The preventive effects of electro-acupuncture stimulation on acute and chronic radiation-induced masseter contractile dysfunction-animal study
|Keywords:||放射照射;電針刺激;咀嚼肌收縮功能;氧化壓力;抗氧化能力;Irradiation;Electro-acupuncture;Masseter contractile function;Oxidative stress;Antioxidant capacity||Issue Date:||2016||Abstract:||
研究背景：過去動物模式研究發現，肌肉組織在接受非標的之低劑量放射照射後，過量氧化壓力會造成蛋白質羰基化並導致急性收縮功能異常，慢性過量的氧化壓力對肌肉收縮功能之影響則尚不清楚。電針刺激（electro-acupuncture, EA）可增加周圍組織抗氧化能力，但是否可應用於降低放射誘發之肌肉收縮功能異常則尚未確定。研究目的：利用動物模式探討電針刺激對減緩放射線誘發之咀嚼肌收縮功能異常之急、慢性效果，並探討其可能之作用機轉。研究方法：本研究使用7至8週的成年Sprague-Dawley公鼠，實驗分急、慢性期進行。急性期實驗將大鼠隨機分入以下6組（n=4/組）：Ctrl、IR、EA2、EA100、EA2-IR及EA100-IR。接受EA介入之大鼠（EA2、EA100、EA2-IR及EA100-IR）進行1週3次，1次20分鐘之預防性電針刺激，刺激位置在咀嚼肌肌腹及顳顎關節，刺激頻率為2或100 Hz。接受放射照射之大鼠（IR、EA2-IR及EA100-IR）則於頰部接受單次10 Gy之放射照射。待各組相關介入完成24小時後犧牲大鼠，取下咀嚼肌進行收縮功能測試、氧化傷害及抗氧化能力分析。氧化傷害以蛋白質羰基濃度分析，抗氧化能力以CuZnSOD及MnSOD mRNA表現量分析。慢性期實驗將大鼠隨機分入以下4組（n=4/組）：cCtrl、cIR、cEA2-IR及cEA100-IR。介入及測量分析方式同急性期，唯犧牲時間延長至所有相關介入完成3週後，纖維化相關反應以H&E染色、Masson trichrome染色及TGF-β1 mRNA表現量來進行分析。結果：急性期實驗結果顯示，放射照射會造成咀嚼肌收縮張力顯著下降（p<0.05），張力-頻率曲線顯著向下偏移（p<0.05）及蛋白質羰基濃度顯著上升（p<0.01）。接受EA後之大鼠，咀嚼肌之SOD mRNA表現顯著上升。與無EA對照，接受預防性EA後再進行放射照射，收縮張力下降之情形顯著較小（p<0.05），且蛋白質羰基濃度較少（p<0.01）較少。慢性期實驗結果顯示，cIR之咀嚼肌收縮張力仍顯著較cCtrl差（p<0.05）、蛋白質羰基濃度依舊較高（p=0.01）。而接受預防性EA後再進行放射照射對咀嚼肌收縮功能的保護效益，在慢性組依然存在（包含較佳之收縮功能及較低之蛋白質羰基濃度）。此外，接受過IR之組別（cIR、cEA2-IR及cEA100-IR）TGF-β1 mRNA表現量都呈現顯著正調控（p值均<0.05），但纖維化之形態學分析各組之間無明顯差異。結論：放射照射會造成咀嚼肌之急、慢性收縮功能受損，而預防性電針刺激可透過正調控咀嚼肌之抗氧化能力來減少急慢性之肌肉收縮功能傷害，但其在預防纖維化之角色則尚無定論。
Background: Previous study has found that the off-target low dose irradiation could cause muscle contractile dysfunction which was related to radiation-induced oxidative damage to muscle protein. However, the effect of radiation related chronic oxidative stress on muscle contractile function was not clear. Electro-acupuncture (EA) stimulation has been used to decrease oxidative damage in various injury models but whether EA prior to radiation could ameliorate radiation related muscle contractile dysfunction remains to be determined. Purpose: The aims of this study were to investigate the acute and chronic effect of EA prior to radiation on radiation-induced masseter contractile dysfunction and exploring the potential underlying mechanism in animal model. Methods: Sprague-Dawley rats aged 7-to-8 week-old were used in this study. Whole study was divided into acute phase and chronic phase. In acute phase, rats were randomized into 6 groups (n=4 per group): Ctrl, IR, EA2, EA100, EA2-IR, and EA100-IR. EA stimulation was applied at the masseter muscle belly and temporomandibular joint, 20 minutes per section, for a total of 3 sections in one week (EA2, EA100, EA2-IR, and EA100-IR). Upon the completion of EA interventions, a single dose of 10 Gy radiation was delivered to bilateral masseter muscles (IR, EA2-IR, and EA100-IR). All rats were sacrificed 24 hours post-irradiation and bilateral masseter muscles were removed and analyzed for contractile function, oxidative injury (protein carbonyl), and antioxidant capacity (CuZnSOD and MnSOD mRNA expression). In chronic phase, rats were randomized into 4 groups (n=4 per group):cCtrl, cIR, cEA2-IR, and cEA100-IR. All interventions and assessments were performed identically as those described in acute phase, expect the time points for sacrificing animals were 3-week- post-irradiation. H&E stain, Masson trichrome stain, and TGF-β1 mRNA expression were used to assess fibrotic response. Results: In acute phase, compared to Ctrl, the contractility of masseter muscle was significantly lower (p<0.05), the force-frequency curve showed significant downward shift (p<0.05), and the protein carbonyl concentration was significantly increased in IR (p<0.01). In rats received EA stimulation, the SOD mRNA expression of masseter muscle was upregulation after EA intervention. In rats received EA stimulation before irradiation showed less contractility decline and lower concentration of protein carbonyl of masseter muscle (both p<0.05), compare to no EA group. In chronic phase, compare to cCtrl, the contractility of masseter muscle remained lower and protein carbonyl concentration remained higher in cIR (both p<0.05). The beneficial effects of EA prior to radiation on masseter muscle persisted in chronic phase, including better contractile function and less protein carbonyl concentration. In groups receiving IR (cIR, cEA2-IR, and cEA100-IR), TGF-β1 mRNA was significantly upregulated (all p<0.05) with no apparent evidence of deposition of collagen Conclusion: The present study showed that irradiation could induce acute and chronic masseter muscle contractile dysfunction and EA pre-treatment could attenuate this harmful radiation-induced effect through upregulation muscle’s antioxidant capacity and its role on prevention of fibrosis is inconclusive.
|Appears in Collections:||物理治療學系所|
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.