Coexistence of varying combinations of neuropeptides with 5-hydroxytryptamine in neurons of the raphe pallidus et obscurus projecting to the spinal cord.
The coexistence of varying combinations of substance P (SP), somatostatin (SOM), thyrotropin-releasing hormone (TRH) and met-enkephalin-Arg-Gly-Leu (ENK) with 5-hydroxytryptamine (5-HT) as semiquantitatively revealed by immunocytochemistry in neuronal perikarya of the raphe pallidus et obscurus in the guinea-pig was analyzed. SOM coexisted most frequently with 5-HT, followed by SP, ENK and TRH. Many 5-HT neurons were immunoreactive to 2 or more peptides such as SP/SOM, SOM/ENK, SP/ENK, SOM/TRH, SP/TRH or SOM/SP/ENK. Most of these neurons were shown to project to the spinal cord by retrograde HRP labeling combined with immunocytochemistry. After hemisection of the cervical spinal cord at the C5 level, ENK and 5-HT immunoreactive nerve terminals in the ipsilateral intermediolateral nucleus of the thoracic spinal cord were decreased in number. The results indicate that neurons in the raphe pallidus et obscurus projecting to the spinal cord can be classified into subpopulations according to which peptides coexist with 5-HT, and may have different functions.
Chiba
T
T
Department of Anatomy, Chiba University School of Medicine, Japan.
Masuko
S
S
D000818:Animals; D006168:Guinea Pigs; D007150:Immunohistochemistry; D008297:Male; D009479:Neuropeptides / Q000378:metabolism*; D011903:Raphe Nuclei / Q000166:cytology / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D013004:Somatostatin / Q000378:metabolism*; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism*
D009479:Neuropeptides; D012701:Serotonin; D013004:Somatostatin