Sleep deprivation has been shown to exacerbate pain sensitivity and may contribute to the onset of chronic pain, yet the precise neural mechanisms underlying this association remain elusive. In our study, we explored the contribution of cholinergic neurons within the medial habenula (MHb) to hyperalgesia induced by sleep deprivation in rats. Our findings indicate that the activity of MHb cholinergic neurons diminishes during sleep deprivation and that chemogenetic stimulation of these neurons can mitigate the results. Interestingly, we did not find a direct response of MHb cholinergic neurons to pain stimulation. Further investigation identified the interpeduncular nucleus (IPN) and the paraventricular nucleus of the thalamus (PVT) as key players in the pro-nociceptive effect of sleep deprivation. Stimulating the pathways connecting the MHb to the IPN and PVT alleviated the hyperalgesia. These results underscore the important role of MHb cholinergic neurons in modulating pain sensitivity linked to sleep deprivation, highlighting potential neural targets for mitigating sleep deprivation-induced hyperalgesia.
Animals ; Habenula/physiology* ; Sleep Deprivation/physiopathology* ; Cholinergic Neurons/physiology* ; Male ; Hyperalgesia/physiopathology* ; Rats, Sprague-Dawley ; Rats ; Interpeduncular Nucleus/physiology* ; Pain Threshold/physiology* ; Midline Thalamic Nuclei/physiology* ; Neural Pathways/physiopathology*

OBJECTIVE: To analyze the differentially expressed proteins in the dorsal raphe nucleus of rats treated with olanzapine and explore the possible mechanism of metabolic disorders in the early stage of olanzapine treatment. METHODS: Twenty male and 20 female SD rats were both randomized equally into olanzapine group and control group for daily treatment with olanzapine and saline for 4 weeks, respectively. One hour after the last treatment, the dorsal raphe nucleus of the rats was dissected for proteomic analysis using iTRAQ combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). GO, KEGG pathway, COG, pathways and protein interaction network analyses of the differentially expressed proteins were performed. Several target genes were selected from the proteomic list, and their expression levels in the dorsal raphe nucleus of another 24 mice with identical grouping and treatment using real time real-time quantitative PCR and Western blotting. RESULTS: A total of 214 differentially expressed proteins were identified in the dorsal raphe nucleus of olanzapine-treated mice, including 72 unregulated and 142 downregulated proteins. GO analyses showed that the differentially expressed proteins were enriched in cellular process, biological regulation, metabolic process, response to stimulus, multicellular organismal process, bindings, catalytic activity, molecular function regulator and transcription regulator activity. KEGG analysis suggested that these proteins were enriched in fluid shear stress and atherosclerosis, serotonergic synapse, butanoate metabolism, thyroid hormone synthesis and IL-17 signaling pathway. The differentially expressed proteins Cav1, Hsp90b1, Canx, Gnai1, MAPK9, and LOC685513 were located at the nodes of the protein-protein interaction network in close relation with metabolic disorders. In olanzapine-treated mice, the expression of Hmgcs2, a negative regulator of apoptosis, was significantly down-regulated in the dorsal raphe nucleus, where the expressions of Pla2g4e, Slc6a4 and Gnai1 involved in serotonergic synapse were significantly upregulated. CONCLUSION In the early stage of treatment, olanzapine may contribute to the occurrence of metabolic disorders in rats by regulating the expressions of Cav1, Hsp90b1, Canx, Gnai1, MAPK9, LOC685513 (Gng14) and 5-HTR2 synapse-related proteins in the dorsal raphe nucleus.
Animals ; Chromatography, Liquid ; Computational Biology ; Dorsal Raphe Nucleus ; Female ; GTP-Binding Protein alpha Subunits, Gi-Go ; Male ; Mice ; Olanzapine/adverse effects* ; Proteomics ; Rats ; Rats, Sprague-Dawley ; Tandem Mass Spectrometry

