Comparative Microdistribution of the Activity of Catecholamine-Synthesizing Enzymes in Horizontal Sections of the Rat Lower Brainstem

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Abstract
The activities of the 3 major catecholamine-synthesizing enzymes were determined in brain tissue pellets dissected from 500-.mu.m thick horizontal sections of rat lower brainstem. The rostrocaudal distributions of the 3 enzymatic activities were generally not parallel, suggesting differences in the respective localization of the noradrenergic [norepinephrine] and adrenergic [epinephrine] neurons. The difference was most important in the A2-C2 region where the maximal activity of phenylethanolamine-N-methyltransferase (EC 2.1.1.28) was located 1.5 mm more rostrally than the maximal activities of the tyrosine hydroxylase (EC 1.14.16.2) and dopamine .beta.-hydroxylase (EC 1.1.4.17.1). A more specific dissection of the adrenergic and noradrenergic neurons could be performed in the A2-C2 area of the rat brainstem.