Maternal glucocorticoid hormones influence neurotransmitter phenotypic expression in embryos.

Treatment of pregnant rats with reserpine prevented the normal disappearance of catecholamine fluorescence in presumptive neuroblasts of the embryonic gut. These cells normally express the noradrenergic phenotype transiently during embryonic development. The effect of reserpine was reproduced by treating mothers with hydrocortisone acetate. Moreover, the reserpine effect was blocked by treatment with dexamethasone, which inhibits the stress-induced increase in plasma glucocorticoids, and by mitotone, which causes adrenocortical cytolysis. It is concluded that reserpine, through the mediation of maternal glucocorticoid hormones, alters the phenotypic expression of these embryonic neuroblasts.