Analysis of Sex Differences in Human Cortical Tissue using Oligonucleotide Microarrays

Evans, S.J; Thompson, R; Jones, E.; Bunney, W.E.;Watson, S.J.; Akil, H.
Society for Neuroscience 2001. 2001.


We used Affymetrix GeneChips to analyze gene expression differences between male and female human brains, focusing on dorsal lateral pre-frontal cortex (DLPFC) and cingulate cortex (Cg). These studies are being used for both novel discoveries into gender differences and as protocol standardizations for future DNA microarray studies into human affective disorders. Using blocks from human postmortem tissue total RNA was extracted from each brain region (males, n=6; females, n=5) and used to produce biotinylated cRNA for hybridization to Affymetrix U95A arrays. One GeneChip was used for each sample yielding 6 male and 5 female data sets for each brain region for 30 pair wise comparisons per region. A stringent analysis based on Affymetrix data analysis tools found several genes to be differentially expressed between all male/female comparisons. In other words, this filter identified genes that were different in every male brain compared to every female brain. A subset of these genes are sex chromosome-linked. Two genes were found to be differentially expressed in both the Cg and DLPFC. Differentially expressed genes are being investigated by in-situ hybridization techniques to establish both a specific neuroanatomical expression profile and to provide an independent quantitative estimate of gene expression differences. These general findings have been replicated by Vawter et al (SFN 2001 abstract) using the same tissue but independent cRNA preparations, GeneChip hybridizations, and data analysis methods, demonstrating that two independent laboratories can produce compatible results with this methodology.