Whole genome analysis of nicotine-exposed cells from the brainstem of spontaneously hypertensive and Wistar Kyoto rats

The development of hypertension may be highly influenced by the use of nicotine especially in genetically susceptible subjects. In this study the effects of nicotine on gene expression of cultured cells from the brainstem of spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats were evaluated using whole genome microarray platforms. It was described for the first time that nicotine may act differentially on the gene expression profile of SHR and WKY. The influence of strain was present in 348 genes that were differentially expressed in SHR as compared to WKY brainstem cells independently of the nicotine treatment. 176 genes had their expression altered in both strains after nicotine exposure. Interaction between nicotine treatment and the strain was observed for the expression of 269 genes which participate of cellular pathways related to neurotrabnsmitter secretion, intracellular trafficking and cell communication. In conclusion, this study leaves a list of genes whose expression shall be better studied since they are good candidates to the phenotypic differentiation between SHR and WKY, including hypertension as well as demonstrated that alterations in the systems of intracellular trafficking and neurotransmission may be relevant to the development of hypertension. Global measurements of gene expression from normotensive and hypertensive were obtained using the CodeLink Expression Bioarray System (GE Healthcare, UK), which interrogates 34,000 annotated genes and ESTs expressed in the rat genome. Each rat strain was hybridized in three independent biological replicates. Target labeling and hybridization was performed strictly as recommended by the array manufacturer. CodeLink Expression Analysis software (GE Healthcare) was used to extract background-subtracted spot intensities from microarray images. Measurements that were bellow the intensity of negative controls plus 2 standard deviations were excluded. Only genes with valid measurements in all three biological replicates of normotensive or hypertensive animals were further analyzed. To make experiments comparable, intensity data from different hybridizations were normalized by the quantile method