Vitamin D Deficiency Is Associated with Muscle Atrophy and Reduced Mitochondrial Function in Patients with Chronic Low Back Pain

Figure 7

The vitamin D action in the skeletal muscle under the vitamin D deficiency conditions. Bold lines represent established pathways confirmed with our results while thin lines represent possible interactions as a result of vitamin D deficiency. Vitamin D deficiency decreases IGF-1 and PGC-1α via VDR—the nuclear receptor. IGF-1/Akt/FOXO3a signalling cascade triggers the muscle atrophy through atrogin-1. ROS generation causes the inhibition of PGC-1α and potentially activates FOXO3a thus inducing the muscle atrophy through atrogin-1. The lower protein content of PGC-1α directly aggravates mitochondrial biogenesis and function and may cause the oxidative stress. Furthermore, mitochondria are both the source and target of ROS generation. We assume that vitamin D deficiency induces oxidative stress, which is involved and played an important role in muscle atrophy and leads to mitochondrial dysfunction.