Effect of early weaning of the neonatal rat on pancreatic acinar cell responsiveness to urecholine.

Pancreatic response to urecholine was studied in rats weaned prematurely on the morning of their 13th, 15th, 17th and 19th day and killed 2 1/2 days later. In pups kept with their mother and weaned at 21 days, amylase chymotrypsin and lipase concentrations increased gradually. Weaning after 12, 14 and 16 complete days is associated with significant increases in pancreatic amylase and chymotrypsin concentrations; if it occurs after 16 and 18 days, a significant delay in lipase development is observed. Premature weaning is associated with modifications in the basal release of the three enzymes and their secretion in response to urecholine. Amylase and chymotrypsin secretions are increased if weaning occurred before day 18. Lipase secretion, however, is decreased in rats weaned after 16 days. If, however, secretion is expressed in percentages, as the amount of enzyme released over the total tissue content, premature weaning does not seem to modify the capacity of the tissue to secrete enzymes under basal and urecholine stimulation. It thus seems that solid food intake as early as 12 days is not an important factor in the maturation of the pancreatic response to urecholine.