Effect of adenosine on gonadotropin and prolactin secretion by hemipituitaries in vitro.

Incubation of hemipituitaries from male rats (200-220 g) with 10 nM to 1 microM adenosine induced a dose-dependent decrease of the release of luteinizing hormone (LH) and follicle stimulating hormone (FSH) into the medium, and increased prolactin (PRL) secretion. The effects of 10 nM adenosine were blocked by 100 nM caffeine, whereas 100 nM caffeine alone had no effect on the release of the hormones. Preincubation of hemipituitaries with 1 microM adenosine also inhibited 10 nM luteinizing hormone-releasing hormone (LHRH)-induced LH and FSH release by greater than 90%. These data indicate a regulatory role for adenosine in pituitary LH, FSH and PRL release, and also a possible modulatory effect of adenosine on the LHRH-LH and FSH system.