Effect of a neonatal low-protein diet on the morphology of myotubes in culture and the expression of key proteins that regulate myogenesis in young and adult rats

To investigate the effects of a neonatal low-protein diet on the morphology of myotubes in culture and the expression of key proteins that regulate myogenesis in young and adult rats. Male Wistar rats (n = 18) were suckled by mothers fed diets containing 17% protein (controls, C) or 8% protein (undernourished, UN). All rats were fed a normal protein diet after weaning. Muscles were removed from the legs of 42-, 60- and 90-day-old rats. Muscle cells were cultured to assess cell number, morphology and the expression of major proteins involved in myogenesis (Pax7, cadherins, beta 1 integrin, IL-4R alpha and myogenin) by western blotting. IL-4 levels in culture supernatants were measured by ELISA. Offspring from mothers fed a low-protein diet showed a lower body weight gain. Cell number and myotube expansion were reduced in cultured muscle cells from UN, but the expression of myogenic marker proteins was unaltered. Dietary restriction during lactation had no impact on the synthesis of myogenic marker proteins, and myocyte differentiation occurred normally in the muscles of offspring aged 42, 60 or 90 days. Nevertheless, the number and morphology of the myotubes are altered.