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Abstract. In conventional relative gene expression analysis (Northern blotting, RT-PCR, and in situ hybridization), housekeeping genes such as the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and β-actin genes, whose expression levels are considered stable, have been used as control genes for normalization of RNA quantitation. However, it has been reported that the expression levels of these two control genes are affected by ischemia. Therefore, we have been searching for novel control genes whose expression levels are stable in a mouse model of transient forebrain ischemia. Using the GeneChip Mu6500 array set, we monitored the expression levels of approximately 6000 murine genes in the mouse hippocampus during 24 h of ischemia-reperfusion. To select stable genes, we applied the restricted criterion of a 1.5-fold change in expression level as the threshold. By adding statistical analysis with this criterion, we identified 10 genes as candidates for control genes from the GeneChip data. In this criterion, GAPDH and β-actin genes were not included in the 10 genes as candidates for control genes. The present findings might be relevant to the use of control genes in quantitation of RNA, particularly in the study of mouse transient forebrain ischemia.

Abstract. The present study examined the levels of Angiotensin II type 1 receptor (AT 1 ) and type 2 receptor (AT 2 ) in the brain stem and cerebral cortex of the stroke-prone spontaneously hypertensive rat (SHR-sp) after long-term treatment with three types of antihypertensive drugs: valsartan, enalapril, and amlodipine. In both tissues, expression of the AT 1 was decreased by administration of each drug. Expression of the AT 2 was decreased in the cerebral cortex by drug administration, but did not change in the brain stem. This study may contribute to elucidating the relationship between AT 1 and AT 2 expressions and the effect of antihypertensive drugs in SHRsp brain.

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