비 알콜성 지방간 모델에서 rosiglitazone의 알코올 독성으로부터 간 보호작용

Dept. of Medical Science/박사[한글]Peroxisome proliferator activated receptor (PPAR)-γ agonist인 rosiglitazone은 혈당 조절 작용 외에 항염증, 활성산소 생성 억제와 세포 사멸을 억제하는 효과를 지닌 것으로 알려져 있다. 본 연구에서 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, 세포사멸에 관련한 유전자 발현양상 확인, 그리고 간의 조직소견과 TUNEL 분석에 의한 세포사멸 측정을 통하여 rosiglitazone의 알코올에 의한 비알코올성 지방 간 손상방지 기전을 분석하였다.세포 실험인 경우, 고지방상태의 간세포 (HepG2)에서 아세트알데하이드를 무독화시키는 mitochondrial aldehyde dehydrogenase (ALD2)와 항 산화효소의 발현이 감소된 것을 rosiglitazone의 처리에 의한 ALD2와 항 산화 효소의 회복을 확인하였다. 아세트알데하이드 단독투여와, 고지방과 아세트알데하이드 동시 투여 모두 ALD2, 항 산화효소의 감소를 유발하였고 rosiglitazone의 처리로 인한 회복을 확인하였다. 동물실험인 경우, Rosiglitazone을 투여한 군의 혈액을 분석한 결과 고지방식과 에탄올로 인하여 높아진 혈중 aspartate aminotransferase, alanine aminotransferase, 중성지방, 유리지방산, 총 bilirubin의 농도의 감소를 확인하였고, 각 군 간의 조직소견을 분석하였을 때 고지방식과 에탄올로 인한 지방간의 호전과 간세포사멸의 감소를 관찰하였다.위와 같은 연구결과로 rosiglitazone의 사용은 지방간 상태에서 알코올 독성을 완화하는 작용을 지니고 있는 것을 확인 하였고 이에는 ALD2와 항 산화효소의 발현 유도가 한 기전이라고 사료된다. [영문]Rosiglitazone, a peroxisome proliferator activated receptor (PPAR)-γ agonist and originally developed as an anti-diabetic agent, have been known to have a protective effect against alcoholic toxicity in patients with non-alcoholic fatty liver. To investigate the underlying mechanisms of this protective effects of rosiglitazone, several in vitro experiments including the measurement of cell viability, mitochondrial aldehyde dehydrogenase (ALD2) expression, anti-oxidant enzymes activities, the mitochondrial apoptotic cascades and in vivo experiments including histopathologic examinations of liver by hematoxylin & eosin and TUNEL staining and blood chemistry were performed. We found that ALD2 and anti-oxidant enzymes expressions were inhibited in HepG2 cells under hyperlipidemic condition, and rosiglitazone reversed the expression of these genes. Sole acetaldehyde and acetaldehyde-free fatty acids (FFAs) impaired both ALD2 and anti-oxidant enzymes expressions. However, these conditions were reversed by rosiglitazone treatment indicating that rosiglitazone may regulate ALD2 and anti-oxidant enzymes in HepG2 cells. It also prevented apoptotic cascades including Bax and Bcl-2 ratio, cytochrome c release, and caspase-3 activation. In in vivo experiment, we found that high fat diet and alcohol-induced aspartate aminotransferase, alanine aminotransferase, triglycerides, free fatty acids, and total bilirubin were significantly decreased and hepatic apoptosis was prevented by rosiglitazone treatment. Finally, we propose that rosiglitazone treatment may provide therapeutic strategy for the prevention of alcohol toxicity in non-alcoholic fatty liver via recovery of ALD2 and anti-oxidant enzymes.ope

Depot-specific regulation of perilipin by rosiglitazone in a diabetic animal model

Treatment with rosiglitazone, a potent peroxisome proliferator–activated receptor (PPAR) γ agonist, results in lipid storage coupled with reduced release of free fatty acids into the circulation. Many studies have reported that PPAR-γ agonists increase subcutaneous adiposity but have no effect on visceral fat mass. Perilipin, a family of phosphoproteins that coat intracellular lipid droplets in adipocytes, is essential for enlargement of lipid droplets. Recently, a functional PPAR-responsive element was identified within the murine perilipin gene. We hypothesized that the depot-specific regulation of perilipin by rosiglitazone may be associated with the fat-redistribution and insulin-sensitizing effects of rosiglitazone. After 6 weeks of rosiglitazone treatment in Otusuka Long-Evans Tokushima Fatty rats, an animal model of type 2 diabetes mellitus, we measured changes in adiposity, triglyceride content in liver and muscle, morphology of the pancreas, and perilipin messenger RNA and protein expression in adipose tissue. Rosiglitazone increased subcutaneous adiposity, decreased triglyceride content of liver and muscle, decreased plasma free fatty acids (2107 ± 507 μmol/L in the placebo group vs 824 ± 148 μmol/L in the rosiglitazone group; P < .05), and improved insulin resistance. The islets of placebo-treated rats showed hypertrophy and destruction, whereas the islets of rosiglitazone-treated rats showed hypertrophy, but the islet architecture remained intact. Perilipin messenger RNA and protein expression increased in subcutaneous fat, but did not change in visceral fat, after rosiglitazone treatment. In 3T3-L1 cells, rosiglitazone pretreatment decreased lipolysis and increased perilipin protein. In conclusion, increased perilipin expression in subcutaneous fat after rosiglitazone treatment is likely to be a mediator of reduced lipolysis, resulting in lipid storage in subcutaneous fat, fat redistribution, and insulin sensitization.ope

Rosiglitazone protects human neuroblastoma SH-SY5Y cells against MPP+ induced cytotoxicity via inhibition of mitochondrial dysfunction and ROS production

1-Methyl-4-phenylpyridinium ion (MPP+), an inhibitor of mitochondrial complex I, has been widely used as a neurotoxin because it elicits a severe Parkinson's disease-like syndrome with elevation of intracellular reactive oxygen species (ROS) level and apoptotic death. Rosiglitazone, a peroxisome proliferator-activated receptor (PPAR)-γ agonist, has been known to show various non-hypoglycemic effects, including anti-inflammatory, anti-atherogenic, and anti-apoptotic. In the present study, we investigated the protective effects of rosiglitazone on MPP+ induced cytotoxicity in human neuroblastoma SH-SY5Y cells, as well as underlying mechanism. Our results suggested that the protective effects of rosiglitazone on MPP+ induced apoptosis may be ascribed to its anti-oxidative properties, anti-apoptotic activity via inducing expression of SOD and catalase and regulating the expression of Bcl-2 and Bax. These data indicated that rosiglitazone might provide a valuable therapeutic strategy for the treatment of progressive neurodegenerative disease such as Parkinson's disease.ope