L-arginine and Physical Exercise Interference on the Morphology of the Skeletal Muscle in Young Rats

Mailing address: Liriane Baratella Evêncio Departamento de Histologia e Embriologia Rua Professor Moraes Rego, 1.235, Cidade Universitária 50670-900 – Recife, PE, Brasil. [email protected] ABSTRACT Introduction: Exercise and the amino acid L-Arginine can promote anatomical and physiological changes in the skeletal muscle. Objective: The objective of this work was to analyze the influence of L-arginine associated with exercise in the skeletal muscle fibers. Methods: To carry out our research, 24 male Wistar rats divided into 4 groups according to the administration of Arginine and physical exercise were used. The experimental groups were distributed as follows: Arginine-Exercise (AE, n = 6), Arginine-Not Exercised (AN, n = 6), Water-Exercise (WE, n = 6) and Water-Not Exercised (WN, n = 6). The amino acid L-Arginine was administered via orogastric intubation, at dose of 300mg/kg, daily from the 7th to 35th days of life of the animal. The exercise was performed on motorized treadmill for 30 minutes/day, 5 times a week, from 15th to 35th days of life of the animal. At the age of 35-45 days, the animals were weighed and sacrificed in order to collect the gastrocnemius muscle. The gastrocnemius muscle was measured, weighed and processed for histological analysis. The muscle’s images were taken in order to calculate the mean diameter of the muscle fiber. Data were expressed as mean ± standard deviation and analyzed using SPSS. The Shapiro-Wilk, one-way ANOVA and Tukey’s tests (p <0.05) were applied. Results: Concerning body weight and gastrocnemius weight, there was no significant difference when all the experimental groups were compared. However, the AN group presented the highest mean diameter when compared to the other groups. Conclusion: This fact suggests that orogastric administration of Arginine offered to the animals that were not exercised, promotes muscle hypertrophy. On the other hand, exercise by itself did not lead to increase in mean diameter of the skeletal muscle.