Zeng Lin, Liu Jing
1College of Stomatology, Jinan University, Guangzhou 510632, China; 3Department of Stomatology, First Affiliated Hospital of Jinan University, Guangzhou 510630, China. E-mail:
Nan Fang Yi Ke Da Xue Xue Bao. 2018 Jun 20;38(6):755-760. doi: 10.3969/j.issn.1673-4254.2018.06.18.
To investigate the changes in mitochondrial calcium and extracellular sodium concentrations in the masseter muscle of rats with occlusal interference and the regulatory mechanism of mitochondrial Ca overload by calmodulin kinase II (CaMK II).
SD rat models of occlusal interference were established by placing a stainless steel segments (0.8 mm in diameter) to raise the occlusal surface of the upper right first molar. At 3, 7, 14, and 21 days after occlusal interference and at 3 days after removal of occlusal interference, HE staining was used to observe the histomorphological changes of the masseter muscle. Mitochondrial calcium concentration in the masseter muscle was detected using fluorescence spectrophotometry, and direct turbidimetry with potassium pyroantimonate was used to detect the extracellular sodium concentration; the expression levels of masseter muscle p-CaMK II (Thr287) and CaMK II were detected using Western blotting.
Compared with those in the corresponding control groups, mitochondrial Ca concentration in the masseter muscle on occlusal interference side increased significantly at 3, 7, 14 and 21 days after occlusal interference (P<0.05), but was significantly lowered at 3 days after removal of the interference (P<0.05). The concentration of extracellular Na increased progressively with time at 3, 7, 14 and 21 days after occlusal interference (P<0.05), and was significantly decreased at 3 days after interference removal (P<0.05). Occlusal interference for 3, 7 and 14 days resulted in significantly increased expressions of p-CaMK II (Thr287) and CaMK II (P<0.05), which was significantly decreased at 21 days compared with those in the control groups (P<0.05) and further decreased after removal of occlusal interference (P<0.05). Similar changes were also observed on the side without interference, but the changes on the interference side were more obvious (P<0.05).
Occlusal interference causes elevated mitochondrial Ca and extracellular Na concentrations in the masseter muscle of rats to lead to calcium overload; the increase in mitochondrial Ca concentration is correlated with the phosphorylation level of CaMK II signaling pathway, suggesting a negative feedback regulation mechanism by the CaMK II signal pathway.
探讨咬合干扰大鼠咬肌线粒体钙和细胞外钠浓度的变化以及钙调蛋白激酶II（CaMK II）对线粒体钙超载的调控机制。
通过在右上第一磨牙咬合面放置直径0.8 mm的不锈钢片建立咬合干扰SD大鼠模型。在咬合干扰后3、7、14和21天以及去除咬合干扰后3天，采用苏木精-伊红（HE）染色观察咬肌组织形态学变化。采用荧光分光光度法检测咬肌线粒体钙浓度，用焦锑酸钾直接比浊法检测细胞外钠浓度；采用蛋白质印迹法检测咬肌p-CaMK II（Thr287）和CaMK II的表达水平。
与相应对照组相比，咬合干扰侧咬肌线粒体钙浓度在咬合干扰后3、7、14和21天显著升高（P<0.05），但在去除干扰后3天显著降低（P<0.05）。咬合干扰后3、7、14和21天细胞外钠浓度随时间逐渐升高（P<0.05），在干扰去除后3天显著降低（P<0.05）。咬合干扰3、7和14天导致p-CaMK II（Thr287）和CaMK II表达显著增加（P<0.05），与对照组相比，21天时显著降低（P<0.05），去除咬合干扰后进一步降低（P<0.05）。在无干扰侧也观察到类似变化，但干扰侧变化更明显（P<0.05）。
咬合干扰导致大鼠咬肌线粒体钙和细胞外钠浓度升高，引发钙超载；线粒体钙浓度升高与CaMK II信号通路的磷酸化水平相关，提示CaMK II信号通路存在负反馈调节机制。
