Andi Shi, Lin Zeng, Jing Liu
College of Stomatology, Jinan University, Guangzhou 510632, China.
Dept. of Prosthodontics, College of Stomatology, Jinan University, Guang-zhou 510632, China.
Hua Xi Kou Qiang Yi Xue Za Zhi. 2017 Jun 1;35(3):258-263. doi: 10.7518/hxkq.2017.03.006.
This study aims to determine the influence of unilateral chewing on metabolic characteristics of masseter muscle fibers in rats and the regulatory effect of an adenosine monophosphate activated protein kinase (AMPK) signal pathway on metabolism.
Rats were submitted to exodontia of all the right maxillary molars and divided into 2, 4, 6, and 8 weeks groups, and corresponding control groups were set as well. Sections were stained by nicotine adenine dinucleotide tetrazolim reductase(NADH-TRase) to demonstrate the types, proportion, and density of masseter muscle fibers. AMPKα1 and p-AMPK(Thr172) levels in bilateral masseter muscles were detected by Western blot.
In the 2-week group, the percentage of dark fibers augmented in the ipsilateral side, whereas the percentage of intermediary fibers in the contralateral side was increased accompanied by a decrease of light fibers, compared with the control group (P<0.05). The percentage of dark fibers was increased in the bilateral sides, whereas the percentage of dark fiber in the ipsilateral sides surpassed that of the contralateral sides in the 4, 6, and 8-week groups. The percentage of intermediary fibers was decreased in the bilateral sides in the 6 and 8-week groups (P<0.05). The percentage of light fibers was reduced in the ipsilateral sides in the 8-week group, whereas no alteration was observed in contralateral sides (P>0.05). In the ipsilateral sides, p-AMPK (Thr172)/AMPKα1 levels were increased in the 2 and 4-week groups (P<0.05), whereas no change was observed in the contralateral sides in either group (P>0.05).
CONCLUSIONS: Unilateral chewing increases the oxidative metabolic ability in bilateral masseter muscle fibers especially in the non-working side accompanied with change of muscle fiber types. The improvement of aerobic metabolism ability is related to the AMPK signal pathway. .
本研究旨在确定单侧咀嚼对大鼠咬肌纤维代谢特征的影响以及腺苷酸活化蛋白激酶（AMPK）信号通路对代谢的调节作用。
拔除大鼠右侧上颌所有磨牙，分为2周、4周、6周和8周组，并设置相应的对照组。切片用烟酰胺腺嘌呤二核苷酸四唑还原酶（NADH-TRase）染色，以显示咬肌纤维的类型、比例和密度。采用蛋白质免疫印迹法检测双侧咬肌中AMPKα1和p-AMPK（Thr172）的水平。
与对照组相比，2周组同侧深色纤维百分比增加，而对侧中间纤维百分比增加，浅色纤维减少（P<0.05）。4周、6周和8周组双侧深色纤维百分比均增加，且同侧深色纤维百分比超过对侧。6周和8周组双侧中间纤维百分比降低（P<0.05）。8周组同侧浅色纤维百分比降低，对侧无变化（P>0.05）。同侧2周和4周组p-AMPK（Thr172）/AMPKα1水平升高（P<0.05），两组对侧均无变化（P>0.05）。
单侧咀嚼可提高双侧咬肌纤维尤其是非工作侧的氧化代谢能力，并伴有肌纤维类型的改变。有氧代谢能力的提高与AMPK信号通路有关。
