title: Nicotine increases cytosolic Ca2+ in vasopressin neurons.
abstract: Strong immunoreactivity for neuronal nicotinic acetylcholine receptor alpha4 subunit was detected in neurons of the supraoptic nucleus (SON). At the ultrastructural level, immunoreactivity for alpha4 was detected in the post-synaptic membranes as well as in the cytoplasmic matrices in the magnocellular neurons. Nicotine (1-10 microM) increased cytosolic Ca2+ concentrations ([Ca2+]i) in isolated arginine-vasopressin (AVP)-containing neurons in the rat SON. Nicotine (10 microM) was less potent in increasing [Ca2+]i in AVP-containing neurons than noradrenaline (1 microM), a known neurotransmitter in the SON. The nicotine-induced [Ca2+]i increase in AVP-containing neurons was markedly reduced when pre-treated with a protein kinase A (PKA) blocker, H89 (40 microM). These findings suggest that nicotine, a known neurotransmitter in the SON, activates AVP-containing neurons via nicotinic acetylcholine receptor which is linked to stimulation of cAMP-PKA-regulated Ca2+ signaling pathway.
authors.affiliation: Department of Anatomy, Showa University School of Medicine, Tokyo, Japan. shioda @ med. showa-u.ac.jp
authors.forename: S
authors.initials: S
authors.lastname: Shioda
authors.forename: T
authors.initials: T
authors.lastname: Yada
authors.forename: S
authors.initials: S
authors.lastname: Muroya
authors.forename: M
authors.initials: M
authors.lastname: Takigawa
authors.forename: Y
authors.initials: Y
authors.lastname: Nakai
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011978:Receptors, Nicotinic / Q000378:metabolism; D017483:Receptors, Vasopressin / Q000187:drug effects*; D013495:Supraoptic Nucleus / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D018722:Nicotinic Agonists; D011978:Receptors, Nicotinic; D017483:Receptors, Vasopressin; D009538:Nicotine; D002118:Calcium; D009638:Norepinephrine