칼로리량 급여 제한이 OLETF 흰쥐의 콜레스테롤량에 미치는 영향

박재윤,김태형,이병래,차종희 조선대학교 부설 의학연구소 2002 The Medical Journal of Chosun University Vol.27 No.1

본 실험은 식이 제한 급여에 따른 비만형 당뇨병 환자의 체중 및 혈중 지질량의 변화에 대한 연구의 일환으로 사람의 비만형 당뇨병과 유사한 병리소견을 나타내는 OLETF 흰쥐를 이용하여 칼로리 급여량 비 제한군, 칼로리 급여량 20% 제한군과 40% 제한군으로 나누어 12주간 사육한 후 체중과 혈당, 혈액 cholesterol 및 중성지질량을 측정하여 칼로리 급여량제한에 따른 혈액 지질량의 변화를 관찰하였다. 체중은 칼로리 급여량 20% 제한군에서는 체중증가 억제 비율이 LETO와 OLETF흰쥐가 비슷하였고, 칼로리 급여량 40% 제한군에서는 OLETF 흰쥐에서 체중 증가 억제가 더 크게 나타났다. 칼로리 급여량 제한에 의한 혈당량의 저하는 비만형 당뇨쥐인 OLETF 증 흰쥐가 LETO 흰쥐에 비하여 더 크게 나타났다. 칼로리 급여량 제한으로 OLETF 종 흰쥐에서 혈액 중성지질량, 총 콜레스테롤량 및 LDL- 콜레스테롤량이 감소되었고, HDL-콜레스테롤량은 증가되므로, 비만형 당뇨병환자에서 칼로리 제한 식사는 OLETF 종 흰쥐에서와 유사한 혈액 콜레스테롤량의 변화를 유발시켜서 혈관 합병증을 억제할 수 있을 것으로 예상된다. 이상의 실험결과로서 칼로리 급여량 제한에 의한 체중, 혈당, 혈액 총 콜레스테롤량, LDL-콜레스테롤 및 HDL-콜레스테롤량의 변화가 비당뇨 흰쥐보다 당뇨흰쥐에서 더 큰 변화가 있음이 확인되어 칼로리 제한 급여는 당뇨병에서 체중, 혈당, 콜레스테롤량의 조절에 유의한 것으로 생각되고, 칼로리 급여 20% 제한군과 40% 제한군 사이에서 체중, 혈당, 콜레스테롤량의 변화는 칼로리 제한량의 변화에 비하여 적기 때문에 적절한 체중, 혈당, 혈중 지질량의 유지를 위해서는 칼로리 급여량을 적절히 유지하는 것이 중요할 것으로 생각된다. 또한 칼로리 급여 제한에 의한 체중, 혈당, 혈중 중성지질과 콜레스테롤량의 감소는 혈관 합병증 발생이 예방 할 수 있을 것으로 추측되는데, 이에 대해서는 계속적인 연구가 있어야 할 것으로 생각된다. Objective: To determine the effects of caloric restriction on blood cholesterol levels of obese type 2 diabetes, we measured blood glucose and cholesterol level in Otsuka Long Evans Tokushima Fatty(OLETF) rats after caloric restriction. Methods: OLETF rats(obese diabetic rats) and Long Evans Tokushima Otsuka(LETO) rats(nondiabetic control rats) were grouped into 3 groups, control group, 20% caloric restriction(20% CR) group and 40% caloric restriction(40% CR) group, respectively. The blood glucose and cholesterol level in OLETF and LETO rats were determined after 12 weeks caloric restriction. The levels of triglyceride(TG) and cholesterol(total cholesterol, LDL-cholesterol, HDL-cholesterol) in blood of rats were determined by automatic biochemical analyser(Hitachi 747 Japan). Results: Blood glucose level of LETO rats were decreased by 12% on 40% CR compared to control group but the differences of blood glucose levels between control group and 20% CR group was not observed. OLETF rats blood glucose levels were decreased by 20% in 40% CR group and by 15% in 20% CR group. The levels of blood triglyceride in 20% CR and 40% CR groups were decreased by 20%, 15% in LETO rats and by 37%, 32% in OLETF rats respectively. Total cholesterol level was not changed by dietary restriction in LETO rats, but in OLETF rats, total cholesterol levels was decreased significantly by caloric restriction. The HDL-cholesterol levels were increased while LDL-cholesterol levels were decreased by dietary restriction in both LETO and OLETF rats. Conclusion: These results suggested that OLETF rats may be more susceptive to changes of body weight and blood glucose, triglyceride and cholesterol levels than LETO rats by caloric restriction. Reduced LDL-cholesterol and triglyceride levels in diabetes by caloric restriction may have some roles on prevention of diabetic vascular complication.

