Objective To observe the effect of acupuncture at “Houxi”(SI3) and “Huantiao”(GB30) on high mobility group box 1(HMGB1) protein and mRNA in spinal nerve trunk(SNT) of rats with lumbar disc herniation(LDH)

so as to explore the mechanisms of acupuncture at this paired points on the treatment for LDH. Methods SD rats were randomly divided into sham operation

model

conventional acupuncture(CA) and paired points(PP) groups(with 8 rats in each group). The LDH model was established by injection of autologous suspension made from rats' own nucleus pulsus into the epidural space. Rats in the CA group received acupuncture treatment at bilateral “Weizhong”(BL40)

“Dachangshu”(BL25) and “Shenshu”(BL23)

while rats in the PP group received acupuncture at bilateral SI3 and GB30

30 min each time

once daily for 14 consecutive days. The thermal pain threshold of bilateral hind feet of rats was detected by thermal pain stimulator. The contents of serum IL-1β

IL-6 and IL-8 of rats were detected by ELISA. Western blot and immunofluorescence were used to detect the expression of HMGB1 protein in the lumbar(L)5 SNT of rats. The relative expression of HMGB1 mRNA in L5 SNT was determined by qPCR. HE staining was used to observe the morphological changes of L5 SNT. Results Compared with the sham operation group

the thermal pain threshold of bilateral hind feet in the model group was decreased(P<0.05); compared with the model group

the thermal pain threshold of bilateral hind feet in the CA group and the PP group were increased(P<0.05). The expressions of HMGB1 protein and mRNA in L5 SNT

and the contents of serum IL-1β

IL-6 and IL-8 of rats in the model group were significantly increased(P<0.000 1

P<0.001) in contrast to the sham operation group. The expressions of HMGB1 protein and mRNA in L5 SNT

and the levels of serum IL-1β

IL-6 and IL-8 were significantly decreased(P<0.01

P<0.000 1

P<0.001

P<0.05) in the CA and PP group

in comparison with those of the model group. Compared with the CA group

the above indexes of rats in the PP group recovered more significantly(P<0.05

P<0.001

P<0.01

P<0.000 1). The histomorphological results showed scattered and various-sized nerve fibers

vacuolation

a large number of disintegrating myelin sheath and lysed Schwann cells in the model group. Myelin sheaths regeneration

regularly-arranged nerve fibers were seen in the CA group and the PP group

with more obvious histopathological recovery observed in the PP group than the CA group. Conclusion Acupuncture intervention inhibites the expressions of HMGB1 protein and mRNA in rats with LDH

and further reduces the production of IL-1β

IL-6 and IL-8

which is beneficial to inflammatory response inhibition and pain alleviation. The therapeutic effect of the PP group is more obvious than that of the CA group.