Green tea polyphenols improve isoflurane-induced cognitive impairment via modulating oxidative stress.

Anesthetic exposure induces learning and memory impairment and the mechanisms remain unknown. Green tea polyphenols(GTP) have been reported to be neuroprotective. The present study was performed to examine the therapeutic potential of GTP on isoflurane-induced cognitive deficits. Six-week-old male C57BL/6J mice were treated with 1.6% isoflurane for 6 hours. Multiple-dose of GTP at 25 mg/kg for 7 consecutive days and single-dose at 75 mg/kg on the 7th day were respectively administered intraperitoneally to model mice before anesthesia. Fear conditioning test and novel objection recognition were conducted to assess cognition of mice. Superoxide dismutase (SOD) was evaluated using assay kits. Protein expression levels of right hippocampus p-CaMKII, p-CREB and BDNF were examined by Western blot. Our results indicated that 6 h isoflurane anesthesia induced cognitive impairment in early 3 days. Meanwhile, the hippocampus SOD declined in step. The expression levels of p-CaMKII, p-CREB and BDNF were also downregulated. GTP 25mg/kg per day significantly attenuated cognitive dysfunction on Day 3 following isoflurane anesthesia. Moreover, GTP 25mg/kg per day effectively mitigated isodlurane-induced declines of SOD, as well as the p-CaMKII, p-CREB and BDNF levels. However, single-dose at 75 mg/kg of GTP had no significant effects. This study indicated that GTP attenuate isoflurane-induced cognition impairment and this positive effects may be related to its antioxidant properties.