Catecholamine synthesizing enzymes in brain stem and hypothalamus during the development of renovascular hypertension.

The activities of tyrosine hydroxylase (TH) and phenylethanolamine N-methyltransferase (PNMT) have been measured in brain stem and hypothalamic nuclei during the development of renovascular hypertension. TH activity fell at 72 h in the posterior hypothalamic and peri- and paraventricular nuclei of the hypothalamus, but had returned to control levels by 7 days. PNMT activity was raised in the nucleus of the solitary tract at 7 days and was also elevated in the nucleus of the solitary tract, parahypoglossal nucleus, locus coeruleus and cerebellar cortex at 4 weeks. No change in PNMT was noted in hypothalamus. It appears from these results that both central noradrenergic and adrenergic pathways are involved in the development of this model of experimental hypertension.