Best proportion of two Chinese herbal medicines on central muscular hypertonia rats to relax spasm and relieve pain: a screening process for Shaoyao Gancao decoction composed of Paeonia latiflora Pall. and Glycyrrhiza uralensis Fisch.

Objective To explore the spasmolysis and analgesia effects of Shaoyao Gancao decoction at different proportions on spastic paralysis rats. Methods The spasmo- rat model was made by using thread approach to occlude middle cerebral artery. Compared with bacolfen( bacolfen group),altogether five Shaoyao Gancao decoction groups were designed at five different proportions of Paeonia lactiflora Pall.( Shaoyao) and Glycyrrhiza uralensis Fisch.( Gancao) with 1 ∶ 1( TCM 1 group),1. 5 ∶ 1( TCM 2group),3∶ 1( TCM 3 group),7∶ 1( TCM 4 group) and 24∶ 0( TCM 5 group). After 3 weeks,neurological symptom score,muscular tone and pain threshold were measured. Results All the five TCM groups relieved spasm and pain,but different proportions showed different effects on neurological symptom score,muscular tone and pain threshold. The proportion of 1 ∶ 1 reduced neurological symptom score significantly compared with the other groups,while the proportion of 3∶ 1 decreased muscular tension and proportion of 7∶ 1 increased pain threshold dramatically. Conclusion Shaoyao Gancao decoction relieved spasm and pain induced by central muscular hypertonia at the best proportion 3 ∶ 1 at the comprehensive evaluation.