[Effect of a conditioned medium of pinealocytes on prolactin secretion in primary culture of adenohypophyseal cells of male rats].

Conditioned medium of pinealocytes (CMP, 18-20%) added to primary cultures of rat pituitary cells for 1.5 h changed neither the basal rate of PRL secretion nor dopamine-inhibited release. However CMP markedly attenuated PRL secretion induced by thyroliberin or isobutyl-menthylxanthine. Besides CMP reduced basal PRL release during 18-h-incubation. The results obtained indicate possible involvement of the pineal gland in direct inhibitory control of PRL secretion in male rats.