Effects Of Dexmedetomidine On Expression Of AQP1 And Related Inflammatory Factors After Ischemia And Hypoxia In Schwann Cells

Objective:Neuropathic Pain is a kind of chronic intractable Pain with complex pathological mechanism and difficult recovery after treatment,which often causes serious mental stress and economic burden to patients.Dexmedetomidine is a novel alpha2 adrenergic receptor agonist,which has been widely used in clinic for its sedative,analgesic and anti-anxiety effects on central and peripheral nervous systems.A large number of studies have found that DEX can relieve chronic neuropathic pain,and has neuroprotective and anti-inflammatory effects.Previous literature has reported that aquaporin-1 is closely related to neuropathic pain and plays a key role after peripheral nerve injury.After peripheral nerve injury,a large number of inflammatory mediators are released,leading to local cell edema,triggering peripheral nociceptors,and thereby producing pain sensation.Some studies have pointed out that pain originates from inflammation,and neuropathic pain is closely related to inflammatory factors.Whether DEX alleviates neuropathic pain by affecting AQP1 and inflammatory factors remains unclear.In this study,we simulated neuropathic pain through ischemia and hypoxia model of Schwann cells,and determined the cell edema status and the expression changes of AQP1 and inflammatory factors（IL-6 and TNFα）after ischemia and hypoxia.To investigate whether DEX can reduce inflammation and cell edema,and affect the expression of IL-6 and TNFαthrough AQP1.Methods:1.The sciatic nerve of rats was taken within 48 hours after birth,and the nerve were lysed by enzyme digestion to conduct primary culture of Schwann cells.The expression of Schwann cell markers S-100βand AQP1 and whether they were co-localized were observed by immunofluorescence staining.2.The Schwann cell ischemia and hypoxia model was constructed.After Schwann cells were attached to the wall,low concentrations（2%）of FBS and CoCl₂ were used to simulate cell ischemia and hypoxia,and the optimal CoCl₂ concentration and incubation time were selected by Western blot and CCK8.3.The expression level of AQP1 was detected by Western blot to determine the safe concentration and incubation time of Schwann cells treated by DEX.4.To observe the repair effect of safe concentration DEX on ischemia and hypoxia injury of Schwann cells.They were divided into blank control group（NC）,ischemia and hypoxia model+dd H₂O group（CoCl₂）,ischemia and hypoxia model+DEX group（CoCl₂+DEX）.The expression levels of HIF-1αand AQP1 were detected by Western blot and RT-qPCR.5.To observe the effects of safe concentration of DEX on inflammatory factors after ischemia and hypoxia injury of Schwann cells,and to detect the expression levels of IL-6 and TNFαby ELISA and RT-qPCR.Results:1.AQP1 and S100βco-localized in primary Schwann cells;Incubation of 100μM CoCl₂ for 6h was the optimal condition for cell incubation.2.1μM DEX is a safe concentration without affecting the expression level of AQP1 in normal cells.3.Western blot and RT-qPCR showed that the expressions of HIF-1αand AQP1were relatively increased in CoCl₂ group,while the expressions of HIF-1αand AQP1were relatively decreased in CoCl₂+DEX group.4.ELISA and RT-qPCR showed that the expressions of IL-6 and TNFαwere relatively increased in the CoCl₂ group,while the expressions were relatively decreased in the CoCl₂+DEX group.Conclusions:1.Expression of AQP1 was increased after ischemia and hypoxia injury in Schwann cells.DEX can reduce Schwann cell edema and decrease the expression of AQP1.2.The expression of inflammatory cytokines IL-6 and TNFαincreased after ischemia and hypoxia injury in Schwann cells,and DEX could reverse the expression trend of these inflammatory cytokines.