| Objective:In the present study,we aim to investigate the characteristics of mitochondrial calcium ions concentration and extracellular sodium ions concentration in masseter muscle of rats with occlusal interference,and itscorrelation with calmodulin kinase ??CaMK ??on the mitochondrial calcium overload,so as to provide theoretical and experimental support for therapies which intended to modify and block the dysfunction and structural distortion of masticatory muscle.Methods:Thirty eight-weeks old male SD rats were randomly divided into experimental group and control group.?1?Establishment of occlusal interference mode:the occlusal surface of the upper right first molar of experimental group was raised by placing a stainless steel segments of 0.6 mm in diameter to induce occlusal interference model of SD ratwhen they were anesthetized by intraperitoneal injection of 3%sodium pentobarbital.Thirty rats were divided into six groups:3-days,7-days,14-days,21-days and 3-days after removal of occlusal interference group,and the control group was set as well,each group was composed of five rats.?2?Using hematoxylin-eosin?HE?staining method to demonstrate the histological changes of masseter muscle in each group.?3?Using fluorescence spectrophotometry to detect the mitochondrial calcium concentration of masseter muscle.?4?Using 6-antimony hydroxide potassium,direct turbidimetry to detect the extracellular sodium concentration of masseter muscle.?5?The p-CaMK ?/CaMK ??Thr286?expression level of masseter muscle were detected by Western blot.The correlation of ionic characteristics of calcium overload in mitochondria and the degree of CaMK ? phosphorylation were analyzed.Results:?1?Compared with the control group,the myocyte arrangement of the occlusion interference side in the experimental group was slightly disordered on the 3-days group,the muscle fiber gap widened and a small amount of leukocyte infiltration between connective tissues could be seen;the inflammatory reaction was aggravated in HE section of 7-days group and 14-days group,while the inflammatory cell infiltration was decreased in HE section of masseter muscle in 21-days group and 3-days after removal group;And the same change could also be seen in the non-interference side of the experimental group.However,the degree of leukocyte infiltration in the intercellular connective tissue was less than that in the occlusal interference side,and no obvious inflammatory reaction and cell degeneration were found in the other experimental group.?2?In comparison with control group,the mitochondrial Ca2+concentration of the occlusal interference side of masseter muscle increased in the 3-days,7-days,14-days and 21-days group?P<0.05?,3-days after removal group of the occlusal interference side was significantly lower than the control group?P<0.05?;and the mitochondrial Ca2+concentration of the non-interference side has a coincident trend with the interference side but slightly lower?P<0.05?.?3?The concentration of extracellular Na+in the 3-days group,7-days group,14-days group and 21-days groups continued to rise?P<0.05?,and the 3-days after removal group of occlusal interference side was significantly decreased?P<0.05?.?4?The 3-days,7-days and 14-days groups have increased in the expression level of p-CaMK ??Thr286?/CaMK ??P<0.05?,the 21-days group decreased in the expression level and lower than the control groups?P<0.05?,the 3-days after removal of occlusal interference group decreased significantly and lower than 21-days group?P<0.05?,the non-interference group has a coincident trend with the interference side but less significant?P<0.05?.Conclusions:Occlusal interference can cause elevated in the mitochondrial Ca2+concentration andextracellular Na+concentration in masseter muscle of rats and lead to calcium overload;the concentration of mitochondrial Ca2+increased may be correlated with the phosphorylation level of CaMK ?,and a negative feedback regulation mechanism of the CaMK ? signal pathway may be involved. |
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