OBJECTIVE: It is unclear whether the decline in dopamine transporters (DAT) differs among idiopathic rapid eye movement sleep behavior disorder (iRBD) patients with different levels of olfactory impairment. This study aimed to characterize DAT changes in relation to nonmotor features in iRBD patients by olfactory loss. METHODS: This prospective cohort study consisted of three age-matched groups: 30 polysomnography-confirmed iRBD patients, 30 drug-naïve Parkinson's disease patients, and 19 healthy controls without olfactory impairment. The iRBD group was divided into two groups based on olfactory testing results. Participants were evaluated for reported prodromal markers and then underwent 18F-FP-CIT positron emission tomography and 3T MRI. Tracer uptakes were analyzed in the caudate, anterior and posterior putamen, substantia nigra, and raphe nuclei. RESULTS: Olfactory impairment was defined in 38.5% of iRBD patients. Mild parkinsonian signs and cognitive functions were not different between the two iRBD subgroups; however, additional prodromal features, constipation, and urinary and sexual dysfunctions were found in iRBD patients with olfactory impairment but not in those without. Tracer uptake showed significant group differences in all brain regions, except the raphe nuclei. The iRBD patients with olfactory impairment had uptake reductions in the anterior and posterior putamen, caudate, and substantia nigra (p < 0.016 in all, adjusted for age), which ranged from 0.6 to 0.8 of age-normative values. In contrast, those without olfactory impairment had insignificant changes in all regions ranging above 0.8. CONCLUSION: There was a clear distinction in DAT loss and nonmotor profiles by olfactory status in iRBD.
Brain ; Cognition ; Cohort Studies ; Constipation ; Dopamine Plasma Membrane Transport Proteins ; Dopamine ; Humans ; Magnetic Resonance Imaging ; Parkinson Disease ; Positron-Emission Tomography ; Prospective Studies ; Putamen ; Raphe Nuclei ; REM Sleep Behavior Disorder ; Sleep, REM ; Smell ; Substantia Nigra

PURPOSE: Stress during pregnancy is a risk factor for the development of anxiety-related disorders in offspring later in life. The effects of treadmill exercise on anxiety-like behaviors and hippocampal cell proliferation were investigated using rats exposed to prenatal stress. METHODS: Exposure of pregnant rats to a hunting dog in an enclosed room was used to induce stress. Anxiety-like behaviors of offspring were evaluated using the elevated plus maze test. Immunohistochemistry for the detection of 5-bromo-2'-deoxyuridine and doublecortin (DCX) in the hippocampal dentate gyrus and 5-hydroxytryptamine 1A receptors (5-HT(1A)) in the dorsal raphe was conducted. Brain-derived neurotrophic factor (BDNF) and tyrosine kinase B (TrkB) levels in the hippocampus were evaluated by western blot analysis. RESULTS: Offspring of maternal rats exposed to stress during pregnancy showed anxiety-like behaviors. Offspring also showed reduced expression of BDNF, TrkB, and DCX in the dentate gyrus, decreased cell proliferation in the hippocampus, and reduced 5-HT(1A) expression in the dorsal raphe. Postnatal treadmill exercise by offspring, but not maternal exercise during pregnancy, enhanced cell proliferation and expression of these proteins. CONCLUSIONS: Postnatal treadmill exercise ameliorated anxiety-like behaviors in offspring of stressed pregnant rats, and the alleviating effect of exercise on these behaviors is hypothesized to result from enhancement of cell proliferation through 5-HT(1A) activation in offspring rats.
Animals ; Anxiety* ; Blotting, Western ; Brain-Derived Neurotrophic Factor ; Bromodeoxyuridine ; Cell Proliferation* ; Dentate Gyrus ; Dogs ; Dorsal Raphe Nucleus ; Exercise Test ; Hippocampus ; Immunohistochemistry ; Pregnancy ; Prenatal Exposure Delayed Effects ; Protein-Tyrosine Kinases ; Rats* ; Receptor, Serotonin, 5-HT1A* ; Risk Factors ; Serotonin*

The present study is aimed to investigated the firing activity of pyramidal neurons and interneurons in the medial prefrontal cortex (mPFC) in rats with bilateral intraventricular injection of 5,7-dihydroxytryptamine (5,7-DHT) by using in vivo extracellular recording. The results showed that the injection of 5,7-DHT reduced the 5-hydroxytryptamine (5-HT) levels in the mPFC and dorsal raphe nucleus in the rats. The firing rate of mPFC pyramidal neurons in rats with 5,7-DHT injection was significantly higher than that of normal rats, and the firing pattern of these neurons also changed significantly towards a more burst-firing, while the injection decreased the firing rate of mPFC interneurons and changed the firing pattern of the interneurons towards a more irregular. These results indicate that the lesions of the serotonergic neurons lead to the changes in the firing activity of mPFC pyramidal neurons and interneurons, suggesting that serotonergic system plays an important role in the regulation of the neuronal activity in the mPFC.
5,7-Dihydroxytryptamine ; pharmacology ; Action Potentials ; Animals ; Dorsal Raphe Nucleus ; cytology ; Injections, Intraventricular ; Interneurons ; drug effects ; Prefrontal Cortex ; cytology ; Pyramidal Cells ; drug effects ; Rats ; Serotonin ; metabolism

