Neuronal nicotinic acetylcholine receptor in the hypothalamus: morphological diversity and neuroendocrine regulations.
The subcellular localization and functional significance of neuronal nicotinic acetylcholine receptor alpha4-subunits were investigated in the rat hypothalamic supraoptic nucleus. A high level of alpha4 mRNA expression was found in the magnocellular neurons in the supraoptic nucleus. Strong immunoreactitivy for alpha4 in neurons of the supraoptic nucleus was detected in the rough endoplasmic reticulum and cytoplasmic matrix, although it was very weak in the Golgi apparatus, except for the transport vesicles. Immunoreactivity for alpha4 was detected in both the pre-synaptic axon terminals and post-synaptic axon terminals. A high level of signals for vasopressin mRNA was detected in the supraoptic nucleus after the animals were injected s.c. with nicotine. These findings suggest that alpha4-containing subtypes are synthesized in the rough endoplasmic reticulum and transported to the plasma membrane and serve as pre- and post-synaptic nicotinic acetylcholine receptors. Nicotine may up-regulate vasopressin gene expression in the supraoptic nucleus, acting through nicotinic acetylcholine receptors.
Shioda
S
S
Department of Anatomy, Showa University School of Medicine, Tokyo, Japan. shioda@med.showa-u.ac.jp
Nakajo
S
S
Hirabayashi
T
T
Nakayama
H
H
Nakaya
K
K
Matsuda
K
K
Nakai
Y
Y
D000818:Animals; D001369:Axons / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D017931:DNA Primers; D018870:Endoplasmic Reticulum, Rough / Q000378:metabolism; D014644:Genetic Variation; D007031:Hypothalamus / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D016253:Microscopy, Immunoelectron; D009474:Neurons / Q000378:metabolism*; D009538:Nicotine / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D011978:Receptors, Nicotinic / Q000096:biosynthesis* / Q000235:genetics; D013495:Supraoptic Nucleus / Q000187:drug effects / Q000378:metabolism; D013569:Synapses / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D014158:Transcription, Genetic / Q000187:drug effects*; D015854:Up-Regulation; D014667:Vasopressins / Q000096:biosynthesis
D017931:DNA Primers; D009538:Nicotine; D012333:RNA, Messenger; D011978:Receptors, Nicotinic; D014667:Vasopressins