Beta-adrenergic stimulation of cAMP and progesterone in rat ovarian tissue

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Abstract
In vitro effects of adrenergic agonists and antagonists on cAMP and progesterone production in rat ovarian tissue were studied. Ovarian tissue from immature rats treated with pregnant mares'' serum (PMS) or PMS and human chorionic gonadotropin (hCG) was incubated in defined medium 199. The addition of isoproterenol to follicular-dominant ovaries (PMS-treated rats) produced an increase in cAMP in a dose-related manner (10-8-10-5 M). Luteal-dominant tissue (PMS- and hCG-treated rats) was considerably less responsive to isoproterenol. No changes in cGMP were seen after the addition of 10-4 M isoproterenol for various incubation times. Stimulation of cAMP in follicular-dominant tissue by either 10-5 M isoproterenol or 10-5 M epinephrine was significantly reduced by the addition of 10-5 M propranolol, a .beta.-adrenergic antagonist; phentolamine, an .alpha.-adrenergic antagonist, was ineffective. Neither propranolol nor phentolamine had any significant effect on luteinizing hormone (LH [lutropin])-promoted increases in cAMP in luteal-dominant tissue. Both isoproterenol and Arterenol promoted an increase in progesterone production after 1 h of incubation with follicular-dominant ovaries; the agents were ineffective when added to luteal-dominant tissue. Activation of .beta.-adrenergic receptors in ovarian tissue may mediate increases in cAMP and progesterone production. Apparently the receptors for LH and .beta.-adrenergic agents are different. A distinct difference in response to .beta.-adrenergic agents in follicular-dominant and luteal-dominant tissues was also found.