Dynamic Changes Of Bone Histomorphometry In Type1Diabetic Rats

ObjectiveTo investigate the dynamic change of bone histomorphometry and the key points of bone metabolism in diabetic osteoporosis rats, so as to explore the reasonable intervention time of prevention and treatment for diabetic osteoporosis.Methods1. Grouping and modelingSixty four6-8week-old female Wistar rats were randomized to two groups: diabetic model group (group D) and control group (group C). Experimental diabetes models were obtained by intraperitoneally injected with STZ (60mg/kg body weight). According to the sampling time point, Group C and group D were further subdivided into Cld、Clw、C2w、C3w、C4w、C8w、C12w、C16w groups(n=4, respectively) and D1d、Dlw、D2w、D3w、D4w、D8w、D12w、D16w groups(n=4, respectively).2. Sample collectionAfter weighted, rats in group C and group D were intraperitoneally injected with ketamine for general anesthesia. The upper end of tibia was embedded in4%paraformaldehyde solution.3. Slicing and measurementThe bone were decalcified, dehydrated, embedded with paraffin, sectioned and photographed. Bone trabeculae area, bone trabeculae number, bone trabeculae thickness and bone trabeculae seperation were calculated via ImageJ1.37V image analysis software.Results1. Bone microarchitecture observationBone trabeculae was rich with wide width and compact connection in all rats in group Cs. Comparing with group C, there was no obvious variation in bone trabeculae of D1d. Bone trabeculae became thinner and more narrow from the1st week, and fracture happened in group D at the same point. In D4w, bone trabeculae thickness got down clearly. In D12w、D16w, bone trabeculae split obviously and bone trabeculae number reduced.2. Fracture resistance ability observationThe upper end of tibia in each contrast group was tough and was difficult to be cut. However, it became fragile and easy to be broken in diabetes mellitus groups from the8th week after modeling.3. Bone histomorphometry1) Compared with group C:(1)Compared with Cld, Tb.Ar, Tb.N and Tb.Th decreased, and Tb.Sp increased in Did. But the differences had no statistical significance.(2)Compared with Clw, Tb.Ar got down, and Tb.Sp got up in D1w (P<0.05). But Tb.N and Tb.Th got down with no statistical significance in D1w.(3)Compared with C2w, Tb.Ar reduced, Tb.Sp increased, Tb.N decreased and Tb.Th reduced in D2w (P<0.05).(4) Compared with C4w, Tb.Ar, Tb.N and Tb.Th got down (P<0.05), and Tb.Sp got up in D4w (P<0.01, respectively).(5)Compared with C4w, Tb.Ar, Tb.N and Tb.Th rose (P<0.05), and Tb.Sp reduced in D4w (P<0.01, respectively).(6)Compared with C8w, Tb.N decreased (P<0.05), Tb.Ar, Tb.Th decreased and Tb.Sp increased in D8w (P<0.01, respectively).(7)Compared with C12w and C16w, Tb.N and Tb.Th got down significantly in D12w and D16w (P<0.01). Tb.Sp got up significantly in D12w and D16w (P<0.05, respectively).2) Compared with group Ds:(1) Tb.Ar:From the4th week, Tb.Ar began to reduce obviously (compared with that of D1d, the falling rate was8.18%). When it came to the8th week, Tb.Ar decreased more greatly till48.42%of that of D1d. While the reductive amplitude was the sharpest during the4th to the8th week, the falling rate reached to43.83%.(2) Tb.Th:From the4th week, Tb.Th began to decrease obviously (compared with that of D1d, the falling rate was7.32%). When it came to the8th week, Tb.Ar decreased more greatly till43.76%of that of D1d. While the reductive amplitude was the sharpest during the4th to the8th week, the falling rate reached to47.88%.(3)Tb.N:Tb.N increased tenderly. From the8th week to the12th week, the reductive amplitude was greastest (0.66%).(4) Tb.Sp:From the4th week, Tb.Th began to increase obviously (compared with that of D1d, the incremental rate was8.76%). When it came to the8th week, Tb.Ar increased more greatly till35.65%of that of D1d. While the incremental amplitude was the sharpest during4th to8th weeks, the incremental rate reached to46.62%.ConclusionFor6-8week-old female Wistar rats, osteopenia appears in the1st week after type1diabetes modeling. Bone mass reduces significantly in the4th week. When it comes to the8week, Bone mass decreases till50%. It account for that bone destruction begins at the early diabetes stage. So it point out that the prevention and treatmentment should start during early days of diabetes.