ABSTRACT
Objective To observe the expression of Glu、mGluR 5 and EAAT 1 in bone tissues of ovariectomized osteoporotic rats and the effects of Total Flavonoids of Rhizoma Drynariae (TFRD) on it. Methods 45 SPF 3-month-old Sprague-Dawley (SD) female rats were randomly divided into sham operation (Sham, n=15) group and ovariectomized (OVX, n=30) group. The osteoporotic(OP) model was established by bilateral ovariectomy, 14 weeks later, we measured bone mineral density(BMD) by dual-energy X-ray and determined that OP model was successfully replicated, OVX group rats were then divided into OVX group (n=15) and OVX+TFRD group (n=15). The OVX+TFRD group was given TFRD for 12 weeks. Glutamate (Glu), metabotropic glutamate receptor 5 (mGluR 5), and Glutamate/Aspartate Transporter (GLAST/EAAT 1)’s expression of femur was examined in order to clarify the characteristics of bone glutamate signaling pathway and the effects of TFRD on it. Results Glu and ionotropic receptors mGluR 5 mainly distributed in bone marrow cells and osteoblasts closed to the bone marrow cavity walls. There were no significant differences in Glu expression among Sham group, OVX group and OVX+TFRD group. The mGluR 5 expression of OVX+TFRD group was significantly higher than that of Sham group and OVX group(P=0.009), while no significant difference was found between the latter two groups. In addition to large distribution in bone marrow cells, small amount of transporter EAAT 1 was noted to express in bone cells of the bone lacunae. There were no significant differences in EAAT 1 expression among the three groups. Conclusion In bone glutamate signaling pathway, this study demonstrated that TFRD could significantly improve the ionotropic receptor mGluR 5’s expression, but had no inlfuence for Glu and EAAT 1.