Do catecholamines play a physiologic role in regulating corpus luteum function in the pseudopregnant rabbit?
In these studies the beta-adrenergic receptor antagonist propranolol was administered to estrogen-treated hypophysectomized pseudopregnant rabbits in vivo, and serum progesterone concentrations were measured to monitor luteal function. In Experiment 1, which was designed to determine an effective dose of propranolol, 1 mg/(kg X h) s.c. propranolol for 3 h (integral of 80 ng/ml in serum) gave an adequate level of beta-adrenergic receptor blockade, i.e., a 1000-fold inhibition of the blood pressure/isoproterenol dose-response relationship. In Experiment 2, "acute" administration of propranolol (P; 1 mg/(kg X h) s.c.) or saline (control, C) for 24 h on Days 7-8, 10-11, and 13-14 of pseudopregnancy did not produce any marked differences in serum progesterone concentrations in P or C animals on any of the days tested, although hourly fluctuations were observed. In Experiment 3, "chronic" (4-day) treatment with propranolol was achieved by the use of propranolol-containing pellets placed s.c. (integral of 200-600 ng/ml in serum), on Days 13-17. Control animals received pellets of vehicle only. Serum progesterone concentrations were very similar in P and C animals throughout the period of treatment (Days 13-17) and on Days 18 and 20. We conclude that endogenous catecholamines play no major role in regulating luteal steroidogenesis or corpus luteum regression in the pseudopregnant rabbit.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002395:Catecholamines / Q000502:physiology*; D003338:Corpus Luteum / Q000503:physiopathology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D007016:Hypophysectomy; D007545:Isoproterenol / Q000494:pharmacology; D011374:Progesterone / Q000097:blood; D011433:Propranolol / Q000097:blood / Q000494:pharmacology; D011555:Pseudopregnancy / Q000503:physiopathology*; D011817:Rabbits
D002395:Catecholamines; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D011433:Propranolol; D007545:Isoproterenol