OBJECTIVETo investigate the relationship between serotonin (5-HT) and epilepsy and the mechanism of learning-memory in pilocarpine (PILO)-induced epileptic rats after 5,7-dihydroxytryptamine (5,7-DHT) microinjection in median raphe nucleus.

METHODSAdult S D rats were randomly divided into 3 groups: PILO group, PILO+ 5,7-DHT group, vehicle control group; PILO group was divided into two groups by status epilepticus (SE): PILO + SE group and PILO - SE group. The rats' seizures and cortex electroencephalography (EEG) were observed by video EEG. The rats' spatial learning-memory was evaluated by Morris water maze. Finally, serotonergic neuron in raphe nuclei was observed by immunohistochemistry.

RESULTSAfter treatment of 5,7-DHT (PILO + 5,7-DHT group), the success rate, the mortality and the frequency of chronic spontaneous seizures in pilocarpine-induced epilepsy model were all improved. Compared with the control group, the number of serotonergic neuron in raphe nuclei was decrease in PILO + SE group (P < 0.05). Moreover, it's extremely decrease in PILO + 5,7-DHT group (P < 0.01). Compared with control group, the mean escape latency was prolonged, the times of crossing target was decreased and the retention time in target zone was shortened in PILO + SE group (P < 0.05), but there was no significant difference between PILO + SE group and PILO + 5,7-DHT group.

CONCLUSIONDepletion of serotonin may facility the rats' epileptic seizures, but we could not interpret which may cause epileptic rats' cognitive deficit.

5,7-Dihydroxytryptamine ; toxicity ; Animals ; Epilepsy ; chemically induced ; metabolism ; psychology ; Male ; Maze Learning ; Memory ; Pilocarpine ; adverse effects ; Raphe Nuclei ; Rats ; Rats, Sprague-Dawley ; Serotonin ; metabolism

Sleep is not just a rest for brain activity during daytime, but also has a vital function for memory consolidation after learning as well as restoration of both body and brain. While restoration of the body mainly occurs during non-rapid eye movement (NREM) sleep, especially during slow wave sleep, restoration of brain and memory consolidation occurs mainly during REM sleep. Adenosine acts as a sleep-inducing agent, so called somnogen or hypnotoxin which accumulates while awake. Sleep deprivation results in the disruption of every aspect of physical, cognitive, and behavioral function, which can be reversed only by sleep. Many neurotransmitter-secreting nuclei in the brain stem, hypothalamus, and basal forebrain are key structures for wakefulness, NREM, and REM sleep. They have been localized in the basal forebrain (acetylcholine), ventrolateral preoptic area (VLPO, GABA and galanin), tuberomamillary nucleus (TMN, histamine), lateral and posterior hypothalamus (orexin/hypocretin), reticular formation (glutamate), substantia nigra/ventral tegmental area (SN/VTA, dopamine), pedunculopontine nucleus and lateral dorsal tegmentum (PPT-LDT, acetylcholine), locus ceruleus (norepinephrine), and the raphe nuclei (serotonin). All are activated during wakefulness except VLPO which secrets GABA and galanin, which suppress other nuclei for sleep induction. Acetylcholine-secreting PPT-LDT is a major locus for REM sleep, and is inhibited by the raphe nuclei and locus ceruleus which act as REM-off neurons inducing NREM sleep. The suprachiasmatic nucleus is a pacemaker for circadian rhythms, which can be modified by bright light and melatonin. It should be emphasized that the best performance of cognitive function including reactivity, abstract thinking, creativity, memory, executive function, and accurate and efficient work as well as physical well-being is achieved by sufficient and appropriate sleep.
Adenosine ; Adolescent ; Brain ; Brain Stem ; Child ; Circadian Rhythm ; Creativity ; Executive Function ; Eye Movements ; Galanin ; gamma-Aminobutyric Acid ; Humans ; Hypothalamus ; Hypothalamus, Posterior ; Learning ; Light ; Locus Coeruleus ; Melatonin ; Memory ; Neurons ; Preoptic Area ; Prosencephalon ; Raphe Nuclei ; Reticular Formation ; Sleep Deprivation ; Sleep, REM ; Suprachiasmatic Nucleus ; Thinking ; Wakefulness

