FOS INDUCED IN BRAIN OF SPONTANEOUSLY HYPERTENSIVE RATS BY ANGIOTENSIN-II AND COLOCALIZATION WITH AT-1 RECEPTORS

The induction of Fos-like immunoreactivity (FLI) by peripheral adminis tration of angiotensin II (Ang II) was used to determine whether centr al activation was greater in spontaneously hypertensive rats (SHR) tha n in normotensive WKY and outbred Wistar controls. FLI was induced in the same brain regions (circumventricular organs and neurosecretory hy pothalamic cell groups) in all three groups of rats, but the FLI in se veral of these regions was markedly less in WKY than in either SHR or Wistar. This reduced responsiveness in supraoptic and paraventricular nuclei was selective to Ang II, because the FLI induced in these nucle i by hypertonic NaCl did not differ between groups. We also report tha t a considerable number of cells in the SON and PVH expressing FLI to these stimuli show immunostaining with an antibody to the AT-1 Ang II receptor. These data indicate that central angiotensinergic pathways m ay be more sensitive in SHR than WKY, and that WKY are less sensitive than outbred Wistars.