Fos induced in brain of spontaneously hypertensive rats by angiotensin II and co-localization with AT-1 receptors.

The induction of Fos-like immunoreactivity (FLI) by peripheral administration of angiotensin II (Ang II) was used to determine whether central activation was greater in spontaneously hypertensive rats (SHR) than in normotensive WKY and outbred Wistar controls. FLI was induced in the same brain regions (circumventricular organs and neurosecretory hypothalamic cell groups) in all three groups of rats, but the FLI in several 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 nuclei by hypertonic NaCl did not differ between groups. We also report that 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 may be more sensitive in SHR than WKY, and that WKY are less sensitive than outbred Wistars.