Electron microscopic examination of the orexin immunoreactivity in the dorsal raphe nucleus.
The ultrastructure and the synaptic relationships of the orexin-A-like immunoreactive fibers in the dorsal raphe nucleus were examined with an immunoelectron microscopic method. At the electron microscopic level, most of the immunoreactive fibers, a varicosity appearance at the light microscopic level, were found as axon terminals. The large dense-cored vesicles contained in the immunoreactive axon terminals were the most intensely immunostained organellae. These axon terminals were often found to make synapses. While the axo-dendritic synapses were usually asymmetric in appearance, the axo-somatic synapses were symmetric. Orexin-A-like immunoreactive processes with no synaptic vesicles were also found. These processes often received asymmetric synapses. With less frequency, the synapses were found between the orexin-like immunoreactive processes. The results suggest that the orexin peptides are stored in the large dense-cored vesicles; the orexin-containing fibers may have influences on the physiological activities of the dorsal raphe nucleus through direct synaptic relationships.
Wang
Qing-Ping
QP
Department of Anatomy, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan.
Guan
Jian-Lian
JL
Matsuoka
Takashi
T
Hirayana
Yumi
Y
Shioda
Seiji
S
D000818:Animals; D002352:Carrier Proteins / Q000032:analysis / Q000276:immunology* / Q000648:ultrastructure*; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D016253:Microscopy, Immunoelectron; D009479:Neuropeptides / Q000032:analysis / Q000276:immunology*; D000068797:Orexins; D011903:Raphe Nuclei / Q000276:immunology / Q000378:metabolism* / Q000648:ultrastructure*; D051381:Rats; D017208:Rats, Wistar
D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins