Basal and resistance exercise-induced increase in protein synthesis is impaired in skeletal muscle of iron-deficient rats

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ObjectivesWe aimed to investigate the effect of iron deficiency on basal- and contraction-induced increases in muscle protein synthesis. MethodsFour-wk-old male Sprague–Dawley rats were divided into three groups. The rats in two of the three groups had free access to a control diet (AD) or iron-deficient diet (ID) for 4 wk. The rats in the third group (CON) were pair-fed the control diet to the mean intake of the ID group. ResultsIn comparison with the CON group, the ID group showed significantly lower hematocrit and hemoglobin concentrations, iron-containing protein levels, and total iron content in skeletal muscle, but non-iron-containing protein levels did not show any differences between the groups. Protein synthesis, measured by puromycin-labeled peptides, was lower in the ID group compared with the CON group in both basal- and contraction-stimulated states. The ID diet impaired the activation levels of signaling pathways involved in protein synthesis, such as ribosomal protein S6 and eukaryotic translation initiation factor 4E-binding protein 1. Furthermore, dietary iron deficiency decreased autophagy capacity, but did not affect the ubiquitinated protein content. ConclusionsThese results suggest that severe iron deficiency decreases not only basal but also muscle contraction-induced increases in protein synthesis due to, at least in part, downregulation of the protein synthesis signaling pathway in the skeletal muscle.