Infant gastrostomy and chronic formula infusion as a technique to overfeed and accelerate weight gain of neonatal rats.

Female rat pups were overfed by continuous intragastric infusion of a milk formula from day 4 through day 128 postpartum. These rats dramatically accelerated weight gain after day 109. By day 18 the overfed pups weighted significantly more than both normally reared 18-day-old pups and pups reared artificially but maintained at the same growth rate as normally reared pups. On day 18 the catheters were removed from gastrostomized pups and normally reared pups were removed from their dams. Thereafter, all groups were maintained ad libitum on a standard diet. The body weights of overfed pups were still significantly greater than those of both other groups on day 120. The procedure provides an important new tool to examine the role of early nutrition in the etiology of obesity.