반복적인 금식으로 인한 렙틴 농도 변동이 렙틴 감수성에 미치는 영향

박성철,박용훈,박소영,김종연,박윤기,이태형,원규장,김용운 대한내분비학회 2008 Endocrinology and metabolism Vol.23 No.5

Background: Leptin resistance is a common feature in obese subjects and animals, and this is commonly accompanied with hyperleptinemia. We speculated that one of the causes of leptin resistance is a persistently elevated leptin concentration and then we hypothesized that fluctuations of serum leptin would increase leptin sensitivity in the leptin-resistant state. Methods: We used a repeated fasting and refeeding (RFR) protocol to produce fluctuation in leptin levels in 7 month-old Otsuka Long-Evans Tokushima Fatty (OLETF) rats and Long-Evans Tokushima Otsuka (LETO) rats, We then measured the leptin sensitivity following an intracerebroventricular (i.c.v.) infusion of leptin. Results: The OLETF rats exhibited severe visceral fat deposition, hyperleptinemia and leptin resistance. However, in the OLETF-RFR rats, the anorexic effect following i.c.v. leptin infusion was restored. Moreover, the visceral fat mass and serum leptin levels decreased, while the serum adiponectin levels were elevated in the OLETF-RFR rats compared to the OLETF-Control rats. The leptin receptor content in the hypothalamus increased in the OLETF-RFR rats compared to the OLETF-Control rats, and the leptin receptor content in the OLETF-RFR rats decreased compared to that in the the LETO-Control rats. Conclusions: These results suggest that the intermittent suppression of the serum leptin level reversed the leptin resistance in OLEFT rats, and this may have occurred due to an increased number of leptin receptors in the hypothalamus. Background: Leptin resistance is a common feature in obese subjects and animals, and this is commonly accompanied with hyperleptinemia. We speculated that one of the causes of leptin resistance is a persistently elevated leptin concentration and then we hypothesized that fluctuations of serum leptin would increase leptin sensitivity in the leptin-resistant state. Methods: We used a repeated fasting and refeeding (RFR) protocol to produce fluctuation in leptin levels in 7 month-old Otsuka Long-Evans Tokushima Fatty (OLETF) rats and Long-Evans Tokushima Otsuka (LETO) rats, We then measured the leptin sensitivity following an intracerebroventricular (i.c.v.) infusion of leptin. Results: The OLETF rats exhibited severe visceral fat deposition, hyperleptinemia and leptin resistance. However, in the OLETF-RFR rats, the anorexic effect following i.c.v. leptin infusion was restored. Moreover, the visceral fat mass and serum leptin levels decreased, while the serum adiponectin levels were elevated in the OLETF-RFR rats compared to the OLETF-Control rats. The leptin receptor content in the hypothalamus increased in the OLETF-RFR rats compared to the OLETF-Control rats, and the leptin receptor content in the OLETF-RFR rats decreased compared to that in the the LETO-Control rats. Conclusions: These results suggest that the intermittent suppression of the serum leptin level reversed the leptin resistance in OLEFT rats, and this may have occurred due to an increased number of leptin receptors in the hypothalamus.

칼로리 급여량 제한이 OLETF 쥐의 혈당 및 혈청 지질량에 미치는 영향

박상묵 ( Sang Muk Park ),차종희 ( Jong Hee Cha ) 대한임상검사과학회 2004 대한임상검사과학회지(KJCLS) Vol.36 No.2

