Objective:To observe the effects of acupuncture at Houxi(SI3)and Huantiao(GB30)on the expression levels of nuclear factor kappa B(NF-κB),inducible nitric oxide synthase(iNOS),and nitric oxide(NO)of NF-κB inflammatory signaling pathway in L5 spinal nerve root of lumbar disc herniation(LDH)model rats and explore the mechanism of acupuncture in LDH treatment.Methods:Forty specific-pathogen-free healthy male Sprague-Dawley rats were randomly divided into a sham operation group,a model group,acupuncture group 1,and acupuncture group 2,with 10 rats in each group.The non-compression nucleus protrusion model was made by puncturing L4-L5 spinous process space and injecting autologous nucleus suspension.Acupuncture at bilateral Shenshu(BL23),Dachangshu(BL25),and Weizhong(BL40)was carried out in acupuncture group 1,and acupuncture at bilateral Houxi(SI3)and Huantiao(GB30)in acupuncture group 2.All rats were treated with balanced reinforcing and reducing needling manipulations,and the needles were retained for 30 min/time with one episode of needling manipulation every 10 min,once a day,14 times in total.The threshold value of paw withdrawal pain was measured by a thermal stimulation pain instrument;the serum NF-κB,iNOS,and NO levels were measured by enzyme-linked immunosorbent assay.The pathomorphological changes of spinal nerve roots were observed by hematoxylin-eosin(HE)staining;quantitative reverse transcription polymerase chain reaction was used to detect iNOS mRNA expression in spinal nerve roots;the NF-κB and iNOS protein expression in spinal nerve roots was detected by the immunofluorescence method.Results:Compared with the sham operation group,the threshold of paw withdrawal pain in the model group was decreased,and the expression levels of serum NF-κB,iNOS,and NO were increased;HE staining showed many degenerated and dissolved Schwann cells in spinal nerve roots with vacuolar changes;meanwhile,the expression levels of NF-κB and iNOS proteins,and the iNOS mRNA in spinal nerve roots were increased.Compared with the model group,the paw withdrawal pain thresholds in acupuncture group 1 and acupuncture group 2 were increased,and the increase in acupuncture group 2 was greater(P<0.05);the expression levels of serum NF-κB,iNOS,and NO in acupuncture group 1 and acupuncture group 2 were decreased,especially in acupuncture group 2(P<0.01);the vacuolar changes of spinal nerve roots,and the degeneration and lysis of Schwann cells in acupuncture group 1 and acupuncture group 2 were decreased,which were more obvious in acupuncture group 2;the NF-κB and iNOS protein expression and the iNOS mRNA expression levels in spinal nerve roots of acupuncture group 1 and acupuncture group 2 were decreased,especially in acupuncture group 2(P<0.01).Conclusion:Acupuncture at Houxi(SI3)and Huantiao(GB30)can improve the morphology of spinal nerve roots,inhibit the NF-κB and iNOS protein expression levels in spinal nerve roots and the serum NO level,and relieve the pain caused by inflammation of spinal nerve roots,which may be one of the mechanisms of acupuncture in LDH treatment.