Effect of estradiol replacement in ovariectomized NMRI mice in response to acute and chronic stress

Abstract

The effect of intraperitoneal (IP) and intraventricular (ICV) injection of 17-β-estradiol on hormonal and metabolic changes induced by acute and chronic stress in ovariectomized female NMRI mice was evaluated. NMRI female mice (30 ± 5 g) were used. Animals' ovaries were surgically removed and one cannula was inserted into their skull under deep anesthesia. One week later, animals were received 17-β-estradiol either IP (0.05, 0.01, 0.1 mg/kg) 30 min before or ICV (0.05, 0.01, 0.1 μg/mouse) 5 min before the stress. Results showed that acute and chronic stress, increased plasma cortisol concentration in ovariectomized mice, but IP and ICV injection of 17-β-estradiol after stress induction reduced plasma cortisol concentration. Stress decreased delay to eating time, food and water intake and weight of ovariectomized animal significantly decreased. ICV and IP administration of estradiol in acute stress reduced delay to eating time significantly, but did not any change in water intake. In the acute stress IP administration of estradiol significantly, decreased food intake. In chronic stress both intraperitoneal and intraventricular administration of estradiol caused significant reduction in food intake in ovariectomized mice. Moreover, Stress reduces the brain to the adrenal volume ratio, which, IP and ICV administration of estradiol could inhibit this effect. It can be concluded that 17-β-estradiol has different effects when administered IP or ICV on stress-induced metabolic changes in the ovariectomized mice.