Abstract

Hypoxic preconditioning (HP) induces neuroprotective effect against cerebral ischemia, but the mechanism still remains unclear. In this study, we investigated whether the toll-like receptor 4 (TLR4) signal pathway was involved in cerebral ischemic tolerance. According to the treatment of HP and asphyxial cardiac arrest (ACA), rats were assigned to ACA group, HP + ACA group, HP group and Sham group. Rat mortality was 5% in HP + ACA group and 30% in ACA group (P<0.01); neurofunctional scores in HP and HP + ACA group were better than in ACA group (P<0.05). Compared with Sham group, TLR4 mRNA expression, NF-кB activity and the production of TNF-α and IL-6 in HP or HP + ACA or ACA group were significantly increased. The increase was progressively significant in groups (AHP < AHP + ACA < ACA) (P<0.01). HP induced mild inflammation via activating the TLR4 signal pathway and then further inhibited inflammatory response induced by ACA.

Key words: Asphyxial cardiac arrest, hypoxic preconditioning, cerebral ischemic tolerance, toll-like receptor 4.