Pyridines ; pharmacology ; Raphe Nuclei ; physiopathology ; Rats ; Rats, Sprague-Dawley ; Serotonin ; metabolism ; Serotonin Antagonists ; pharmacology