Effects of Pulsed Radiofrequency on Nerve Repair and Expressions of GFAP and GDNF in Rats with Neuropathic Pain

Abstract

Objective. To study the effect of pulsed radio frequency (PRF) on nerve repair and the expression of GFAP and GDNF in rats with neuropathic pain. Methods. Thirty SPF healthy SD rats were randomly divided into control group (Group C), PSNL group (partial ligation of sciatic nerve) + sham group (Group PS), and PSNL group (partial ligation of sciatic nerve) + PRF group (Group PR), with 10 rats in each group. In group C, the right sciatic nerve was exposed without ligation. In the PS group, the model of neuropathic pain was established by partial ligation of sciatic nerve. The mice in the PR group were treated with PRF after establishing the neuropathic pain model. The general behavior of rats during the treatment was observed. The mechanical and thermal hyperalgesia were measured before operation and 1, 3, 7, and 14 days after operation. The content of inflammatory factors in nerve tissue was detected by ELISA. The pathological condition of nerve tissue was observed by HE. The gene and protein changes of GFAP and GDNF in nerve tissue were determined by QRT PCR and Western blot. Results. Rats in the control group were free to move and in good condition. In the PS group, there were different degrees of claudication, weakness of the lower limbs, lateral toe valgus, nerve injury, and other behavioral changes. After the pulsed radiofrequency in the PR group, the above symptoms decreased gradually with the prolongation of the treatment time. The mechanical pain sensitivity and thermal allodynia of the PS group were reduced after the operation. The mechanical pain sensitivity and thermal pain sensitivity of the PR group gradually increased with the prolongation of the treatment time, and the 14 days were basically close to the control group. The levels of TNF-α and IL-6 in ELISA were significantly higher in the PS group than in the control group, and the content in the PR group was gradually reduced, which was close to the control group. HE staining showed that the sciatic nerve fibers disappeared, and the formation of nerve cavities was obvious in the 14-day PS group. The nerve fibers were found in the sciatic tissue of the PR group, and there was no obvious hemorrhagic edema and cell deformation. The expression of GFAP mRNA in the PS group was significantly higher than that in the control group and the PR group ( $p<0.05$ ), and the expression of GDNF was opposite ( $p<0.05$ ). The results of western blot showed that the expression of GFAP protein in the 14-day PS group was significantly higher than that in the control group. The expression of the PR group decreased compared with the control group, and the expression of GDNF was opposite ( $p<0.05$ ). Conclusion. Pulsed radiofrequency ablation can promote neurological repair, promote GDNF, and reduce the expression of GFAP in rats with neuropathic pain.