REGIONAL EXPRESSION OF ANGIOTENSINOGEN MESSENGER-RNA IN THE BRAIN OF ONE-WEEK-OLD, ADULT AND OLD MALE-RATS

The purpose of this study was to investigate possible regional differe nces in the distribution of angiotensinogen-mRNA in the postnatal vers us the aging animal using in situ hybridization and computer-assisted microdensitometry. An essentially identical regional distribution patt ern of angiotensinogen-mRNA in the brains of postnatal, adult and old rats was demonstrated. Substantial differences in angiotensinogen expr ession were observed in brain areas of postnatal versus adult and old animals. Also large differences were seen in the ratios of angiotensin ogen-mRNA levels in different brain areas within one age. The medulla of young animals contained the largest amounts of angiotensinogen-mRNA compared to hypothalamus and midbrain. In contrast, adult and old ani mals showed approximately the same expression levels in midbrain and m edulla, whereas the largest amounts of angiotensinogen-mRNA were expre ssed in the hypothalamus.