Early weaning and prolonged nursing induce changes in cell proliferation in the gastric epithelium of developing rats

Food deprivation stimulates cell proliferation in the gastric epithelium of suckling, but not weanling rats. This study was designed to investigate th e role of diet on proliferation in developing animals, using early weaning and prolonged nursing models. Rat pups were subjected to these dietary cond itions at d 15 and were killed 3 or 7 d afterwards. One day before killing, half of pups were deprived of food. Body weights were recorded. After mito sis blockade, the histologic sections of the stomach were used for the eval uation of cell proliferation and methapasic cell distribution along the gla nd, and for the measurement of mucosa thickness. Body weight was impaired a t 18 d by early weaning and at 22 d by prolonged nursing. Food restriction promoted a 10-15% weight loss regardless of dietary conditions. At 18 d, fo od deprivation inhibited cell division (P < 0.01) and reduced the thickness of the mucosa (P < 0.05) in rats that were weaned early. At 22 d, only the thickness of the mucosa was different between the groups that were subject ed to early weaning and prolonged nursing (P < 0.05), regardless of feeding state. The frequency of dividing cells along the gland was affected by ear ly weaning in 18- and 22-d-old rats. These results suggest the following: I ) food deprivation effects are dependent on dietary condition at 18 d becau se different proliferative responses were achieved after early weaning and prolonged nursing; 2) the lack of changes after dietary manipulation in 22- d-old rats indicates a nonresponsive period during postnatal development. W e conclude that milk is a modulatory factor for cell proliferation in the g astric mucosa of rats.