Effect of salviae miltiorrhizae and ligustrazine hydrochloride injection on axonal regeneration and nerve growth factor expression in a rat model of sciatic nerve injury

BACKGROUND: Studies have shown that both salviae miltiorrhizae and ligustrazine can promote protein expression of nerve growth factor (NGF) and regeneration of peripheral nerve. OBJECTIVE: To verify the effect of salviae miltiorrhizae and ligustrazine hydrochloride injection on axonal regeneration and NGF protein expression in a rat model of sciatic nerve injury. DESIGN, TIME AND SETTING: A randomized, controlled, animal experiment was performed at the Laboratory of Traditional Chinese Medicine and the Institute of Bioengineering of Jinan University from July to December 2008. MATERIALS: Salviae miltiorrhizae and ligustrazine hydrochloride injection (containing 20 mg salviae miltiorrhizae and 100 mg ligustrazine per 100 mL injection) was provided by Guizhou Baite Pharmaceutical, China; salviae miltiorrhizae and ligustrazine decoctions (containing 1 g raw drug per I mL decoction) were provided by Guangzhou Baiyunshan Factory for Traditional Chinese Medicine, China; rabbit-anti-rat NGF monoclonal antibody was provided by Beijing Biosynthesis Biotechnology, China. METHODS: A total of 80 healthy, male, Sprague Dawley rats were used to establish a sciatic nerve injury model via neurotomy, and were then randomly assigned to 4 groups: salviae miltiorrhizae and ligustrazine hydrochloride injection group (intraperitoneal injection of 35 mL/kg per day salviae miltiorrhizae and ligustrazine hydrochloride injection), salviae miltiorrhizae group (intragastric perfusion of 2 mL salviae miltiorrhizae), ligustrazine group (intragastric perfusion of 2 mL ligustrazine), and model group (intraperitoneal injection of 35 mL/kg per day saline), with 20 rats in each group. Thereafter, rats in each group were then divided into 4 subgroups according to varying time points of 1, 2, 4, and 8 weeks post-surgery, with 5 rats in each subgroup. MAIN OUTCOME MEASURES: Axons were quantified using chromotrope 2R-brilliant green and silver staining combined with image analysis to calculate the axonal regeneration rate; NGF expression was detected using immunohistochemistry and Western blot analysis; toe interspace was measured by behavior at 4 and 8 weeks. RESULTS: With increasing time after sciatic nerve injury, the axonal regeneration rate, NGF protein expression, and toe interspace gradually increased. At 4 and 8 weeks post-surgery, axonal regeneration rate and NGF protein expression were significantly increased in the injured tissue of the salviae miltiorrhizae and ligustrazine hydrochloride injection, salviae miltiorrhizae, and ligustrazine groups, compared with the model group (P < 0.05 or P < 0.01), and toe interspace was remarkably enlarged (P < 0.05 or P < 0.01), especially in the salviae miltiorrhizae and ligustrazine hydrochloride injection group. CONCLUSION: Salviae miltiorrhizae and ligustrazine hydrochloride injection promoted axonal regeneration and NGF protein expression in the injured sciatic nerve, and also enhanced neurofunctional recovery. Its effect was superior to salviae miltiorrhizae or ligustrazine alone.