EFFECTS OF EARLY UNDERNUTRITION AND SUBSEQUENT NUTRITIONAL REHABILITATION ON BRAIN-DEVELOPMENT .1. THE MOST CRITICAL PERIOD

The effects of early undernutrition and subsequent nutritional rehabilitation on brain growth were investigated in suckling mice subjected to 5- or 10-day undernutrition at different times. Undernutrition was induced by increasing the litter size from 6 to 18 nursed by a dam. Even in adulthood, the brain weights of animals in the U-8-12 (nursed in litters of 18 from day 8 to 12), U-1-10, U-11-20 and U-1-20 groups were significantly lower than in controls, though the brain weight in the U-1-5 group showed catch-up to the control level. At 60 days, the brain weight of the U-8-12 group was significantly less than that of the U-1-5 group, and that of the U-11-20 group was less than that of the U-1-10 group. The brain weight was significantly lower in the U-8-12 than in the U-1-10 group. These results suggest that even though duration and severity of undernutrition were the same, the effect on brain growth differs if undernutrition is experienced at different times during the period of brain growth spurt and that the most vulnerable period for the mouse brain seems to be around 10 days of age.