Pathological Changes in Neurons of the Mesocorticolimbic Dopaminergic System in Healthy Humans and Rats

• Published in: Neuroscience and behavioral physiology 2011-07, Vol.41 (6), p.578-585
• Main Author: Droblenkov, A. V.
• Format: Article
• Language: English
• Subjects: Alcohol; Behavioral Sciences; Biomedical and Life Sciences; Biomedicine; Brain; Dopamine; Neurobiology; Neurons; Neurosciences; Pathology; Psychotropic drugs
• ISSN: 0097-0549; 1573-899X
• DOI: 10.1007/s11055-011-9458-x

The aim of the present work was to identify normal levels of pathologically altered neurons and the intensity of neuron-glial interactions in interconnected parts of the mesoaccumbocingulate dopaminergic system (MDS) of the brain in adult intact female Wistar rats ( n  = 6) and healthy humans aged 24–45 years ( n  = 5). The proportions of unaltered, hypochromic, pyknomorphic, and ghost neurons were identified in the anteromedial segment of the paranigral nucleus of the ventral tegmental area (VTA) and the compact zone of the substantia nigra, in the central medial part of the nucleus accumbens (NA) close to the anterior commissure of the brain, and the central part of layer III of the pregenual part of field 24b (Cg3 in rats). Controls consisted of brain formations which are not part of the MDS, i.e., layers III and V of field 1. Our data provide evidence of significant changes in MDS neurons in healthy people as compared with the level of changes in intact rats. The number of pathologically altered MDS neurons in humans decreased with increases in the distance from the catecholaminergic nuclei of the reticular formation, as did the number of fibers in the medial forebrain bundle, reaching a minimum in the non-dopaminoceptive and low-noradrenalinoceptive layer V of field 1. In the VTA, more than 25% of neurons were ghost cells. More than 30% of NA neurons were hypochromic and ghosted. About 25% of neurons in field 24b were ghost cells, hypochromic, and pyknomorphic. The intensities of neuron-glial interactions in the dopaminergic nuclei in humans and intact rats were significantly greater than in the projection areas of the MDS and the non-MDS layers of field 1. Local changes in human MDS neurons and the high intensity of neuron-glial interactions in the dopaminergic nuclei reflect blurring of the boundaries between normal conditions and pathology and the lower durability of this system as compared with cortical fields distant from the origin of catecholaminergic fibers.