Food intake of infant rats after intraperitoneal administration of insulin.

The effects of intraperitoneal insulin on the food intake have been determined in infant rats up to weaning. It was found that intraperitoneal (IP) insulin reduced the milk intake of 13 and 17 day-old pups for three hours after treatment. In 5, 9 and 24 day-old pups the food intake was not significantly changed after IP insulin administration. Only in 28 day-old rat pups IP insulin induced an increase of food intake. Since subcutaneously (SC) administered insulin gave rise to short-term hyperphagia in 24 day-old rat pups we assessed the effects of SC versus IP insulin on the blood glucose level. Blood glucose was lower 3 hours after SC administration compared to the IP route. Results indicate that IP insulin causes a short lasting hypoglycaemia and consequently IP insulin increases food intake only after the 28th day of life.