Captopril prevents depressive-like behavior in an animal model of depression by enhancing hippocampal neurogenesis via activation of the ACE2/Ang (1-7)/Mas receptor/AMPK/BDNF pathway.

Abstract

The brain's Renin-Angiotensin System plays an important role in the modulation of mental state. Previously we demonstrated that activated angiotensin (Ang) converting enzyme (ACE) 2, which converts Ang II into Ang (1-7), or the intracerebroventricular administration of Ang (1-7) produced an antidepressant-like effect in mice via Mas receptors (MasR). Since the ACE inhibitor Captopril (Cap) increases Ang (1-7) in the brain, it remains unknown whether Cap affects the depressive-like behavior of olfactory bulbectomized (OBX) mice, an animal model of depression. We tested the effect of Cap on the depressive-like behavior of these mice in the tail-suspension test, quantified ACE2, p-AMP activated protein kinase (AMPK), and brain-derived neurotrophic factor (BDNF) using western blots, and examined the changes in Ang (1-7) level, neurogenesis, and in the expression of ACE2 and MasR on various cell types in the hippocampus using immunohistochemistry. While OBX mice exhibited a depressive-like behavior in the tail-suspension test, as well as a reduction in ACE2, Ang (1-7), p-AMPK, BDNF, and hippocampal neurogenesis, these changes were prevented by Cap administration. The intracerebroventricular administration of Ang (1-7) improved the OBX-induced depressive-like behavior. Except for the changes in ACE2 and Ang (1-7), the effects of Cap were inhibited by the coadministration of A779 (MasR inhibitor) or Compound-C (AMPK inhibitor). ACE2 localized to all cell types, while MasR localized to microglia and neurons. Our results suggest that Cap may act on ACE2-positive cells in the hippocampus to increase ACE2 expression level, thereby enhancing signaling in the ACE2/Ang (1-7)/MasR/AMPK/BDNF pathway and producing antidepressant-like effects.