| Budget Amount *help |
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2002: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2001: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2000: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
It was reported teat isoflavone, one of pytoestrogen,was effective to protect the decrease in bone mass caused by diminished estrogen action on animals and human In this research, we investigated influence of estrogen (E2), vitamin D3 (D3) and genistein (Ge: one of isoflavones found in soybean seeds) on mRNA levels of vitamin D3 receptor (VDR) and osteocalcin (OC) in hind limb of tail-suspended rats and in rat osteoblast-like cells.(ROS17/2.8) Experiment (1):Ovariectomized rats were divided into two groups of OVX-E2 (E2 administiation for 2 weeks) and OVX (no E2 administration). Then, tail-suspension was performed, and VDR and OC mRNA.levels were determined by.Northern blot memod Experiment (2): RDS17/2.8cell cells were treated with 10^<-6>M D3 and/or 10^<-9>M E2, resulting in 4 groups of D3(-)E2(-), D3(+)E2(-), D3(-)E2(+)and D3(+)E2(+). After 12 hours, RNA was extracted, and VDR and OC mRNA levels were determined. Also we examined effect of Ge and D3 on VDR and OC mRNA. levels.
In Experiment (1), VDR mRNA expression in OVX-E2 group increased compared with that of OVX group. In contrast;OC mRNA level in OVX-E2 group decreased significantly. This might be due to E2-dependent increase in serum glucocoricoid levels, because glucocorticoid was shown to decrease OC expression at the transaiptional levels.
In Experiment (2), VDR and OC mRNA levels in D3(+)E2(+) group increased by 2 and 1.5 folds, respectively compared with those of VD3(-)E2(-) group. VDR mRNA also increased in VD3(+)E2(-) or VD3(-)E2(+) groups. However, its level was lower than that of VD3(+)E2(+) group. D3 or E2 alone had no effect on OC mRNA level. Similar results were obtained from the experiment using Ge.
In conclusion, these results suggested that prevention of osteoporosis by pytoestrogen might be partially clue to its stimulatory action on VDR expression.
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