Tryptophan hydroxylase activity in hypothalamus and brainstem of neonatal and adult rats treated with hydrocortisone or parachlorophenylalanine.

The present study has been undertaken to determine whether glucocorticoid, and parachlorophenylalanine (PCPA, a tryptophan hydroxylase inhibitor) affects tryptophan hydroxylase (TPH) levels in brainstem and hypothalamus of neonatal and adult rats. Our results show that: (1) administration of hydrocortisone causes small but significant increases in TPH activity of neonatal brainstem: (2) treatment with PCPA plus glucocorticoid results in a marked decrease of TPH activity in brainstem and hypothalamus of both neonatal and adult rats.