Strain-dependent effects of sub-chronically infused losartan against kainic acid-induced seizures, oxidative stress, and heat shock protein 72 expression.

We studied the involvement of angiotensin (Ang) II AT1 receptors in the pathophysiology of kainate (KA)-induced neurotoxicity, focusing on the regulation of the oxidative stress state and expression of HSP 72 in the frontal cortex and hippocampus in two strains, spontaneously hypertensive rats (SHRs) and normotensive Wistar rats. The KA injection was executed after the rats were infused subcutaneously via osmotic mini-pumps with losartan (10 mg/kg day) for 14 days. Losartan delayed the onset of KA-induced seizures in SHRs but not in Wistar rats without affecting the seizure intensity score. This selective AT1 receptor antagonist decreased the lipid peroxidation only in naive SHRs. However, it attenuated the KA-induced increase in lipid peroxidation in both SHRs and Wistar rats. The adaptive enhancement of cytosolic superoxide dismutase (SOD) activity in KA-treated SHRs was recovered to control level after sub-chronic losartan infusion while no change in mitochondrial SOD activity was detected in the two strains. Both losartan and KA produced a higher expression of HSP 72 in the hippocampus of the two strains compared to naive rats infused with vehicle. Taken together, our findings demonstrate that the efficacy of a sub-chronic systemic losartan infusion in preventing the KA-induced seizure activity and neurotoxicity is more pronounced in SHRs, considered as a model of essential hypertension, than in normotenisve Wistar rats. The results suggest that the blockade of AT1 receptors, commonly used as a strategy for prevention of high blood pressure, may be useful as an adjunctive treatment in status epilepticus to reduce oxidative stress and neurotoxicity.