Relationship between nicotinamide adenine dinucleotide phosphate-diaphorase-reactive neurons and blood vessels in basal ganglia

Morphometric variability of nicotinamide adenine dinucleotide phosphate diaphorase neurons in the primary sensory areas of the rat

Even though there is great regional variation in the distribution of inhibitory neurons in the mammalian isocortex, relatively little is known about their morphological differences across areal borders. To obtain a better understanding of particularities of inhibitory circuits in cortical areas that correspond to different sensory modalities, we investigated the morphometric differences of a subset of inhibitory neurons reactive to the enzyme nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) within the primary auditory (A1), somatosensory (S1), and visual (V1) areas of the rat. One hundred and twenty NADPH-d-reactive neurons from cortical layer IV (40 cells in each cortical area) were reconstructed using the Neurolucida system. We collected morphometric data on cell body area, dendritic field area, number of dendrites per branching order, total dendritic length, dendritic complexity (Sholl analysis), and fractal dimension. To characterize different cell groups based on morphology, we performed a cluster analysis based on the previously mentioned parameters and searched for correlations among these variables. Morphometric analysis of NADPH-d neurons allowed us to distinguish three groups of cells, corresponding to the three analyzed areas. S1 neurons have a higher morphological complexity than those found in both A1 and V1. The difference among these groups, based on cluster analysis, was mainly related to the size and complexity of dendritic branching. A principal component analysis (PCA) applied to the data showed that area of dendritic field and fractal dimension are the parameters mostly responsible for dataset variance among the three areas. Our results suggest that the nitrergic cortical circuitry of primary sensory areas of the rat is differentially specialized, probably reflecting peculiarities of both habit and behavior of the species.

Maternal behaviors: central integration or independent parallel circuits? Theoretical comment on Popeski and Woodside (2004)

N. Popeski and B. Woodside (2004) report that the injection of L-NAME into the 3rd ventricle, which would suppress the synthesis of nitric oxide, disrupts both maternal retrieval of pups and maternal aggression in postpartum rats. These findings are discussed around the question of whether a single central integrative site regulates retrieval and maternal aggression or whether independent neural mechanisms, each dependent upon nitric oxide, regulate the 2 behaviors. A case is made for each point of view. Future research utilizing direct injections of L-NAME into specific neural sites is needed to resolve this important question.