Alcoholic myopathy: vitamin D deficiency is related to muscle fibre atrophy in a murine model

Abstract

Aims: Chronic myopathy has been described in alcoholics, characterized by atrophy of type II fibres, and vitamin D deficiency. Low serum vitamin D levels are frequent in alcoholics. The possibility exists that serum vitamin D levels are related to muscle changes in a murine experimental model.

Methods: Histological analysis of the right gastrocnemius muscle was performed in four groups of adult Sprague-Dawley rats, sacrificed after 5 weeks of treatment following the Lieber-DeCarli model. We studied the association between muscle histological changes and the activity of glutathione peroxidase (GPX), superoxide dismutase (SOD) and lipid peroxidation products (malondialdehyde); parathyroid hormone (PTH), insulin-like growth factor 1 (IGF-1), free testosterone, 1,25 dihydroxyvitamin D3 (vitamin D) and corticosterone; and serum calcium and magnesium.

Results: Alcoholic animals showed type IIa and IIb fibre atrophy, especially the low-protein-fed ones, an effect dependent on protein deficiency. A significant relationship was observed between serum vitamin D levels and IIa fibre area (rho = 0.56, P = 0.002), and also, as a trend, between vitamin D and type IIb fibre area (rho = 0.39, p = 0.053); between vitamin D and muscle GPX (rho = 0.40, P = 0.025) and SOD activities (rho = 0.43, P = 0.012). Muscle GPX activity was significantly related with type I fibre area (rho = 0.49, P = 0.01) and muscle SOD, with type IIa fibre area (rho = 0.38, P = 0.045). Serum testosterone was also related with type IIa fibre area (rho = 0.61, P < 0.001). No relation was observed between serum PTH, corticosterone, or IGF-1 and fibre area PTH and antioxidant systems. Multiple regression analysis disclosed that the only parameter independently related with type IIa fibre area was serum vitamin D.

Conclusion: Low vitamin D levels are related to muscle fibre atrophy, and altered levels of muscle antioxidant enzymes could play a role in alcoholic myopathy.