Influence of Adrenal Epinephrine on Postnatal Development of Tyrosine Hydroxylase Activity in the Superior Cervical Ganglion

Abstract

The effects of bilateral adrenalectomy on postnatal development of tyrosine hydroxylase (TH) activity in the superior cervical ganglion were examined in the rat. Adrenalectomy on day 12 blocked further developmental rise of TH activity, while adrenalectomy on day 7 did not affect normal development of enzyme activity when examined on day 12. The effect of adrenalectomy could be reversed by replacement with daily injections of epinephrine, but not by similar replacement with corticosterone. Chronic administration of SKF 64139 [7,8-dichloro-1,2,3,4-tetrahydroisoquinoline hydrochloride], a specific inhibitor of adrenal phenylethanolamine N-methyltransferase activity that depletes circulating epinephrine levels, led to a cessation of normal development of TH activity. Similar to adrenalectomy, the effect of SKF 64139 could be observed only after 2 wk of postnatal development. After 2 postnatal weeks, further developmental rise of TH activity in the sympathetic ganglion is an epinephrine-dependent process.