The short- and long- term effects of estrogen deficiency on apoptosis in musculoskeletal tissues: an experimental animal model study.

Abstract

Estrogen is the major sex steroid affecting the growth, remodeling, and homeostasis of the female skeleton. Estrogen loss in postmenopausal women leads to osteoporosis. The aim of this study was to evaluate the early and long- term effects of estrogen loss on bones, tendons, muscles, and menisci in ovariectomized rats. Fifteen rats were randomized into three groups of five animals each. The first group was the control group with no additional surgical procedure, but the rest (groups 2 and 3) were bilaterally ovariectomized . All animals in the group 2 were sacrificed at 14th week to evaluate the short- term effect, and all of other animals in the groups 1 and 3 were sacrificed at 28th week to analyze the long- term effect of estrogen loss in the ovariectomized group and to control with the group 1. Quadriceps muscles, Achilles tendons, menisci, and femur cortical bones from both lower extremities were taken. The amount of apoptosis was measured. There was a significant increase in cell apoptosis in bones, muscles, and tendons with insignificant increase in cell apoptosis in menisci at early and late periods in rats with ovariectomies than the control. The results indicated that estrogen loss after ovariectomy does not only affect bones; it may also increase cell apoptosis in different tissues such as muscles, tendons, and menisci.