제 2 형 당뇨병 실험쥐 모델에서 PPAR-γ Agonist의심근 섬유화 억제 효과 = PPAR-γ Agonist Attenuates Myocardial Fibrosis in a Type 2 Diabetic Rat Model

다국어 초록 (Multilingual Abstract)

Background and Objectives：Receptor for advanced glycosylation end product (RAGE) plays an importantrole in the development of myocardial fibrosis in diabetics. Activation of peroxisome proliferator activatedreceptor (PPAR)-γ agonist, rosiglitazone, reduces the RAGE expression. We investigated whether rosiglitazonecould prevent left ventricle (LV) diastolic dysfunction and attenuate the myocardial fibrosis in a type 2 diabeticrat model. Materials and Methods：Otsuka Long-Evans Tokushima Fatty (OLETF) rats were treated with rosiglitazone(20 mg/kg/d) for 20 weeks. At the age of 20 and 40 weeks, all rats underwent intraperitoneal glucosetolerance tests, hemodynamic studies and Doppler echocardiography. At the age of 40 weeks, the hearts wereexamined by performing histopathological and immunohistochemical analyses. Results：At the age of 40 weeks,rosiglitazone significant improved the parameters of the LV diastolic function such as the E/A ratio (treated vs.untreated: 1.7±0.1 vs. 1.5±0.1, p<0.05), the deceleration time and the isovolumic relaxation time in the OLETFrats, and this was correlated histologically to the reduced LV collagen volume fraction in the rosiglitazonetreatedOLETF rats (3.2±1.3% vs. 5.7±2.0%, respectively, p<0.001). Rosiglitazone also significantly reducedthe percentage of staining of the LV CTGF (7.4±2.5% vs. 15.4±4.7%, respectively, p<0.001) and RAGE (1.1±0.4% vs. 2.0±0.8%, respectively, p<0.001), as compared with the untreated OLETF rats. Conclusion：Theseresults suggest that rosiglitazone could prevent LV diastolic dysfunction and attenuate myocardial fibrosis in type2 diabetic rats by its inhibition of the RAGE and CTGF expression. PPAR-γ agonist may provide a potentialtherapeutic approach for diabetic heart disease.

국문 초록 (Abstract)

배경 및 목적 :Receptor for advanced glycosylation end products(RAGE)는 당뇨병에서 최종 당화 산물인 advanced glycosylation end products(AGEs)를 활성화 시켜 심근 섬유화를 유발한다. Peroxisome proliferator activated receptor(PPAR)- γ agonist인 rosiglitazone은 인슐린 저항성의 개선 제이면서 항염증 작용이 있으며 혈관 내피세포에서 RAGE 발현을 억제한다. 본 연구의 목적은 rosiglitazone이 제 2 형 당뇨병 실험쥐 모델에서 좌심실 이완기능의 개선과 심근 섬유화의 억제 효과가 있는지 알아보고자 하였다.
방 법：
20주령된 제 2 형 당뇨병 모델인 Otsuka Long-Evans Tokushima Fatty(OLETF)쥐 20마리를 rosiglitazone(20mg/kg/d) 치료군 10마리와 비치료군 10마리로 나누고, 비당뇨병 대조군인 Long-Evans Tokushima Otsuka(LETO) 쥐 10마리를 실험대상으로 하여 20주 동안 치료하였다. 모든 실험쥐에서 실험시작 시점인 20주령과 종료시점인 40주령에 복강내(intraperitoneal) 당부하검사와 혈압 및 맥박 측정 그리고 심초음파 검사를 하였다. 40주령 때 모든 실험쥐의 심장을 적출하여 콜라겐 특이적인 picrosirius red 염색을 하였고 connective tissue growth factor(CTGF)와 RAGE에 대한 면역조직화학적 염색을 시행한 뒤 발현의 정도를 분석하였다.
결 과：
40주령의 당뇨병 쥐에서 시행한 심초음파에서 rosiglitazone 치료군은 비치료군에 비하여 좌심실 이완기 지표 중E/A비는 증가하였고(치료군 vs. 비치료군: 1.7±0.1 vs. 1.5±0.1, p<0.05), 감속시간(DT)과 좌심실 등용적 이완기 시간(IVRT)은 유의하게 짧아지므로 좌심실 이완기 개선효과가 있었다(치료군 vs. 비치료군; DT: 50±3 vs. 59±9 msec,p<0.05; IVRT: 29±3 vs. 35±3 msec, p<0.05). 그러나 좌심실의 수축기능을 나타내는 지표는 치료 전·후로 세 군(당뇨병 치료군, 비치료군, 비당뇨병군)간에 차이는 없었다.심근에서 시행한 picrosirius red 염색 결과 당뇨병 쥐에서 rosiglitazone 치료군은 비치료군에 비하여 콜라겐 용적 분획률(Collagen Volume Fraction, CVF)은 현저히 감소하여 LETO군과 거의 비슷하였다(치료군 vs. 비치료군: 3.2±1.3 vs. 5.7±2.0%, p<0.001). 또한 면역조직화학적 염색 검사상 당뇨병쥐에서 rosiglitazone 치료군이 비치료군에 비하여 CTGF와 RAGE 모두 현저히 감소하였다(치료군 vs. 비치료군; CTGF: 7.4±2.5 vs. 15.4±4.7%, p<0.001; RAGE:1.1±0.4 vs. 2.0±0.8%, p<0.001).
결 론：
제 2 형 당뇨병 실험쥐 모델에서 rosiglitazone은 RAGE 와 CTGF 발현을 억제하여 좌심실 이완기능의 개선과 함께심근 섬유화를 억제하였다. 그러므로 PPAR-γ agonist는 당뇨병 환자에서 심근 섬유화를 억제하여 당뇨병성 심근증의 예방에 효과가 있을 것으로 기대된다

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