Studies on the role of insulin in N metabolism changes in cafeteria-fed rats

The present work studies the serum insulin response to cafeteria feeding and the possible role of this hormone in the marked N retention induced by cafeteria feeding. Rats fed a cafeteria diet for periods of 10, 20 and 30 days showed a significant and progressive increase in serum insulin levels. In order to elucidate the possible intervention of this hormone in the marked N retention induced by cafeteria feeding we studied the changes in N metabolism in non-diabetic and streptozotocin-diabetic rats fed a cafeteria diet for 10 days. The amount of N ingested was the same in all experimental groups. Our results suggest that insulin is not absolutely indispensible in the N retention exhibited by cafeteria-fed rats, inasmuch as cafeteria feeding also promotes a decrease in N excretion in streptozotocin-diabetic rats. This is in accordance with the reduction in urea excretion and the activities (U/g liver) of the ureogenic enzymes in streptozotocin-diabetic rats fed a cafeteria diet.