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Objective To investigate the effects of exposure to glucocorticoids with different dosage on skeleton of normal 3-month-old rats by dual energy X-ray absorptiometry (DXA), biomechanical testing and bone histopathology. Methods Thirty-one 3-month-old female clean level SD rats were randomly divided into 3 GC-treated groups, with tail intravenous injections of dexamethasone (Dex) at the dosage of 1, 2.5, 5 mg/kg twice per week for 8 weeks, respectively, and 1 normal control group treated with saline. At the end of experiment, bone mineral content (BMC) and bone mineral density (BMD) of the femur and the 3rd lumbar vertebrae in rats were measured by DXA. The 3-point bending test of the total femur and compression test of the 5th lumbar vertebrae were also conducted, respectively. Microstructure of the trabecula in proximal metaphysis of the tibia was observed by bone pathological section for quantitative analysis. Results Compared with control group, the body weight was significantly decreased in all Dex-treated groups, while no obvious decrease in vertebral BMC, BMD and maximum compressive loads was found. The total femoral BMC was also reduced significantly in all Dex-treated groups, while the total femoral BMD, proximal and distal femoral BMD were reduced only in Dex 1mg group. The fracture load, maximum load and elastic load for 3-point bending test were all evidently decreased in Dex 1mg group, while the Dex 2.5mg group and Dex 5mg group only showed a decline in elastic load. All Dex-treated groups showed an unevenly spatial distribution of the trabecula, which indicated a low bone metabolic state. Conclusions The exposure to GC for 8 weeks brings negative effects on skeleton of the 3-month old rats, which will cause more bone loss and worse mechanical properties in femur than in lumbar vertebrae. Higher dosage of Dex does not increase bone mass loss or change the mechanical properties. Both the decline in bone mechanics, especially elastic load, and unevenly density distribution of trabecula indicate that Dex will affect more bone quality other than bone mass. The side effects of GCs on skeleton in clinical application should be evaluated with various methods.
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Objective To study the effect of fluorine on the bone histomorphometry of humbar in rats.Methods Ninety 2-month-old SPF Sparague-Dawley rats,half male and female,were randomly divided into 9 groups:control[(childhood(CS),adult(AS),long-time(NS)]group and drug group[childhood high-fluoride and low-fluoride group(CHS,CLS),adult high-fluoride and low-fluoride(AHS,ALS),long-term high-fluoride and low-fluoride(CLHS,CLLS)].The control group was administered orally with solution of 0.9%NaCl,while the drug group was given orally with different dose of NaF at the same time. Sections of the fifth lumbar were made which was undecalicified for bone histomorphometric analysis, including the percentage of trabecular bone area (% Tb.Ar),trabecular thickness(Tb.Th), trabecular number(Tb.N), trabecular separation(Th.Sp) ; broken trabecular bone area cells (Oc.N), osteoclast perimeter percentage (% Oc.Pm), the percentage of labeled perimeter (% L.Pm), bone mineral apposition rate(MAR), osteoblast perimeter(Ob.PM), trabecular bone perimeter formation rate (BFR/BS),trabecular bone area formation rate (BFR/BV), the total area of bone formation rate (BFR/TV). Results [1]The percentage of Tb.Ar, Tb.Th, Tb.N,%L.Pm, MAR, BFR/BS, BFR/BV and BFR/TV of CHS group [(50.63 ±7.44)%, (150.26 ± 27.51 )μm, (3.44 ± 0.47)N/mm, (50.63 ± 7.44)%, (0.85 ± 0.03)μm/d, (8.45 ± 2.36)μm/d ×100, (381.16 ± 41.62)%/year, (75.07 ± 4.81)%/year] was higher than that of CS group [(29.71 + 9.32)%,(110.93 ± 28.19)μm, (2.68 ± 0.34)N/mm, (24.00 ± 1.22)%, (0.65 ± 