Abstract
This study compares the histochemical and microchemical localizations of nicotinamide adenine dinucleotide phosphate (reduced) and nicotinamide adenine dinucleotide (reduced) diaphorases and four nicotinamide adenine dinucleotide phosphate (oxidized)-dependent enzymes (glucose 6-phosphate, 6-phosphogluconate, malate and isocitrate dehydrogenases) in areas of rat metencephalon and spinal cord. For the four nicotinamide adenine dinucleotide phosphate (NADP) enzymes, the pattern of localization following use of a modified tetrazolium procedure was compared with quantitative data obtained by microdissection from the same areas in adjacent sections. Optimal experimental conditions for reaction pH, temperature, substrate, cofactor and divalent cation concentrations were used for both the quantitative analysis following microdissection and the histochemical tetrazolium procedure. Consecutive sections were also examined for isocitrate dehydrogenase (nicotinamide adenine dinucleotide (oxidized)) and nicotinamide adenine dinucleotide (reduced) diaphorase activities in addition to seriatim thionine reference sections. Our results indicate that, within the central nervous system, certain characteristic qualitative differences exist in the distribution of the nicotinamide adenine dinucleotide phosphate (oxidized)- and nicotinamide adenine dinucleotide (oxidized)-dependent dehydrogenase enzymes. Nicotinamide adenine, dinucleotide enzymes are visualized predominantly in neuronal cell bodies or neuropil consisting primarily of neuronal processes; in adjacent sections, NADP enzyme activities are visualized almost exclusively in glial elements with two important exceptions. The first is the cerebellar molecular layer where the results from both micro- and histochemical techniques indicate high levels of the NADP enzymes relative to other dehydrogenases and high activity relative to the levels of these NADP enzymes in other nervous system areas. The second exception occurs in those neuronal groups known to contain high levels of catecholamines; these data are the subject of a companion report.