The effects of chronic undernutrition over generations on rat development.

Experimental rats were fed 2/3 (10g/24 hours) of adlibitum diet throughout pregnancy and post-weaning, thus far for six generations; their brain and body development was compared with those of controls fed ad libitum (15.5 g/24 hours). As expected from previous reports, neonatal F1 offspring exhibited highly significant decreases in body weight, cerebral wet weight, cerebral DNA and cerebral protein. However, neonatal decreases were not greater in F2 through F6 than in F1 indicating that there was no cumulative effect of this undernutrition on offspring's parameters over generations. Maternal body weight at mating (90 days) and percentage of females that did not litter steadily decreased over generations. The observed high mortality in F1 through F6 and the resulting strong natural selection in favor of best mothers and weanlings could explain these findings. The phenomena contributing to high mortality are multiple and involve maternal factors during pregnancy and before weaning, as well as offspring factors.