RESUMEN
Objective: To observe the mRNA levels of Orexin and its receptors in the hypothalamus of ovariectomized osteoporosis rats, in order to explore the pathogenesis of postmenopausal osteoporosis(PMOP) and the mechanism Zuoguiwan. Method: An osteoporosis model induced by ovariectomy was established in rats. Totally 32 female Sprague-Dawley (SD) rats were randomly divided into sham-operated group, ovariectomized model group, 17β-estradiol treated positive group, and Zuoguiwan group, with 8 rates in each group. After 12 weeks of intragastric administration, the bone mineral density (BMD) and trabecular microstructural changes of femur were detected by micro-CT (μ-CT), and the morphological changes of bone tissue were observed by hematoxylin-eosin staining (HE) staining. The markers of bone turnover in serum osteocalcin (OCN), N-terminal propeptide of type Ⅰ procollagen (PINP), tartrate-resistant acid phosphatase (TRAP) were measured using enzyme-linked immunosorbent assay (ELISA). The mRNA expressions of orexin, orexin receptor 1 (OX1R) and orexin receptor 2 (OX2R) were measured by Real-time PCR. Result: Compared with sham-operated group, the μ-CT showed that BMD, bone volume fraction(BV/TV), trabecular thickness(Tb. Th)and trabecular number(Tb. N)in ovariectomized model group were significantly decreased (PPN-terminal propeptide of type Ⅰ procollagen (PINP) levels decreased, whereas tartrate-resistant acid phosphatase (TRAP) content increased (PPPPPPPPPPConclusion: Decreased mRNA levels of Orexin and its receptors in the hypothalamus may be one of the mechanisms of PMOP. Zuoguiwan may correct the imbalance of bone metabolism, improve the trabecular microstructure and improve bone by up-regulating the mRNA expressions of Orexin and its receptors in the hypothalamus, density, so as to show a therapeutic effect on PMOP.