Untargeted muscle tissue metabolites profiling in young, adult, and old rats supplemented with tocotrienol-rich fraction

Abstract

The greatest significant influence on human life span and health is inevitable ageing. One of the distinguishing characteristics of ageing is the gradual decrease of muscle mass and physical function. There has been growing evidence that tocotrienol can guard against age-associated chronic diseases and metabolic disorders. This study aimed to elucidate the effects of tocotrienol-rich fraction (TRF) on muscle metabolomes and metabolic pathways in ageing Sprague Dawley (SD) rats. Three months, 9 months, and 21 months old male SD rats were divided into control and treated groups with 10 rats per group. Rats in control and treated groups were given 60 mg/kg body weight/day of palm olein and 60 mg/kg body weight/day of TRF, respectively, via oral gavage for 3 months. Muscle performance was assessed at 0 and 3 months of treatment by measuring muscle strength and function. Our results showed that TRF treatment caused a significant increase in the swimming time of the young rats. Comparison in the control groups showed that metabolites involved in lipid metabolisms such as L-palmitoyl carnitine and decanoyl carnitine were increased in ageing. In contrast, several metabolites, such as 3-phosphoglyceric acid, aspartic acid and aspartyl phenylalanine were decreased. These findings indicated that muscle metabolomes involved in lipid metabolism were upregulated in aged rats. In contrast, the metabolites involved in energy and amino acid metabolism were significantly downregulated. Comparison in the TRF-supplemented groups showed an upregulation of metabolites involved in energy and amino acid metabolism. Metabolites such as N6-methyl adenosine, spermine, phenylalanine, tryptophan, aspartic acid, histidine, and N-acetyl neuraminic acid were up-regulated, indicating promotion of amino acid synthesis and muscle regeneration. Energy metabolism was also improved in adult and old rats with TRF supplementation as indicated by the upregulation of nicotinamide adenine dinucleotide and glycerol 3-phosphate compared to the control group. In conclusion, the mechanism underlying the changes in skeletal muscle mass and functions in ageing was related to carbohydrate, lipid and amino acid metabolism. Tocotrienol supplementation showed beneficial effects in alleviating energy and amino acid synthesis that may promote the regeneration and renewal of skeletal muscle in ageing rats.

Keywords: ageing; sarcopenia; skeletal muscle; tocotrienol; untargeted metabolites.

FIGURE 1

(A) Weight-loaded performance swim test. (B). Hang time. (C) Holding Impulse. Data are presented as mean ± SD. *p < 0.05, significantly different compared to control, ^a p < 0.05, significantly different compared to young control rats; ^bp < 0.05, significantly different compared to young treated rats; ^cp < 0.05, significantly different compared to adult control rats. Data was analysed using one way ANOVA with a post hoc LSD.

FIGURE 2

Biochemical pathway analysis of metabolites profiled for YC vs. AC.

FIGURE 3

Biochemical pathway analysis of metabolites profiled for YC vs. OC.

FIGURE 4

Biochemical pathway analysis of metabolites profiled for AC vs. OC. a: Fructose and mannose metabolism.

FIGURE 5

Biochemical pathway analysis of metabolites profiled for YC vs. YT.

FIGURE 6

Biochemical pathway analysis of metabolites profiled for AC vs. AT.

FIGURE 7

Biochemical pathway analysis of metabolites profiled for OC vs. OT.

FIGURE 8

Muscle metabolomes changes in ageing rats. Metabolite concentrations in muscle specimens are depicted graphically and subjected to quantitative analysis. Box and whiskers plots with 95% confidence intervals are presented for quantified amino acids. Analysis was performed using one-way Anova with Tukey’s post hoc analysis. *p < 0.05.

FIGURE 9

Significant metabolic changes after tocotrienol-rich fraction treatment.