Reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) profiles in the amygdala of human and new world monkey (Saimiri sciureus)

The topographic distribution of nicotinamide adenine dinucleotide-diaphorase (NADPH-d) stained profiles in the amygdala of the human and new world monkey (Saimiri sciureus) were studied histochemically. Fiber and terminal staining were heterogeneously distributed within the amygdala. The most intense staining occurred in the basolateral subdivision, consisting of the lateral, basolateral and accessory basal nuclei. Moderate staining intensity was observed throughout the cortical and medial nuclei and cortical transition area, constituents of the corticomedial subdivision. The central amygdaloid area was characterized by minimal NADPH-d histochemical reactivity. NADPH-d positive neurons were pleomorphic and divisible into two classes based on their staining characteristics: intensely or lightly stained neurons. Their distribution was generally complementary, with the majority of intensely stained neurons occupying the basolateral subdivision. There were no appreciable species differences in the patterns of neuronal, fiber and terminal staining between monkey or human amygdala. These results may be relevant to our understanding of the selective vulnerability of neural systems within the human amygdala in neurodegenerative diseases.