The differential effect of angiotensin II and angiotensin 1-7 on norepinephrine, epinephrine, and dopamine concentrations in rat hypothalamus: The involvement of angiotensin receptors

Angiotensin 1-7 has been recently claimed the active member of the angioten sins' family. In the present study we compared the effect of angiotensin II and angiotensin 1-7 on the concentration of dopamine, serotonin, epinephri ne, and norepinephrine and some of their metabolites in the rat hypothalamu s, where the levels of angiotensins are particularly high. Intracerebrovent ricular injection of angiotensin II, but not angiotensin 1-7, time-dependen tly elevated the levels of both epinephrine (p < 0.05) and norepinephrine ( p < 0.05) in the hypothalamus and both effects could be prevented by intrac erebroventricular injection of either AT(1) (candesartan), AT(2) (PD123319) or AT(1-7) (A-779) receptor antagonist. Neither angiotensin II nor angiote nsin 1-7 produced any changes in the level of dopamine, dihydroxyphenylacet ic acid, homovanilic acid, serotonin, 5-hydroxyindoleacetic acid, or trypto phan at any time point in comparison with the control groups. However, AT(1 ) but not AT(2) receptor blockade, unmasked the stimulatory effect of angio tensin 1-7 on dopamine concentration in the hypothalamus. Thus, angiotensin II and its active metabolite angiotensin 1-7 regulate selectively, albeit differentially, adrenergic, noradrenergic and dopaminergic systems in the h ypothalamus, the effects that involve AT(1), AT(2) and AT(1-7), angiotensin receptors. (C) 2001 Elsevier Science.