Rosiglitazone prevents the impairment of human islet function induced by fatty acids:: evidence for a role of PPARγ2 in the modulation of insulin secretion

被引:119
作者
Lupi, R
Del Guerra, S
Marselli, L
Bugliani, M
Boggi, U
Mosca, F
Marchetti, P
Del Prato, S
机构
[1] Univ Pisa, Dept Endocrinol & Metab, Metab Unit, I-56100 Pisa, Italy
[2] Univ Pisa, Dept Oncol, Surg Unit, I-56100 Pisa, Italy
来源
AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM | 2004年 / 286卷 / 04期
关键词
pancreatic islets; peroxisome proliferator-activated receptors; polymerase chain reaction; messenger ribonucleic acid; lipotoxicity; glucotoxicity; prostaglandin; free fatty acids;
D O I
10.1152/ajpendo.00561.2002
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
Peroxisome proliferator-activated receptors (PPARs) are a subgroup of the superfamily of nuclear receptors, with three distinct main types: alpha, beta and gamma (subdivided into gamma(1) and gamma(2)). Recently, the presence of PPARgamma has been reported in human islets. Whether other PPAR types can be found in human islets, how islet PPARgamma mRNA expression is regulated by the metabolic milieu, their role in insulin secretion, and the effects of a PPARgamma agonist are not known. In this study, human pancreatic islets were prepared by collagenase digestion and density gradient purification from nonobese adult donors. The presence of PPAR mRNAs was assessed by RT-PCR, and the effect was evaluated of exposure for up to 24 h to either 22.2 mmol/l glucose and/or 0.25, 0.5, or 1.0 mmol/l long-chain fatty acid mixture ( oleate to palmitate, 2: 1). PPARbeta and, to a greater extent, total PPARgamma and PPARgamma(2) mRNAs were expressed in human islets, whereas PPARalpha mRNA was not detected. Compared with human adipose tissue, PPARgamma mRNA was expressed at lower levels in the islets, and PPARbeta at similar levels. The expression of PPARgamma(2) mRNA was not affected by exposure to 22.2 mmol/l glucose, whereas it decreased markedly and time dependently after exposure to progressively higher free fatty acids (FFA). This latter effect was not affected by the concomitant presence of high glucose. Exposure to FFA caused inhibition of insulin mRNA expression, glucose-stimulated insulin release, and reduction of islet insulin content. The PPARgamma agonists rosiglitazone and 15-deoxy- Delta-(12,14)prostaglandin J(2) prevented the cytostatic effect of FFA as well as the FFA-induced changes of PPAR and insulin mRNA expression. In conclusion, this study shows that PPARgamma mRNA is expressed in human pancreatic islets, with predominance of PPARgamma(2); exposure to FFA downregulates PPARgamma(2) and insulin mRNA expression and inhibits glucose-stimulated insulin secretion; exposure to PPARgamma agonists can prevent these effects.
引用
收藏
页码:E560 / E567
页数:8
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