July - September 2009, Volume 5, Issue 3

Ahmadi R, Oryan S

Effects of estradiol or progesterone on body weight and insulin sensitivity in rats

Acta Endo (Buc) 2009, 5 (3): 299-308
doi: 10.4183/aeb.2009.299

Female sex steroids play considerable roles in body weight and insulin physiology.\r\nEnhanced or reduced female sex steroids affect insulin sensitivity.\r\nThe aim of the present study was to examine the effects of female sex steroids on body\r\nweight and insulin sensitivity through ovariectomy and progesterone or estradiol\r\nadministration in rats.\r\nMaterials and Methods. 7 week old female albino (Wistar) rats were used in our study.\r\nAnimals were randomly divided into control, uni-ovariectomised, bi-ovariectomised, sham,\r\nvehicle receiving sham and vehicle or hormone receiving female groups. Progesterone (20\r\nmg/kg/day) or estradiol valerate (200 &#956;g/kg/day) were injected subcutaneously, starting on the\r\nthird day after surgery and continued at daily intervals. After 4 weeks, animals were measured\r\nfor body weight and killed. Following serum collection, fasting serum insulin and glucose were\r\nmeasured and fasting glucose to insulin ratio was considered as index of insulin sensitivity\r\nwhich were compared statistically between the groups.\r\nThe results showed increased insulin sensitivity (glucose to insulin ratio) (IS) and body\r\nweight (BW) in both bi-ovariectomised (bi-ovx) (IS=14.76, BW=237.40 g) and uniovariectomised\r\n(IS=11.33, BW=225.53) rats compared with the control group (IS=9.36,\r\nBW=205.32) (p<0.01). Progesterone or estradiol replacement in bi-ovx rats was followed by\r\nincreased or decreased body weight (264.50 or 205.10) and increased or decreased insulin\r\nsensitivity (20.38 or 8.50) compared with bi-ovx rats, respectively (p<0.05). In nonovariectomised\r\nrats, administration of progesterone resulted in increased and of estradiol in\r\ndecreased body weight (220.6 g and 185.35 g) and insulin sensitivity (18.36 and 5.35)\r\ncompared with control animals (p<0.01).\r\nConclusively, our findings indicate that progesterone is enhancer and estradiol is reducer\r\nof insulin sensitivity in rats. In addition, weight gain after ovariectomy or progesterone\r\ntreatment and weight loss following estradiol treatment did not probably contribute in acting on\r\ninsulin sensitivity.

Keywords: insulin sensitivity, body weight, ovariectomy, progesterone, estradiol, rat

Correspondence: Rahim Ahmadi, PhD, Islamic Azad University, Hamedan Branch, Hamedan, Iran. Phone: +98-9126120353; Fax: +98-8114290977. E-mail: rahahmadi2001@yahoo.com