Recent studies show that vitamin D deficiency may be responsible for muscle atrophy. The purpose of this study was to investigate markers of muscle atrophy, signalling proteins, and mitochondrial capacity in patients with chronic low back pain with a focus on gender and serum vitamin D level. The study involved patients with chronic low back pain (LBP) qualified for posterior lumbar interbody fusion (PLIF). Patients were divided into three groups: supplemented (SUPL) with vitamin D (3200 IU/day for 5 weeks), placebo with normal levels of vitamin D (SUF), and the placebo group with vitamin D deficiency (DEF). The marker of muscle atrophy including atrogin-1 and protein content for IGF-1, Akt, FOXO3a, PGC-1α, and citrate synthase (CS) activity were determined in collected multifidus muscle. In the paraspinal muscle, IGF-1 levels were higher in the SUF group as compared to both the SUPL and DEF groups (p<0.05). In the SUPL group, we found significantly increased protein content for pAkt (p<0.05) and decreased level of FOXO3a (p<0.05). Atrogin-1 content was significantly different between men and women (p<0.05). The protein content of PGC-1α was significantly higher in the SUF group as compared to the DEF group (p<0.05). CS activity in the paraspinal muscle was higher in the SUPL group than in the DEF group (p<0.05). Our results suggest that vitamin D deficiency is associated with elevated oxidative stress, muscle atrophy, and reduced mitochondrial function in the multifidus muscle. Therefore, vitamin D-deficient LBP patients might have reduced possibilities on early and effective rehabilitation after PLIF surgery.

Melatonin (Mel) is the major biologically active molecule secreted by the pineal gland. Mel and its metabolites, 6-hydroxymelatonin (6(OH)Mel) and 5-methoxytryptamine (5-MT), possess a variety of functions, including the scavenging of free radicals and the induction of protective or reparative mechanisms in the cell. Their amphiphilic character allows them to cross cellular membranes and reach subcellular organelles, including the mitochondria. Herein, the action of Mel, 6(OH)Mel, and 5-MT in human MNT-1 melanoma cells against ultraviolet B (UVB) radiation was investigated. The dose of 50 mJ/cm² caused a significant reduction of cell viability up to 48%, while investigated compounds counteracted this deleterious effect. UVB exposure increased catalase activity and led to a simultaneous Ca⁺⁺ influx (16%), while tested compounds prevented these disturbances. Additional analysis focused on mitochondrial respiration performed in isolated mitochondria from the liver of BALB/cJ mice where Mel, 6(OH)Mel, and 5-MT significantly enhanced the oxidative phosphorylation at the dose of 10⁻⁶ M with lower effects seen at 10⁻⁹ or 10⁻⁴ M. In conclusion, Mel, 6(OH)Mel and 5-MT protect MNT-1 cells, which express melatonin receptors (MT1 and MT2) against UVB-induced oxidative stress and mitochondrial dysfunction, including the uncoupling of oxidative phosphorylation.

Background: Recently, skeletal muscle atrophy, impairment of iron metabolism, and insulin signalling have been reported in rats suffering from amyotrophic lateral sclerosis (ALS). However, the interrelationship between these changes has not been studied. We hypothesize that an impaired Akt–FOXO3a signalling pathway triggers changes in the iron metabolism in the muscles of transgenic animals.Methods: In the present study, we used transgenic rats bearing the G93A hmSOD1 gene and their non‐transgenic littermates. The study was performed on the muscles taken from animals at three different stages of the disease: asymptomatic (ALS I), the onset of the disease (ALS II), and the terminal stage of the disease (ALS III). In order to study the molecular mechanism of changes in iron metabolism, we used SH‐SY5Y and C2C12 cell lines stably transfected with pcDNA3.1, SOD1 WT and SOD1 G93A, or FOXO3a TM‐ER.Results: A significant decrease in P‐Akt level and changes in iron metabolism were observed even in the group of ALS I animals. This was accompanied by an increase in the active form of FOXO3a, up‐regulation of atrogin‐1, and catalase. However, significant muscle atrophy was observed in ALS II animals. An increase in ferritin L and H was accompanied by a rise in PCBP1 and APP protein levels. In SH‐SY5Y cells stably expressing SOD1 or SOD1 G93A, we observed elevated levels of ferritin L and H and non‐haem iron. Interestingly, insulin treatment significantly down‐regulated ferritin L and H proteins in the cell. Conversely, cells transfected with small interfering RNA against Akt 1, 2, 3, respectively, showed a significant increase in the ferritin and FOXO3a levels. In order to assess the role of FOXO3a in the ferritin expression, we constructed a line of SH‐SY5Y cells that expressed a fusion protein made of FOXO3a fused at the C‐terminus with the ligand‐binding domain of the oestrogen receptor (TM‐ER) being activated by 4‐hydroxytamoxifen. Treatment of the cells with 4‐hydroxytamoxifen significantly up‐regulated ferritin L and H proteins level.Conclusions: Our data suggest that impairment of insulin signalling and iron metabolism in the skeletal muscle precedes muscle atrophy and is mediated by changes in Akt/FOXO3a signalling pathways.

The aim of this experimental study was to assess whether five weeks preoperative supplementation with vitamin D will affect the intensity of pain and level of inflammatory markers in patients undergoing posterior lumbar interbody fusion (PLIF) followed by rehabilitation. 42 patients were divided by double-blind randomization into two groups: supplemented (SUPL) vitamin D (3200 IU dose of vitamin D/day for 5 weeks) and placebo group (PL) treated with vegetable oil. The 10-week program of early rehabilitation (3 times a week) was initiated 4 weeks following PLIF. Measurements of serum 25(OH)D3 and CRP, IL-6, TNF-α, and IL-10 were performed. Pain intensity was measured using VAS. After supplementation with vitamin D serum concentration of 25(OH)D3 significantly increased in the SUPL group (*p<0.005) and was significantly higher as compared to the PL group (*p<0.001). Significant reduction in pain intensity was observed 4 weeks after surgery and after rehabilitation in both groups. In the SUPL group serum CRP and IL-6 concentration significantly decreased after rehabilitation compared with postsurgical level (ap<0.04). The level of TNF-α was significantly lower after rehabilitation only in the supplemented group (*p<0.02). There were no significant changes in IL-10 level in both groups during the study. Our data indicate that supplementation with vitamin D may reduce systemic inflammation and combined with surgery and early postsurgical rehabilitation may decrease the intensity of pain in LBP patients undergoing PLIF. Data indicate that LBP patients undergoing spine surgery should use vitamin D perioperatively as a supplement.