Sulpiride effects on nigral and striatal glutamic acid decarboxylase activity: a possible involvement of prolactin.

Sulpiride, a benzamide derivative neuroleptic, was shown to significantly increase glutamic acid decarboxylase activity in substantia nigra and corpus striatum in either acutely or chronically injected male rats. Hypophysectomy completely prevented this effect suggesting an involvement of an anterior pituitary factor in the central action of sulpiride. Prolactin might possibly mediate the effects of sulpiride since it is known to increase prolactin secretion by an action at the level of the anterior pituitary. Consistent with this hypothesis was the finding of a similar increase in nigral and striatal glutamic acid decarboxylase activity in hyperprolactinemic animals in which an anterior pituitary had been implanted under the kidney capsule.