Impaired Binding of Estradiol to Vaginal Mucosal Cells in Postmenopausal Osteoporosis

Abstract

Estrogen binding to vaginal mucosa (an easily accessible estrogen-sensitive tissue) was studied in 20 osteoporotic women and in 20 normal postmenopausal women. Mean age, years since menopause, and serum levels of estrogen, luteinizing hormone, and follicle-stimulating hormone did not differ significantly between the groups. Binding of tritiated-estradiol to vaginal epithelial cells was assessed by quantitative autoradiography and corrected for nonspecific binding by pretreatment of duplicate samples with an excess of unlabeled estrogen to saturated binding sites. Results (mean ± SE) expressed as counts/cell showed that binding was significantly less (p < 0.001) in the osteoporotic women (44.1 ± 4.0) than in the normal postmenopausal women (153.3 ± 39.3). Assuming that the quantity of estrogen receptors in bone paralleled those in vaginal cells, the data suggest that a defect in specific estrogen receptors including bone may be one of the fundamental abnormalities responsible for postmenopausal osteoporosis.

Postmenopausal and Senile Osteoporosis: Current Concepts of Etiology and Treatment

“…Accelerated bone loss could result from a greater than normal postmenopausal reduction in residual sex hormone production in women with osteoporosis. We have measured serum gonadotropins and sex steroids in a large group of osteoporotic patients (Riggs et al, 1937b;Bartizal et al, 1976) and have not found significant differences from agematched normal postmenopausal women (Table4).…”