The effects of monocular deprivation on astrocytes in the visual cortex: A stereological study of glial fibrillary acidic protein positive cell bodies and processes

An antibody that recognizes the astrocyte specific protein, glial fibrillary acidic protein (GFAP), was used to examine the effect of monocular visual deprivation on astrocytes in the visual cortex of young and adult rats. Stereological techniques and light microscopy were used to assess the numerical density (Nv) of GFAP positive cell bodies and the surface density (Sv) of GFAP positive processes in tissue sections of the visual cortex processed for immunohistochemistry and counterstained with pyronin Y. The monocular deprivation during development was accomplished by suturing one eye closed just before eye opening (postnatal day 12). In one group the sutures remained until postnatal day 80 (n = 6, MD). In a second group the sutures were removed at postnatal day 75 and the rats were allowed 5 days of light exposure (n = 6, MD + L). A light experience group was used for comparisons (n = 6, L). The Nv of astrocytes and was not significantly different among the three groups. In contrast, the Sv of astrocytic processes was significantly decreased by monocular deprivation. The decreased Sv was specific to layer IV. The reduction of Sv in the monocularly deprived rats were similar in Oc1M and Oc1B. The ratio of Sv astrocytic processes to the Nv of neurons (Sv/Nv), an estimate of the amount of astrocytic membrane per neuron, was significantly decreased in layer IV in both the MD and MD + L groups.; In contrast, the Nv astrocytes and Sv of their processes were not significantly altered in layer IV of adult rats that were monocularly deprived for 5, 10 and 30 days. There was however of an increase in the numerical density of total glial cells in layer IV following 10 and 30 days of adult monocular deprivation compared to light experienced control rats.; These results provide evidence that GFAP expression in the visual cortex is influenced by visual experience.