EFFECT OF GLUCOCORTICOIDS ON MITOCHONDRIAL GENE EXPRESSION IN AMYGDALAR AND HYPOTHALAMIC NEURONAL CELL LINES

Purpose: To determine the effect of glucocorticoids on mitochondrial gene expression in amygdalar AR-5 and hypothalamic IVB cell lines. Methods: Microarray was used to identify differentially expressed genes between AR-5 and IVB cell lines at the basal level. The RNA samples were analyzed on the Affymetrix Rat Genome 230 2.0 array using the UTSW microarray core facility. Microarray data was verified by real time PCR (RT-PCR). To determine the effect of glucocorticoids on mitochondrial gene expression, the cells were treated with 100 nM dexamethasone (dex) for 2 hours. RNA was extracted and mRNA levels were measured by RT-PCR. Results: 30,000 genes were analyzed on the array, of which 1710 genes were found to be differentially expressed. Mitochondrial-encoded genes NADH-ubiquinone oxidoreductase chain 1, 2, 3 (ND1, ND2, ND3), cytochrome C oxidase subunit 1, 2 (COX1, COX2), and Cytochrome b (CYTB) were relatively abundant in AR-5 compared to the IVB cells. The mRNA expression of these genes was 400-fold or greater in the AR-5 relative to IVB cells. Following 2 hr, 100 nM dex treatment, there was no difference in expression of mitochondrial encoded genes. Conclusions: The amygdalar AR-5 cell line have significantly greater abundance of mitochondrial encoded message than the hypothalamic cell line. Dexamethasone does not appear to regulate mitochondrial encoded genes, atleast when treated with 100 nM dex for 2 hours.