DIFFERENTIAL LOCALIZATION OF NADPH-DIAPHORASE AND CALBINDIN-D(28K) WITHIN THE CHOLINERGIC NEURONS OF THE BASAL FOREBRAIN, STRIATUM AND BRAIN-STEM IN THE RAT, MONKEY, BABOON AND HUMAN

The localization of Calbindin-D28k and NADPH-diaphorase in the choline rgic neurons of the basal forebrain, striatum and brainstem was invest igated in the rat, monkey, baboon and human using calbindin and cholin e acetyltransferase immunohistochemistry and NADPH-diaphorase histoche mistry. Considerable regional and species-specific variations were obs erved. Double-stained sections demonstrated that NADPH-diaphorase acti vity occurred in as much as 20-30% of basal forebrain cholinergic neur ons in the rat but in virtually none of those neurons in the monkey, b aboon or human. In all of the species studied, virtually every choline rgic neuron within the pedunculopontine and laterodorsal tegmental nuc lei contained NADPH-diaphorase activity, while none of the cholinergic neurons of the striatum did so. In the rat brain, calbindin immunorea ctivity was not present in any of the cholinergic neurons of the basal forebrain, while in the primate brain virtually all of the basal fore brain cholinergic neurons were also calbindin-positive. None of the ch olinergic neurons of the striatum, pedunculopontine nucleus or laterod orsal tegmental nucleus were found to be calbindin-positive in any of the species examined. These results demonstrate major species-specific differences in the cytochemical signatures of the basal forebrain cho linergic neurons, in contrast to the cholinergic neurons of the striat um and brainstem, which displayed little interspecies variation with r espect to the markers that were used in this study. Our findings also suggest that caution must be exercised in using results from studies o f rodent basal forebrain cholinergic systems to infer the role of this system in the primate brain.