To determine the effects of caloric restriction on obese type 2 diabetes we measured body blood glucose and serum lipid level in dietary restricted Otsuka Long Evans Tokushima Fatty (OLETF) rats. OLETF rats (obese diabetic rats) and Long Evans Tokushima Otsuka (LETO) rats (control rats) were grouped into 2 groups; control (free feed) group and 30% caloric restricted (30% CR) group. At 24 weeks of age the 30% CR animals were provided a diet at a level of 30% less food (by weight) than control rats consumed during the previous week. Blood glucose levels and serum triglyceride, total cholesterol, and high density lipoprotein (HDL)-cholesterol levels of CR rats were determined every 2 weeks for 8 weeks total. Blood glucose, triglyceride and total cholesterol levels of OLETF rats were significantly higher compared to LETO rats. In OLETF rats, the blood glucose levels were decreased to 61% by 8 weeks in the 30% CR compared to the non-CR control group, but changes of blood glucose levels were not observed in LETO rats during the 8weeks in the 30% CR. The serum triglyceride levels of OLETF rats were decreased significantly in the 30% CR but no change in the serum of LETO rats was found. The total cholesterol level was not changed by dietary restriction in LETO rats, but significant changes were observed in OLETF rats by 30% dietary restriction. HDL-cholesterol levels were also increased by dietary restriction in both LETO and OLETF rats. These results suggested that elevated blood glucose, triglyceride and total cholesterol levels in diabetes II patients may be reduced by caloric restriction.

Otsuka Long-Evans Tokushima Fatty(OLETF) 쥐에서 내피세포 의존성 혈관이완 장애의 기전

전국진,손석만,김인주,김치대,유석동,김용기 대한당뇨병학회 2002 Diabetes and Metabolism Journal Vol.26 No.1

연구배경:여러 연구에서 당뇨병 환자와 당뇨병 동물모델에서 내피세포 의존성 혈관 이와 반응이 저하되어 있음이 밝혀졌다. 이에 대한 여러가지 가설들이 제시되었으며, 특히 산화 스트레스가 중요한 원인으로 생각되고 있다. 따라서, 본 연구에서는 제2형 당뇨병 동물모델인 OLETF 쥐에서 내피세포 의존성 혈관 이완반응이 감소되는 기전을 알아보고자 하였다. 방법:제2형 당뇨병 동물모델로 생후 30주된 수컷 OLETF 쥐와 비당뇨병 대조군으로 생후 30주된 수컷 LETO 쥐의 대동맥을 적출하여 혈관 이완반응을 측정하였고, 대동맥조직에서 eNOS의 발현과 superoxide 음이온의 생성량을 측정하였다. 결과:내피세포층이 존재하는 대동맥환을 U46619로 처리하여 혈관을 수축시킨 후 acetylcholine에 대한 혈관 이완반응을 보았을 때 OLETF 쥐에서 대조군인 LETO 쥐보다 의미있게 이완반응이 저하되었지만, acetylcholine에 대해 감소되었던 혈관 이완반응은 SOD(500U/mL)로 전처리하면 의미있게 회복되었다 eNOS의 발현은 OLETF 쥐와 LETO 쥐 사이에 차이가 없었다. 대동맥 조직에서 생성된 superoxide 음이온의 생성량은 OLETF 쥐와 LETO 쥐 사이에 차이가 없었다. 대동맥 조직에서 생성된 superoxide 음이온의 생성량은 OLEFT 쥐에서 LETO 쥐보다 의미있게 높았다. DPI(10μmol/L)와 SOD(500U/mL)로 처리하였을 때 OLETF 쥐와 LETO 쥐의 대동맥조직에서 superoxiede 음이온의 생성량이 두 약물로 처리하지 않은 vehicle 군보다 의미있게 감소하였지만, allopurinol(100μmol/L), rotenone(100μmol/L)과 L­NMMA(10μmol/L)으로 처리하였을 경우에는 superoxide 음이온의 생성량에 변화는 없었다. 결론:이상의 결과로 OLETF 쥐에서 내피세포 의존성 혈관 이완반응이 감소된 것은 산화질소의 생성이 감소항였기 보다는 혈관조직의 NAD⒫H oxidase에 의해 superoxide 음이온 생성이 증가하여 산화질소의 생체 내 이용률이 감소하였기 때문이다. Background : Impaired vascular endothelium-dependent relaxation and augmented contractile responses have been reported in several long-term animals hyperglycemia models and human diabetic patients. Since oxidative stress has been implicated as a contributor to impaired vascular function, the mechanism of an impaired endothelium-dependent vasodilation in Otsuka Long-Evans Tokushima Fatty (OLET) rats was investigated. Methods : This present study was undertaken to characterize both the vascular production and the enzymatic source of the superoxide anion in the type 2 diabetic rats. Results : In the thoracic aortas of OLETF rats, endothelium-dependent relaxation was markedly attenuated compared to that of the control rats (LETO, Long-Evans Tokushima Otsuka) in association with a significant increase in superoxide production (2421.39±407.01 nmol/min/mg). There was no difference in eNOS expression between the OLETF rats and LETO rats. The increased production of superoxide anion was significantly attenuated by diphenyleneiodonium (DPI,10 ?ol/L), NAD (P)H oxidase inhibitor. In line with these results, studies using various enzyme inhibitors such as DPI, allopurinol, rotenone and L-NMMA suggest that the main source of superoxide anions in the aorta is NAD (P)H oxidase. Conclusion: These results suggest that enhanced NAD(P)H oxidase activity and reduced nitric oxide(NO) availability through an interaction between NO and superoxide anion contribute to the impaired endothelium-dependent vasodilation in OLETF rats (J Kor Diabetes Asso 26:46~56, 2002).

