Abstract
Background and Aims
In clinical settings, diabetics remain on higher risk of ischemic renal injury (IRI) than nondiabetic patients. In addition, IRI predisposes distant organs to dysfunction such as neurological impairments via activation of the pressor arm of renin-angiotensin system (RAS). In contrast, the role of depressor arm of RAS on IRI-associated neurological sequalae remains elusive. Hence, this study explored the role of angiotensin II type 2 receptor (AT2R) and angiotensin-converting enzyme 2 (ACE2) in IRI-associated neurological dysfunctions under nondiabetic (ND) and diabetes mellitus (DM) condition.
Method
Type 1 diabetes was induced by injecting streptozotocin (55 mg/kg i.p.). ND and DM rats with bilateral IRI were treated with AT2R agonist-Compound 21 (C21) (0.3 mg/kg/day, i.p.) or ACE2 activator-Diminazene Aceturate (Dize), (5 mg/kg/day, p.o.) per se or in combination therapy. Behavioural, biochemical, and histopathological analysis were done to assess IRI-induced neurological impairment. Moreover, immunohistochemistry, ELISA and qRT-PCR experiments were conducted for molecular mechanism analysis.
Result
In ND and DM rats, IRI caused hippocampal complications as evidenced by increased MDA and nitrite levels, augmented inflammatory cytokines (granulocyte colony stimulating factor, glial fibrillary acidic protein), altered protein and mRNA expressions of Ang II, Ang-(1-7), AT1R, AT2R and MasR. In contrast, concomitant therapy of C21 and Dize effectively normalised aforementioned hippocampal alterations. The protective effect of combination therapy was exerted due to augmented protein and mRNA levels of depressor arm components.
Conclusion
The current study demonstrated the protective role of AT2R agonist and ACE2 activator in IRI-associated neurological dysfunction through preventing oxidative stress, inflammation and upregulating brain depressor arm of RAS under ND and DM conditions.
Possible Role of Angiotensin-Converting Enzyme 2 and Activation of Angiotensin II Type 2 Receptor by Angiotensin-(1–7) in Improvement of Vascular Remodeling by Angiotensin II Type 1 Receptor Blockade
