Effect of maternal protein and/or energy deficiency during pregnancy on catecholamines and serotonin in fetal rat brain

An investigation was made of the effect of maternal protein and/or energy deficiency during pregnancy on developmental changes in the levels of catecholamines and serotonin in fetal brain. Pregnant rats were fed on a 20%, 6% or 0% casein diet from day 1 of pregnancy to the day of autopsy (day 18, 20 or 22 of pregnancy). In the control group, the catecholamine content of the brain increased during pregnancy, being 21 ng on day 18, 48 ng on day 20 and 52 ng on day 22. A similar increase was found in the group on a 6% casein diet. In contrast, with complete protein deprivation there was no developmental increase in catecholamine. A slight increase in serotonin and a marked increase in 5-hydroxyindole acetic acid occurred during late pregnancy, irrespective of the maternal diet. At term, the levels of norepinephrine and dopamine and the tyrosine hydroxylase activity in the forebrain, cerebellum and brain stem of the fetuses in the group on a 0% casein diet were significantly less than those in the groups on 20% and 6% casein diets. The free tyrosine concentrations (mumol/g) in the brain of fetuses in the groups on 20%, 6% and 0% casein diets were 0.701, 0.213 and 0.661, respectively. From the above results it is concluded that the low catecholamine content of the brain in fetuses in the group on a 0% casein diet was due to disturbance of the system for catecholamine synthesis, rather than to deficiency of precursors.