Abstract WP113: Administration of Direct Angiotensin II Type-2 Receptor Agonist, Compound 21, Even After Stroke Prevents Ischemic Brain Damage
Objectives: Previous our studies showed that angiotensin II type-2 (AT2) receptor stimulation protects neurons after brain ischemic damage using AT2 receptor-deficient mice. Recently, Compound 21 (C21) is available to use as a direct AT2 receptor agonist. We reported that administration of C21 induces vascular dilatation via bradykinin-nitric oxide pathway and maintains cerebral blood flow, resulting in prevention of cognitive impairment. These results inspired us the possibility that administration of C21 could protect ischemic brain damage; therefore, we assessed the effect of C21 on stroke expansion by not only pre-treatment, but also a treatment immediately after stroke.
Methods: 10 week-old wild-type male C57BL6 mice were subjected to the middle cerebral artery occlusion (MCAO) by electrocoagulation using a subtemporal approach. Ischemic area after stroke was evaluated by time-course analysis by magnetic resonance imaging (MRI) of the brain. C21 was administrated to mice 2 weeks before MCAO or immediately after MCAO treatment by intraperitoneal injection. Cerebral blood flow was evaluated by using 2D-laser speckle blood flow imaging system.
Results: No significant remarkable change was observed in blood pressure in mice with or without C21 treatment. Pretreatment of C21 prevented ischemic brain damage 1 day after MCAO. In contrast, such preventive effect by C21 was not observed in AT2 receptor-deficient mice. On the other hand, C21 treatment immediately after MCAO did not reduce ischemic area 1 day after MCAO, but remarkably reduced this 3 days after MCAO. Treatment with C21 prevented the reduced cerebral blood flow after MCAO.
Conclusions: These findings indicate that AT2 receptor stimulation by C21 prevents ischemic brain damage at least in part via maintaining cerebral blood flow even after stroke. Therefore, administration of C21 could work as a new therapeutical option in patients with stroke even in acute phase.
- © 2012 by American Heart Association, Inc.