INTESTINAL TRANSIT AND BODY-WEIGHT RESPONSES TO OVARIAN HORMONES AND DIETARY FIBER IN RATS

A two-part experimental design was used to study the effects of ovaria n hormone cessation, hormone supplementation, and dietary fiber compos ition on body weight, appetite, and intestinal transit. In Part 1, eff ects of ovarian hormone status on body weight and baseline and stimula ted intestinal transit were measured in chow-fed rats. Sprague-Dawley rats were ovariectomized (OVX), then injected daily (22 days) with est rogen (E), progesterone (P), the combination (E+P), or placebo. Contro ls were sham operated and placebo injected. Among OVX rats, E and E+P had the least body weight gain (9%, 6%); placebo and P bad the greates t (3696, 3496). In OVX-P, baseline intestinal transit (measured in ane sthetized rats as distance traveled by a charcoal marker) was relative ly low, but vagal stimulation via centrally administered thyrotropin-r eleasing hormone evoked an increase significantly larger than that in other groups. In Part 2, experiments probed the interacting effects of ovarian hormone cessation and dietary fiber composition on body weigh t and baseline intestinal transit. Caloric intake was measured to dete rmine the contribution of altered appetite. Rats OVX or sham operated, then fed liquid diets with or without dietary fiber (25 days), OVX fi ber-fed rats bad significantly higher caloric intake, weight gain, and baseline intestinal transit than other groups. Caloric intake did not fully account for group differences. These results demonstrate modula tion of GI function by ovarian hormones and dietary fiber.