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

## TL;DR

This study shows that inhaling Citrus aurantium essential oil can reduce body weight and fat in mice despite increased food intake.

## Contribution

The novel finding is that C. aurantium essential oil inhalation suppresses fat accumulation without reducing food intake in mice.

## Key findings

- C. aurantium essential oil inhalation reduced body weight gain per feed intake in mice.
- The treatment lowered liver fat, blood cholesterol, and triglyceride levels in mice.
- Gene expression analysis showed altered regulation of thermogenesis and cholesterol synthesis genes.

## Abstract

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 Lavandula angustifolia (LO) and Citrus aurantium (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 C. aurantium 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 Ucp1 and the cholesterol synthesis-related genes Hmgcs1 and Hmgcr. The inhalation of C. aurantium 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.