Stimulation and maintenance by nerve growth factor of phenylethanolamine-N-methyltransferase in superior cervical ganglia of adult rats.
Treatment of newborn rats with nerve growth factor (NGF) results in a striking increase in phenylethanolamine-N-methyltransferase (PNMT) in the superior cervical ganglia. Between one and three weeks of age there is normally a 10-fold decrease in PNMT activity in ganglia of infant rats. NGF treatment maintains the PNMT in ganglia at levels 10-fold greater than in untreated controls, but the levels of enzyme in the ganglion show the same magnitude of decrease with age. Epinephrine levels are markedly increased in ganglia of NGF-treated rats younger than one week of age, but at older ages the levels of the catecholamine are only slightly greater than the controls. Dexamethasone is less effective than NGF in increasing the levels of PNMT in ganglia of infant rats and, unlike NGF, becomes ineffective by 44 days of age. These results suggest that there may be two types of PNMT-containing cells in ganglia of newborn rats.