성인형 당뇨병의 모델인 OLETF 쥐에서 성장 호르몬의 효과

노정현(Jeong-Hyun Noh),김성운(Sung-Woon Kim) 대한임상노인의학회 2000 대한임상노인의학회지 Vol.1 No.1

연구배경 : 내분비계는 면역계와 밀접한 상호 연관성이 있는 것으로 알려져 있으며, 성장호르몬은 초기 염증반응에 분비되는 interleukin-1beta (IL-1β)나 tumor necrosis factor-alpha(TNF-a)의 분비를 직접적으로 조절하는 것으로 생각된다. 한편, IL-1β와 TNF-a는 당뇨병성 신증의 발생에 관여하는 것으로 알려져 있다. 이에 본 저자들은 성인형 당뇨병 동물모델인 OLETF(Otsuka Long-Evans Tokushima Fatty) 쥐에서 성장호르몬의 IL-1β 와 TNF-a의 유전자 발현에 미치는 영향을 보고자 하였다. 방법 : 6주 된 OLETF 쥐를 무작위로 실험군(n=4)과 대조군(n=4)으로 나누어, 실험군 쥐에게 성장호르몬을 일주일에 6일간 복강내로 2IU/Kg 용량으로 투여하였다. 대조군은 같은 방법으로 생리식염수를 주입하였다. 각각 2마리씩 10주령과 26주령에 쥐를 희생하였고, 간조직과 신장조직에서 IL-1β와 TNF-a의 mRNA 발현 정도를 RT-PCR 방법으로 관찰하였다. 결과 : IL-1β는 10주령의 OLETF 쥐의 간조직과 신장조직에서 성장호르몬 투여 전후 일률적으로 비슷한 정도의 발현을 보였으며 26주령에서도 성장호르몬 투여 전후 비슷한 발현을 보였다. TNF-a의 발현은 10주령에서는 불규칙적이었으며, 26주령에서는 간조직에서는 성장호르몬 투여와 상관없이 감소하는 양상을 보였고 신장조직에서는 성장호르몬 처치 후에 발현이 억제되었다. 결론 : 성장호르몬은 IL-1β의 유전자 발현에는 영향을 주지 않으나 성인형 당뇨병을 가진 쥐의 신장조직에서 TNF-a의 유전자 발현을 억제하는 것으로 생각되며, 앞으로 본 연구 결과에서 나타난, 신장조직에서 성장호르몬의 TNF-a 유전자의 발현감소효과가 당뇨병성 신증 발생을 억제하는가에 대한 연구가 필요할 것으로 생각된다. Background : Neuroendocrine system has been thought to interact with immune system, and growith hormone (GH) has been suggested to modulate directly both interleukin-1beta(IL1β) and tumor necrosis factor-alpha(TNF-a) release. The OLETF(otsuka Long-Evans Tokushima Fatty) rats are the animal models for human NIDDM with nephrotic complication. IL-1 and TNF-a have been believed to play an improtant role for pathogenesis of diabetic nephropathy. The objective of this study is to investigate the effects of growth hormone on the production of IL-1β and TNF-a in the hyperglycemic rats. Methods : OLETF rats were randomized into a placebo-treated control group(n=4) and a GH-treated grup(n=4). GH and placebo administration were started in 6 weeks old OLETF rats. They were injected GH or normal saline 6days per week intraperitoneally until sacrifice. GH treated group was given 2IU/kg of GH. I measured body weight weekly. The mRNAexpressions of IL-1β and TNF-a in liver and kidney tissues were investigated by RT- PCR method. Results : The expressions of IL-1β and TNF-a in GR-treated group were compared with in control group at 10 weeks and 26 weeks of age. There were no differences of IL-1β expressions between GH-treatment rats and placebo-treated rats at 10 and 26 weeks of age. TNF-a expressions at 10 weeks were not consistent. At 26 weeks, TNF-a expressions were decreased with or without GH treatment in liver tissues. In kidney tissues, TNF-a expressions were decreased with GH treatment, but weren't in control group. Conclusions : The growth hormone has no effect on the production of IL-1β, but inhibits the production of TNF-a in kidney tissues of diabetic OLETF rats.

