机械张力作用下新生大鼠颅骨缝组织中NOS三种同形异构体的表达

目的：观察体外培养的新生SD大鼠颅顶骨骨缝在牵张力作用下,一氧化氮合酶（Nitric Oxide Synthase,NOS）三种同形异构体（eNOS,nNOS,iNOS）的表达及分布;探讨一氧化氮（nitric oxide,NO）在机械应力调节骨缝组织改建过程中所起的作用。方法：取一周龄SD大鼠颅顶骨正中矢状缝组织块进行体外器官加力培养。实验组施加0.2g张力,对照组将弹簧固定不施力,两组分别于0、1、6、24、48h收获标本。标本用常规免疫组化的方法,分别检测NOS三种同形异构体在颅骨缝组织中的分布和表达变化情况。结果：正常新生SD大鼠颅骨缝组织中内皮型一氧化氮合酶（eNOS）及神经元型一氧化氮合酶（nNOS）有轻微表达,而诱导型一氧化氮合酶（iNOS）基本不表达;施加机械张力后,三种NOS在颅骨缝组织中的表达强度及位置随受力时间长短均有改变。eNOS在最初就有少量表达,6h表达开始增加,24h呈强阳性高表达,48h各种细胞表达强度均有所减弱。nNOS在不同时间点均有较弱表达,其结果无统计学意义（P〉0.05）。iNOS在对照组和加力0h基本未见表达;加力1h后偶有成骨细胞、成纤维细胞弱表达;加力6h组可见散在轻微表达;加力24h组各种骨缝细胞均显著表达;加力48h,骨缝组织各种细胞表达呈强阳性。结论：机械牵张力刺激可以导致内源性eNOS及iNOS生成的增加,NO可能在机械张力调节骨缝组织改建过程中发挥重要作用。

The expression of three kinds of Nitric Oxide Synthase in cranial suture of neonatal rats under tensile stress in vitro calvaria culture

Objective：To observe the expression and distribution of Nitric Oxide Synthase （NOS） in cranial sutures of neonatal rats under tensile stress in vitro calvaria culture;and to discuss the effect of nitric oxide （NO） in the process of regulating remodeling cranial sutures under tensile stress.Method：Calvaria samples with middle cranial suture（8.0 ×10.0 mm2） were achieved from one week old Sprague-Dawley rats.Helical springs were put on both experimental and control groups.The springs were calibrated to deliver 0.2 g（0.00196 N） of tensile force on the experimental group with no force on the control group.After 0 h、1 h、6 h、24 h、48 h of incubation,the specimen were harvested to do immunohistochemical research on NOS（eNOS,nNOS,iNOS）,in order to test the expression and distribution of NOS.Result：Weak staining for eNOS and nNOS,and little staining for iNOS were seen in the cranial sutures of control group.The degrees and positions of the three kinds of NOS were changed by the time under tensile stress.The eNOS in the experimental group had positive express at the first beginning,it increased at the point of 6 h,and reached the peak at 48 h group,and then it decreased at 48h group.The expression of nNOS was observed but weak in four points,and there are no statistical significance（P 0.05）.Little iNOS expression was seen in experimental groups but it increased in 1h and 6 h points,then increased significantly at 24 h group,and reached peak at 48 h.Conclusion：Expression of the endogenous eNOS and iNOS is increased under the mechanical force stimulation.Nitric oxide may play an important role in remodeling cranial sutures under tensile stress.