间歇性低氧对大鼠骨骼发育的影响

Effects of intermittent hypoxia on bone growth in rats

目的研究间歇性低氧条件下大鼠体重、身长、尾长、股骨长、骨密度、血清骨钙素含量及骨细胞凋亡的变化,以探讨间歇性低氧对大鼠骨骼发育的影响。方法选取40只3~4周龄健康雄性SD大鼠,根据随机数字表法分为2组,每组20只。A组:常氧对照组,即正常饮食,常氧环境。B组:间歇低氧组,正常喂养的同时放入低氧舱内建立间歇性低氧环境,每天8 h(09:00–17:00),造模4周。两组均于每日清晨称量体重、身长、尾长。实验4周末麻醉后称量体重、身长、尾长、右股骨长,计算体重增长率、身长增长率、尾长增长率,处死大鼠后经腹主动脉采血,应用酶联免疫吸附法检测大鼠血清骨钙素含量;应用全自动双能X线骨密度仪检测大鼠右股骨骨密度;应用免疫荧光染色+TUNEL法检测骨细胞凋亡情况。结果 A组体重增长率、身长增长率、尾长增长率及右股骨长均高于B组(P<0.05);A组血清骨钙素含量高于B组(P<0.05);A组股骨骨密度高于B组(P<0.05);B组骨细胞凋亡指数较A组升高(P<0.05)。行Pearson相关分析后发现,间歇低氧组大鼠血清骨钙素含量与身长增长率、股骨长、骨密度呈显著正相关(P<0.01)。结论间歇性低氧可引起骨钙素分泌减少,抑制骨的生长及硬化,并诱导骨细胞凋亡,从而延缓大鼠骨骼的生长发育。

Objective To study the changes of body weight, body length, tail length, femur length, bone mineral density, serum osteocalcin content and apoptosis of bone cells in rats under intermittent hypoxia condition, so as to explore the effects of intermittent hypoxia on bone growth. Methods Forty healthy male SD rats aged 3 to 4 weeks were selected and divided into 2 groups, 20 rats in each group. Group A: normoxic control group(normal diet and normoxic environment);group B: intermittent hypoxia group(normal feeding and was put into the hypoxic chamber to establish intermittent hypoxia environment), 8 hours a day(09:00 to 17:00), 4 weeks of modeling. The body weight, body length and tail length of the two groups were measured in every morning. At the end of 4 weeks after anesthesia, the body weight,body length, tail length and right femur length were measured. The body weight growth rate, body length growth rate and tail length growth rate were calculated. Blood samples were collected from the abdominal aortic, and the content of serum osteocalcin was measured by enzyme linked immunosorbent assay;the right femur bone mineral density was measured by automatic dual-energy X-ray bone densitometer;the apoptosis of bone cells was detected by immunofluorescence staining+TUNEL. Results The body weight growth rate, body length growth rate, tail length growth rate and right femur length in group A were all higher than those in group B(P<0.05);serum osteocalcin content in group A was higher than that in group B(P<0.05);bone mineral density in group A was higher than that in group B(P<0.05);the apoptotic index of bone cells in group B was higher than that in group A(P<0.05). Pearson correlation analysis showed that the serum osteocalcin content was significantly positively correlated with the growth rate of body length, femoral length and bonemineral density(P< 0.01). Conclusion Intermittent hypoxia could reduce osteocalcin secretion, inhibit bone growth and sclerosis, and induce osteocyte apoptosis, thus delay the bone growth.