Effects of Essential Oil Inhalation on the Enhancement of Plasma and Liver Lipid Metabolism in Mice

The purpose of this study was to determine the effects of essential oil inhalation on body weight, blood lipid profile, and liver and adipose tissue in mice. Middle-aged male mice (C57BL/6J) were exposed to <i>Lavandula angustifolia</i> (LO) and <i>Citrus aurantium</i> (CAO) essential oils for 7 weeks and compared to mice that did not receive essential oil inhalation treatment. Liver, white adipose tissue, and brown adipose tissue were sampled, kept at -80 °C. Although essential oil inhalation increased feed intake and body weight compared to control group, the amount of weight gain per feed intake was lower in the <i>C. aurantium</i> essential oil group. Moreover, relative weight of fat to body weight, liver fat amount, and blood cholesterol was lower, and triglyceride levels were significantly reduced. Reverse transcription polymerase chain reaction (RT-PCR) expression profiling of genes related to lipid metabolism confirmed changes in the regulation of thermogenesis-related gene <i>Ucp1</i> and the cholesterol synthesis-related genes <i>Hmgcs1</i> and <i>Hmgcr</i>. The inhalation of <i>C. aurantium</i> essential oil did not reduce the feed intake in mice; however, its effectiveness in suppressing the increases in body weight and fat mass was demonstrated.