title: Effects of nicotine and mecamylamine on rat dorsal raphe neurons.
abstract: This study investigates the hypothesis that serotonin mediates certain nicotine effects, such as mood improvement and the suppression of the ponto-geniculo-occipital spikes of rapid eye movement sleep. The influence of nicotine (10-300 microM) on the firing rate of dorsal raphe neurons and on serotonin release was therefore, studied in rat midbrain slices. Nicotine increased the firing rate, 10-90%, in 67.5% recorded neurons and decreased it, 8-100%, in the remaining 32.5%. Serotonin release increased 2-7 times after nicotine administration, regardless of firing frequency, but the absolute value of serotonin release was 3 times higher during the decreases than during the increases in firing rate. Mecamylamine (1-20 microM) transiently stimulated the dorsal raphe neurons and competitively antagonized the nicotine-induced serotonin release. The results support the working hypothesis and additionally show that mecamylamine also stimulates dorsal raphe neurons.
authors.affiliation: Departamento de Fisiología, Facultad de Medicina, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, DF.
authors.forename: S
authors.initials: S
authors.lastname: Mihailescu
authors.forename: M
authors.initials: M
authors.lastname: Palomero-Rivero
authors.forename: P
authors.initials: P
authors.lastname: Meade-Huerta
authors.forename: A
authors.initials: A
authors.lastname: Maza-Flores
authors.forename: R
authors.initials: R
authors.lastname: Drucker-Colín
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004594:Electrophysiology; D005731:Ganglionic Stimulants / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D008464:Mecamylamine / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D009538:Nicotine / Q000494:pharmacology*; D018733:Nicotinic Antagonists / Q000494:pharmacology*; D011903:Raphe Nuclei / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism
chemical_list: D005731:Ganglionic Stimulants; D018733:Nicotinic Antagonists; D012701:Serotonin; D008464:Mecamylamine; D009538:Nicotine