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Effect of vitamin D intake levels on vitamin D metabolism in high fat diet‐induced obese mice compared to the control
Author(s) -
Park Chan Yoon,
Zhu Shuang,
Jung Youngsun,
Han Sung Nim
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.800.9
Subject(s) - endocrinology , medicine , vitamin d and neurology , vitamin , vitamin d deficiency , chylomicron , chemistry , calcifediol , cd36 , cholesterol , very low density lipoprotein , lipoprotein , receptor
An inverse relationship between vitamin D levels and body mass index (BMI) has been observed and vitamin D deficiency has been often reported in obese human. Previously, we observed an alteration of vitamin D metabolism associated with obesity in mice. In this study, we investigated whether obesity affects vitamin D status when various levels of dietary vitamin D were provided. We compared serum 25‐hydroxyvitamin D (25(OH)D) levels and expression of genes involved in vitamin D absorption and transportation in obese and control mice fed different levels of vitamin D. Six week old C57BL/6 mice were fed control (10% kcal fat, CON) or high fat diets (45% kcal fat, HFD) containing three different levels of vitamin D (cholecalciferol); low vitamin D (50 IU/kg of diet, LVd), control vitamin D (1000 IU/kg of diet, CVd) or high vitamin D (25000 IU/kg of diet, HVd) for 13 weeks. Serum 25(OH)D levels were determined by radioimmunoassay. mRNA levels of Mtp which is involved in assembly of chylomicron and cholesterol membrane transporters ( Cd36, Sr‐b1, Npc1l1, and Abca1 ) in jejunum, and chylomicron remnant receptor ( Lrp1 ) and 25‐hydroxylases ( Cyp2r1 and Cyp27a1 ) in liver were determined by real‐time PCR. Overall, dietary vitamin D levels affected serum 25(OH)D levels. Serum 25(OH)D levels were lower in LVd groups and higher in HVd groups compared with CVd groups ( P < 0.001). However, when 25(OH)D levels were compared between HFD and CON group, differential pattern was observed depending on dietary vitamin D levels. In vitamin D deficiency diet groups, HFD‐LVd group showed higher serum 25(OH)D levels than CON‐LVd group ( P = 0.001, 76.6% higher). On the other hand, when vitamin D intake was at a supplementation level, HFD‐HVd group had lower serum 25(OH)D levels than CON‐HVd group ( P = 0.005, 19.7% lower). In jejunum, mRNA levels of Mtp and Abca1 were significantly higher and Cd36 mRNA levels tended to be higher ( P = 0.083) in HFD group compared with CON group. However, jejunal mRNA levels of Sr‐b1 were significantly lower in HFD group than CON group, notably HFD‐HVd group showed lower Sr‐b1 expression compared with CON‐HVd group (P = 0.013, 82.7% lower). Hepatic Lrp1 mRNA levels were also lower in HFD‐HVd group than CON‐HVd group (P = 0.004, 52.5% lower). mRNA levels of hepatic 25‐hydroxylases ( Cyp2r1 and Cyp27a1 ) were not significantly different among groups. In conclusion, expression of genes involved in dietary vitamin D absorption and metabolism was altered by HFD‐induced obesity. When vitamin D intake was at a supplementation level, expression of Sr‐b1 and chylomicron remnant receptor was reduced in HFD group and might have contributed to a lower 25(OH)D level comapred with the control. Support or Funding Information Supported by the grant from the National Research Foundation (NRF) of Korea (NRF‐2015R1D1A1A01059679)