A New StudyResearchers at Georgetown University have conducted studies using these SERMs to determine the roles of the ER_ and ER_ in mediating food intake and body weight gain in OVX rats. In addition to contributing to the understanding of the mechanisms by which estrogens modulate food intake and body weight, these studies help determine the feasibility of using SERMs in the future to prevent postmenopausal weight gain. The results of one study are the topic of a presentation, "Effect of Selective Estrogen Receptor Agonists on Body Weight Gain in Ovariectomized Rats." Darren M. Roesch, Ph.D., Division of Endocrinology and Metabolism & Center for the Study of Sex Differences in Health, Aging, and Disease, Georgetown University, Washington, DC will present his findings at the American Physiological Society ™s (APS) (the-aps) annual scientific conference, Experimental Biology 2004, being held April 17-21, 2004, at the Washington, D.C. Convention Center. Dr. Roesch ™s research is funded by grants from the Center for Biological Modulators (Dr. Sung-Eun Yoo, Director), Korea Research Institute of Chemical Technology, and the National Kidney Foundation of the National Capital Area.

MethodologyRats were OVX and treated with daily injections of control substance, or E2, or one of a range of doses of the ER_ selective drug PPT or the ER_ selective drug DPN for 21 days. Rats were supplied liquid diet and water throughout the study. Body weights and food intake were measured daily.

ResultsDr. Roesch found the following: Body weight: Over the 21-day treatment period, body weight increased by 33% in OVX rats. In rats treated with E2, body weight only increased by 17%. All doses of the ER_ selective drug PPT studied significantly reduced body weight gain in OVX rats to levels comparable to those observed in rats treated with estradiol. None of the doses of ER_ beta selective drug DPN studied significantly altered the weight gain in OVX rats.

Food intake: Food intake was not altered by treatment with E2. The ERa selective drug PPT reduced food intake on some days of the study at high doses, but at lower doses the ERa selective drug PPT had no effect on food intake and still reduced body weight gain. None of the doses of the ERb selective drug studied significantly altered food intake.

ConclusionsThe results of this study indicate that the ER_ receptor is the primary mediator of the attenuating effects of estrogens on body weight gain, and indicate that E2 and the ER_ selective drug reduce body weight gain in rats without reducing food intake. Based on these results, the author speculates that ER_-selective drugs may prove to be useful therapeutically to reduce postmenopausal weight gain in women.