Assessment of the interaction of progesterone and estrogen administered intraperitoneally on food intake, water intake and body weight in ovariectomized albino rats

Abstract

Background and Aim: The gonadal hormones like estrogen and progesterone play important role in the regulation of ingestive behaviors and body weight. Recent report from our laboratory indicates the inhibitory role of intraperitoneally injected estrogen on food intake in rats. However, the reports of progesterone, the other important female gonadal hormone on ingestive behaviors are not clearly elucidated. Moreover, the interaction of progesterone with estrogen in mediating ingestive behaviors is also not clear. Therefore in the present study, we have assessed the effects of progesterone injected alone and in combination with estrogen on ingestive behaviors and body weight in ovariectomized albino rats. Methods: Bilateral ovariectomy was performed in 24 rats, and postovariectomy basal food and water intake and body weight were recorded. The animals were divided into two groups: progesterone group (n = 12) and estrogen-progesterone group (n = 12). Three different dosages (5, 10 and 15 µg/ml) of progesterone were injected intraperitoneal (i.p.) separately and in combination with estrogen on 5 days, following which 24 h food and water intake and body weight were recorded for each injection. Results: It was observed that ovariectomy significantly increases food intake, water intake and body weight. I.p. injection of progesterone resulted in a dose-dependent increase in water intake without significant alteration in food intake and body weight. Anorectic effect of estrogen and dipsogenic effect of progesterone were prominent when estrogen and progesterone were injected combinely. Conclusion: It was concluded that estrogen inhibits food and water intake and progesterone facilitates water intake without affecting body weight. The effects of estrogen and progesterone are independent of each other.