Reciprocal control of oxytocin and cAMP production by porcine granulosa cells in vitro.

Oxytocin and cAMP accumulation in the medium after 4 days incubation of porcine granulosa cells was measured and confirmed the production of these substances by porcine ovaries. Both cAMP analogue dbcAMP (10, 100, 1,000 or 10,000 microM/ml) and 3-isobutyl-1-methyl-xanthine (intracellular cAMP metabolization inhibitor, 0.1, 1, 10 or 100 microM/ml) additions increased granulosa cells oxytocin production in a dose-dependent manner. Low doses of oxytocin or posterior pituitary extract (10 or 100 mIU/ml) had no significant effect on granulosa cAMP output, but higher dose (1,000 mIU/ml) inhibited it. Thus, porcine ovarian oxytocin production can be stimulated via cAMP-dependent intracellular mechanisms. On the other hand, excess of oxytocin can inhibit ovarian cAMP production through a ultra-short loop negative feedback regulation.