[Effect of electroacupuncture of "Guanyuan" (CV 4) on Wnt-β-catenin signaling in osteoporosis rats].

OBJECTIVE

To observe the effect of electroacupuncture of "Guanyuan" (CV 4) on bone miner density, bone biomechanics, serum osteocalcin (BGP) and alkaline phosphatase (ALP) contents, and femoral osteoblastic Wnt-β-catenin signaling in postmenopausal osteoporosis (PMOP) rats.

METHODS

Forty female SD rats were randomly divided into sham operation (sham), model, EA-CV 4, and EA-non-acupoint (below the costal region) groups (n = 10 in each group). The PMOP model was established by performing an ovariectomy in the rats of the later 3 groups. EA (2 Hz, 1 mA) was applied to CV 4 for 20 min, once daily for one month, with one day's break between every 10 days. After the treatment, serum BGP and ALP contents were detected using ELISA, the right femoral bone miner density and biomechanics (maximum load, breakage load) were measured using a Dual Energy X-Ray Bone Densitometer and a Universal Material Testing Instrument, respectively. The expression levels of Wnt 3 a mRNA, β-catenin mRNA and the bone-specific factors runt-related transcription factor 2 (Runx 2) mRNA of the femoral bone tissue were determined by real time RT-PCR.

RESULTS

HE staining results suggested EA of "Guanyuan" (CV 4) can improve the morphological changes (trabeculae) of osteoporosis in ovariectomized rats. Compared with the control group, femoral maximum load and breakage load, bone density and serum BGP and ALP contents, femoral Wnt 3 a mRNA, β-catenin and Runx 2 mRNA expression levels, and femoral Wnt 3 a.and β-catenin immunoactivity were significantly down-regulated in the ovariectomized rats (model group) (P < 0.05). Following EA treatment, all the decreased levels of femoral maximum load and breakage load, bone density and serum BGP and ALP, femoral Wnt 3 a mRNA and protein, β-catenin mRNA and protein and Runx 2 mRNA expression were obviously reversed in the EA-CV 4 group (P < 0.05) rather than in the non-acupoint group (P > 0.05).

CONCLUSION

EA of CV 4 can improve the femoral biomechanics, increase bone density in OVX rats, which are associated to its effects in up-regulating levels of serum BGP and ALP, femoral Wnt 3 a mRNA and protein, β-catenin mRNA and protein and Runx 2 mRNA expression, suggesting an involment of improved bone metabolism and activation of osteoblastic Wnt-β-catenin signaling.