Gene expression in mouse visual cortex after visual input deprivation: gene systems mediating distinct effects of activity

Tropea, D., Lyckman, A.W., Kreiman, G., Mukherjee, S. and M. Sur

Society for Neuroscience, San Diego, 2004

Functional plasticity in visual cortex after visual deprivation is a powerful model system for understanding how activity and experience shape connections in cortical circuits. It is as yet unknown whether mechanisms that require the presence of activity are different from those that mediate competitive effects of activity. Here, we ask whether specific deprivation paradigms have distinct effects on gene expression in visual cortex. We extracted mRNA from the primary visual cortex of three experimental groups of mice at P27: control (non-deprived); dark-reared (DR, P0-P27); and, monocularly deprived (MD, P11-P27). RNA samples were run on the MG-U74 v2 ABC microarray chip set (Affymetrix) covering 36701 cDNA target sequences. The effects of the two sensory deprivation regimens (DR and MD) were determined by comparing their average gene expression levels with the average control levels. Using a criterion of p<0.001 (Student's t-test), 177 genes were down-regulated in DR, 85 genes were down-regulated in MD, 597 genes were up-regulated in DR and 22 genes were up-regulated in MD. Expression profiles of selected genes were confirmed by semi-quantitative PCR. For the known genes that showed a significant change in gene expression (either up- or down-regulated), we studied the enrichment of Gene Ontology (GO) categories in the set. We found that although genes affecting multiple cellular processes are affected by both MD and DR (including cell communication, metabolism, and secretion), ). some Some biological processes are influenced much more by only one of the deprivation paradigms: cellular and organismal physiological processes by MD, and cell growth and maintenance, cell death and cell motility by DR. This is consistent with the hypothesis that vision per se is required for certain activity activity-dependent mechanisms, whereas an imbalance of visual activity initiates distinct mechanisms that lead to a re-shaping of functional connections.