Effects of maternal dietary protein restriction on growth of the brain and body in the rat.

We studied the growth of the brain and body in rats born of dams fed a low-protein (8% casein) diet ad lib beginning 5 weeks prior to mating and continuing throughout gestation and lactation. Control dams were fed an isocaloric 25% casein diet. Litters were culled at birth to 8 pups. At birth, brain weights and body weights of pups of protein restricted dams were similar to those of control pups. During the period of lactation, pups of restricted exhibited severely retarded body growth but only mildly retarded brain growth resulting in an elevated brain/body weight ratio. This relative macrocephaly was maximal at 10-20 days of age, declining completely by 35 days of age. The relative macrocephaly could not be accounted for by increased retention of water in the brain of the malnourished rats. Following weaning, pups were maintained ad lib on the diets fed their mothers. At adulthood brain/body weight ratios were normal in the protein restricted group.