Effect of corticosterone treatment and adrenalectomy on phenylethanolamine N-methyltransferase and catecholamines in brain stem and hypothalamic nuclei and superior cervical ganglion of rats.

The effects of corticosterone treatment and adrenalectomy with or without corticosterone replacement on the activity of phenylethanolamine N-methyltransferase (PNMT) and catecholamine content has been studied in isolated brain stem nuclei containing adrenergic and noradrenergic nerve cell bodies, hypothalamic nuclei and in the superior cervical ganglion (SCG) of adult rats. Changes of PNMT activity were found only in a few brain stem areas. In adrenalectomized rats, PNMT activity was decreased in Cl area and in the locus coeruleus, but after corticosterone replacement it returned to the control values. The treatment of rats with corticosterone resulted in a rise of PNMT activity only in C2 area. No significant changes in PNMT activity were seen in the hypothalamic areas in any experimental group of rats. The observed changes of PNMT activity occurred without any measurable changes of noradrenaline (substrate) or adrenaline (product of the reaction catalysed by PNMT). Our results may suggest the involvement of brain stem adrenaline and noradrenaline producing neurons in the central modulation of the pituitary-adrenal function. The basal PNMT activity in SCG of adult rats was very low, but the treatment of rats with high dose of corticosterone or corticosterone replacement to adrenalectomized rats increased PNMT activity in the SCG to the same extent.