Role of silent information regulator 1 signaling pathway in stellate ganglion block-induced reduction of postoperative cognitive dysfunction in aged rats

Objective To evaluate the role of silent information regulator 1(SIRT1)signaling pathway in stellate ganglion block(SGB)-induced reduction of postoperative cognitive dysfunction(POCD)in aged rats. Methods Ninety-six pathogen-free healthy male Sprague-Dawley rats, aged 20-22 months, weighing 550-700 g, were divided into 4 groups(n=24 each)using a random number table: control group(group C), POCD group, SGB group and SIRT1 inhibitor EX527 group(group EX). Transaction of the right cervical sympathetic trunk was performed to induce SGB in SGB and EX groups.POCD, SGB and EX groups underwent 30 min of exploratory laparotomy starting from 15 min after the end of transaction.In group EX, EX527 1 μg/kg was injected intravenously at 5 min before operation.Morris water maze test was performed in 8 rats selected from each group at days 1, 3 and 7 after operation.The rats were then sacrificed, and hippocampi were removed for determination of SIRT1 expression(by Western-blot)and nuclear factor kappa B(NF-κB)activity(by electrophoretic mobility shift assay)in neurons. Results Compared with group C, the escape latency was significantly prolonged, the frequency of crossing the original platform was decreased, SIRT1 expression was down-regulated, and the activity of NF-κB was increased in POCD and EX groups(P 0.05). Compared with group SGB, the escape latency was significantly prolonged, the frequency of crossing the original platform was decreased, SIRT1 expression was down-regulated, and the activity of NF-κB was increased in group EX(P<0.05). Conclusion SIRT1 signaling pathway is involved in SGB-induced reduction of POCD in aged rats. Key words: Sirtuin 1; NF-kappa B; Stellate ganglion; Nerve block; Aged; Postoperative complications; Cognition disorders