Effects Of Total Flavones Of Pueraria Lobata On Osteoporosis And The Possible Mechanisms

Osteoporosis is a common systemic bone disorder that is characterized bymicroarchitectural deterioration of bone tissue and low bone mass, which results in bonevulnerability and susceptibility to fractures. It has no obvious symptoms until occurringosteoporosis fracture and affecting patients’ quality of life seriously. A number of drugshave side effects to patients for the treatment of osteoporosis. So, it is significant that toinvestigate the mechanism of osteoporosis and seek for high efficiency natural medicinewith less side effects.Pueraria Lobata is the root of kudzu or dried kudzu, and belongs to the reptileleguminous plants. It has many effects including: antipyretic, anti-inflammatory,reducing vascular resistance, increasing coronary blood flow and so on. As to thereferences, isoflavones is one of flavones, and has exact effectson the treatment ofosteoporosis. The aim of the present study is to investigate antiosteoporotic activity oftotal flavones of Pueraria Lobata (TFPL) induced by ovariectomy and prednisoneacetate and to explore its possible mechanisms.ObjectiveTo investigate antiosteoporotic activity of total flavones of Pueraria Lobata (TFPL)induced by ovariectomy and prednisone acetate and to explore its possible mechanisms. Contents1. To establish the osteoporosis model induced by ovariectomy, and observeantiosteoporotic activity of total flavones of Pueraria Lobata (TFPL) induced byovariectomy.2. To establish the secondary osteoporosis model induced by prednisone acetate(Pred),and observe antiosteoporotic activity of total flavones of Pueraria Lobata (TFPL)induced by prednisone acetate(Pred).Methods1.Osteoporosis model was induced by ovariectomy and assigned to groupsincluding: normal group, ovaricetomized (OVX) group, sham OVX group (only in theovaricetomized osteoporosis model), Tibolone Tablets group(TT,1.25mg kg/d) andTFPL groups (50，100，200mg/kg/d). All experiment substances were administered for12weeks and efficacy index were evaluated.（1） Uterus wet weight and uterus index were measured.（2） Bone minernal density (BMD), bone minernal content (BMC) of the rightfemur were measured by dual-enery x-ray absorptiometry (DEXA).（3） Bone breaking strength of the left femur was measured by three-pointbending test.（4） Histomorphology of the left tibia was analyzed for bone microstructure afterhaematoxylin and eosin (HE) staining.（5） Urine hydroxyproline (HOP), serum bone specific alkaline phosphatase(BALP), follicle-stimulating hormone (FSH), luteotropic hormone (LH) and estrogen(E2) were mersured by ELISA kits.（6） The mRNA level of hypothalamus gonadotropin-releasing hormone (GnRH),estrogen receptorα(ERα) and estrogen receptorβ (ERβ) were evaluated by RT-PCR.2. Osteoporosis model was induced by prednisone acetate (Pred) and randomlyassigned to six groups including: normal group, Pred group, TFPL groups (50,100,200mg/kg/d), TT group (1.25mg/kg/d). Index were evaluated after treatment ofTFPL for12weeks.（1） BMD and BMC of lumbar vertebra (L4-L5) were measured by DEXA.（2） Bone breaking strength of the left femur was evaluated by three-pointbending test.（3） Histomorphology of left tibia and right adrenal glands were analyzed forbone microstructure after HE staining.（4） Urine HOP and serum BALP were mersured by ELISAkits.（5） The mRNA level of hypothalamus GnRH, ERα, ERβ andCorticotropin-Releasing Hormone (CRH) were evaluated by RT-PCR.Results1. The uterine was atrophy and its weight significantly decreased in OVX rats,which demonstrated the success of OVX model.2. TFPL distinctly improved BMD of the right femur, bone biomechanicalproperties of the right femur, which demonstrated that TFPL could improve bone lossand decreased of biomechanical property.3. TFPL could turn bone trabecula to be thicken and dense, and keep regular array.Moreover, TFPL could significantly improve the average thickness of trabecular bone(Tb.Th), the average bone volume fraction (BV/TV) and decrease the average bonetrabecular spacing (Tb.Sp). It suggested that TFPL could keep bone microstructureintegrity.4. TFPL could decrease urine HOP, serum BALP, FSH, LH levels and decreasebone absorption. Furthermore, it may lead to negative feedback regulation of thehypothalamic-pituitary-ovarian axis as the predominant hypothalamic signals.5. TFPL could up regulate hypothalamus GnRH, Erα and ERβmRNA expression.6. Osteoporosis model was induced by prednisone acetate for12weeks. BMD and BMC of lumbar vertebra (L4-L5) were decreased, which demonstrated the success ofPred model. TFPL distinctly improved BMD and BMC of lumbar vertebra (L4-L5),bone biomechanical properties of the right femur.7. TFPL could not only turn bone trabecula to be thicken and dense, and keepregular array of Pred rats, but also it maintain zona glomerulosa，zona fasciculate andzona reticularis uniform and tidy.8. TFPL could distinctly decrease levels of urine HOP and serum BALP in Predrats, which suggested TFPL could decrease bone turnover.9. TFPL could up regulate GnRH, CRH, ERα and ERβ mRNA expression in thehypothalamus of Pred rats.Conclusions1. Results of current study demonstrat that treatment of TFPL may enhance BMD,bone breaking strength, and preventively treat osteoporosis in rats induced byovariectomy or prednisone acetate. The mechanism of TFPL on osteoporosis might beassociated with its activity of inhibitting bone absorption and decreasing bone turnover.2. FSH and ER paly a crucial role in bone metabolism. TFPL may accommodatebone remodeling through up decreasing serum FSH levels and regulating ER mRNAexpression and achieve the effect on bone protection in OVX rats. Moreover, TFPL mayup-regulate CRH, ER mRNA expression and prevent bone loss in Pred rats. However,the specific regulatory mechanism remains to be further explored.