Alterations in the gastrocnemius muscle of undernourished suckling rats.
Protein-energy undernutrition (PEU) during both the gestational and suckling periods causes a reduction in muscle fiber cross-section and a delay in fiber type differentiation. Such changes are not found when PEU occurs after the suckling period. To elucidate the consequences of PEU on muscle during the suckling period, we undernourished (UND) newborn rats by reducing their food intake, including a 6-hour fast every day, and doubling the number of pups suckled by the nursing rat. At day 24 of life, the gastrocnemius muscle showed a discrete reduction in lipids in the fibers of 5 control rats, and in 15 UND rats (P < 0.001). The type 2a and 2b fibers of the UND rats showed a smaller cross-sectional area than control rats (P < 0.05). The distribution frequency histogram for the muscle fibers was skewed to the left in the undernourished rats, and this was significant for type 2a and 2b fibers. PEU during the suckling period may thus induce a delay in muscle fiber maturation but does not produce significant structural alterations.
Silvado
Carlos Eduardo
CE
Neuromuscular/Neurology Division, Internal Medicine Department, Hospital de Clinicas, Universidade Federal do Paraná, Rua General Carneiro 181, Curitiba, Paraná 80069-900, Brazil. silvado@hc.ufpr.br
Werneck
Lineu Cesar
LC
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal; D005260:Female; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000145:classification / Q000473:pathology; D018482:Muscle, Skeletal / Q000473:pathology* / Q000503:physiopathology*; D011247:Pregnancy; D011502:Protein-Energy Malnutrition / Q000473:pathology* / Q000503:physiopathology*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013391:Sucking Behavior / Q000502:physiology*
D000251:Adenosine Triphosphatases