[Intrauterine energetic malnutrition in rats: muscle skeletal changes in the 1st and 2nd generations]

OBJECTIVE: To study by histochemical analysis the skeletal muscle in malnourished newborn rats submitted to intrauterine malnutrition. METHODS: 90 days old female, Wistar EPM-1 rats, with 200 -/+ 20g body weight, malnourished during the gestation period were studied. At the 21th day of gestation, muscular biopsy was performed in the biceps bracchi of the newborns, obtained by cesarean (1st generation). One group of newborn intrauterine malnourished rats had nutritional recovery after birth by staying six/lactating rat and by free feeding up to the 90th day of life, when the females became pregnant and their offspring formed the 2nd generation. RESULTS: Weight gain during gestation and body weight of the newborn were significantly different when each malnourished group was compared to its respective control. The muscular biopsies of the malnourished newborns presented tissue involvement, characterized by loss of predominance of type II fibres, low oxidative activity, lessening of muscular fiber diameter, proliferation of intersticial tissue, and edema. In the 2nd generation, the newborns presented adequate body weight, but maintained muscular tissue involvement, with lessening of predominance of type II fibers, reduction of muscular fiber diameter, low oxidative activity, increase of intersticial space, necrosis, but without edema. CONCLUSION: The energetic malnutrition affects the skeletal muscle at birth, when it occurs during miogenesis, in both 1st and 2nd generation, maintaining permanent or temporary lesions in the muscular tissue.