Angiotensin-(1–7) Via the Mas Receptor Alleviates the Diabetes-Induced Decrease in GFAP and GAP-43 Immunoreactivity with Concomitant Reduction in the COX-2 in Hippocampal Formation: An Immunohistochemical Study

Abstract

We have previously shown that chronic treatment with angiotensin-(1-7) [Ang-(1-7)] can prevent diabetes-induced cardiovascular dysfunction. However, effect of Ang-(1-7) treatment on diabetes-induced alterations in the CNS is unknown. The aim of this study was to test the hypothesis that treatment with Ang-(1-7) can produce protection against diabetes-induced CNS changes. We examined the effect of Ang-(1-7) on the number of cyclooxygenase-2 (COX-2) immunoreactive neurons and the glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes and assessed the changes in the neuronal growth-associated protein-43 (GAP-43) of the hippocampal formation in streptozotocin-induced diabetes in rats. Animals were sacrificed 30 days after induction of diabetes and/or treatment with Ang-(1-7). Ang-(1-7) treatment significantly prevented diabetes-induced decrease in the number of GFAP immunoreactive astrocytes and GAP-43 positive neurons in all hippocampal regions. Co-administration of A779, a selective Ang-(1-7) receptor antagonist, inhibited Ang-(1-7)-mediated protective effects indicating that Ang-(1-7) produces its effects through activation of receptor Mas. Further, Ang-(1-7) treatment through activation of Mas significantly prevented diabetes-induced increase in the number of the COX-2 immunolabeled neurons in all sub-regions of the hippocampus examined. These results show that Ang-(1-7) has a protective role against diabetes-induced changes in the CNS.