Effect of electroacupuncture on muscular atrophy and Slit/Robo signaling in sciatic nerve and lumbar spinal cord tissues in rats with sciatic nerve injury

Abstract

To observe the effect of electroacupuncture (EA) of "Huantiao"(GB30) and" Zusanli"(ST36)on muscular atrophy and expression of Slit-Robo GTPase-activating protein(srGAP)1, 2 and 3 in the injured sciatic nerve and lumbar spinal cord tissues in sciatic nerve injury (SNI) rats, so as to reveal its mechanisms underlying improvement of peripheral nerve injury (PNI)．. A total of 120 healthy male SD rats were randomly divided into control, sham-operation, model and EA groups (n＝30 rats in each) which were further divided into 7, 15 and 23 d subgroups (n＝10 rats in each subgroup). The SNI model was established by transecting the right sciatic nerve beneath the piriformis and immediately subsequent end-to-end suture. Rats of the sham operation group received an incision of the corresponding skin and suture. EA (5 Hz/20 Hz, 2－3 mA) was applied to the right GB30 and ST36 for 15 min, once daily, 6 days a week separately for 1，2 and 3 weeks. Rats in the sham-operation and model groups were grasped in the similar procedure as the EA group. The wet weight of gastrocnemius muscles (WWG) on both sides was measured to calculate the recovery rate (weight of the right WWG/weight of the left WWG×100%), and the expression levels of srGAP1, srGAP2 and srGAP3 proteins in the sciatic nerve and the spinal cord (L4-L6) tissues were detected by Western blot. After modeling and compared with the control and sham-operation groups, the recovery rate of WWG was significantly reduced, and the expression levels of srGAP1, srGAP2 and srGAP3 proteins of the sciatic nerve and lumbar spinal cord on day 7, 15 and 23 were considerably increased in the model group (P<0.01). Following the EA treatment, the reco-very rate of WWG was obviously increased and the expression levels of srGAP1, srGAP2 and srGAP3 proteins of both sciatic nerve and spinal cord on day 7, 15 and 23 were further significantly up-regulated in the EA group relevant to the model group (P<0.05，P<0.01). In addition, the expression levels of the 3 proteins in both sciatic nerve and lumbar spinal cord peaked on day 15 and attenuated on day 23. EA of GB30 and ST36 may relieve gastrocnemius atrophy in SNI rats, which is related to its function in up-regulating the Slit/Robo signaling in the sciatic nerve and lumbar spinal cord to promote the axonal targeting regeneration and repair of axonal plasma nutrition transportation.