Role of corticoids independent of food intake in premature increase of pancreatic enzyme activities following early weaning in rats.

The effects of early weaning and food deprivation on the development of pancreatic exocrine enzymes were compared in a rat model. Suckling rats, 15 days old, were weaned onto powdered laboratory diet. Within 24 hours, early weaned rats increased their pancreatic enzyme activities with amylase increased to twice that of the continuous suckling nonweaned littermates. During this period, early weaned rats lost weight and pancreatic growth ceased. Suckling rats of the same age (15 days old), when fasted or injected with hydrocortisone had similar increases in pancreatic enzyme activities within 24 hours. Serum corticosterone levels were increased in early weaned and fasted rats to three to four times that found in continuously suckling littermates. An additional 48 hours of treatment (up to day 18) maintained the high pancreatic enzymes in fasted and early weaned rats. These results show that the increase in pancreatic enzyme activities following early weaning was independent of food intake. The close relationship between serum corticosterone levels and pancreatic enzyme activities together with the ability of hydrocortisone to induce pancreatic enzyme concentrations in pups of the same age suggests the involvement of corticosteroid as a mediator of pancreatic development in early weaning. These experiments demonstrated the importance of endocrine factors in the pancreatic "adaptive" response to early weaning in the rat, and further emphasized the importance of evaluating endocrine changes following any nutritional alterations during the development period.