title: Galanin interacts with serotonin in stimulating prolactin secretion in the rat.
abstract: Abstract The interaction of galanin (GAL) with serotonin (5-HT) in the regulation of prolactin (PAL) secretion was investigated in urethaneanesthetized male rats. Intracerebroventricular administration of 5-HT (1 and 10 mu g) and GAL (1 mu g) caused an increase in plasma PRL levels, but co-administration of GAL did not show any additive effect on 5-HT-induced PRL secretion. Pretreatment with methysergide (0.25 mg/kg), a nonselective 5-HT1 and 5-HT2 receptor antagonist, partially inhibited the PRL increase induced by GAL. On the other hand, neither ketanserin (0.25 mg/kg), a selective 5-HT2 receptor antagonist, nor ICS 205-930 (0.25 mg/kg), a selective 5-HT3 receptor blocker, had any effect on GAL-induced increase in PRL secretion. Parachlorophenylalanine (300 mg/kg), a 5-HT synthesis inhibitor, however, caused a marked enhancement of PRL release induced by GAL, which was partially inhibited by a 5-HT neurotoxin, 5, 6-dihydroxytryptamine. Parachlorophenylalanine also caused a potentiation of 5-HT-induced PRL release, possibly by sensitizing 5-HT receptors. These findings suggest that 5-HT receptors are, at least partly, involved in GAL-induced PRL release in the rat.
authors.affiliation: Second Division, Department of Internal Medicine, Kyoto University Faculty of Medicine, Kyoto 606, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Koshiyama
authors.forename: A
authors.initials: A
authors.lastname: Shimatsu
authors.forename: H
authors.initials: H
authors.lastname: Assadian
authors.forename: N
authors.initials: N
authors.lastname: Hattori
authors.forename: Y
authors.initials: Y
authors.lastname: Ishikawa
authors.forename: T
authors.initials: T
authors.lastname: Tanoh
authors.forename: N
authors.initials: N
authors.lastname: Yanaihara
authors.forename: Y
authors.initials: Y
authors.lastname: Kato
authors.forename: H
authors.initials: H
authors.lastname: Imura