Fasting enhances cell proliferation of gastric epithelium during the suckling period in rats.

The effect of fasting on cell proliferation was studied during the postnatal development of the maturing stomach. Metaphase indices were obtained after counting mitotic cells blocked by vincristine. The indices were examined at different times of day (10:00 a.m. and 6:00 p.m.) in 16 Wistar rats for each age (10, 18, 22 and 30 days) with different dietary patterns: only milk; weaning with milk and chow; recently weaned, with only chow, and fully weaned, respectively. Metaphase indices (mean +/- SEM) for both periods taken together for 10 and 18-day old animals were significantly higher in fasted (2.25 +/- 0.22% and 2.49 +/- 0.28%, respectively) than in control fed animals (1.67 +/- 0.09% and 1.84 +/- 0.05%, respectively), even if not significantly different for one period alone (18 h). No significant difference in indices was observed for 22-day old rats (fasted = 1.65 +/- 0.28%). The metaphase index of 30-day old rats was significantly higher in fed (1.02 +/- 0.16%) than in fasted animals (0.20 +/- 0.03%). We conclude that fasting enhances cell proliferation in stomach epithelium during the milk intake period, in contrast to the inhibitory effect observed in adult animals. The weaning period marks a transition to the opposite effect of fasting, i.e., a decrease in cell proliferation in 30-day old animals.