Realization of estradiol effects in the uterus of ovariectomized rats under acute stress.

The aim of this study was to examine the influence of acute stress on the realization of the effects of estrogens in the uterus of ovariectomized rats. The rats were immobilized for 6 h and given a single injection of estradiol dipropionate (E2; 10 micrograms/rat, i.m.). E2-only treated rats, olive oil injected and stressed rats, olive oil-only treated rats and untreated ovariectomized animals were used as controls. The effect of E2 was assessed by the volumes of cells, nuclei and nucleouli (morphometry), DNA content (Feulgen technique) and proliferative activity (mitotic index) in luminal epithelium, in glandular epithelium and in stromal cells of endometrium 24, 36 and 48 h after the injection of E2 or olive oil. All the effects of E2 were reduced in E2-treated rats subjected to stress in all the uterine structures. In olive oil treated rats, stress induced certain increase in the volume of cells and nuclei and slight increase in the DNA content in all the structures. It is suggested that the influence of stress on the uterus is mediated by impairment of some septs in the mechanism of action of estrogen on the uterus, which leads to a decrease in the sensitivity of the uterine structures to estrogens. Without estrogen stimulation the effect of stress on the uterus is realized via estrogen-independent pathways.