Angiotensin 1 receptor antagonist attenuates acute kidney injury-induced cognitive impairment and synaptic plasticity via modulating hippocampal oxidative stress

The activation of the angiotensin (Ang) II after acute kidney injury (AKI) triggers oxidative stress and inflammatory cascade which involved not only the kidneys but also the brain. Ang II through the Ang II type 1 receptor (AT1R) may have deleterious effects on hippocampal synaptic transmission and cognitive functions under uremic encephalopathy. The present study was conducted to examine the effects of AT1R antagonist on AKI-induced cognitive and synaptic plasticity impairment. Here, we investigated the effect of AKI and possible pathophysiological roles of AT1R with the selective AT1R antagonist losartan (10 mg/kg/day for consecutive 9 days) on cognitive performance using passive avoidance and Morris water maze tests. In order to understand the synaptic transmission, in vivo short and long-term plasticity were evaluated at the Schaffer collateral-CA1 synapse. Biochemical analysis was also performed to detect possible hippocampal nitric oxide and oxidative stress mechanisms. Our data provide evidence of hippocampal complication following AKI with increased level of nitrite (P < 0.01 vs. sham) as well as oxidative stress (P < 0.01 vs. sham) that may be responsible for behavioral dysfunction under uremia (spatial memory, P < 0.001; passive avoidance P < 0.01 vs. sham). Losartan treatment effectively protects against cognitive (spatial memory, P < 0.01; passive avoidance P < 0.05 vs. AKI-veh) and synaptic plasticity impairments induced by AKI possibly via modulation of oxidative stress in the hippocampus (P < 0.01 vs. AKI-veh). The present study conclusively demonstrated a protective role of AT1R antagonist losartan in hippocampal complication and neurocognitive dysfunction after AKI via modulating oxidative stress.