Increase in noradrenaline-synthesizing enzyme activity in medulla oblongata in Parkinson's disease

Abstract
Dopamine beta hydroxylase (DBH), the noradrenaline-synthesizing enzyme, and phenylethanolamine-N-methyltransferase (PNMT), the adrenaline-synthesizing enzyme, were assayed in 18 areas of brain stem in eight cases of parkinsonian syndromes and of four age- and postmortem delay-matched controls. Dissection was performed by the “punch” technique and enzyme activities assayed by radiometric methods. No significant change was found for PNMT activity. DBH activity was significantly increased in the A2-C2 area of the medulla oblongata (including the nucleus tractus solitarius) in the cases of Parkinson's disease. The A2-C2 area is known to be implicated in the control of blood pressure in rats. These findings are discussed in relation to orthostatic hypotension and the influence ofl-dopa therapy.