DNA microarray analysis of transcriptional responses of rats housed on solid and grid cage flooring.

We performed DNA microarray analysis on the white blood cells (WBCs) of rats housed on solid and grid cage flooring. The expression levels of 50 genes were found to increase more than 2-fold in the WBCs on grid cage flooring, including many genes encoding proteins involved in inflammatory or immune responses. It is therefore suggested that the health and welfare of laboratory rats is likely to be improved by housing rats on solid floors.