[Pathologic changes of neurons of mesocorticolimbic dopaminergic system in healthy humans and rats]

The purpose of the present study was to demonstrate pathologically changed forms of neurons and intensity of the neuronoglial interactions which represented the normal standard for the interconnected parts of mesocorticolimbic dopaminergic system (MDS) in 6 intact adult female Wistar rats and in 5 healthy humans aged 24-45 years. The percentages of unchanged, hypochromic, pyknomorphic and ghost neurons in proportion to their total number were determined in the anteromedial part of paranigral nucleus of ventral tegmental region of midbrain tegmentum (TVR), compact part of black substance (BS), anteromedial part of accumbent nucleus (NA) close to anterior brain commissure and in middle of layer III of a pregenual part of field 24b (Cg3 in rats). The structures of the brain, unrelated to MDS--layers III and V of field 1--were investigated as the control. The data obtained indicate significant changes of MDS neurons in the healthy people as compared to those in the intact rats. The number of pathologically changed MDS neurons, as well as the number of fibers in medial forebrain bundle, were shown to decrease with the increase of distance from catecholaminergic nuclei of reticular formation, reaching the minimum in non-dopaminoceptive and low-noradrenoceptive layer V of field 1. More than 25% of the neurons in TVR paranigral nucleus were ghost cells. Over 30% of NA neurons were hypochromic and ghost cells. About 25% of neurons in field 24b were ghost cells, hypochromic and pyknomorphic. The intensity of neuronoglial interaction in human and rat dopaminergic nuclei is significantly greater than in the projectional parts of MDS and in the layers of field 1, unrelated to it. Local changes of MDS neurons in man and high intensity of neuronoglial interactions in dopaminergic nuclei reflect the blurring of the boundaries between the normal state and pathology and lower durability of this system, as compared to that of the cortical fields remote from the source of catecholaminergic fibers.