Effect of two dopamine agonists, TL-99 and 3-PPP, on prolactin secretion in the rat

TL-99 and 3-PPP, two putative dopamine autoreceptor agonists, effectively suppressed serum prolactin (PRL) concentrations in rats treated with alpha-methyltyrosine. In addition, the secretion of PRL from anterior pituitary tissue under in vitro conditions was significantly inhibited by TL-99 and 3-PPP. These findings are supportive of the view that TL-99 and 3-PPP exert a dopamine agonist action at dopamine receptors in the anterior pituitary gland.