Ethanol modifies the effect of handling stress on gene expression: Problems in the analysis of two-way gene expression studies in mouse brain

Studies analysing the effects of acute treatments on animal behaviour and brain biochemistry frequently use pairwise comparisons between sham-treated and -untreated animals. In this study, we analyse expression of tPA, Grik2, Smarca2 and the transcription factor, Sp1, in mouse cerebellum following acute ethanol treatment. Expression is compared to saline-injected and -untreated control animals. We demonstrate that acute i.p. injection of saline may alter gene expression in a gene-specific manner and that ethanol may modify the effects of sham treatment on gene expression, as well as inducing specific effects independent of any handling related stress. In addition to demonstrating the complexity of gene expression in response to physical and environmental stress, this work raises questions on the interpretation and validity of studies relying on pairwise comparisons.