The dopaminergic inhibition of the gonadotropin-releasing hormone-induced gonadotropin release: an in vitro study with fragments and cell suspensions from pituitaries of the African catfish, Clarias gariepinus (Burchell).

Pituitary fragments and pituitary cell suspensions of the African catfish in a perifusion system released gonadotropic hormone (GTH) spontaneously. After a few hours of perifusion a baseline of GTH release was established. The dopamine (DA) agonist apomorphine (APO) caused a decreased in the release from pituitary fragments but not from pituitary cell suspensions. APO abolished the luteinizing hormone-releasing hormone analog (LH-RHa)-induced GTH release from both pituitary fragments and cell suspensions. It was concluded that DA inhibits the GTH release induced by gonadotropin-releasing hormone.