Immunocytochemical localization of angiotensin-(1-7) in the rat forebrain.

Recent findings by this group have led us to reconsider the view that amino (N-) terminal fragments of angiotensin (Ang) II are inactive degradation products of renin-angiotensin system. To further examine this possibility, an antibody to Ang-(1-7), the N-terminal heptapeptide, was produced to demonstrate the neuroanatomical distribution of the rat brain. Ang-(1-7)-immunoreactivity was found in paraventricular, supraoptic, and suprachiasmatic nuclei, bed nucleus of the stria terminalis, substantia innominata, median eminence, and neurohypophysis. This distribution of Ang-(1-7) in the rat forebrain, together with our previous demonstrations of vasopressin secretion in response to this peptide, suggest that Ang-(1-7) functions as a neuromodulator.