Ethanol extracts from Ilex pubescens promotes cerebral ischemic tolerance via modulation of TLR4-MyD88/TRIF signaling pathway in rats.

Mao Dong Qing, the dry roots of Ilex pubescens Hook. et Arn, it has been often used for treating stroke and coronary artery disease. But whether IPEE treatment could promote cerebral ischemic tolerance (CIT) and induced endogenous neuroprotective effects to alleviate the nerve injury caused by the subsequent persistent cerebral ischemic attacks was unknown.To investigate the effects of ethanol extracts of Ilex pubescens (IPEE)on enhancing CIT and explore the potential mechanisms.108 adult male Wistar rats were employed in the present study. The bilateral common carotid arteries were blocked for 10 min, and then reperfusion were allowed for cerebral ischemic preconditioning (CIP); 3 days after CIP surgery, rats were subjected to middle cerebral artery occlusion/reperfusion (MCAO/R)-injury. Rats were continuous fed with IPEE for 5 days at the dose of 100 mg/kg or 200 mg/kg 24 h after the MCAO/R-injury, the brain infarct volume, histopathology, neurological deficits, and the expressions of TLR4-MyD88/TRIF signaling pathway were evaluated.IPEE pretreatment significantly reduced the cerebral infarct volume, the neurological deficit scores, and the plasma level of NSE at the dose of 100 mg/kg. Meanwhile, IPEE treatment could better reduce the levels of inflammatory cytokines such as TNF-α, IL-6, MCP-1, MIP-1α and RANTES, and increased the levels of anti-inflammatory cytokines such as IL-10 and TGF-β at the dose of 100 mg/kg or 200 mg/kg than CIT treatment alone. Moreover, the effect of 100 mg/kg IPEE treatment was better than that of 200 mg/kg IPEE treatment. In addition, IPEE treatment significantly inhibited the expressions of MyD88 mRNA and protein, and reduced the expressions of COX-2 and the transposition of NF-κBp65 to the nucleus, and activated the expressions of TRIF mRNA and protein. The effect of IPEE pretreatment was better than CIT alone.The present study demonstrates that IPEE treatments can enhance cerebral ischemic tolerance by regulating the toll-like receptor 4 (TLR4) signaling pathway. The mechanisms of this response come in two primary forms: inhibiting MyD88 dependent pro-inflammatory pathways and activating TRIF dependent anti-inflammatory pathways.