Effect of Increased Dietary Calcium on Body Weight, Food and Water Intake in Oral Contraceptive Treated Female Rats

The effects of high calcium diet on body weight in OC treated rats are unknown. This study therefore investigated the effect of increasing dietary calcium from 0.9% to 2.5% on body weight, food ingestion, water intake, heart weight index and renal weight index in female Sprague-Dawley rats treated with a combination of OC steroids (ethinyloestradiol + norgestrel). The rats were assigned into three groups of average of 11 rats each; control, OC-treated and OC + Calcium – treated groups and administered orally for 10 weeks. Food and water intake, body weight, cardiac weight index, left ventricular weight index, renal weight index and serum calcium level were determined. The result shows that OC treated rats had significantly lower serum calcium concentration, body weight gain, food, water and calcium intake than those of the control rats. The OC + Calcium – treated rat had significantly higher serum calcium concentration, food, water and calcium intake but significantly lower body weight than those of the OC – treated rats. OC + Calcium – treated rats had significantly higher water intake, calcium intake and significantly lower body weight and food intake when compared with the control rats. Cardiac weight index and renal weight index was comparable in all groups. In conclusion, combined OC-induced reduction in weight gain might be associated with inhibition of the feeding center and consequent inhibition of the thirst center. Co-administration of dietary calcium augmented the reduction in weight gain seen in OCtreated rats probably by further suppression of the feeding and thirst centers.Keywords: Calcium, oral contraceptives, food intake, feeding centre, body weightNig. J. Physiol. Sci. 25(2010) 73 – 7