WIN55,212-2 protects oligodendrocyte precursor cells in stroke penumbra following permanent focal cerebral ischemia in rats

Aim:

To explore whether the synthetic cannabinoid receptor agonist WIN55,212-2 could protect oligodendrocyte precursor cells (OPCs) in stroke penumbra, thereby providing neuroprotection following permanent focal cerebral ischemia in rats.

Methods:

Adult male SD rats were subjected to permanent middle cerebral artery occlusion (p-MCAO). The animals were administered WIN55,212-2 at 2 h, and sacrificed at 24 h after the ischemic insult. The infarct volumes and brain swelling were assessed. The expression of cannabinoid receptor type 1 (CB1) in the stroke penumbra was examined using Western blot assay. The pathological changes and proliferation of neural glial antigen 2-positive OPCs (NG2⁺ cells) in the stroke penumbra were studied using immunohistochemistry staining.

Results:

p-MCAO significantly increased the expression of CB1 within the stroke penumbra with the highest level appearing at 2 h following the ischemic insult. Administration of WIN55,212-2 (9 mg/kg, iv) significantly attenuated the brain swelling, and reduced the infarct volume as well as the number of tau-immunoreactive NG2⁺ cells (tau-1⁺/NG2⁺ cells) in the stroke penumbra. Moreover, WIN55,212-2 significantly promoted the proliferation of NG2⁺ cells in the stroke penumbra and in the ipsilateral subventricular zone at 24 h following the ischemic insult. Administration of the selective CB1 antagonist rimonabant (1 mg/kg, iv) partially blocked the effects caused by WIN55,212-2.

Conclusion:

Tau-1 is expressed in NG2⁺ cells following permanent focal cerebral ischemic injury. Treatment with WIN55,212-2 reduces the number of tau-1⁺/NG2⁺ cells and promotes NG2⁺ cell proliferation in the stroke penumbra, which are mediated partially via CB1 and may contribute to its neuroprotective effects.