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

BACKGROUND/AIMS: While it is well established that acupuncture relieves somatic pain, its therapeutic effect on visceral pain such as irritable bowel syndrome (IBS) is unclear. We evaluated the effect of acupuncture in treating visceral hyperalgesia in an animal model. METHODS: Sprague-Dawley rats (n = 8 per group) with prior neonatal maternal separation stress were randomly allocated to receive 3-day treatment of either electroacupuncture (EA) or sham acupuncture at acupoint ST-36. Another group of rats without prior maternal separation was included as non-handled controls. Colorectal distension was performed on the day after acupuncture treatment. The 3 groups were compared for pain threshold as determined by abdominal withdrawal reflex and visceromotor response as measured by electromyogram. Colon, spinal cord, and brainstem were sampled for topographic distribution and quantitative assessment of serotonin and Fos expression by immunohistochemistry. RESULTS: Rats in EA group had significantly higher pain threshold compared to those in sham acpuncture group (25.0 +/- 5.7 mmHg vs 18.7 +/- 5.2 mmHg, p = 0.01) and it was comparable with that of non-handled treatment naive controls (29.4 +/- 9.3 mmHg, p = 0.28). They also had lower visceromotor response as measured by electromyogram compared to those received sham acupuncture at all colorectal distension pressures. EA significantly suppressed Fos expression in doral raphe nuclei of brainstem, superficial dorsal horn of spinal cord and colonic epithelium but suppressed 5-HT expression only in brainstem and spinal cord. CONCLUSIONS: Electro acupuncture attenuates visceral hyperlagesia through down-regulation of central serotonergic activities in the brain-gut axis.
Acupuncture ; Acupuncture Points ; Animals ; Axis, Cervical Vertebra ; Benzodiazepines ; Brain Stem ; Colon ; Down-Regulation ; Electroacupuncture ; Epithelium ; Horns ; Hyperalgesia ; Immunohistochemistry ; Irritable Bowel Syndrome ; Models, Animal ; Nociceptive Pain ; Pain Threshold ; Raphe Nuclei ; Rats ; Rats, Sprague-Dawley ; Reflex ; Salicylamides ; Serotonin ; Spinal Cord ; Visceral Pain

This study was conducted to define the underlying mechanism of hypophagia induced by increased central serotonergic action. Rats received 3 daily injections of 5-hydroxy-L-tryptophan (5-HTP), a serotonin precursor, at a dose of 100 mg/kg/10 ml saline at 1 h before lights off. A significant suppression in food intake was observed shortly after the 5-HTP injection and persisted during 3 daily 5-HTP injections. Neuropeptide Y (NPY) expression in the arcuate nucleus increased after 3 days of 5-HTP treatment, as high as in the pair-fed group. Immunoreactivity of phosphorylated extracellular signal-regulated protein kinase (pERK1/2) in the hypothalamic paraventricular nucleus (PVN) was increased markedly by 3 days of 5-HTP treatment, but not by 3 days of pair-fed. mRNA expression levels of serotonin reuptake transporter (5-HTT) was increased in the dorsal raphe nucleus of the 5-HTP treated rats, but not in the pair-fed group. Results suggest that increased pERK1/2 in the PVN of 5-HTP injected rats may be a part of serotonergic anorectic signaling, perhaps blunting the orectic action of NPY; i.e., 5-HTP injected rats showed hypophagia despite of increased NPY expression in the arcuate nucleus.
5-Hydroxytryptophan ; Animals ; Arcuate Nucleus ; Eating ; Hypothalamus ; Light ; Neuropeptide Y ; Paraventricular Hypothalamic Nucleus ; Protein Kinases ; Raphe Nuclei ; Rats ; RNA, Messenger ; Serotonin