Chang Eugene, Kim Yangha
Department of Nutritional Science and Food Management, Ewha Womans University, Seoul, Republic of Korea.
Department of Nutritional Science and Food Management, Ewha Womans University, Seoul, Republic of Korea.
Nutrition. 2016 Jun;32(6):702-8. doi: 10.1016/j.nut.2015.12.032. Epub 2015 Dec 29.
Previous studies suggest that low vitamin D status is associated with obesity characterized by excess lipid storage in adipocytes. The aim of the present study was to determine the effects of the most hormonally active form of vitamin D 1,25-dihydroxyvitamin D [1,25(OH)2D] on adipocyte fat storage and lipid metabolism in mature 3T3-L1 cells.
Differentiated 3T3-L1 cells were treated with various concentrations of 1,25(OH)2D. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cell proliferation, intracellular lipid content, and basal and isoproterenol-stimulated lipolysis were measured to investigate the regulatory role of 1,25(OH)2D in adipocyte lipid metabolism. Reverse transcription polymerase chain reaction was performed to determine the effects of 1,25(OH)2D on adipogenesis-related markers, fatty acid oxidation-associated genes, and lipolytic enzymes. Sirtulin 1 (SIRT1) activity, nicotinamide adenine dinucleotide (NAD) and NADH were measured.
1,25(OH)2D treatment (24 h, 100 nmol/L) induced a decrease in intracellular fat accumulation and an increase of basal and isoproterenol-stimulated lipolysis without cell toxicity in adipocytes. Adipogenic gene levels were decreased. In contrast, mRNA levels of β-oxidation-related genes, lipolytic enzymes, and vitamin D responsive gene were elevated by 1,25(OH)2D. Additionally, significant incremental changes in NAD levels, the ratio of NAD to NADH, and SIRT1 expression and activity were noted in 1,25(OH)2D-treated 3T3-L1 adipocytes.
The observed potent inhibitory effect of 1,25(OH)2D on adipocyte fat storage in mature 3T3-L1 cells suggests that vitamin D might improve adipocyte metabolic function and protect against obesity. Increased NAD concentrations and SIRT1 activity may play a role in the mechanism of 1,25(OH)2D action.
先前的研究表明，维生素D水平低与以脂肪细胞中脂质储存过多为特征的肥胖有关。本研究的目的是确定维生素D的最具激素活性形式1,25-二羟基维生素D[1,25(OH)₂D]对成熟3T3-L1细胞中脂肪细胞脂肪储存和脂质代谢的影响。
用不同浓度的1,25(OH)₂D处理分化的3T3-L1细胞。测量3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四氮唑溴盐细胞增殖、细胞内脂质含量以及基础和异丙肾上腺素刺激的脂解作用，以研究1,25(OH)₂D在脂肪细胞脂质代谢中的调节作用。进行逆转录聚合酶链反应，以确定1,25(OH)₂D对脂肪生成相关标志物、脂肪酸氧化相关基因和脂解酶的影响。测量沉默调节蛋白1(SIRT1)活性、烟酰胺腺嘌呤二核苷酸(NAD)和NADH。
1,25(OH)₂D处理(24小时，100 nmol/L)可使脂肪细胞内脂肪积累减少，基础和异丙肾上腺素刺激的脂解作用增强，且无细胞毒性。脂肪生成基因水平降低。相反，1,25(OH)₂D可使β-氧化相关基因、脂解酶和维生素D反应基因的mRNA水平升高。此外，在1,25(OH)₂D处理的3T3-L1脂肪细胞中，NAD水平、NAD与NADH的比率以及SIRT1表达和活性有显著增加。
观察到1,25(OH)₂D对成熟3T3-L1细胞中脂肪细胞脂肪储存有强大的抑制作用，这表明维生素D可能改善脂肪细胞代谢功能并预防肥胖。NAD浓度增加和SIRT1活性可能在1,25(OH)₂D作用机制中发挥作用。
