LASTING BIOLOGICAL EFFECTS OF EARLY ENVIRONMENTAL INFLUENCES

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Abstract
The effects of neonatal infection, perinatal malnutrition, and crowding on the metabolism of brain catecholamine were studied in specific pathogen-free mice. Metabolic turnover of catecholamine was determined by measuring the incorporation of precursor tyrosine-(14)C into brain tissue, catabolic activity of norepinephrine-(3)H at various times after intracisternal injection, and tissue levels of dopamine and norepinephrine. The rate of tyrosine incorporation was decreased by neonatal infection but was increased by perinatal malnutrition and crowding. There was no difference in catabolic activity of norepinephrine between infected, crowded, and control groups. In the malnourished group, however, the total radioactivity from norepinephrine was significantly higher than in the control group (1/2) and 2 hr after injection. The brain contents of dopamine and norepinephrine were depressed in the malnourished group. There was no significant difference in catecholamine levels between infected, crowded, and control groups. In the malnourished group, treatment of the mothers with growth hormone prevented almost completely weight loss during lactation, and also resulted in higher fetal weight. Hormone treatment restored to normal the levels of brain catecholamine and the enzymatic activity of brain tyrosine hydroxylase in progeny of malnourished mothers.