[Effect of electroacupuncture of "Mingmen" (GV 4) on bone morphogenetic protein-2 expression in osteoporosis rats]

To observe the effect of electroacupuncture (EA) stimulation of "Mingmen" (GV 4) on the bone morphogenetic protein-2 (BMP-2) content and biomechanics in osteoporosis rats so as to explore its mechanism underlying improvement of osteoporosis.

Fifty female SD rats were randomized into sham operation (sham), model, EA-GV 4, EA-non-acupoint (non-acupoint) and estrogen (medication) groups, with 10 rats in each group. Postmenopausal osteoporosis model was established by removing the rats' bilateral ovaries under anesthesia. EA (2 Hz/15 Hz, 1.0 mA) was applied to "Mingmen" (GV 4) or non-acupoint for 20 min, once daily for 30 times, with one day's interval between every two 10 times. Rats of the medication group were lavaged with Pentanoic Acid Estradiol (25 microg/mL, 2 mL/500 g), once every day (the dosage of estradiol was adjusted according to their body weight) continuously for 1 month. Rats of the model and sham groups experienced the fixing and fastening procedures as the other rats in the EA and medication groups. After intervention, the BMP-2 expression level of the femoral bone tissue, and bone biomechanical values were determined by immunohistochemistry and three-point bending tests, respectively.

(1) In comparison with the sham operation group, the femoral biochemical maximum load and fracture load values were significantly decreased in the model group (P < 0.05). While compared with the model group, the biochemical maximum load and fracture load values were obviously increased in the EA-GV 4 and medication groups (P < 0.05), but not in the non-acupoint group (P > 0.05). (2) Compared with the sham group, the femoral BMP-2 expression of model group was significantly decreased (P < 0.05), compared with the model group, the expression of BMP-2 of GV 4 and medication groups significantly increased (P < 0.05).

EA-GV 4 intervention can improve bone biomechanical changes in osteoporosis rats.