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    Melatonin effects on serotonin synthesis and metabolism in the striatum, nucleus accumbens, and dorsal and median raphe nuclei of rats.
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    A substance P antagonist has recently been reported to have clinical efficacy in the treatment of depression. We have therefore analysed sections from human pons, including the raphe region, with double in situ hybridization using riboprobes complementary to substance P and the 5-hydroxytryptamine transporter (5-HT-T mRNAs). A distinct overlap of cell bodies expressing these two markers was observed in the dorsal and median raphe nuclei. Analysis of double-labelled sections revealed that almost half of the 5-HT neurons in the dorsal raphe and around 25% in the median raphe nucleus expressed substance P mRNA. The highest percentage was observed in the ventrolateral dorsal raphe nucleus and the lowest in the caudal raphe nucleus. These results demonstrate that the phenotype of the raphe 5-HT neurons varies between species, since so far no 5-HT-substance P co-existence has been demonstrated in the dorsal raphe complex of rat. The question is raised whether the present results may be of significance for understanding a possible role of substance P in depression.
    Dorsal raphe nucleus
    Raphe nuclei
    Serotonergic cell groups
    Raphe
    Median raphe nucleus
    Nucleus raphe magnus
    Objective: To study the expression changes of serotonin transporter(SERT) in the rostral raphe nuclei of postmortem brainstem in alcoholic human.Methods:Immunoautoradiography method was used to reveal SERT immunoreactive intensity and the results were compared with those of healthy controls.Results: Strongly labeling signals of SERT were mainly found in the rostral raphe nuclei of the rostral pons and midbrain in control group,while the signal was reduced in those nuclei of alcoholic group.Quantitative analysis revealed that the intensity of SERT immunoreactivity(SERT-IR) was significantly lower in median raphe nucleus(MnR),caudal part of dorsal raphe nucleus(DRC),interfascicular part of dorsal raphe nucleus(DRI),ventral part of dorsal raphe nucleus(DRV) and dorsal part of dorsal raphe nucleus(DRD) of alcoholic group compared with that in corresponding nuclei of control group.The difference of SERT-IR intensity in those nuclei of both group was statistically significant(P0.05: MnR,DRV and DRD;P0.01:DRI and DRC respectively).Conclusion: Reduced expression of the serotonin transporter in the rostral raphe nuclei is found in the alcoholic human.
    Dorsal raphe nucleus
    Serotonergic cell groups
    Raphe nuclei
    Raphe
    Median raphe nucleus
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    Dorsal raphe nucleus
    Retrograde tracing
    Raphe
    Raphe nuclei
    Median raphe nucleus
    P-Chloroamphetamine
    Anterograde tracing
    Abstract: Extracellular 5‐hydroxytryptamine (5‐HT) in the median raphe and dorsal hippocampus was measured using in vivo microdialysis. Administration of 60 m M K + through the probe into the median raphe region significantly increased 5‐HT output from the median raphe and the right dorsal hippocampus. Local infusion of 10 µ M tetrodotoxin into the median raphe region substantially decreased 5‐HT in the median raphe and left and right dorsal hippocampus. Systemic administration (0.3 mg/kg s.c.) of 8‐hydroxy‐2‐(di‐ n ‐propylamino)tetralin (8‐OH‐DPAT) decreased the 5‐HT levels in the dialysates from both the median raphe region and dorsal hippocampus. Administration of 30 n M 8‐OH‐DPAT through the dialysis probe into the median raphe region decreased 5‐HT output from the median raphe and dorsal hippocampus significantly, whereas at concentrations from 60 n M to 10 µ M , no significant effects were found in either region. With 100 µ M 8‐OH‐DPAT, a significant increase was seen in the median raphe region, but not in dorsal hippocampus. Similar findings were obtained following microinjections of different doses of the compound into the median raphe region. The results of this study indicate that the somatodendritic release of 5‐HT is impulse flow‐dependent. Moreover, the decrease of 5‐HT in the median raphe region by low nanomolar concentrations of 8‐OH‐DPAT supports the notion that somatodendritic 5‐HT release is subject to a local negative feedback mechanism through 5‐HT 1A autoreceptors.
    Dorsal raphe nucleus
    Raphe nuclei
    Median raphe nucleus
    Raphe
    Microdialysis
    Serotonergic cell groups
    Abstract Nucleus raphe pallidus (RPa) lies ventrally in the caudal brainstem, where it is coextensive rostrally with the nucleus raphe magnus (RMg) and caudally with the nucleus raphe obscurus (ROb). Retrograde neuronal tracing studies of our laboratory, carried out in rats and presented elsewhere, with fluorogold, true-blue or fast-blue, iontophoretically injected or by crystalline deposit, along the RPa extent, displayed many labeled pericaria at the preoptic area (POA), as well as lateral (LH) and dorsomedial (DMH) hypothalamus; paraventricular nucleus (PVN) and dorsal (DR) and median (MnR) raphe nuclei among others structures. In addition, RPa, which projects to the intermediolateral column, has been demonstrated to bear relation to many of the somatic-visceral functions also reported for POA. Iontophoretic injections of PHA-L, an anterograde tracer, in the POA subnuclei, presented terminal and varicose labeled fibers in RPa, as well as in the RMg, ROb, paraventricular thalamic (PVA), PVN and supraoptic nucleus (SO), LH, subparaventricular zone (sPVZ) and locus coeruleus (LC). Interestingly, POA, PVA, PVN, LH and SO have been described as retino- and suprachiasmatic-recipients. Taken together, these neuronal connections between brainstem raphe nuclei and POA, the similarity of functions to which they are related, as well as connections with other retino-suprachiasmatic-recipient structures, suggest that these caudal brainstem raphe nuclei could be part of the output system for the expression of some biological rhythms.
    Dorsal raphe nucleus
    Raphe nuclei
    Serotonergic cell groups
    Nucleus raphe magnus
    Locus coeruleus
    Raphe
    Preoptic area
    Median raphe nucleus
    Supraoptic nucleus