8주간 저항성 운동이 OLETF 쥐 췌장 조직의 GSH, SOD, TBARS 활성 및 GLUT2 mRNA 발현에 미치는 영향

이민기(LeeMin-ki),윤진환(YoonJin-hwan) 한국체육학회 2017 한국체육학회지 Vol.56 No.3

본 연구는 8주간 저항성 운동이 OLETF 쥐 췌장 조직의 GSH, SOD, TBARS 활성 및 GLUT2 mRNA 발현에 미치는 영향을 관찰하기 위하여 20주령의 수컷 LETO control(n=8), OLETF control(n=8), OLETF+resistance exercise(n=8)으로 구분 한 후 8주간 저항성 운동을 실시하였다. 본 연구 결과 8주간 저항성 운동은 OLETF 쥐 췌장 조직의 TBARS 농도 및 HOMA-IR은 유의하게 감소시켰으며, GSH 및 SOD 활성은 유의하게 증가시키는 것으로 나타났다. 또한, 췌장 조직의 GLUT2 Mrna 발현을 유의하게 증가시키는 것으로 나타났다. 이상과 같이 8주간의 저항성 운동은 당뇨 모델인 OLETF 쥐 췌장 조직의 산화스트레스를 감소시키고 인슐린 저항성을 개선하는데 효과적인 방법으로 생각된다. The aim of this study was to investigate the effects of 8 weeks resisance exercise on GSH, SOD, TBARS activities and GLUT2 mRNA expression of pancreas in OLETF rat. 24 male OLETF rats were randomly divided into three groups : LETO control group(n=8), OLETF control group(n=8), OLETF+resistance exercise group(n=8). Rats in the exercised groups were subjected to resistance exercise for 8 weeks. At the end of eight weeks blood and pancreas tissue samples were collected and used for determination of antioxidant enzymes GSH, and SOD activities, and TBARS level, and GLUT2 mRNA expression. Resistance exercise significantly reduced TBARS levels in the pancreas tissue (p<0.05). In addition, resistance exercise significantly increased GSH, and SOD (p<0.05) in the pancreas tissue. HOMA-IR significantly reduced. resistance exercise diminishes the TBARS level in pancreas tissue of OLETF rats. It also accentuates activities of GSH, SOD. Therefore, it may be considered a effective tool for the reduction of oxidative stress in diabetes.

LP9M80-H Isolated from Liriope platyphylla Could Help Alleviate Diabetic Symptoms via the Regulation of Glucose and Lipid Concentration

Ji Eun Kim(김지은),In Sik Hwang(황인식),Jun Seo Goo(구준서),So Hee Nam(남소희),Sun Il Choi(최선일),Hae Ryun Lee(이혜련),Young Ju Lee(이영주),Yoon Han Kim(김윤환),Se Jin Park(박세진),Nahm-Su Kim(김남수),Young Hwan Choi(최영환),Dae You 한국생명과학회 2012 생명과학회지 Vol.22 No.5

