Objectives: We aimed to investigate the effect of iron deficiency on basal- and contraction-induced increases in muscle protein synthesis.
Methods: Four-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.
Results: In 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.
Conclusions: These 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.
Keywords: Anemia; Autophagy; Eccentric contraction; Protein breakdown; mTOR.
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