Stimulatory effects of prostaglandin E 1 on rat anterior pituitary cyclic amp and luteinizing hormone release

Abstract

The effect of prostaglandin E 1 (PGE 1) on rat anterior pituitary cyclic AMP accumulation and luteinizing hormone (LH) release was studied both in vivo and in vitro. Addition of PGE 1 to incubation medium over a concentration range of 10 -6 to 10 -4 M produced a graded increase in pituitary cyclic AMP. At the lowest concentration (10 -6 M) there was no significant increase in LH release, but proportional increments in LH release were seen with increasing concentrations of PGE 1. Ten minutes after intravenous administration of 5 μg of PGE 1 to adult male rats, pituitary cyclic AMP was substantially increased while serum LH levels were not changed. Administration of a higher dose of PGE 1 (20 μg) produced a greater increase in pituitary cyclic AMP; and, at this dose serum LH was significantly increased. These results suggest that the PGE 1 effect on LH release is mediated by the adenyl cyclase — cyclic AMP system.