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Alterations in the gastrocnemius muscle of undernourished suckling rats
Carlos Eduardo Silvado1, Lineu Cesar Werneck
1Neuromuscular/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
Insights
Protein-energy undernutrition (PEU) during the suckling period delays muscle fiber maturation in rats. This nutritional deficit impacts muscle fiber size and lipid content but avoids significant structural damage.
Area of Science:
- Developmental biology
- Muscle physiology
- Nutritional science
Background:
- Protein-energy undernutrition (PEU) impacts development, particularly muscle growth.
- The timing of PEU is critical, with suckling period undernutrition having distinct effects compared to later-life PEU.
- Understanding PEU's effects on muscle during suckling is crucial for developmental health.
Purpose of the Study:
- To investigate the structural consequences of PEU during the suckling period on rat skeletal muscle.
- To determine if PEU during suckling affects muscle fiber size, type differentiation, and composition.
- To elucidate the long-term effects of early-life nutritional deficits on muscle development.
Main Methods:
- Undernourished (UND) newborn rats by reducing food intake and increasing litter size.
- Daily 6-hour fasting was imposed on UND rats.
- Gastrocnemius muscle was analyzed at day 24 for fiber cross-sectional area, lipid content, and fiber type distribution.
Main Results:
- Undernourished rats showed a significant reduction in muscle fiber lipids (P < 0.001).
- Type 2a and 2b muscle fibers in UND rats had smaller cross-sectional areas (P < 0.05).
- Muscle fiber distribution histograms were skewed leftward in UND rats, indicating delayed maturation.
Conclusions:
- PEU during the suckling period can delay muscle fiber maturation in rats.
- While structural alterations are not significant, changes in fiber size and lipid content are observed.
- Early-life nutrition plays a vital role in skeletal muscle development and maturation.
Abstract:
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.
