Effects of Contralateral Lesions and Aging on the Neuronal and Glial Population of the Cerebral Cortex of the Rat

Glial cells and pericytes are strongly involved in the neurodegenerative processes of the central nervous system. In the present study, we analyzed the cytomorphological effects as well as the reactive changes of glial cells and pericytes of two different neurodegenerative processes: normal aging and changes induced by contralateral implantation of a microdialysis probe. Quantifications were made in the frontal and parietal cortex of the rat. The results show that the microdialysis induced lesions affected all contralateral cortical layers, the microglia being the most proliferating type of cells. The aging process mainly affected the layer V where density of astrocytes was increased. Pericytes in frontal cortex did not show significant changes under our experimental conditions. We detected a significant increase in the number of these cells only in the parietal cortex of aging rats. In addition, pericytes and perivascular microglial cells accumulated a great number of dense and foamy inclusions during aging. Finally, both neurodegenerative processes, lesion and aging, seems to produce glial hyperplasia and hypertrophia through a different mechanism which also differentially affects the neuronal sprouting response.