Effects of forskolin, luteinizing hormone and prostaglandin F2α on isolated rat corpora lutea

Abstract

Abstract. The diterpene forskolin increased in a dosedependent way cyclic AMP (cAMP) accumulation in isolated corpora lutea from immature rats injected with an ovulatory dose of pregnant mare's serum gonadotropin (PMSG). The cAMP increase was significant already after 1 min of incubation with forskolin, and cAMP continued to rise to a maximum at about 30–60 min, with a clear decrease after 240 min of incubation. The forskolin effect was more pronounced in very young corpora lutea (1-day-old) than in older corpora lutea. There was a clear discrepancy between the marked effect on cAMP accumulation by forskolin and the steroidogenic response when compared with the corresponding effects of LH. Forskolin also increased progesterone production, but this effect was marginal compared with that of LH. Prostaglandin F2α (PGF2α) did not influence the forskolin stimulated cAMP increase. PGF2α has previously been shown to inhibit the stimulatory effect of LH on cAMP formation in this type of corpora lutea. The fact that PGF2α did not inhibit the forskolin stimulated cAMP production indicates that PGF2α does not act directly on the adenylate cyclase.