Effects of Siwu decoction on chondrocyte proliferation of growth plate in adolescent rats

Abstract Ethnopharmacological relevance According to traditional Korean medicine theory in which children's growth retardation is attributed to blood deficiency, Siwu decoction (SWD), a representative treatment for blood deficiency, was chosen as a sample. Aim of the study : To evaluate the effects of SWD on chondrocyte proliferation of growth plate in adolescent female rats. Materials and methods Female adolescent rats were allocated to one of the following four groups; SWD 100 and 300 mg/kg, recombinant human growth hormone, and vehicle for 4 days. Tetracycline was intraperitoneally injected at 48 h before sacrifice to obtain a band exhibiting fluorescence by binding newly formed bone. Bromodeoxyuridine was injected at day 2–4 to mark proliferating chondrocytes. To evaluate possible mechanisms of SWD, expressions of insulin-like growth factor-1 (IGF-1) and bone morphogenetic protein-2 (BMP-2) in the growth plate were examined by immunohistochemistry. Results Treatment with SWD significantly increased the number of BrdU-positive chondrocytes and the new bone formation in the proximal growth plate of tibia compared to the vehicle treated control group. SWD also increased the expression of IGF-1 and BMP-2 in the proliferative and hypertrophic zones of the growth plate. Conclusions SWD 300 mg/kg stimulates chondrocyte proliferation and new bone formation in the growth plate. Immunohistochemical studies indicate that the effects of SWD may be due to upregulation of local IGF-1 and BMP-2 expression in the growth plate, which may be considered as a GH-dependent paracrine-autocrine pathway.