Nutritional studies in the pregnant rhesus monkey--the effect of protein-calorie or protein deprivation on growth of the fetal brain.

Twenty four pregnant nulliparous rhesus monkeys were distributed in three groups. While pregnant, the mothers were fed a diet, adequate in mineral and vitamins, that afforded 4.2 g protein and 100 cal; 1.2 g protein and 100 cal; or 1.2 g protein and 50 cal per kg per day. The fetuses were taken by cesarian section at 156 days gestation (term = 165 days) and the cerebrum and cerebellum were subsequently analysed chemically to assess composition and growth. Analyses revealed no statistically significant changes in protein, DNA, RNA, cholesterol, phospholipid, water, or chloride space of either tissue. The zinc concentration per gram of cerebral tissue or protein was significantly elevated in the low protein low calorie group. These results indicate that the brain of the fetus of this primate is protected during frank protein-calorie restriction of the mother. Moreover it is during this time that the major part of brain development takes place. It is argued that the differences observed after maternal restriction of protein and/or calories in subprimate mammals are not necessarily applicable to the human situation.