Depression of antral and serum gastrin concentration by food deprivation in the rat.

In rats fasted 4 days, immunoreactive gastrin concentrations decreased to one-third of the fed levels in antral tissue and to one-eight of the fed levels in serum. The number of antral cells that reacted with fluorescent antigastrin antiserum was also correspondingly decreased. After refeeding, serum gastrin returned to normal levels in 6 days, whereas antral gastrin concentration recovered after 9 days. Normal gastrin levels were maintained in rats fed a nutritious liquid diet over a 6-day period, whereas tissue and serum hormone concentrations decreased to low levels in rats placed on a high bulk non-nutritive diet over the same period. These results suggest that food in the gastrointestinal tract is necessary for the maintenance of normal serum and antral gastrin concentration in rats. The effect of food is most likely attributable to chemical constituents and not distention by bulk.