RESUMO
OBJECTIVE: In the present study, we investigated whether systemic pretreatment with the AT1 receptor antagonist, candesartan, reduces neuronal injury after cerebral ischaemia in rats. DESIGN AND METHODS: Focal cerebral ischaemia in male, normotensive Wistar rats was induced by 90 min middle cerebral artery occlusion (MCAO) followed by reperfusion. Experiment 1: Candesartan was injected intravenously (i.v.) at doses of 0.1 or 0.3 mg/kg, 4 h prior to ischaemic injury. Experiment 2: Rats were treated with candesartan [0.1 mg/kg, subcutaneously (s.c.) twice daily], on 5 consecutive days prior to ischaemia. The last injection was administered 12 h before MCAO. Mean arterial pressure (MAP) was measured before, during and after ischaemic injury. Twenty-four hours after ischaemia, neurological outcome, infarct volume and brain oedema were evaluated. RESULTS: Acute i.v. pretreatment with candesartan, 0.1 and 0.3 mg/kg, dose-dependently decreased MAP before, during and after ischaemic injury but did not improve recovery from brain ischaemia. Systemic long-term s.c. pretreatment with 0.1 mg/kg candesartan, reduced MAP during and after ischaemia to the same extent as did the i.v. dose of 0.1 mg administered 4 h before MCAO, but significantly improved neurological outcome and reduced infarction size and oedema of the ipsilateral hemisphere when compared with the vehicle-treated group. CONCLUSION: Long-term blockade of AT1 receptors improves neurological outcome of focal cerebral ischaemia and protects brain tissue against ischaemic injury.
