Anti-fatigue activities of γ-aminobutyric acid-enriched soymilk in an acute exercise-treated mouse model via regulating AMPK/PGC-1α pathway

Abstract

Gamma-aminobutyric acid (GABA), a four carbon non-protein amino acid, is extensively distributed in nature and shows various biological functions. In the present study, Lactobacillus brevis ATCC 367 and Lactobacillus plantarum ASCC 276, two producers with high GABA production capacity, were selected to ferment soymilk and their optimal culture conditions were investigated. Then, the anti-fatigue ability of GABA-enriched soy protein isolate (SPI) fermented milk was assessed by the weight-loaded forced swimming test and the related biochemical parameters were recorded to find possible reasons. Results demonstrated that soymilk added with glucose was capable of yielding the highest GABA content when used Streptococcus thermophilus 1303 and Lactobacillus brevis ATCC 367 as starter bacteria, and exhibited the high anti-fatigue effect in mice, mainly manifested in extending the forced swimming time, suppressing the blood lactic acid, urea nitrogen and lactate dehydrogenase content, and promoting the level of liver glycogen, muscle glycogen and muscle ATP. More importantly, SPI fermented milk beverages decreased reactive oxygen species levels via improving the concentrations of superoxide dismutase and glutathione peroxidase and inhibiting the content of malondialdehyd and promoted energy reserves by stimulating the expression of AMPK and PGC-1α in muscle, thus showing its fatigue-alleviating effect. Our study disclosed that there was a positive correlation between GABA content and anti-fatigue-related indicators of SPI fermented milk, which will be of interest for developing fermented milk with high anti-fatigue activity.