Regulation of Tyrosine Hydroxylase Activity By Prostaglandin E1 in Guinea Pig Adrenal Gland

Abstract

Abstract-The action of prostaglandin E, on tyrosine hydroxylase activity in adrenal slices of guinea pig was studied. The activity of tyrosine hydroxylase was decreased by the incubation of adrenal slices with prostaglandin E, at concentrations beyond 2 I-eg per ml for 2 hours. The activity of tyrosine hydroxylase was stimulated by dibutyryl adenosine 3',5'-monophosphate in slices of guinea pig adrenal glands. Incubation of adrenal slices with the combination of PGE1 and DBc-AMP led to a tyrosine hydroxy lase activity higher than that with PGE, alone, but not as great as DBc-AMP alone. It was suggested that PGE, inhibited the enzyme activity independently of the cyclic AMP level. Other prostaglandins such as PGA, and PGB1 were deficient to the extent that the tyrosine hydroxylase activity was decreased. PGE, inhibited the enzyme activity much to the same extent seen with protein synthesis inhibitors such as cyclo heximide and actinomycin D. However, PGE, did not influence the incorporation of L-leucine-1 C into acid insoluble protein. The studies reported here showed that PGE, inhibited the synthesis of tyrosine hydroxylase.