LP9M80-H는 맥문동(Liriope platyphylla)으로부터 메탄올과 헥산을 이용하여 추출한 새로운 추출물로서 ICR 마우스에서 인슐린분비를 촉진하며, 간과 뇌 조직에서 인슐린 신호경로를 활성화시키는 것으로 알려져 있다. 본 연구에 서는 LP9M80-H가 당뇨와 비만의 치료에 미치는 효과를 조사하기 위하여, OLETF 모델동물에 LP9M80-H를 2주간 투여한 후 당뇨와 비만과 관련된 주요인자의 변화를 관찰하였다. 비록 체중은 두 집단간에 차이가 없었으나 복부 지방량은 vehicle 투여군보다 LP9M80-H 투여군에서 적었다. 또한, 혈중 포도당농도는 LP9M80-H를 투여한 OLETF랫드가 대조군에 비하여 약간 낮았으나 인슐린의 농도는 유의적으로 크게 증가하였다. 혈청 내 3가지 주요 지질의 농도는 LP9M80-H를 투여한 OLETF 랫드에서 유의적으로 감소하였고, 지방의 산화를 촉진하는 아디포넥틴의 농도도 LP9M80-H를 투여한 OLETF 랫드에서 감소하였다. 더불어, 체내에 분비된 인슐린이 표적장기에 미치는 영향을 관찰하기 위하여 간조직에서 인슐린 수용체와 인슐린 수용체기질(IRS)의 발현을 관찰하였으며, 이러한 2가지 단백질은 LP9M80-H를 투여한 OLETF 랫드에서 vehicle 투여군에 비해 유의미하게 감소하였다. 또한, 인슐린 신호경로의 다운스트림에 위치하는 포도당 수송체 중에서 Glut-2와 Glut-3 발현은 LP9M80-H를 투여한 OLETF 랫드에서 유의미하게 감소하는 반면에, Glut-4 발현은 일정하게 유지되었다. 따라서 이러한 결과는 LP9M80-H는 포도당항상성과 지질농도의 조절을 통하여 당뇨와 비만의 증상을 완화시키는데 기여할 것으로 사료된다. It was reported that the novel compounds (LP9M80-H) of Liriope platyphylla regulate glucose transporter (Glut) biosynthesis by activating the insulin-signaling pathway in the liver and brain of ICR mice. To investigate the therapeutic effects of LP9M80-H on the pathology of diabetes and obesity, alterations of key factors related to symptoms were analyzed in the Otsuka Long Evans Tokushima Fatty (OLETF) rats treated with LP9M80-H for 2 weeks. The abdominal fat masses in the LP9M80-H-treated group were lower than the vehicle-treated group, although there was no difference in body weight between the two groups. Additionally, when compared to the vehicle-treated group, LP9M80-H treatment induced a significant decrease in glucose levels and an increase in the insulin concentration in the blood of OLETF rats. A high level of insulin protein was also detected in pancreatic β cells of LP9M80-H-treated OLETF rats. A significant reduction in the concentration of lipids and adiponectin was detected only in LP9M80-H-treated OLETF rats. Furthermore, the expression of insulin receptor β and the insulin receptor substrate (IRS) was dramatically decreased in LP9M80-H-treated OLETF rats compared to the vehicle-treated group. Of the glucose transporters located downstream of the insulin-signaling pathway, glucose transporters (Glut) -2 and -3 were significantly decreased in LP9M80-H-treated OLETF rats, while the level of Glut-4 was maintained under all conditions. Therefore, these results suggest that LP9M80-H may contribute to relieving symptoms of diabetes and obesity through glucose homeostasis and regulation of lipid concentration.

제2형 당뇨병 동물모델인 OLETF 쥐에서 장기간 라미프릴 투여가 내당능 및 췌도 베타세포에 미치는 효과

고승현,윤건호,김명미,안유배,송기호,유순집,손현식,차봉연,이광우,손호영,강성구 대한당뇨병학회 2002 Diabetes and Metabolism Journal Vol.25 No.6

