Abstract WP263: Protective Role Of Microglial Alpha7 Nicotinic Receptor In Ischemia
Background and Purpose: It is well known that activation of α7 nicotinic acetylcholine receptors (nAChR) protects neurons against neurotoxic and neuro-inflammatory stimuli. However, little is known about the importance of this receptor in microglia. This study was planned to evaluate the contribution of microglial α7 nAChRs in controlling inflammation and affording neuroprotection in brain ischemia models.
Methods: Organotypic hippocampal cultures (OHCs) were conducted on 8-10 day-old Sprague Dawley rats. Oxygen-glucose deprivation (OGD) was used as an in vitro model of cerebral ischemia. Viability assays with PNU282987 (a selective α7 agonist) were performed 24 hours after the OGD period. Focal ischemia was induced in C57BL/6J mice by photothrombotic stroke; PNU 282987 was administered i.p. 1 h after the ischemia onset. We performed the beam walk test as a measured of motor activity. Infarct volume and beam walk assay were measured 24 hours after the ischemia.
Results: In OHCs, 15 minutes of OGD followed by 24 hours of reoxygenation increased cell death (180 ± 2.13, n=6, p<0.001) with respect to the basal slices (100%). Under these experimental conditions, 10μM-PNU282987 administered after the OGD period significantly reduced cell death (110.1 ± 10.41, n=6, p≤0.001). In microglia-depleted slices, we observed that the same period of OGD increased cell death compared to control slices (p<0.05). In addition, the protective effect of PNU282987 was significantly lower (p<0.001). In the phototrombotic stroke model, PNU282987 administered at 1 and 10 mg/kg, reduced the infarct volume in a dose-dependent manner (12.22 ± 0.52, n=8, p<0.05 and 9.28 ± 0.58, n=8, p<0.001, respectively) with respect to the saline animals (15.93 ± 1.2, n=7). In the beam walk test, 10 mg/kg-PNU282987 reduced the studied parameters compared with the saline-mice: freezing time (2.36±0.43 vs 7.29±0.87) time to cross (10.53 ± 0.85 vs 16.95 ± 1.65) and paw slips (5.41 ± 0.77 vs 10.83 ± 0.53).
Conclusion: Activation of microglial α7 nAChR contributes to neuroprotection against OGD in OHCs and to reduction of infarct volume and improvement of motor activity in mice subjected to photothrombotic stroke. Taken all together, α7 nicotinic modulation could be a good target for stroke.
- © 2012 by American Heart Association, Inc.