Abstract:

Objective   To explore the effect of hemimastication on the mitochondria of rat masseter muscle and to study the mechanism of masseter muscle dysfunction induced by hemimastication. Methods   Mitochondrial morphology and number changes were observed by electron microscope, and the mitochondrial damage index was measured; Ca2+ content was measured with atomic absorption spectrometry; The mitochondrial permeability transition pore(MPTP) opening was detected by UV spectrophotometry. Results   The mitochondrial damage index score of the extraction side was lower than that of the non-extraction side, and significantly lower than that of the control group（P＜0.01）. The 4-week group had the lowest score.Compared with those of the control groups, Ca2+ contents in the experimental groups had the higher level except the 8week group （P＜0.05）. The opening of mitochondrial permeability transition pore had a higher level on the extraction side than that on the non-extraction side and the control group（P＜0.05）. The 6-week group had the highest level. The opening of mitochondrial permeability transition pore was negatively correlated to mitochondrial damage index （r=-0.74，P＜0.05）. Conclusion   The signal way of the mitochondrial permeability transition pore opening can be activated by high concentration of calcium, which may cause the damage of mitochondria and apoptosis.This pathway may play an important role in the mechanism that hemimastication results in masticatory muscles dysfunction.

Key words: Hemimastication； Mitochondrial permeability transition pore； Mitochondrial damage index; Calcium;  Rats， Wistar