Erythropoietin (EPO) has been well characterized as a renal glycoprotein hormone regulating red blood cell production by inhibiting apoptosis of erythrocyte progenitors in hematopoietic tissues. EPO exerts regulatory effects in cardiac and skeletal muscles. Duchenne muscular dystrophy is a lethal degenerative disorder of skeletal and cardiac muscle. In this study, we tested the possible therapeutic beneficial effect of recombinant EPO (rhEPO) in dystrophic muscles in mdx mice. Total strength was measured using a force transducer coupled to a computer. Gene expression for myostatin, transforming growth factor-β1 (TGF-β1), and tumor necrosis factor-α (TNF-α) was determined by quantitative real time polymerase chain reaction. Myostatin expression was significantly decreased in quadriceps from mdx mice treated with rhEPO (rhEPO=0.60±0.11, control=1.07±0.11). On the other hand, rhEPO had no significant effect on the expression of TGF-β1 (rhEPO=0.95±0.14, control=1.05±0.16) and TNF-α (rhEPO=0.73±0.20, control=1.01±0.09). These results may help to clarify some of the direct actions of EPO on skeletal muscle.

Foram utilizadas 22 novilhas, 11 da raça Holandesas e 11 da Guzerá, com peso vivo (PV) inicial de 189kg. Após o abate inicial de seis animais de cada raça, outros dois grupos, cinco animais de cada raça, passaram a receber dieta à base de feno de Tifton 85 (Cynodon spp.), milho, farelo de soja e mistura mineral, para ganho diário de 1kg de peso vivo (PV). O abate final ocorreu após ganho de peso de 100kg. Durante os dois abates, todos os tecidos foram pesados e amostrados, retirando-se como amostra representativa da carcaça entre a nona e a décima primeira costela para determinação dos conteúdos corporais de Ca, P, Mg, Na e K. Determinaram-se a composição corporal e as exigências nutricionais desses minerais para ganho de 1kg de PV. Houve decréscimo na concentração dos cinco macrominerais no peso de corpo vazio e no peso ganho com a elevação do PV. Não houve diferença entre as raças quanto às exigências nutricionais dos macrominerais. As exigências dietéticas totais de Ca, P, Mg, Na e K para animais de 200kg de PV foram de 11,57; 5,97; 0,36; 1,30 e 0,86g/dia, respectivamente.

Twenty-two heifers, 11 Holstein and 11 Guzera, with initial live weight (LW) of 189kg were used in this study. Six animals of each breed were slaughtered (treatment R), and two groups of five animals of each breed were fed ad libitum diet of Tifton 85 (Cynodon spp.) hay, ground corn, soybean meal and mixture minerals, for a daily gain of 1kg. The animals were slaughtered after reaching weight gain of 100kg. All tissues were weighted and representative samples were taken from the ninth to eleventh rib, and analyzed for body contents of Ca, P, Mg, Na and K. The body composition and the mineral requirements for a 1kg LW daily weight gain were determined. Decreases in the concentration of macrominerals in the empty body weight and in carcass weight gain were related to LW increased. No differences among breeds for macrominerals were observed. The Ca, P, Mg, Na and K dietary requirements for animals of 200kg of LW were 11.57; 5.97; 0.36; 1.30 and 0.86g/day, respectively.