연구배경:최근 소개된 HOPE(Heart Outcomes Prevention Evaluation)study의 결과에 의하면, 심혈관질환이나 이에 대한 위험인자가 1가지 이상인 9,541명을 대상으로 안지오텐신 전환효소 억제제의 일종인 라미프릴을 투여하여 사망율과 뇌졸증, 심부전, 당뇨병 합병증이 개선되었을 뿐 아니라 다른 항고혈압제에 비해 새롭게 당뇨병으로 진단되는 환자가 줄었음을 보고한바 있다. 이에 저자들은 라미프릴(ramipril)을 제2형 당뇨병 동물모델에 장기간 투여함으로써 당뇨병을 예방하거나 고혈당 상태 또는 인슐린 감수성을 개선시킬수 있는지를 알아보고자 하였다. 방법:생후 24주된 체중 400∼450g의 OLETF와 LETO 쥐를 대상으로 6개월간 라미프릴 경구투여 하였고 혈압, 24시간 단백뇨 및 인슐린 내성검사를 시행하였다. 6개월 이후로는 8주간 투여군과 대조군의 체중을 비슷하게 맞추어 내당능 상태를 평가하였고 이후 다시 8주간 고농도 포도당을 투여하였다. 경구당부하검사를 시행한 후 희생시켜 조직표본을 만들어 guinea pig anti­human insulin 항체로 염색후 DAB로 발색하여 point count 법으로 베타세포를 정량하였고, 면역염색으로 췌도의 변화와 섬유화의 정도를 관찰하였다. 결과:라미프릴을 6개월간 투여하였을 때 OLETF 쥐에서 1)체중 증가가 적었으며 2)경구 당부하검사시 포도당하 면적은 의미있게 감소하였고 3)인슐린 내성검사상 Kitt가 증가되는 경향을 보였으며 4)수축기, 이완기 혈압과 24시간 단백뇨양이 의미있게 감소하였고 5)체중을 맞추면 내당능 상태가 비슷해졌다가 고농도 포도당 주입시 다시 포도당하 면적이 대조군에서 더 증가되었다. 라미프릴 투여군에서 췌도변형 및 파괴와 탈과립, 췌도내 섬유화가 감소하였다. 결론:본 실험에서는 인슐린 비의존성 당뇨병 동물 모델인 OLETF 쥐에서 당뇨병 발생 이전 단계부터 장기간 라미프릴을 투여할 경우 체중증가가 적었고, 투여군과 대조군의 체중을 맞추었을 때는 내당능상태의 차이가 없아가 고혈당 투여시 다시 투여군과 대조군에서 의미있는 차이를 보였다. 라미프릴 투여가 베타세포의 기능면에서 이로운 효과를 보일 것으로 생각되었다. 따라서 비만한 환자에서 안지오텐신 전환효소 억제제의 장기투여는 단백뇨 감소, 혈압강하 효과 이외에 체중증가의 억제 및 당뇨병 발생을 억제할 가능성을 시사한다. Background : In a Heart Outcomes Prevention Evaluation HOPE study, ramipril, a long-acting angiotensin-converting enzyme (ACE) inhibitor, significantly reduced the death rates the number of myocardial infarctions, strokes, heart failure as well as the risk of complications related to diabetes and of diabetes itself. However, it is known that ACE inhibitors improve glucose tolerance or insulin sensitivity or reduce the incidence of diabetes. Methods : 24 week-old OLETF (Otsuka Long Evans Tokushima Fatty) rats weighing 400 ~ 450 g were used in this study. 4 groups of rats were examined in parallel for 40 weeks. The OLETF rats were randomized for treatment with an aqueous solution of ramipril (5 mg/Kg) daily [OL (RMP), n=10)] and with saline [OL (CON), n=10)]. The LETO rats were also randomized in the same was as the OLETF rats (LT(RMP), n=10, LT (CON), n=10). The blood glucose level, body weight, systolic and diastolic blood pressure was assessed every month. At 3 and 6 months, the 24hrs urinary protein concentration was measured, and as insulin tolerance test and oral glucose tolerance test were conducted in all experimental groups. After 6 months, the body·weight was matched for 2 months in each corresponding group. Subsequently, a 15% sucrose loading was done for 2 months. After the glucose tolerance test, the pancreas was excised and immuno histochemical staining was conducted for insulin to quantify the beta cell mass by a point-counting method. In addition, the islet morphology was evaluated in the pancreas. Results : Ramipril treatment for a period of 6 months improved the 2hr blood glucose level, the area under the glucose curve in the oral glucose tolerance test, insulin sensitivity in addition to lowering significantly systolic and diastolic blood pressure and 24hrs urinary protein level significantly in OLETF rats. Of note, a lower weight gain was observed in both the ramipril-treated animals at 6 months. After weight matching, the AUC g and 2hr blood glucose level values were similar between the corresponding groups, but a 15% sucrose loading worsened the AUC g value. Histologically, the islets were less disorganized and the extent of fibrosis was lower in the ramipril-treated OLETF rats in the trichrome stain. Conclusion : Long-term treatment of ramipril, a long acting angiotensin-converting enzyme inhibitor may be useful for suppressing weight gain and proteinuria in addition to having a protective effect on the islet to harmful stimuli such as hyperglycemia (J Kor Diabetes Asso 25:469~482, 2001).

