Shenfu Injection postpones the production of neuropathic pain in CCI rats

AIM:To investigate whether Shenfu Injection, an intravenous injection made from traditional Chinese medicinal herbs, could postpone the production of neuropathic pain in CCI rats. METHODS: Thirty-two SD rats were divided into 4 groups randomly: ①CCI group in which the rats underwent the CCI (the sciatic nerve chronic constriction injury) procedure, ②CCI+saline group in which the rats were given saline injection (25 mL/kg) once daily for 7 consecutive days immediately after the CCI procedure, ③CCI+Shenfu group in which the rats were given Shenfu injection(25 mL/kg) once daily for 7 consecutive days immediately after the CCI procedure, and ④Sham group in which the rats underwent the same procedure as CCI group but without ligature of the sciatic nerve. At -2, 1, 3, 7, 10 and 14 d after the surgery, we examined the time course of hyperalgesia including thermal paw withdrawal latency and Von Frey withdrawal threshold. RESULTS: Compared with those in Sham group, the scores of thermal paw withdrawal latency(TWL) and Von Frey withdrawal threshold(MWT) in CCI group and CCI+ saline group decreased significantly after surgery(P0.01). The scores of MWT in these two groups declined from the first day and eventually reached the bottom at the 7th day after surgery. The scores of TWL in these two groups were significantly lower than the scores in Sham group from the first day after surgery, and reached the bottom at 3rd day after surgery. There was no significant difference in TWL and MWT between CCI group and CCI+ saline group. At 1, 3 and 7 d after surgery, the scores of MWT in CCI+Shenfu group were significantly higher than those in CCI and CCI+saline group(P0.05). However, There was no significant difference in TWL and MWT since the 10th after surgery. Compared with those in CCI and CCI+saline group, the scores of TWL in CCI+Shenfu group were significantly higher than those in CCI and CCI+saline group only on the 1st after CCI surgery(P0.05). CONCLUSION: Early administration of Shenfu injection once daily for 7 consecutive days immediately after CCI surgery mildly postpones the production of mechanical hyperalgesia induced by CCI surgery, and reduces thermal hyperalgesia only on the 1st day after surgery.