Abstract
Histochemical and cytochemical methods have been used to localize glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, isocitrate (nicotinamide adenine dinucleotide phosphate (NADP)) dehydrogenase and malic enzyme in the nucleus locus ceruleus and other catecholamine-containing neuronal groups of the rat brain stem. The four NADP-dependent dehydrogenases were studied by both quantitative and qualitative histochemical techniques using adjacent tissue sections. Both types of analyses were done on neuronal nuclei known to contain catecholamines in high concentration, the nucleus locus ceruleus and the superior cervical sympathetic ganglion; other known catecholamine-containing nuclei were surveyed by the cytologic technique only. There was intense staining of cell bodies and neuropil of the nucleus locus ceruleus after all four of the NADP dehydrogenase histochemical reactions. In contrast, little staining was observed in the adjacent vestibular nuclei or mesencephalic root nucleus of the trigeminal with the exception of appreciable glucose 6-phosphate dehydrogenase activity present in neuropil elements. Quantitative microchemical determinations in the nucleus locus ceruleus corroborate the histochemical results which indicated high NADP dehydrogenase activities particularly for 6-phosphogluconate dehydrogenase. This same pattern of high NADP enzyme activity as determined by combined cytochemical and quantitative chemical techniques was also observed in the superior cervical ganglion and cytochemically in other catecholamine-containing nuclei of the brain stem. Our findings suggest that a high capacity to generate or utilize nicotinamide adenine dinucleotide phosphate (reduced) may be characteristic of those neurons which either receive adrenergic terminals or synthesize catecholamines.