Brain development in neonatal rats nursing asparagine-deprived dams

A possible requirement for dietary asparagine during lactation was investigated by measuring any adverse effect of maternal asparagine deprivation on the body growth and brain development of nursing rat pups. Each dam was given 7 pups to nurse. Three groups of 5 dams each were deprived from the 1st (T1), 8th (T2), or 15th (T3) day of lactation until weaning (day 22); at weaning, the pups of each group weighed approximately 10% less than those of asparagine-fed controls. Brain development was also affected: the cerebra of T3 pups contained less cholesterol and cerebrosides than control pups, indicating decreased myelination. Both T2 and T3 pups required more trials in a water maze to acquire a learned behavior than control pups. T1, T2, and T3 pups also displayed higher seizure thresholds. The groups of pups whose brains contained the lowest amounts of myelin lipids (T3) were those who displayed the greatest deviation in behavior from the control pups. Thus, the development of neonatal rat brain is sensitive to even mild or transient forms of malnutrition, and a requirement for dietary asparagine during lactation seems evident.