Effect of exogenous female sex-steroid hormones on beta 2-adrenoceptors in healthy males.
OBJECTIVE
We have previously demonstrated that exogenous progesterone, but not oestrogen, upregulated lymphocyte beta 2-adrenoceptors (beta 2-AR) when given during the follicular phase in healthy females. In the present study, we were interested to see whether this facilitatory effect of female sex-steroid hormones could be demonstrated in healthy males.


METHODS
Nine healthy male volunteers with a mean age of 24 years completed this randomised, double-blind, placebo-controlled, cross-over study. They were randomised to receive either oral placebo, oestradiol valerate (4 mg) or medroxyprogesterone (40 mg). The study medication was given in two divided doses 12 h apart. Subjects attended the laboratory at baseline (T0 is baseline), 1 h after ingestion of the second dose of study medication (T1) and 24 h later (T24). At each visit, 60 ml of peripheral blood was withdrawn for measurement of serum oestradiol, progesterone and testosterone levels, and for lymphocyte beta 2-AR parameters; density (Bmax), binding affinity (Kd) and maximal cyclic AMP response to isoprenaline (Emax).


RESULTS
Baseline levels of sex-steroid hormones were comparable for each of the treatment periods. Serum oestradiol levels increased significantly, twofold, 1 h after ingestion of oestradiol but there was no significant change in levels of serum progesterone and testosterone. Lymphocyte beta 2-AR parameters following treatment with oestradiol and progesterone did not change significantly from baseline and were not different from placebo.


CONCLUSIONS
In contrast to previously reported effects in women, female sex-steroid hormones did not appear to have any significant facilitatory effects on lymphocyte beta 2-AR parameters when given exogenously to healthy males. This lack of effect may be due either to the absence of receptors for female sex hormones in beta 2-AR or to reduced efficacy of female hormone-receptor coupling in male lymphocytes.
Tan
K S
KS
Department of Clinical Pharmacology, Ninewells Hospital & Medical School, University of Dundee, UK.
McFarlane
L C
LC
Lipworth
B J
BJ
D000328:Adult; D004311:Double-Blind Method; D004958:Estradiol / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology; D004966:Estrogens, Conjugated (USP) / Q000494:pharmacology; D012739:Gonadal Steroid Hormones / Q000494:pharmacology*; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008525:Medroxyprogesterone / Q000494:pharmacology*; D011374:Progesterone / Q000097:blood; D045167:Progesterone Congeners / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D018343:Receptors, Adrenergic, beta-2 / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D013739:Testosterone / Q000097:blood
D004966:Estrogens, Conjugated (USP); D012739:Gonadal Steroid Hormones; D045167:Progesterone Congeners; D018343:Receptors, Adrenergic, beta-2; D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D008525:Medroxyprogesterone