Effect On The Bone Metabolism In Ovariectomized Rats With Iron Overload

Objective To investigate the interventive effect of rutin and resveratrol againt the oxidative stress induced by dietary iron overload on the osteoporosis in ovariectomized rats.Methods Forty-eight female SD rats(3 months old) were randomly divided into six groups: sham-operated group(SHAM), ovariectomized group(OVX), dietary iron overload group (FE), 17β-estradiol replacement therapy group(ERT, 0.1mg. kg^-1.d^-1), resveratrol therapy group(RES, 20mg.kg^-1.d^-1), rutin therapy group(RUTIN, 20mg.kg^-1.d^-1). The other groups were operated by bilateral ovariectomy except SHAM group. SHAM and OVX group were fed with normal diet, and other groups with dietary iron overload. On 8th day after operation, the administration started and lasted for 7 weeks. All rats were sacrificed at the end of 8th week after operation. The iron, calcium, phosphonium, Alkaline phosphatase(ALP), Superoxide dismutase(SOD), Total Antioxidative capacity(TAC), Nitric oxide(NO), Malondialdehyde(MDA) in serum and iron, Hydroxyproline(HOP) in urine were measured respectively. Bone mineral density(BMD), bone mineral content(BMC) of femurs and lumber vertebrae were measured. Finally the expression of BGP, TRAP and IGF-1 mRNA were observed by RT-PCR.Results 1. The SOD, TAC and NO were decreased and MDA increased in serum and lumber in OVX group(P<0.05, vs SHAM group); in FE group the SOD, TAC and NO were decreased, but MDA increased in serum, only MDA increased in lumber in FE group(P<0.05, vs OVX group); in RES and RUTIN group the SOD, TAC and NO in surum and the SOD, TAC, MDA and NO in lumber had no difference with SHAM group. 2. The levels of calcium and phosphonium in serum and urine in OVX and FE group were lower than SHAM group; the levels of calcium and phosphonium in serum and in urine did not show signifcant difference in ERT, RES and RUTIN group (P<0.05, vs SHAM group). 3. the levels of ALP in serum was significantly decreased and HOP in urine increased in OVX group (P<0.05, vs SHAM group); in FE group ALP in serum decrease (P<0.05, vs OVX group); ERT, RES and RUTIN group HOP decreased compared with FE group (P<0.05). 4. The BMD and BMC in OVX and FE group were lower than SHAM group, there was not significant difference between SHAM group and both ERT and RUTIN group. 5. OVX group expression of TRAP mRNA was higher than SHAM group, in contrast, BGP and IGF-1 showed opposite results (P<0.05); the expression of the TRAP mRNA was increased in FE group (P<0.05, vs OVX group); the expression of the BGP and IGF-1 mRNA in the ERT, RES and RUTIN group were increased, but TRAP mRNA decreased compared with FE group (P<0.05).Conclusion 1. Oxidative stress may be involved in the pathogenesis of osteoporosis in Ovariectmized rats through accelerating bone resorption and decelerating bone formation; 2. Estradiol, Resveratrol and Rutin can protect from oxidative stress, which is probably one of the mechanism that protecting bone.