Quantitative RT-PCR was performed on four representative genes in different brain tissues from an independent animal experiment involving the same treatments as the corresponding groups in the microarray experiment. Three of these genes (Atp5j, Mt-co1, and Mt-nd6) are related to the electron transport system and were modified in multiple brain regions. Another gene, Nurr1, which is essential for differentiation of dopaminergic neurons, was significantly regulated by nicotine in the striatum and VTA. Figure 2 presents the fold change along with the standard deviation of the four genes in response to nicotine treatment relative to the control samples, as detected by microarray and quantitative RT-PCR. This analysis revealed significant regulation of Atp5j in all the brain regions except the striatum, which is consistent with the result from the microarray analysis. Furthermore, comparison of the fold changes of each gene detected by the two molecular techniques across the six brain regions revealed a correlation coefficient of 0.85 (p = 0.032), 0.92 (p = 9.7×10−3), 0.90 (p = 0.014), and 0.82 (p = 0.044) for Atp5j, Mt-co1, Mt-nd6, and Nurr1, respectively. Although only
