Tomatidine attenuates post-stroke cognitive impairment by reducing neuroinflammation through prevention of M1 microglial polarization via NF-κB signaling

Post-stroke cognitive impairment (PSCI) is a clinical disorder that commonly occurs after a stroke and may persist long-term in most stroke survivors. Neuroinflammation involving proinflammatory M1 microglia, an activated microglial phenotype after stroke injury, is a major risk factor for PSCI. Tomatidine is a steroidal alkaloid of immature green tomatoes that has anti-inflammatory properties. To investigate the effects of tomatidine on cognitive impairment and microglial-associated neuroinflammation after stroke, we performed behavioral experiments and analyses on activated microglia in a transient bilateral common carotid arteries occlusion (tBCCAO) mouse model. Tomatidine attenuated cognitive impairment and neurodegeneration in the CA1 and CA3 hippocampal regions and reduced microglial activation and polarization into an M1 phenotype in the hippocampus in tBCCAO mice. The direct effect of tomatidine on polarization into the M1 phenotype was examined using LPS-stimulated BV2 microglia, as an M1 microglia model. Tomatidine reduced expression of M1 microglial markers and inflammatory mediators and inhibited nuclear translocation and phosphorylation of NF-κB in LPS-treated BV2 microglia. These results suggest that tomatidine suppresses microglial polarization into an M1 phenotype via modulation of NF-κB signaling, resulting in attenuation of neuroinflammation and reduction of PSCI.