Effect of neonatal hydrocortisone treatment on brain monoamines in developing rats

In our previous study, neonatal treatment with hydrocortisone was shown to produce a marked retardation of pituitary-adrenocortical development in infant rats. The present investigation was an attempt to determine whether or not the retarded activity is caused by functional changes in brain monoamine systems. In rats treated with hydrocortisone (0.5 mg/rat, s.c.) on the 2nd day of life, the development of whole brain was suppressed significantly. However, norepinephrine, dopamine and serotonin contents in the brain were higher in these rats than controls. These changes of monoamine contents were apparent in the hypothalamus, diencephalon and pons-medulla oblongata. Our data suggest that monoaminergic nervous systems are potentiated with hydrocortisone in these brain regions, although the results do not necessarily explain the retarded hypothalamo-pituitary function.