Involvement of beta-adrenoceptors in a central regulation of the ovarian progesterone release in rats.

UNLABELLED: The intracerebroventricular (i.c.v.) injection of epinephrine modifies ovarian progesterone (P) release in rats on diestrus day 2 (D2).

OBJECTIVES: To investigate the characteristic of a central adrenergic effect on the ovarian P release on D2. Also, the function of the superior ovarian nerve (SON) is re-examined.

METHODS AND RESULTS: P concentrations were measured using radioimmunoassay techniques. The i.c.v. injection of 5 mg isoproterenol (beta-adrenergic agonist) in SON-intact rats on D2, decreased the P levels in ovarian vein blood from 1 to 25 min after injection (p<0.05). Similar treatment in SON-transected rats did not modify the P concentrations in ovarian vein blood between 1 and 25 min after injection. After 5 microg propranolol (beta-adrenergic antagonist) i.c.v. injection in SON-intact rats, the P levels in ovarian vein blood increased from 2 to 4 min (p<0.05). Similar treatment in SON-transected rats did not change the P concentrations in ovarian vein blood during 25 min after injection. The i.c.v. injection of 5 microg phenylephrine (alpha-adrenergic agonist) in SON-intact or SON-transected rats, did not modify the P levels in ovarian vein blood between 1 and 25 min after injection. After 5 microg phentolamine (alpha-adrenergic antagonist) i.c.v. injection in SON-intact or SON-transected rats, the P concentrations in ovarian vein blood did not change during 25 min.

CONCLUSIONS: These results suggest the participation of central beta-adrenergic receptors in the neural regulation of the ovarian P release in rats on D2, and, furthermore, that the central beta-adrenergic input is conduced almost entirely through the superior ovarian nerve.