Gene Expression of TGF-β Cascade in Osteoporosis

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Postmenopausal deficit of estrogen might cause osteoporosis. For the purpose to verify effects of estrogen in bone regeneration, localizations of TGF-β super family and their specific receptors were investigated during process of bone healing in bone defects in ovariectomized rats (OVX).Rats were ovariectomized. Then the animals receive low calcium diet for 4 months. The upper first molars were extracted, then after 1〜8 weeks then, they were fixed.I. Histological findingsIn the OVX rats, fibrogenesis was observed in the extraction sockets at 3 days after the tooth extractions. A large number of osteoclasts were observed along the wall of the extraction sockets. At 7 days the extraction sockets were filled with fibrous tissue, and bone formation was initiated along the socket walls. At 14 days bone trabecullae wa formed then, the extraction sockets were filled with bone in 14 days. In normal rats bone was formed in 4 days.2. The localizations of TGF-β and receptors (Type I and II)The localizations of TGF-β and receptors showed the same distributions. The intense reaction was detected in the fibroblasts of the regions of fibrogenesis. The most intense reaction was found in the osteoclasts. At 7 days osteoblasts along the bottom of the extraction sockets revealed intense reaction but the reactions of osteoclasts were stronger than those of osteoblasts. At 14 days osteoclats showed intense reaction. The most intense reaction was persisted in the osteoclasts. At 28 days reactions of osteoblasts were stronger than those of osteoclasts.3. The localizations of BMP and receptors (Type IA, IB and II)During the process of bone regenaration, intense reaction was detected in the preosteoblasts and osteoclasts. The reactions of osteoclasts were weak.In OVX rats, bone regeneration was delayed than that of normal rats. This might cause stimulation of TGF-β super family to the osteoclasts.