The angiotensin II pressor system of the rat forebrain

An anterior hypothalamic knife cut that leaves intact two central sites of action of angiotension II produces the same deficits in the pressor responses to angiotensin II that have been attributed to destruction of two circumventricular organs (the subfornical organ and the organum vasculosum of the lamina terminalis). The central pressor actions of angiotensin II are necessary for the full expression of renin-dependent renal hypertension. The anterior hypothalamic knife cut attenuates renin-dependent aortic ligation hypertension. It has been shown that electrolytic destruction more anterior to this knife cut, in the anteroventral 3rd ventricle region, also attenuates two forms of renin-dependent hypertension, aortic ligation hypertension and two-kidney Goldblatt hypertension in the rat. Electrolytic lesions in the subfornical organ also reduce renin-dependent, two-kidney Goldblatt hypertension. These data are consistent with the hypothesis that a common efferent system from the organum vasculosum of the lamina terminalis and subfornical organ mediates the central pressor response to angiotensin II and is involved in the development of renin-dependent hypertension. A model is proposed for the circuitry in the rat forebrain that is involved in the pressor response to angiotensin II.