Effect And Mechanism Of Dexmedetomidine On Sepsis Related Diaphragmatic Function Injury

Objective: To investigate the effect and mechanism of dexmedetomidine on sepsis related diaphragmatic function injury based on α7n ACh R mediated cholinergic anti-inflammatory pathway.Method: 1.Sepsis model was established by intraperitoneal injection of LPS in 30 SPF C57BL/6 male mice at 6-8 weeks.The behavioral changes of mice were observed,and samples were collected at 0 h,8 h,16 h,24 h and 32 h after modeling and the extent of diaphragmatic muscle injury was evaluated.2.Fifty SPF 6-8 week C57BL/6 male mice were selected and randomly divided into 5 groups(n=10): control group(SHAM group),sepsis group(LPS group),sepsis + dexmedetomidine group(LPS+ DEX group),sepsis + α-Argyrophylla venom group(LPS+BT group),sepsis + dexmedetomidine + α-Argyrophylla venom group(LPS+ DEX +BT group).The administration mode was as follows: BT(1ug/kg)was intraperitoneally injected 1 hour before LPS injection;LPS(10mg/kg)was injected intraperitoneally.The intraperitoneal injection of DEX(40ug/kg)was completed 30 minutes after LPS injection.The SHAM group should be intraperitoneally injected with the same amount of normal saline according to the corresponding time nodes.Serum and diaphragm tissue samples were collected 24 hours after LPS injection,and the pathological changes of diaphragm tissue were observed under light microscope.Enzyme linked immunosorbent assay(ELISA)was used to determine the levels of TNF-α,IL-6,IL-1β and LDH in mice’s midrenic muscle and serum.The m RNA relative expression levels of TNF-α,IL-6 and IL-1βin diaphragm tissue were detected by q RT-PCR.The protein expressions of GSDMD,Caspase1,Cleaved IL-1β and α7n ACh R in the diaphragmatic tissue were determined by Western blot.Results: 1.HE: Pathological examinations at 0h,8h,16 h,24h and 32 h after LPS showed that the diaphragm injury of mice was the most serious at 24h;Compared with the LPS group,the injury of the diaphragm in the LPS+DEX group was significantly reduced,while the injury of the diaphragm in the LPS+BT group and the LPS+DEX+BT group was significantly increased,and there was no significant difference in the degree of injury between the latter two groups.2.ELISA: Compared with SHAM group,the contents of TNF-α,IL-6,IL-1β and LDH in LPS group were significantly increased(P < 0.05);Compared with LPS group,the contents of TNF-α,IL-6,IL-1β and LDH in LPS+DEX group were significantly decreased(P < 0.05);Compared with LPS group,the contents of TNF-α,IL-6,IL-1β and LDH in LPS+BT group and LPS+DEX+BT group were significantly increased(P < 0.05),but there was no statistical significance between the latter two groups(P>0.05).3.PCR: Compared with SHAM group,the m RNA relative expression levels of TNF-α,IL-6 and IL-1β in LPS group were significantly up-regulated(P < 0.05);Compared with LPS group,the m RNA relative expression levels of TNF-α,IL-6 and IL-1β in LPS+DEX group were significantly decreased(P < 0.05);Compared with LPS group,the m RNA relative expression levels of TNF-α,IL-6 and IL-1β in LPS+BT group and LPS+DEX+BT group were up-regulated(P <0.05),but there was no statistical significance between the latter two groups(P > 0.05).4.WB: Compared with SHAM group,the relative expression levels of GSDMD,Caspase1 and Cleaved IL-1β in LPS group were significantly up-regulated(P < 0.05);Compared with LPS group,the relative expression levels of GSDMD,Caspase1 and Cleaved IL-1β in LPS+DEX group were significantly down-regulated(P < 0.05);Compared with the LPS group,the relative expression levels of GSDMD,Caspase1 and Cleaved IL-1β were significantly upregulated in the LPS+BT group and the LPS+ DEX +BT group(P < 0.05),but there was no statistical significance between the two groups(P > 0.05).The relative expression level of a7 n ACh R was just opposite to the above results.Conclusion: 1.Sepsis-related diaphragmatic function injury occurs during the development of cell apoptosis.2.The α2 adrenergic receptor agonist dexmedetomidine may reduce cell pyrotosis by activating α7n ACh R to regulate cholinergic anti-inflammatory pathway activity,and thus ameliorate sepsis related diaphragmatic functional injury.