Leptin downregulates heat shock protein-70 (HSP-70) gene expression in chicken liver and hypothalamus |
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Authors: | Denise Figueiredo Arieh Gertler Gérard Cabello Eddy Decuypere Johan Buyse Sami Dridi |
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Affiliation: | (1) Laboratory of Physiology, Immunology and Genetics of Domestic Animals, Catholic University of Leuven, 3001 Heverlee, Belgium;(2) Institute of Biochemistry, Food Science and Nutrition, Faculty of Agriculture, The Hebrew University, Rehovot, 76100, Israel;(3) Unité d’Endocrinologie Cellulaire, UMR Différenciation Cellulaire et Croissance (INRA, Université Montpellier II, ENSAM), 34060 Montpellier Cedex, France |
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Abstract: | Heat shock protein (HSP)-70 is expressed in normal and stressed cells but is highly stress-inducible. Although leptin has long been suggested to be involved in the regulation of stress response, its interaction with the HSP-70 gene is still unknown, under both unstressed and stressed conditions. The present study has aimed to investigate the effect of leptin on HSP-70 gene expression in normal chicken liver, hypothalamus, and muscle. Continuous infusion of recombinant chicken leptin (8 μg/kg per hour) at a constant rate of 3 ml/h for 6 h in 3-week-old broiler chickens significantly (P < 0.05) decreased food intake and HSP-70 mRNA levels in liver and hypothalamus, but not in muscle. In an attempt to discriminate between the effect of leptin and of leptin-reduced food intake on HSP-70 gene expression, we also evaluated the effect of food deprivation on the same cellular responses in two broiler chicken lines genetically selected for low (LL) or high (FL) abdominal fat pad size. Food deprivation for 16 h did not affect HSP-70 gene expression in any of the studied tissues indicating that the effect of leptin was independent of the inhibition of food intake. Regardless of the nutritional status, HSP-70 mRNA levels were significantly (P < 0.05) higher in the hypothalamus of FL compared with LL chickens consistent with higher mRNA levels for hypothalamic corticotropin-releasing factor. To assess, whether the effects of leptin were direct or indirect, we carried out in vitro studies. Leptin treatments did not affect HSP-70 mRNA levels in a leghorn male hepatoma cell line or quail myoblast cell line suggesting that the effect of leptin on HSP-70 gene expression is mediated through the central nervous system. Furthermore, HSP-70 gene expression was gender-dependent with significantly (P < 0.05) higher levels in male than in female chickens. This work was supported by a research grant (G.0402.05) from the FWO-Flanders (Belgium). No conflicts of interest would prejudice impartiality. |
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Keywords: | Heat shock protein Leptin Fasting Gender Oxidative stress Chicken |
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