Platelet α2-Adrenoceptor and Adenylate Cyclase in Patients with Anorexia Nervosa and Bulimia

Abstract

Platelets α²-adrenoceptors were studied in 24 patients with anorexia nervosa shortly after admission to the hospital and after 10% Weight gain. Twenty patients with bulimia and 24 healthy age- and sex-matched normal subjects also were studied. Receptor number was significantly increased in patients with bulimia arid anorexia nervosa. After 10% weight gain, the receptor number almost normalized in anorexia nervosa patients. K_d values were increased in all patient groups at all times of study. In patients with bulimia or anorexia nervosa, both initially and after weight gain, the maximal effect of prostaglandin E₁ (PGE₁) on platelet cAMP production was greatly increased, while the half-maximally effective dose was unchanged. Also, the maximal inhibitory effects of epinephrine and clonidine on PGE₁-stimulated platelet cAMP production were greater, while the half-maximal dose of both α₂-agonists was unchanged. Metabolic and endocrine indicators of starvation were present in both bulmic and anorexia nervosa patients initially. Blood β-hydroxybutyric acid was elevated, and plasma T₃ values and the orthostatic response of plasma norepinephrine (ΔNA) were reduced, while cortisol was elevated (only in anorexia nervosa patients). Among these parameters, only ΔNA significantly correlated with the actions of PGE₁ and epinephrine on cAMP production. In conclusion, the activity of the sympthetic nervous system was reduced in patients with anorexia nervosa and bulimia. This reduction was accompanied by an increased capacity and a decreased affinity of platelet α₂- receptors and an increased PGE₁ stimulatory and epinephrine inhibitory effects on cAMP production.(J Clin Endocrinol Metab61: 1053, 1985)