INCREASED BRAIN TRANSCRIPTION FACTOR EXPRESSION BY ANGIOTENSIN IN GENETIC-HYPERTENSION

A stimulated brain renin-angiotensin system has been implicated in gen etic hypertension. We compared the effects of an intracerebroventricul ar injection of angiotensin II (100 ng) on the expression of inducible transcription factors c-Fos, c-Jun, and Krox-24 in the brain of spont aneously hypertensive rats (SHR), in Wistar rats with nephrogenic hype rtension induced by aortic banding, and in normotensive Wistar-Kyoto a nd Wistar mts immunohistochemically. Generally, the angiotensin II-ind uced transcription factor expression was strictly confined to four dis tinct forebrain areas: the subfornical organ, median preoptic area, pa raventricular nucleus, and supraoptic nucleus. In SHR, the angiotensin II-induced c-Fos and c-Jun expressions were significantly enhanced co mpared with those in normotensive control strains as well as in second ary hypertensive Wistar mts. Krox-24 expression in the subfornical org an, median preoptic area, and paraventricular nucleus of SHR was also significantly increased compared with that in all control strains. In the supraoptic nucleus, significant differences could be discriminated between SHR and secondary hypertensive Wistar rats. Injection of isot onic saline or arginine vasopressin (100 ng) as controls did not induc e any expression of c-Fos, c-Jun, or Krox-24. Our findings demonstrate an enhanced sensitivity of SHR to angiotensin Ii-induced transcriptio n factor expression in distinct brain areas involved in central blood pressure and osmotic control that is independent of blood pressure.