방사선 조사 후 발생한 흰쥐 심장손상에서 Captopril의 방어역할과 기전 = The Radioprotective Effect and Mechanism of Captopril on Radiation Induced-Heart Damage in Rats

국문 초록 (Abstract)

목적: 정상흰쥐의 심장에 방사선을 조사한 군과 captopril과 방사선 조사를 병용한 군의 병리학적 소견과 TNF-a(tumor necrosis factor-alpha), TGF-β1(transforming growth factor-beta), PDGF(platelet-derived growth factor), FGF(fibroblast growth factor)-2의 발현상태를 비교 관찰함으로써 심장의 조기 방사선손상에 captopril의 효과와 보호기전에서의 사이토카인의 역할을 알아보고자 하였다. 대상 및 방법: 실험동물(sprague-Dawley 흰쥐)은 대조군, 방사선 조사 단독군, captopril과 방사선 조사 병용군으로 분류하였다. 방사선 조사 단독군은 12.5Gy의 X-선을 좌흉곽에 단일 조사하였다. Captopril과 방사선 조사 병용군은 1일 50 mg/kg의 captopril을 방사선조사 1주 전부터 실험종료 시인 8주 후까지 식수에 섞어 음용시켰다. 실험 결과는 방사선 조사 2주와 8주 후에 심방과 심실의 병리조직 소견을 비교 관찰하였고 면역조직화학염색으로 TNF-a, TGF-β1.PDGF,FGF-2의 발현을 관찰하였다. 결과: 방사선조사 2주 후 병리조직 소견상 대조군에 비해 심한 심방 심장막(pericardium) 섬유소 침착(p=0.093), 심실 혈관주위(perivascular space) 부종(p=0.082)과 혈관주위 및 사이질(interstitium)의 섬유소 침착(p=0.018)이 보였으며, 심방 심장막의 섬유소 침착은 심실에 비해 현저하였다(p=0.009). 방사선 조사 후 8주의 변화는 2주 소견에 비해 부종 및 섬유소 침착은 소멸되었고, 섬유화가 관찰되었는데 이는 심실보다 심방의 심장막에서 현저하게 나타났다. Captopril과 방사선 병용군은 방사선에 의한 심장손상이 감소되어 병리학적 소견상 대조군과 비교 시 유의한 차이가 없었고, 방사선 조사 단독군과 비교하여 특히 2주 후에 심방의 심내막(endocardium) 섬유소 침착(p=0.047)과 심실의 사이질 섬유소 침착(p=0.019) 및 부종(p=0.042)이 현저히 감소되었다. 방사선조사 2주 후에 TNF-a, TGF-β1,PDGF, FGF-2의 발현이 방사선 조사 단독군에서 대조군과 비교하여 증가되었으며, 특히 심방의 심장막 및 심장내막이 현저하게 증가되었다. 방사선조사 8주 후에는 심장막의 TNF-a, TGF-β1이 계속 증가되 었으며 TGF-β1는 심방 심내막(p=0.015)과 사이질(p=0.025)에서 특히 증가되었으나, PDGF와 FGF-2는 감소되었다. Captopril과 방사선 조사 병용군은 2주에 방사선 조사 단독군에 비하여 TNF-a, TGF-β1, PDGF의 발현이 감소되었으며 8주에는 심방과 심실의 심장막에서 TNF-a가 현저히 감소되었고(p-0.049, p=0.009) TGF-β1, PDGF의 경우 감소되는 경향을 보였으나 유의한 차이는 없었다. 결론: 흰쥐의 심장에 captopril을 방사선과 병용 투여하여 병리조직 소견을 관찰한 결과 방사선에 의한 조기 심장손상이 감소됨을 확인할 수 있었다. EH한 방사선조사 후 2주 및 8주에 병용군에서 단독군에 비하여 TNF-a, TGF-β1, PDGF 등의 발현이 감소하는 양상이 관찰되어, captopril이 사이토가인 발현을 억제함으로써 방사선에 의한 심장손상을 감소시킬 수 있을 것으로 생각된다.

다국어 초록 (Multilingual Abstract)

Purpose:　Captopril (angiotension converting enzyme inhibitor) is known to have a adioprotective effect in the　lungs, intestines and skin, but its effect in the heart is unclear. To investigate the radioprotective effect and　mechanism of captopril in the heart, the histopathological changes and immunohistochemical stains were compared　with radiation alone, and radiation combined with captopril, in the rats.　Materials and Methods:　The histopathological changes and immunohistochemical stains (TNF , TGF 1,PDGF and FGF2) were examined in the radiation alone and the combined captopril and radiation groups, 2　and 8 weeks after irradiation. Each group consisted of 8 to 10 rats (Sprague-Dawley). Irradiation (12.5 Gy) was　given to the left hemithorax in a single fraction. Captopril (50 mg/Kg/d) mixed with water, was given orally and　continuously from the first week prior to, up to the 8th week of the experiment. Results: In the radiation alone group, the ventricle at 2 weeks after irradiation showed prominent edema(p=0.082) and fibrin deposit (p=0.018) compared to the control group. At 8 weeks, the edema was decreased and fibrosis increased compared to those at 2 weeks. The histopathological changes of the combined group were similar to those of the control group, due to the reduced radiation toxicity at 2 and 8 weeks. The endocardial fibrin deposit (p=0.047) in the atrium, and the interstitial fibrin deposit (p=0.019) and edema (p=0.042) of the ventricle were reduced significantly in the combined group compared to those in the radiation alone group at 2 weeks. The expressions of TNF- , TGF- 1, PDGF and FGF-2 in the radiation alone group were more increased than in the control group, especially in the pericardium and endocardium of the atrium at 2 weeks. At 8 weeks, the pericardial TNF- and TGF- 1 in the radiation alone group continuously increased. The expressions of TNF- , TGF- 1 and PDGF were decreased in the combined group at 2 weeks. At 8 weeks, the expressions of TNF- in the atrial and ventricular pericardia were markedly reduced p=0.049, p=0.009). Conclusion: This study revealed that the early heart damage induced by radiation can be reduced by the addition of captopril in a rat model. The expressions of TNF- , TGF- 1 and PDGF were further decreased in the combined compared to the radiation alone group at both 2 and 8 weeks. From these results, it may be concluded that these cytokines probably play roles in the radioprotective mechanism of captopril from the radiation-induced heart toxicity, similarly to in other organs.

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