0.03)μm/d, (5.43 ± 0.18)μm/d × 100,(141.32 ± 9.29)%/year, (58.14 ± 2.3)%/year, all P < 0.05)]. The %Tb.Ar, Tb.Th, %L.Pm, MAR, BFR/BS,BFR/BV, BFR/TV and Ob.PM of CLS group [(40.76 ± 6.43)%, (164.25 ± 45.65)μm, (42.02 ± 6.12)%, (0.85 ±0.04)μm/d, (8.95 ± 3.73)μm/d × 100, (378.73 ± 35.39)%/year, (73.52 ± 8.71)%/year, (1.41 ± 0.05)μm] were increased (all P < 0.05). [2]Compared with AS group, the %Tb.Ar,Oc.N, %Oc.Pm, %L.Pm, MAR, BFR/BS,BFR/BV and BFR/TV of AHS group[ (50.62 ± 5.76)%, (0.51 ± 0.05)N/mm, (1.13 ± 0.05)%, (42.3 ± 7.02)%,(1.28 ± 0.09)μm/d, (12.91 ± 1.52)μm/d × 100, (390.12 ± 43.56)%/year, (65.21 ± 22.13)%/year] was higher than that of AS group[ (42.73 ± 5.22)%, (0.41 ± 0.17)N/ram, (0.77 ± 0.52)%, (28.43 ± 6.93)%, (0.80 ± 0.03)μm/d, (9.83 ± 1.44)μm/d × 100, (324.43±53.44)%/year and(48.35 ± 9.36)%/year, all P < 0.05)] . The %Tb.At, Oc.N, %Oc.Pm, %L.Pm, MAR, BFR/BS, BFR/BV and BFR/TV of ALS group [(51.14 ± 6.22)%, (0.49 ±0.61)N/mm, (1.17 ± 0.11)%, (45.06 ± 6.92)%, (1.39 ± 0.08)μm/d, (12.87 ± 1.35)μm/d × 100, (394.6 ±50.23)%/year and(66.31 ± 18.93)%/year] were higher than that of AS group(P < 0.05) .[3] The Ob.PM ,Oc.N and %Oc.Pm of CLHS group[ (1.47 ± 0.27)μm, (0.58 ± 0.13)N/mm, (1.14 ± 0.07)%] were obviously increased(P <0.05), as compared with NS group [ (0.82 ± 1.20)μm, (0.42 ± 0.25)N/mm and (0.75 ± 0.64)%, all P < 0.05].Conclusions The short-term administration of NaF on rats in the growing period increases the bone formation and osteoblast activities of young rats and adult rats. The long-term administration of NaF on rats does not increase the bone formation of rats in growth period. The osteoblast activities as well as the bone absorption of lumbar vertebra were strengthened. The likelihood of bone fracture became larger. The negative effects on bone metabolism and bone quality of rats were gradually displayed along with the prolongation of sodium fluoride usage.
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<p><b>AIM</b>To determine the effect of piperazinyl estrone, a new estrogen derivative, on bone turnover, bone mass and uteri in ovariectomized rats.</p><p><b>METHODS</b>Female Sprague-Dawley rats were ovariectomized (OVX) or sham operated (sham) at the age of 3 months and treated with estrone (E) at 0.75 mg.kg-1.d-1, or with piperazinyl estrone (P-E) at 1 or 10 mg.kg-1.d-1, orally, for 3 months. At the time of death, the uterine weight was measured. Bone histomorphometric analysis of proximal tibial metaphyses (PTM) was performed in undecalcified sections.</p><p><b>RESULTS</b>Bone histomorphometric data showed that the percent trabecular area (% Tb.Ar) of OVX rats with bone high turnover was significantly decreased. The uteri were atrophied. The percent trabecular area (% Tb.Ar) of estrone treated group was increased in decreasing bone turnover manner. But the size and weight of uteri in this group were increased vs OVX group. The bone loss induced by OVX was preserved by P-E treatment, but the mechanism of maintaining bone is different from that of E-treated rats. P-E treatment in low dose did not decrease any bone formation indices, such as percent labeling perimeter, bone formation rate per bone volume (BFR/BV), except bone mineral apposition rate (MAR) compared with E-treated group, and maintained them at OVX level. The uteri were found to be in atrophy compared with the match dose (0.75 mg) of E-treated OVX rats. But rats treated with high dose of P-E showed the same change like E-treated group.</p><p><b>CONCLUSION</b>The finding of this study shows that lower dosage of piperazinyl estrone has effect on preventing the bone losses in OVX rats, while the bone formation and the uterus are not affected, thus supporting the hypothesis that piperazinyl estrone has the potential to prevent postmenopausal bone loss in women with less side effects.</p>