OLETF 쥐에서 날록손의 MTII에 의한 식욕억제 증가효과

배장호,박용훈,김성호,박소영,김종연,손조영,허정윤,원규장,김용운 대한내분비학회 2008 Endocrinology and metabolism Vol.23 No.1

Background: Leptin, an adipocyte-derived hormone, inhibits obesity in lean subjects, but is not widely used because of leptin resistance. Thus, circumventing the arcuate nucleus of the hypothalamus, the site responsible for leptin resistance, has been evaluated for treatment of obesity. However, chronic treatment of melanotan II (MTII), a synthetic agonist of the melanocortin 3/4 receptor, induces tachyphylaxis. Here, we evaluated whether naloxone, a non-specific agouti-related peptide (AgRP) antagonist, increases the anorexic effect of MTII in Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Methods: We measured food intake following intracerebroventricular (i.c.v.) infusion of MTII and/or naloxone in OLETF rats. Sprague-Dawley rats were used as a normal control group. Results: The anorexic effect of i.c.v. MTII infusion decreased with time in OLETF rats, indicating the development of tachyphylaxis. In normal control rats, naloxone alone decreased AgRP expression in the hypothalamus but failed to induce anorexia. Moreover, there was no additional anorexic effect with co-treatment of naloxone and MTII. In OLETF rats, naloxone alone did not show an anorexic effect despite increased POMC expression in the hypothalamus. However, naloxone sensitized the anorexic effect of MTII when treated together. Conclusion: These results suggest that naloxone augmented the anorexic effect of MTII when treated together in OLETF rats, but had no effect alone. These results suggest that a combination therapy of naloxone and a melanocortin receptor activator would be an effective modality for treatment of obesity. (J Kor Endocr Soc 23:18~26 2008)

The different mechanisms of insulin sensitizers to prevent type 2 diabetes in OLETF rats

Choi, Sung Hee,Zhao, Zheng Shan,Lee, Yong Jik,Kim, Soo Kyung,Kim, Dae Jung,Ahn, Chul Woo,Lim, Sung Kil,Lee, Hyun Chul,Cha, Bong Soo John Wiley Sons, Ltd. 2007 Diabetes/metabolism research and reviews Vol.23 No.5

<B>Objective</B><P>To investigate the effects of pioglitazone and metformin treatment during pre-diabetic period for the prevention of diabetes in a rat model.</P><B>Methods</B><P>OLETF rats aged 18-weeks, were treated with pioglitazone (10 mg/kg/day) and metformin (300 mg/kg/day) for 10 weeks from their pre-diabetic period. We measured weight, lipid profiles, fat distribution, glucose tolerance, and pancreatic insulin content.</P><B>Results</B><P>Prominent weight gain (mostly subcutaneous fat area) was observed in the pioglitazone-treated OLETF (O-P) rats versus significant weight loss was observed in the metformin-treated OLETF (O-M) rats. Pioglitazone reversed the serum triglyceride (TG) and FFAs levels to normal (TG 0.46 ± 0.04 vs 0.88 ± 0.05 mmol/l in LETO). At the age of 28 weeks, the O-P rats showed completely normal glucose tolerance, and the glucose disposal rate (GDR) was markedly improved (25.6 ± 0.4 vs 20.6 ± 0.5 mg/min/kg in O-C, p < 0.05). The O-M rats also showed an improved fasting glucose and GDR level, but not as much as those with O-P rats. The pancreas insulin contents were much improved in the O-P rats (22.9 ± 1.2 vs 18.8 ± 1.3 nmol/pancreas in O-M rats, p < 0.05) with histological improvement.</P><B>Conclusion</B><P>The pre-diabetic treatment with pioglitazone, despite significant weight gain, completely prevents to develop diabetes and enhances beta cell function with preservation of islet cell changes. Metformin treatment was also effective, but mainly by ameliorating the insulin resistance with marked reduction in body weight. The reversal of dyslipidaemia and the fat redistribution might contribute to the greater improvement of pioglitazone treatment compared to metformin in OLETF rats. Copyright © 2007 John Wiley & Sons, Ltd.</P>