The effect of the application of desflurane combined with dexmedetomidine to postoperative cognitive dysfunction in the aged rats

Abstract:
Objective: To explore the effect of desflurane on the central nervous system of rats and to determine the optimal dose of Dexmedetomidine to improve POCD in aged rats. Method: 200 healthy male SD rats aged 18-20 months with the weight of 500-600g were randomly divided into 5 groups, n=40. Group C: no anesthesia and surgical treatment. Group D: anesthetized with desflurane, but no surgery was performed. Group DN, DL, DH were treated with desflurane anesthesia for single nephrectomy. The DN group was injected with the same amount of normal saline. The DL group was intraperitoneally injected with 25ug/kg dexmedetomidine, and the DH group was intraperitoneally injected with 50ug/kg dexmedetomidine. 10 rats randomly selected from the five groups underwent the Morris water maze experiment from the 5th day before surgery until the 5th day after surgery (except the day after the surgery). They were conducted the spontaneous activity experiment and postoperative condition fear experiment on the 6th day after surgery. The hippocampal tissues were removed from brains of another 150 rats at 1,3,7 days after the surgery to measure their expression levels of TNF-α, IL-1beta, NF-kB and GFAP. Results: The escape latent period of rats of Group DN was longer than that of rats of Group DL and Group DH (P < 0.05).The escape latent period of rats of Group DL at the 1,4,5 days after the surgery was significantly longer than that of the DH group (P < 0.05). The times and duration time of rats of Group DN entering the original platform quadrant was significantly lower than that of Group DH (P < 0.05). After rats of Group DH were trained for 24 hours, their rigidity time was significantly shorter than that of Group DN (P < 0.05). Compared with the Group D, in Group DN the expression levels of TNF- 1, IL-1beta, NF-kB and GFAP of hippocampus after the surgery were significantly higher (P < 0.05). The expression levels of hippocampus TNF- 1, IL- 1beta, NF-kB and GFAP of rats in Group DL and Group DH after the surgery were significantly lower than those of rats in Group DN (P?0.05). The expression levels of TNF- 1, IL-1beta, NF-kB and GFAP of hippocampi of rats in Group DH at after the surgery were significantly lower than those of Group DL (P < 0.05). Conclusion: Desflurane had little impact on POCD in aged rats, while Dexmedetomidine had a certain protective effect on POCD. Moreover, Dexmedetomidine with high concentration of composite desflurane could better improve the cognitive function of POCD. The mechanism may be that Dexmedetomidine can reduce the release of inflammatory factors, decrease GFAP expression and ease cognitive dysfunction by inhibiting central inflammatory responses.