Abstract 115: Aspirin-triggered Neuroprotectin D1 Protects The Penumbra In Focal Cerebral Ischemia In Rats
Background and Purpose: Acute ischemic stroke triggers complex neurovascular, neuroinflammatory and synaptic alterations. Aspirin and the omega-3 essential fatty acid, docosahexaenoic acid (DHA), have beneficial effects on cerebrovascular diseases. Unlike most anti-inflammatory agents, aspirin jumpstarts resolution mainly due to acetylation of cyclooxygenase enzymes. Both neuroprotectin D1 (NPD1) and its precursor, DHA, participate in neuroprotection. Here we have tested the effect of aspirin plus DHA administration and discovered the synthesis of aspirin-triggered NPD1 (AT-NPD1) in the penumbra. Then we performed the total chemical synthesis of this molecule and, upon systemic administration 1h after 2h of middle cerebral artery occlusion (MCAo), uncovered remarkable protection.
Methods: Sprague-Dawley rats were anesthetized with isoflurane and received 2h MCAo. Neurological status was evaluated at 24h, 48h, 72h, and 7 days. Treatment with 333µg/kg of AT-NPD1 sodium salt (AT-NPD1-SS) or AT-NPD1 methyl-ester (AT-NPD1-ME) or vehicle (saline) (n=7-8 per group) was administered i.v. at 3h after stroke. On day 7, ex vivo magnetic resonance imaging (MRI) of the brains was conducted on 11.7T MRI. T2WI, 3D volumes, and apparent diffusion coefficient (ADC) maps were generated. In addition, infarct volumes and number of GFAP (reactive astrocytes), ED-1 (activated microglia/microphages) and NeuN (neurons)-positive cells were counted in the cortex and striatum at the level of the central lesion.
Results: All animals showed similar values for rectal and cranial temperatures, arterial blood gases, and plasma glucose during and after MCAo. Treatment with both AT-NPD1-SS and AT-NPD1-ME significantly improved neurological scores compared to saline treatment at 24h, 48h, 72h and 7 days. Total lesion volumes computed from T2WI images were significantly reduced by both AT-NPD1-SS and AT-NPD1-ME treatment in the cortex (by 44% and 81%, respectively), striatum (by 61% and 77%) and total infarct (by 48% and 78%, respectively). Brain edema, computed from T2WI in the cortex (penumbra) and striatum (core), was elevated in the saline group. In contrast, both AT-NPD1-SS and AT-NPD1-ME decreased water content in the striatum on day 7. 3D volumes, computed from T2WI, were dramatically reduced with AT-NPD1-SS and AT-NPD1-ME, and the lesion was mostly localized in the subcortical areas. Treatment with both AT-NPD1-SS and AT-NPD1-ME significantly reduced cortical (by 76% and 96%), subcortical (by 61% and 70%) and total (69% and 84%) infarct volumes as defined by histopathology.
Conclusions: Ex vivo MRI, histopathology, and behavioral testing shows neuroprotective efficacy of novel AT-NPD1 therapy in focal cerebral ischemia and uncover a novel approach for pharmaceutical intervention and clinical translation.
- © 2012 by American Heart Association, Inc.