Journal
LIFE SCIENCES
Volume 116, Issue 1, Pages 51-58Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.lfs.2014.07.039
Keywords
Obesity; Adipose tissue inflammation; beta-Cell dysfunction; Leptin
Funding
- National Science Council of the Republic of China [NSC 101-2320-B-016-001]
- Tr-Service General Hospital [TSGH-C102-134-001]
- Chi-Mei Medical Center [CMNDMC 101-04]
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Aim: This study aimed to examine the causal relationship between adipokines released from visceral fat and pancreatic beta-cell dysfunction in the state of obesity inflammation. Main methods: Adipose tissue and adipocyte conditioned medium were obtained from epididymal fat of B6 mice on regular or high fat diet for 16 weeks. The latter were classified into two groups: overweight (OW, 40 +/- 2 g) and obese (OB, 50 +/- 2 g). Isolated mouse islets and NIT-1 cells were used to evaluate beta-cell function. Key findings: Fasting glucose, leptin, and interleukin-6 levels were increased in OW mice and were further elevated in OB mice. Adipocyte size and number of adipose macrophage infiltrations showed a similar trend. The augmentation of homeostasis model assessment of insulin resistance, islet hyperplasia and macrophage infiltration was noted only in OB mice. The stimulation index was lower, but reactive oxygen species production was higher in islets isolated from OB mice than from controls. In epididymal fat conditioned medium, the increases in leptin, IL-6 and TNF-alpha production in OW mice were further elevated in OB mice except TNF-alpha. Adipose tissue conditioned medium suppressed the stimulation index of islets isolated from B6 mice but not from db/db mice. The suppressive effect was also reversed by co-treatment with N-acetylcysteine or NS-398 (a selective cyclooxygenase-2 inhibitor). Significance: A markedly elevated leptin production from inflamed visceral fat could deteriorate IS-cell function via leptin receptor-mediated oxidative stress and cyclooxygenase-2 activation in the development of obesity. (C) 2014 Elsevier Inc. All rights reserved.
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