n-oleoylethanolamine and Infarction--Middle-Cerebral-Artery

Glial activation and scar formation impede the neurological function recovery after cerebral ischemia. Oleoylethanolamide (OEA), a bioactive lipid mediator, shows neuroprotection against acute brain ischemia, however, its long-term effect, especially on glial scar formation, has not been characterized. In this research, we investigate the effect of OEA on glial activation and scar formation after cerebral ischemia in vitro and in vivo experiments. Glial scar formation in vitro model was induced by transforming growth factor β1 (TGF-β1) in C6 glial cell culture, and experiment model in vivo was induced by middle cerebral artery occlusion (MCAO) in mice. The protein expressions of the markers of glial activation (S100β, GFAP, or pSmads) and glial scar (neurocan) were detected by Western blot and/or immunofluorescence staining; To evaluate the role of PPARɑ in the effect of OEA on glial activation, the PPARɑ antagonist GW6471 was used. Behavior tests were used to assay the effect of OEA on motor function recovery 14 days after brain ischemia in mice. Our results show that OEA (10-50 μM) concentration-dependently inhibited the upregulation of S100β, GFAP, pSmads and neurocan induced by TGF-β1 in C6 glial cells. At the same time, OEA promoted the protein expression and nuclear transportation of PPARɑ in glial cells. PPARα antagonist GW6471 abolished the effect of OEA on glial activation. In addition, we found that delay administration of OEA inhibited the astrocyte activation and promoted the recovery of motor function after brain ischemia in mice. These results indicate that OEA may be developed into a new candidate for attenuating astrocytic scar formation and improving motor function after ischemic stroke.

Topics: Animals; Brain Ischemia; Cell Line; Endocannabinoids; Hand Strength; Infarction, Middle Cerebral Artery; Male; Mice; Neuroglia; Neuroprotective Agents; Oleic Acids; PPAR alpha; Rats; Recovery of Function; Walking

This study was carried out to investigate the exact mechanisms behind the neuroprotective effects of oleoylethanolamide (OEA) after acute cerebral ischemic injury. Transient focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) for 90 min followed by reperfusion. OEA (40 mg/kg, ip) was administered with a single injection upon reperfusion. The number of apoptotic cells was detected by TUNEL staining. The expression of Bax, Bcl-2, and TLR4, as well as the activities of NF-κB, Akt, and ERK1/2 were analyzed by western blot. Our data showed that OEA treatment alleviated cell apoptosis in a mouse model of ischemic stroke, accompanied by suppression of Bax, as well as upregulation of antiapoptotic protein Bcl-2 level. The changes of Bax and Bcl-2 could not be observed in PPARα knockout mice models with OEA administration. Importantly, OEA inhibited MCAO-induced TLR4 expression, NF-κB activation, IκBα degradation, and ERK1/2 phosphorylation. Our findings demonstrated that the neuroprotective effects of OEA on cerebral ischemia may be attributed to its antiapoptotic property achieved, at least in part, through the PPARα signaling and inhibition of both TLR4/NF-κB and ERK1/2 signaling pathways. These results provide new evidence indicating the neuroprotective effect of OEA on ischemic stroke.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; Brain; Cytoprotection; Disease Models, Animal; Endocannabinoids; Enzyme Activation; Infarction, Middle Cerebral Artery; Male; Mice; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Neuroprotective Agents; NF-kappa B; Oleic Acids; Phosphorylation; PPAR alpha; Signal Transduction; Toll-Like Receptor 4