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Decreased resistin expression in mice with different sensitivities to a high-fat diet
Abstract:
The regulation of resistin, a new adipose-derived circulating factor, is the subject of controversy. In particular, the question of its modulation in obesity led to opposite results reported by two different groups. In the current study, we assayed adipocyte resistin mRNA using fluorescent real-time RT-PCR. We studied the expression of resistin in mice which are differently sensitive to diet-induced obesity: the FVB/n strain, which poorly responds to high-fat diet and transgenic mice that express human alpha 2A-AR in adipose tissue in the absence of beta 3-adrenergic receptor (AR) under the FVB genetic background which are highly sensitive to high-fat diet and develop hyperplastic obesity. We observed that FVB mice, which have no significant increased body weight after an 8-week high-fat diet period, exhibited no alteration of resistin expression. In contrast, the transgenic mice developing high-fat diet-induced obesity exhibited markedly downregulated adipocyte resistin mRNA. We also showed that obesity induced by gold thioglucose injection in FVB/n mice reduces the expression of resistin in isolated adipocytes. This argues for decreased expression of resistin as a hallmark of obesity. Moreover, our data show that feeding a high-fat diet is not a primary determinant of resistin regulation.
Insights
Resistin expression in fat cells decreases with obesity, regardless of diet. This finding suggests reduced resistin is a key indicator of obesity, challenging previous notions about its regulation.
Area of Science:
- Metabolism and Endocrinology
- Adipose Tissue Biology
- Molecular Regulation of Obesity
Background:
- Resistin, an adipose-derived factor, has controversial regulation patterns, especially concerning obesity.
- Previous studies reported conflicting results on resistin's modulation in obesity.
Purpose of the Study:
- To investigate resistin mRNA expression in mice with varying obesity sensitivities.
- To determine if high-fat diet or obesity itself primarily regulates resistin.
Main Methods:
- Assayed adipocyte resistin mRNA using fluorescent real-time RT-PCR.
- Utilized FVB/n mice and transgenic mice sensitive to high-fat diet-induced obesity.
- Induced obesity via high-fat diet and gold thioglucose injection.
Main Results:
- FVB/n mice on high-fat diet showed no significant weight gain or resistin alteration.
- Transgenic obese mice exhibited significantly downregulated resistin mRNA.
- Gold thioglucose-induced obesity reduced resistin expression in isolated adipocytes.
Conclusions:
- Decreased resistin expression is a hallmark of obesity.
- High-fat diet is not the primary factor regulating resistin.
- Obesity, rather than diet, is linked to reduced resistin levels.