Increase of ovarian progesterone secretion by β2-adrenergic stimulation in oestrous rats

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Abstract
Estrous rats were anesthetized with pentobarbital and 1 of the femoral arteries, femoral veins and utero-ovarian veins were cannulated. Five min blood fractions were collected from the ovary for 50 min. Following 2 control fractions fenoterol, noradrenaline [norepinephrine], isoproterenol (0.5 .mu.g/min) or 0.9% NaCl (0.02 ml/min) were infused i.v. for 40 min. In a group of estrous animals, fenoterol was given locally to the ovarian bursa. Blood pressure and the ovarian venous outflow were continuously recorded and blood levels of progesterone (P) and estradiol-17.beta. (E2) were determined by RIA [radioimmunoassay]. Fenoterol administered i.v. increased P secretion without altering ovarian blood flow, while noradrenaline and isoproterenol had no effect on P secretion. Fenoterol administered locally stimulated both P and E2 secretion, and this was prevented by i.v. infusion of propranolol. Apparently ovarian .beta.2-adrenergic receptors have a regulatory role in ovarian hormone secretion.