[Effects of genotype-glucocorticoid interaction on the tyrosine hydroxylase activity in the brain of rat fetuses].

The activity of the rate-limiting enzyme of catecholamine synthesis--the tyrosine hydroxylase (TH) increased in the brain of 20-day-old fetuses of the Wistar strain and aggressive gray rats, 6 hours after corticosterone injection to their mothers. However, this treatment had no effect on the TH activity of 20-day-old fetuses of tame gray rats. Corticosterone injection to the females of these strains on the 16th and 18th days of pregnancy caused inhibition of the fetal development within 3 days, assessed by measuring the fetal body weight, and alterations in the TH activity of the fetal brain. Inhibition of the development of Wistar fetuses was accompanied by decrease in the TH activity at 24-day age. The body weight of the 21-old fetuses of aggressive rats did not change and their TH activity increased after hormonal treatment. Corticosterone inhibited general development of 21-day-old fetuses of tame gray rats, and the TH activity in their brains was not elevated. Thus, glucocorticoids stimulate the development of the catecholaminergic system by increasing the TH activity and inhibit it via catabolic action. Each of these effects displays hereditary variability. Simultaneous realization of these opposite actions of the hormone can create the basis for the effect of interaction between the genotype and the glucocorticoid-mediated environmental influences on the development of the neurotransmitter system of the brain.