Efeitos da suplementação de creatina na captação de glicose em ratos submetidos ao exercício físico

Abstract

RESUMOEstudos recentes têm sugerido que a suplementação de creatina é capaz de modular a homeostase da glicose, aumentando sua captação pelos tecidos periféricos. O objetivo deste trabalho foi investigar o efeito da suplementação de creatina na tolerância à glicose e no conteúdo de glicogênio muscular e hepático em ratos submetidos ou não à atividade física por quatro e oito semanas. Ratos Wistar foram divididos em dois grupos: quatro e oito semanas de intervenção. Posteriormente, cada grupo foi subdividido em quatro subgrupos, de acordo com a ingestão do suplemento e o treinamento: controle cedentário, controle treinado, suplementado sedentário e suplementado treinado. Os animais tiveram livre acesso à água e ração; o grupo suplementado teve 2% de sua ração sob a forma de creatina monoidratada. Os grupos exercitados nadaram 40 minutos por dia, quatro dias por semana, com carga entre 2 e 5% do seu peso amarrado ao peito. Após quatro e oito semanas, o teste oral de tolerância à glicose e as dosagens de glicogênio muscular e hepático foram realizadas. Não foram observadas diferenças significativas entre os grupos no teste de tolerância oral à glicose e no conteúdo de glicogênio muscular e hepático. Este estudo mostrou que a suplementação de creatina não exerceu influência na tolerância à glicose nem nas concentrações de glicogênio em ratos submetidos ou não à atividade física por quatro ou oito semanas.Palavras-chave: àcido α metil guanidino acético, condicionamento físico, glicemia. ABSTRACTRecently, studies have suggested that creatine supplementation can modulate glucose homeostasis by increasing glucose uptake in peripheral tissues. The aim of this study was to investigate the effects of creatine supplementation on glucose tolerance, muscle and hepatic glycogen content in rats submitted or not to physical activity for four and eight weeks. Wistar rats were divided in two groups: four and eight weeks of intervention. Afterwards, each group was subdivided in four subgroups, according to supplement intake and exercise: Sedentary Control; Trained Control; Supplemented Sedentary; and Supplemented Trained. The animals had free access to water and chow and the supplemented groups had two % of their diet as creatine monohydrated. The exercise groups swam for 40 minutes a day, four days a week, with two to five % of their body weight attached to their chests. After four and eight weeks, oral glucose tolerance tests were performed and both hepatic and muscle glycogen were determined. No significant differences were observed between groups on glucose tolerance and glycogen content in muscle and hepatic tissue. This study shows that creatine supplementation does not influence neither glucose tolerance nor glycogen concentrations in rats submitted or not to physical activity for four and eight weeks.Keywords: glycine, N-(aminoiminomethyl)-N-methyl-, physical fitness, blood glucose. (1) . Recentemente, essa amina tem sido investigada como uma possível ferramenta capaz de modular o metabolismo dos carboidratos. Ferrante et ...

Potential of Creatine in Glucose Management and Diabetes

“…Similarly, Araujo et al [60] demonstrated that Wistar rats receiving creatine supplementation (diet supplemented with 13% for 7 days followed by 2% for 55 days) plus high-intensity exercise training exhibited a smaller area under the curve for glucose in response to an oral glucose challenge. On the other hand, Freire et al [61] did not show any effect of creatine (2% of creatine in drinking water for 8 weeks) plus swimming training on plasma glucose responses to an oral glucose tolerance test in Wistar rats. Likewise, Vaisy et al [62] did not demonstrate any benefits of creatine supplementation (diet enriched with 2.5% of creatine for 12 weeks) alone or in combination with exercise training on glucose homeostasis and muscular insulin sensitivity in Wistar rats with insulin resistance induced by a sucrose-rich cafeteria diet.…”

“…These conflicting results could be partially explained by the differences in creatine supplementation regimen and exercise types. For instance, both Freire et al [61] and Vaisy et al [62] used a single-phase creatine protocol throughout the entire intervention period, whereas others opted for a loading dose followed by a maintenance phase [62,63]. Training models also varied considerably with the use of treadmill [59,61,62] and swimming exercises [60], which precludes more direct comparisons concerning the exercise stimuli to which the animals were subjected.…”

Creatine supplementation in exercised rats: Effects on the aerobic capacity

“…Furthermore, in aerobic exercise, literature displays differences regarding the possible effects of using creatine supplementation [2,5]. However, there are studies that have showed improvements in the use of creatine on aerobic performance, this would be done by the role of anaerobic energetic buffer generated by creatine supplementation [24,30]. It has been proposed that creatine and creatine phosphate (CP) act as messenger molecules between mitochondria and subcellular sites of production and hydrolysis of adenosine triphosphate (ATP) and thereby may aid aerobic activities [8,29].…”

Influence of creatine supplementation on indicators of glucose metabolism in skeletal muscle of exercised rats

“…Previous studies have reported increased rates of insulin secretion (Souza et al, 2006), increased expression of GLUT-4 receptors (Op'Teijnde et al, 2001;Souza et al, 2006) and increased intramuscular glycogen concentration after supplementation with creatine (Young et al, 2002). Although it is believed that creatine has a hypoglycemic effect, several authors failed to confirm hyperinsulinemia after the ingestion of creatine (Newman et al, 2003;Freire et al, 2008). With regard to the sporting environment, the literature suggests that creatine supplementation alters glucose metabolism.…”