Stellate Ganglion Block Alleviates Acute Lung Injury In Rats

Objective: Acute lung injury(ALI)is caused by a variety of factors both inside and outside the lung,causing damage to the alveolar epithelium and capillary endothelium,which can lead to diffuse interstitial and alveolar oedema and,in severe cases,acute respiratory distress syndrome(ARDS).There are approximately 3 million cases of ARDS worldwide each year,accounting for 10% of the patients admitted to intensive care units,and the mortality rate is as high as 30% to 40%.Stellate ganglion block(SGB)is a minimally invasive treatment that injects local anesthetic around the stellate ganglion to reversibly block the sympathetic circuit.It has been reported that SGB can alleviate ALI in rats,but the exact mechanism needs to be further elucidated.Based on this,this study aims to investigate the possible mechanism of SGB to reduce ALI in rats.Methods: Adult male SD rats weighing about 200-300 g were randomly divided into 4groups: control group(group C),normal saline group(group NS),LPS group(group L)and LPS+SGB group(group LS).The rats in group C did not receive any treatment.The rats in group L received intratracheal instillation of LPS(5mg/kg)after anesthesia,the rats in group NS received intratracheal instillation of normal saline(0.5ml/kg)after anesthesia,and the rats in group LS received a single right SGB(0.5% ropivacaine 0.3ml)half an hour after LPS treatment.Lung histopathology,arterial blood gas,serum inflammatory cytokines(IL-1 β,IL-6,IL-10)and indexes about oxidative stress(ROS,CTP-D,T-SOD,Mn-SOD,CAT),alveolar macrophage differentiation,and SIRT3,CIRP and NLRP3 expression in lung tissue were observed at 0h(T0),6h(T1),12h(T2),24h(T3).Results:There was no significant difference in the above observation indexes in group NS compared with group C(P>0.05).Compared with group NS,alveolar wall was significantly thickened in group L,accompanied by massive inflammatory cell infiltration,decreased arterial oxygenation(P<0.05),increased secretion of inflammatory cytokines IL-1 β and IL-6(P<0.05),decreased secretion of anti-inflammatory cytokine IL-10(P<0.05),increased levels of ROS and CYP-D(P<0.05),decreased activities of T-SOD,Mn-SOD and CAT(P<0.05),macrophage differentiation towards M1 phenotype(P<0.05),CIRP and NLRP3 protein expression increased(P<0.05),and SIRT3 protein expression decreased(P<0.05).Compared with group L,SGB significantly alleviated pathological injury(P<0.05),significantly improved arterial oxygenation(P<0.05),decreased secretion of proinflammatory cytokines(P<0.05),increased secretion of anti-inflammatory cytokines(P<0.05),decreased levels of ROS and CYP-D(P<0.05),enhanced activities of T-SOD,Mn-SOD and CAT(P<0.05),promoted macrophages differentiating from M1 phenotype to M2 phenotype(P<0.05),decreased CIRP and NLRP3 protein expression(P<0.05),and elevated SIRT3 protein expression(P<0.05).Conclusions: SGB can attenuate LPS-induced ALI in rats,and the mechanism may be related to the regulation of macrophage metabolism and inhibition of inflammatory response.