The effects of propranolol and acebutolol on the overnight plasma levels of anterior pituitary and related hormones.

1 The effects of single evening doses of the beta-adrenoceptor blocking agents propranolol (80 mg orally) and acebutolol (200 mg orally) on plasma levels throughout the night of prolactin, growth hormone, luteinising hormone, follicle stimulating hormone, cortisol and testosterone have been studied in seven healthy male volunteers. 2 Three way analysis of variance showed that acebutolol significantly reduced circulating levels of prolactin and follicle stimulating hormone, but did not alter the levels of the other hormones studied. 3 Propranolol significantly reduced follicle stimulating hormone and testosterone, and significantly increased circulating levels of cortisol, but caused no change in the other hormones studied. 4 Prolactin, luteinising hormone, testosterone and cortisol showed a significant variation with time indicating the existence of a diurnal rhythm in the pattern of their secretion. 5 There was a significant inter-subject variability in all the hormones studied. 6 There was a significant between-subject variation in response to both propranolol and acebutolol. 7 Different subjects showed significant variations with respect to time in prolactin, growth hormone and cortisol levels. 8 Neither propranolol nor acebutolol significantly altered the time course of secretion of any of the hormones studied. 9 Possible relationships of these beta-adrenoceptor blocker-induced changes in anterior pituitary and related hormones to the antihypertensive mechanism of acebutolol and propranolol are discussed.