Previous studies have suggested that
vitamin B6 is an ergogenic factor. However, the role of dietary
vitamin B6 in skeletal muscle has not been widely researched. The aim of the present study was to investigate the effects of dietary
vitamin B6 on the gene expression of 19
myokines, 14 nuclear factor erythroid 2-related factor 2 (Nrf2)-regulated factors, 8 myogenesis-related factors and 4
heat shock proteins (HSPs), which may serve important roles in skeletal muscles. Rats were fed a diet containing 1 (marginal
vitamin B6 deficiency), 7 (recommended dietary level) or 35 mg/kg of
pyridoxine (PN) HCl/ for 6 weeks. Gene expressions were subsequently analysed using reverse transcription-quantitative polymerase chain reaction. Food intake and growth were unaffected by this dietary treatment. The rats in the 7 and 35 mg/kg PN HCl groups exhibited a significant increase in the concentration of
pyridoxal 5'-phosphate in the gastrocnemius muscle compared with the 1 mg/kg PN HCl diet (P<0.01). The expressions of
myokines, such as
IL-7,
IL-8, secreted
protein acidic and rich in
cysteine,
IL-6, growth differentiation
factor 11, myonectin, leukaemia inhibitory factor,
apelin and
retinoic acid receptor responder (
tazarotene induced) 1, the expression of Nrf2 and its regulated factors, such as
heme oxygenase 1,
superoxide dismutase 2,
glutathione peroxidase 1 and
glutathione S-transferase, and the expression of
myogenin and HSP60 were significantly elevated in the 7 mg/kg PN HCl group compared with the 1 mg/kg PN HCl diet (P<0.05). No significant differences in levels of these genes were observed between the 35 and 1 mg/kg PN HCl, with the exception of GDF11 and myonectin, whose expressions were significantly increased in the 35 mg/kg PN HCl (P<0.05). Notably, the majority of gene expressions that were affected responded to dietary supplemental
vitamin B6 in a similar manner. The results suggest that compared with the marginal
vitamin B6 deficiency, the recommended dietary intake of
vitamin B6 upregulates the gene expression of a number of factors that promote the growth and repair of skeletal muscle.