Activating Cannabinoid Receptors Reduced Brain Damage After Bleeding Strokes in Mice

WIN55,212-2 treatment after intracerebral hemorrhage significantly reduced hematoma formation, brain edema, blood-brain barrier disruption, and motor impairments. The mechanism involved suppression of both NOX-2 (a major source of damaging reactive oxygen species) and the NLRP3 inflammasome (a key driver of neuroinflammation). Pharmacological NLRP3 inhibition with MCC950 also reduced hemorrhagic brain damage.

Male C57BL/6 mice received intracerebral hemorrhage via collagenase injection, followed by intraperitoneal WIN55,212-2 and/or the NLRP3 inhibitor MCC950. Outcomes included motor activity, hematoma volume, brain water content, and blood-brain barrier permeability (Evans blue assay). NOX activity and protein levels of CB1, gp91phox, NLRP3, AQP4, and caspase-1 were measured by western blot.

Intracerebral hemorrhage is a devastating stroke subtype with limited treatment options. This study identifies two specific inflammatory pathways that cannabinoid receptor activation can suppress, providing a mechanistic basis for potential therapeutic development.

The endocannabinoid system has shown neuroprotective properties in traumatic brain injury, ischemic stroke, and now hemorrhagic stroke. The convergence on NOX-2 and NLRP3 as targets provides a clear mechanistic framework that could guide drug development for acute brain injuries.

Mouse ICH model (collagenase injection) is an approximation of human hemorrhagic stroke. WIN55,212-2 activates both CB1 and CB2 receptors, so the specific receptor contribution is unclear. Only male mice were used. The therapeutic window for treatment was not extensively explored.