Postnatal changes of brain monoamine levels in prenatally malnourished and control rats

The effects of age and prenatal protein malnutrition (6% casein diet) on the concentration of monoamine neurotransmitters and their metabolites and precursors in the hippocampal formation, striatum, brain stem and cerebral cortex were investigated in 1-, 15-, 30-, 45-, 90- and 220-day-old rats. Concentrations of all neurotransmitters, i.e. dopamine, norepinephrine and serotonin, changed significantly during the development. However, two main patterns were recognized. Serotonin in all areas, and dopamine in the striatum, increased from birth to day 45, and declined significantly in 90-day-old rats. In contrast, norepinephrine in all areas, and dopamine in areas other than the striatum, showed the lowest levels in 30-day-old rats, with levels increasing gradually after this age. Concentrations of metabolites paralleled changes in corresponding neurotransmitter levels. Prenatal protein malnutrition did not significantly affect any neurotransmitter concentrations with the exception of increased tryptophan levels (181%) in the hippocampal formation of newborn rats and decreased tyrosine levels (59%) in the striatum of day 30 rats. The results indicate that the monoamine transmitter content varied dynamically throughout postnatal life; however, they seem to counteract the insult from prenatal protein malnutrition after postnatal nutritional rehabilitation.