Effects of swimming training on tissue glycogen content in experimental thyrotoxic rats

• Published in: Canadian journal of physiology and pharmacology 2012-05, Vol.90 (5), p.587-593
• Main Authors: PAULINO RIBEIRO, Luiz Fernando, PIGNATTI TEIXEIRA, Inaian, DA SILVA, Glaucio Aparecido, AUGUSTO DALIA, Rodrigo, COSTA JUNIOR, Marcelo, BERTOLINI, Natalia Oliveira, DE MELLO, Maria Alice Rostom, LUCIANO, Eliete
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; carbohydrate; entrainement; exercice; exercise; Fundamental and applied biological sciences. Psychology; glycogen; Glycogen - metabolism; glycogène; Heart - physiology; hormones thyroïdes; hydrate de carbones; hyperthyroidism; hyperthyroïdie; Lactic Acid - blood; Liver - metabolism; Liver - physiology; Male; muscle; Muscle, Skeletal - metabolism; Muscle, Skeletal - physiology; Muscular system; Myocardium - metabolism; Physical Conditioning, Animal - physiology; Physiology; Proteins; Rats; Rats, Wistar; Rodents; Studies; Swimming - physiology; thyroid hormones; Thyrotoxicosis - blood; Thyrotoxicosis - metabolism; Thyrotoxicosis - physiopathology; Tissues; training; Vertebrates: anatomy and physiology, studies on body, several organs or systems
• ISSN: 0008-4212; 1205-7541
• DOI: 10.1139/y2012-044

Thyrotoxicosis, a condition in which there is an excessive amount of circulating thyroid hormones, leads to reduced glycogen content in different tissues. In this study we analyzed the effects of aerobic swimming training on liver, heart, and skeletal muscle glycogen content in experimentally induced thyrotoxicosis. Wistar male rats were divided into euthyroid sedentary (ES, n = 12), euthyroid trained (ET, n = 11), thyrotoxic sedentary (TS, n = 12), and thyrotoxic trained (TT, n = 10) groups. Thyrotoxic groups received daily i.p. doses of T4 (sodium levothyroxine, 25 µg/100 g body mass) through the experimental period, and trained groups swam for 1 h at 80% of the aerobic–anaerobic transition intensity, 5 days/week for 4 weeks. Heart and liver glycogen stores were ∼30% lower in T4 treated compared with nontreated groups, but were not changed by training status. On the other hand, glycogen content in mixed fiber type gastrocnemius of TT was 1.5- to 2.3-fold greater than those in other groups, whereas no significant differences were found for the slow soleus muscle. Increased gastrocnemius but not soleus, liver, or heart glycogen indicates that in mild long-term thyrotoxicosis chronic swimming affects glycogen stores in a tissue-specific manner.