Hormonal replacement therapy affects calcitonin gene-related peptide and atrial natriuretic peptide secretion in postmenopausal women

Objective: Menopause is associated with critical changes in the cardiovascular system, and the possible effect of hormonal replacement therapy (HRT) on these changes is under investigation. The aim of our study was to evaluate in postmenopausal women the effects of HRT and clonidine on the response of plasma calcitonin gene-related peptide (CGRP) and plasma atrial natriuretic peptide (ANP) to the upright posture test and the saline infusion test respectively. Methods: CGRP and ANP levels were measured with specific radioimmunological assays and expressed in pmol/l (means+/-S.E.M). Design: Postmenopausal women (age 46-53 years) (n=18) were studied before and after 3 months of HRT (n=13) or clonidine treatment (n=5). Results: After HRT or clonidine treatment plasma CGRP levels (14.9+/-1.6 and 15.9+3.8 pmol/l) were significantly higher than before (9.8+0.6 and 10.5+/-1.6 pmol/l) (P<0.01). The assumption of upright posture caused no change in plasma CGRP levels before treatment, while after HRT, but not after clonidine treatment, an increase in plasma CGRP levels was observed (P<0.01 at 5 and 20 min). Basal plasma ANP levels significantly decreased after both HRT and clonidine treatment (P<0.01). In untreated women the saline infusion test did not induce any change in plasma ANP levels; a significant response to the test was restored after HRT but not after clonidine treatment (P<0.01 at 90 and 120 min). Conclusions: The results show that some of the adaptive responses modified by menopausal changes are restored by HRT but not clonidine treatment, suggesting a modulatory role for sex steroid hormones in cardiovascular function and salt and water balance.