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 differences in the distribution of angiotensinogen-mRNA in the postnatal versus the aging animal using in situ hybridization and computer-assisted microdensitometry. An essentially identical regional distribution pattern of angiotensinogen-mRNA in the brains of postnatal, adult and old rats was demonstrated. Substantial differences in angiotensinogen expression were observed in brain areas of postnatal versus adult and old animals. Also large differences were seen in the ratios of angiotensinogen-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 animals showed approximately the same expression levels in midbrain and medulla, whereas the largest amounts of angiotensinogen-mRNA were expressed in the hypothalamus.