β2- and α2-Adrenergic Receptors and Receptor Coupling to Adenylate Cyclase in Human Mononuclear Leukocytes and Platelets in Relation to Physiological Variations of Sex Steroids*

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Abstract
In view of evidence, largely in animals, indicating effects of sex steroids on adrenergic receptors, we measured mononuclear leukocyte (MNL) β2-adrenergic receptors and adenylate cyclase sensitivity to stimulation by isoproterenol as well as platelet α2-adrenergic receptors and sensitivity of sodium fluoride-stimulated adenylate cyclase to inhibition by epinephrine in 3 groups of normal humans with physiologically disparate levels of testosterone, estradiol, and progesterone (10 normal men and 10 normal women, the latter sampled in both the follicular and luteal phases of their menstrual cycles). Differences in testosterone, estradiol, and progesterone were as expected; testosterone levels were 10-fold higher in men, and progesterone levels were 20-fold higher in luteal phase women. T4, cortisol, and norepinephrine levels did not differ. Basal plasma epinephrine concentrations were slightly but significantly higher in luteal phase women [34 ± 5 (±SE) pg/ml] than in follicular phase women (16 ± 3 pg/ml; P ⟨ 0.01) or men (20 ± 3 pg/ml; P ⟨ 0.05). There were no significant differences among these 3 groups in the densities or affinities of MNL /β2- adrenergic or platelet α2-adrenergic receptors or in the corresponding MNL and platelet adenylate cyclase sensitivities. Thus, there is not a generalized effect of physiological variations of testosterone, estradiol, and progesterone on adrenergic receptors or adenylate cyclase. To the extent that the adrenergic receptors and adenylate cyclase activities of circulating cells reflect those of extravascular catecholamine target cells, these data provide no support for a role of physiological variations of testosterone, estradiol, or progesterone in the regulation of catecholamine action in humans.