ANABOLIC-STEROIDS IN PART REVERSE GLUCOCORTICOID-INDUCED ALTERATIONS IN RAT DIAPHRAGM

Animal and clinical studies have shown respiratory muscle dysfunction caused by treatment with glucocorticoids. The present study was design ed to investigate whether anabolic steroids are able to antagonize the loss of diaphragm force induced by long-term low-dose methylprednisol one (MP) administration. Male adult rats mere randomized to receive sa line or MP (0.2 mg.kg(-1).day(-1) SC) during 9 mo, with or without nan drolone decanoate (ND; 1 mg.kg(-1).wk(-1) im) during the last 3 mo. Th e similar to 10% reduction in force generation of isolated diaphragm b undles induced by BAP was completely abolished by addition of ND. The MP-induced decrease in number of fibers expressing type IIb myosin hea vy chains was not reversed by ND. MP slightly reduced type I, IIa, and IIx fiber cross-sectional areas (CSA), but not type IIb fiber CSA. Ad dition of ND abolished the reduction in IIa and IIx Fiber CSA. The MP- induced alterations in glycogenolytic activity and fatty acid oxidatio n capacity were not reversed by ND. In conclusion, the marked reductio n in diaphragm force caused by long-term low-dose MP was completely ab olished by addition of ND. ND in part also antagonized the effects of MP on diaphragm morphology but showed no beneficial effects on biochem ical changes.