Effects of Acupuncture on Monoamine Neurotransmitters in Raphe Nuclei in Obese Rats

Effects of acupuncture on the levels of neurotransmitters in the raphe nuclei were investigated in obeserats.It was found that the levels of tryptophan (Trp) and 5-hydroxyindoleacetic acid (5-HIAA) wereincreased,and 5-hydroxytryptamine (5-HT) level and 5-HT/5-HIAA ratio decreased in the raphe nucleiof the obese group as compared with the normal group;and that acupuncture could produce weightreduction,increase the 5-HT level and 5-HT/5-HIAA ratio,and decrease the contents of Trp and5-HIAA,but did not change the levels of dopamine (DA) and noradrenaline (NA).It is indicated thatbenign regulative action of acupuncture on 5-HT and its metabolism in the raphe nuclei is possibly oneof the factors for reducing weight by acupuncture.

The raphe nuclei are the early lesion site of gastric α-synuclein propagation to the substantia nigra

Parkinson's disease(PD)is a neurodegeneration disease withα-synuclein accumulated in the substantia nigra pars compacta(SNpc)and most of the dopaminergic neurons are lost in SNpc while patients are diagnosed with PD.Exploring the pathology at an early stage contributes to the development of the disease-modifying strategy.Although the“gut–brain”hypothesis is proposed to explain the underlying mechanism,where the earlier lesioned site in the brain of gastricα-synuclein and howα-synuclein further spreads are not fully understood.Here we report that caudal raphe nuclei(CRN)are the early lesion site of gastricα-synuclein propagating through the spinal cord,while locus coeruleus(LC)and substantia nigra pars compacta(SNpc)were further affected over a time frame of 7 months.Pathologicalα-synuclein propagation via CRN leads to neuron loss and disordered neuron activity,accompanied by abnormal motor and non-motor behavior.Potential neuron circuits are observed among CRN,LC,and SNpc,which contribute to the venerability of dopaminergic neurons in SNpc.These results show that CRN is the key region for the gastricα-synuclein spread to the midbrain.Our study provides valuable details for the“gut–brain”hypothesis and proposes a valuable PD model for future research on early PD intervention.

Effects of 5-hydroxytryptamine ascending pathways of dorsal raphe nuclei and habenular nucleus on the respiration and blood pressure of rats

Obstructive sleep apnea syndrome （OSAS） was a disease of breath obstacle happened in the process of sleep. The central mechanism of OSAS has not yet been fully elucidated. Most of studies focused on raphe nuclei and 5-hydroxytryptamine （5-HT）, and showed that brain serotonergic activity might be decreased in OSAS. It is well known that the dorsal and medial raphe nuclei provide almost all the serotonergic innervation to the forebrain. A previous study evaluated the stimulation of the dorsal raphe nuclei （DRN） in the rat inducing mainly pressor and sympathoexcitatory responses.

GLUTAMATE－IMMUNOREACTIVE NEURONS IN MEDULLARY RAPHE－CEREBELLUM PATHWAY IN THE KITTEN

Using a combined microsphere retrograde transport with immunofluorescence technique,the glutamate-immunoreactive neurons in the medullary raphe nuclei that project to the cerebellar cortex were investigated in the present study.The cells double-labeled by glutamate-immunoresctivity and microspheres were found in all medullary raphe nuclei.Among all the cerebellar projection neurons in the medullary raphe nuclei,(49. 49±2.78)% (±)in pallidus (NRP),(62.02±3. 62) % in obscures (NRD),(3. 03±3. 03) % in magnus (NRM) were immunoreactive to glutamate.The results raise the possibility that the cerehellar vermal cortex (lobules Ⅴ-Ⅶ) may receive some excitatory input from medullary raphe nuclei to affect the function of the cerebellum.

Hypoxia-ischemia in the immature rodent brain impairs serotonergic neuronal function in certain dorsal raphé nuclei

Neonatal hypoxia-ischemia(HI) results in losses of serotonergic neurons in specific dorsal raphé nuclei. However, not all serotonergic raphé neurons are lost and it is therefore important to assess the function of remaining neurons in order to understand their potential to contribute to neurological disorders in the HI-affected neonate. The main objective of this study was to determine how serotonergic neurons, remaining in the dorsal raphé nuclei after neonatal HI, respond to an external stimulus(restraint stress). On postnatal day 3(P3), male rat pups were randomly allocated to one of the following groups:(i) control + no restraint(n = 5),(ii) control + restraint(n = 6),(iii) P3 HI + no restraint(n = 5) or(iv) P3 HI + restraint(n = 7). In the two HI groups, rat pups underwent surgery to ligate the common carotid artery and were then exposed to 6% O2 for 30 minutes. Six weeks after P3 HI, on P45, rats were subjected to restraint stress for 30 minutes. Using dual immunolabeling for Fos protein, a marker for neuronal activity, and serotonin(5-hydroxytrypamine; 5-HT), numbers of Fos-positive 5-HT neurons were determined in five dorsal raphé nuclei. We found that restraint stress alone increased numbers of Fos-positive 5-HT neurons in all five dorsal raphé nuclei compared to control animals. However, following P3 HI, the number of stress-induced Fos-positive 5-HT neurons was decreased significantly in the dorsal raphé ventrolateral, interfascicular and ventral nuclei compared with control animals exposed to restraint stress. In contrast, numbers of stress-induced Fos-positive 5-HT neurons in the dorsal raphé dorsal and caudal nuclei were not affected by P3 HI. These data indicate that not only are dorsal raphé serotonergic neurons lost after neonatal HI, but also remaining dorsal raphé serotonergic neurons have reduced differential functional viability in response to an external stimulus. Procedures were approved by the University of Queensland Animal Ethics Committee(UQCCR958/08/NHMRC) on February 27, 2009.