Journal of the Korean Association of Oral and Maxillofacial Surgeons.1999;25(3):242-255.
Osteoporosis is a disease characterized by low bone mass and micro- architectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk. Women are the most likely to suffer osteoporotic fractures. In the second part of life bone mass decreases slowly, starting at about the age of 40 for cortical bone and somewhat earlier for trabecular bone. The total loss will be about 50% of the cancellous bone and 35% of the cortical bone in women. The imbalance between the bone resorption and bone formation can be caused by a decrease in the amount of new bone formed. The biochemical causes of the negative balance are not known. Therefore we studied to know the cause of negative balance after postmenopausal state by histomorphometry and in situ hybridization(ISH) for osteopontin. 84 female Spraque-Dawley rats, weighing approximately 200g, and fed laboratory chow ad libitum, were used in this study. Among those, 42 rats were sham operated, and 42 rats in experimental group were ovariectomized. They were divided into 7 groups consisting of 6 rats/group, and were serially sacrified on the 3, 5, 7, 10, 14, 30, and 60 days after operation and we obtained both femur of rats. After specimen preparation as usual manner, it was stained with H&E, MT. For histomorphometrical study, the bone structure was evaluated using the following parameters with OPTIMAS soft ware: trabecular bone volume/tissue volume(BV/TV, %), trabecular thickness(Tb.Th., micrometer), trabecular separation(Tb.Sp., micrometer). And in the way of ISH(in situ hybridization) procedure, osteopontin mRNA expressing cell was calculated. Statistical differences between OVX and sham-operated rats were evaluated using the ANOVA. After examination and comparision of all specimens, the results of this study were as follows: 1. BV/TV(%) after ovariectomy was decreased to 46.2+/-6.75%, compared with 58.14+/-8.72% of control group, with no statistical significance. These declination continued to 14 days postsurgery, in 30 and 60 days, it was decresed to 14.01+/-4.07% and 11.4+/-4.73% respectively, compared with 47.2+/-8.79% and 48.8+/-7.54% of control group, with statistical significance detected. 2. Trabecular thickness(micrometer) was decresed from 3 days to the remaining periods, with no statistical significance. 3. Trabecular separation(micrometer) was incresed throughout the study, especially in 60 days postsurgery, control group was 124.2+/-7.34micrometer and experimental group was 319.5+/-15.85micrometer, with statistical significance detected at 60 days postsurgery (p<0.05). 4. Osteopontin mRNA expressing cells was decreased from 3 days postsurgery, compared with 92.3+/-5.25 of control group. And these declination was observed throughout the study. Especially in 60 days postsurgery, control group was 93.25+/-2.72 and experimental group was decresed to 24.3+/-6.24, with statistical significance detected(p<0.05). From above results, after ovariectomy, bone formation was decreased, and it is thought that these bone formation declination was due to supression of osteopontin synthesis, which is the one of the bone matrix proteins.
Animals
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Bone and Bones
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Bone Matrix
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Bone Resorption
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Female
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Femur*
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Humans
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Osteogenesis
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Osteopontin*
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Osteoporosis
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Osteoporotic Fractures
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Ovariectomy
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Rats*
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RNA, Messenger*
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