WIN55212-2 attenuates amyloid-beta-induced neuroinflammation in rats through activation of cannabinoid receptors and PPAR-γ pathway

摘要

Cannabinoids have been shown to exert neuroprotective effects in a plethora of neurodegenerative conditions. Over the past decade, some studies demonstrate that cannabinoids can interact with nuclear peroxisome proliferator-activated receptors (PPARs). We investigated protective properties of WIN55212-2 (WIN, a non-selective cannabinoid receptor agonist) in beta-amyloid (Aβ)-induced neurodegeneration in rat hippocampus and possible involvement of PPAR-gamma (PPAR-γ). Aβ (1-42) was injected into the hippocampus of male rats. Animals were administered by intracerebroventricular rout the following treatments on days 1, 3, 5, 7: vehicle, WIN, GW9662 (selective PPAR-γ antagonist) plus WIN, AM251 (selective CB 1 receptor antagonist) plus WIN, SR144528 (selective CB 2 receptor antagonist) plus WIN, each of antagonists alone. Injection of Aβ-induced spatial memory impairment and a dramatic rise in hippocampal TNF-α, active caspase 3, nuclear NF-kB levels and TUNEL-positive neurons. WIN administration significantly improved memory function and diminished the elevated levels of these markers, while antagonizing either CB 1 or CB 2 receptor subtype partially attenuated the protective effects. Intriguingly, WIN significantly increased PPAR-γ level and transcriptional activity, the latter being partially inhibited with AM251 but not with SR144528. The enhancing effect on PPAR-γ pathway was crucial to WIN-induced neuroprotection since GW9662 partially reversed the beneficial actions of WIN. Co-administration of the three antagonists led to the complete abrogation of WIN effects. Our findings indicate that WIN exerts neuroprotective and anti-inflammatory actions against Aβ damage through both CB 1 and CB 2 receptors. Of great note, both direct and CB 1-mediated increase in PPAR-γ signaling also contributes to WIN-induced neuroprotection.