Expression enhancement in brown adipose tissue of genes related to thermogenesis and mitochondrial dynamics after administration of pepsin egg white hydrolysate

Abstract

Nutritional compounds could be a safe and less expensive treatment for complications associated with obesity and metabolic syndrome (MetS). The aim of this study was to investigate the mechanism of action and the target tissues of a pepsin egg white hydrolysate (EWH) which had previously been demonstrated to improve some obesity-related disorders on a high-fat/high-glucose rat model. Wistar rats were used and divided into 3 groups: Control group (C), High-fat/high-glucose diet (MS) and high-fat/high-glucose diet + EWH (MSH). The rats were fed for 20 weeks and the EWH was administered from the 9^th week. At the end of the study, white adipose tissue (WAT), brown adipose tissue (BAT) and muscle samples were collected for RT-qPCR analyses and immunohistochemistry. Our results showed a gene expression enhancement (2-fold basal level) in BAT of genes related to thermogenesis and mitochondrial dynamics. Mitochondrial DNA quantification and immunohistochemistry results also showed an increase of the mitochondrial content in this tissue. In conclusion, our results show the potential metabolic effect of this pepsin EWH by enhancing mitochondrial proliferation and gene expression related to thermogenesis in BAT. The EWH could be used as a functional food ingredient which is able to increase energy expenditure and counteract obesity-related MetS in a chronically obese society.