AGE-RELATED-CHANGES IN THE DNA AND RNA-CONTENT OF THE BRAIN IN SPONTANEOUSLY HYPERTENSIVE RATS

To elucidate the effects of aging accompanied with hypertension on bra in nucleic acid, we measured both the DNA and RNA contents of six spec ific brain regions in adult (5-6 months old) and aged (18-22 months ol d) female spontaneously hypertensive rats (SHRs). Although no statisti cal difference was observed in the RNA content, the DNA content did te nd to increase in the hippocampal CAI of aged SHR (4.24 +/- 0.55 ng/mu g protein, mean +/- SD, n = 6) in comparison to that of adult SHR (3. 21 +/- 0.71 ng/mu g protein, n = 4). Hence, aged SHRs showed a signifi cant decrease in the RNA to DNA ratio in the CA1 subfield of the hippo campus (3.79 +/- 0.61) compared to adult SHR (5.27 +/- 0.81). On the o ther hand, no other regions, except for the dorsolateral region of the striatum, showed any difference in the RNA/DNA ratio between aged and adult SHR. We therefore conclude that subtle changes in the nucleic a cid occur in vulnerable regions of the brain in aged SHRs.