High fat diet (hfd)

Nine-week old male C57BL/6J mice, obtained from The Jackson Laboratory (Bar Harbor, ME, USA), were housed individually in plastic cages under a 12–12-hr light-dark cycle. They were assigned randomly to four groups consisting of 12 mice each. One group (control) was fed a HFD (Dyets Inc., Bethlehem, PA, USA) containing 60%, 20% and 20% total calories from fat, carbohydrate and protein, respectively, and the other three groups were fed the HFD containing XN, DXN, or TXN. The test compounds were dissolved in an isotropic mixture of oleic acid:propylene glycol:Tween 80, 0.9:1:1 by weight (OPT) before incorporation into the HFD. The control diet contained an identical amount of OPT. All diets were prepared in pellet form by Dyets, Inc. (Bethlehem, PA, USA). The mouse diets were formulated to deliver a dose of 30 mg test compound per kg body weight per day. Food intake was measured three times per week and body weights were recorded weekly. At the end of 13 weeks of feeding, the mice were euthanized and blood, liver and skeletal muscle were collected for analyses. All animal protocols were approved by Institutional Animal Care and Use Committee (IACUC) at Oregon State University. Animal experiments were carried out in accordance with the relevant guidelines and regulations.

All animal experiments were conducted in accordance with the NIH Guide for Care and Use of Laboratory Animals (1996) and were approved by the Animal Use and Care Committee at Dongguk University (approval No. IACUC-2013-007). All efforts were made to minimize animal suffering. Male C57BL/6N mice were obtained from OrientBio (Seongnam, Gyeonggi, Korea) and kept in the same temperature- and humidity-controlled holding facility on a light (12 h)-dark (12 h) cycle with food and water ad libitum. At 6 wks of age, the mice were fed a normal fat diet (NFD, 12% calories from fat; Purina) or a high fat diet (HFD, 60% calories from fat; Dyets Inc.) for 14 wks to establish diet-induced obese (DIO) mice. S1 Table lists the detailed compositions of the two diets. Oral glucose tolerance tests (OGTT) and insulin tolerance tests (ITT) were performed after 13 and 14 wks of feeding initiation, respectively. At the end of experiments (3 days after ITT), the mice were overnight-fasted for 12 h and sacrificed by cervical dislocation 30 min after intraperitoneal injection of the vehicle or insulin (2 U/kg of body weight; Sigma-Aldrich). The liver and gastrocnemius skeletal muscle were removed rapidly, washed three times with ice-cold PBS, and then subjected to total RNA and immunoblot analysis.