Vitor Alexandre Pezolato

Leucine minimizes denervation-induced skeletal muscle atrophy of rats through akt/mtor signaling pathways

The aim of the present study was to evaluate the effect of leucine treatment (0.30 mM) on muscle weight and signaling of myoproteins related to synthesis and degradation pathways of soleus muscle following seven days of complete sciatic nerve lesion. Wistar rats (n = 24) of 3–4 months of age (192 ± 23 g) were used. The animals were randomly distributed into four experimental groups (n = 6/group): control, treated with leucine (L), denervated (D) and denervated treated with leucine (DL). Dependent measures were proteins levels of AKT, AMPK, mTOR, and ACC performed by Western blot. Leucine induced a reduction in the phosphorylation of AMPK (p < 0.05) by 16% in the L and by 68% in the DL groups as compared with control group. Denervation increased AMPK by 24% in the D group as compared with the control group (p < 0.05). AKT was also modulated by denervation and leucine treatment, highlighted by the elevation of AKT phosphorylation in the D (65%), L (98%) and DL (146%) groups as compared with the control group (p < 0.05). AKT phosphorylation was 49% higher in the D group as compared with the DL group. Furthermore, denervation decreased mTOR phosphorylation by 29% in the D group as compared with the control group. However, leucine treatment induced an increase of 49% in the phosphorylation of mTOR in the L group as compared with the control group, and an increase of 154% in the DL as compared with the D group (p < 0.05). ACC phosphorylation was 20% greater in the D group than the control group. Furthermore, ACC in the soleus was 22% lower in the in the L group and 50% lower in the DL group than the respective control group (p < 0.05). In conclusion, leucine treatment minimized the deleterious effects of denervation on rat soleus muscle by increasing anabolic (AKT and mTOR) and decreasing catabolic (AMPK) pathways. These results may be interesting for muscle recovery following acute denervation, which may contribute to musculoskeletal rehabilitation after denervation.

Hepatic and skeletal muscle glycogen content in rats treated with metformin and submitted to acute exercise by swimming

The aim of this study was to evaluate the behavior of glycogen reserves over an acute exercise condition (50 minutes of swimming at low intesity), after treatment with metformin in rats. Forty Wistar rats (180- 200g) adults were divided into four groups (treated or not for a fortnight) and represented as follows: Control; Acute exercise by swimming (perform a session of swimming, 50 min on light intensity); Treated with metformin (received the drug metformin at a dose 1.4 mg/ml during the experimental period; Treated with metformin and exercised by swimming (received the drug metformin at a dose 1.4 mg/ml and held a swimming, 50 min on light intensity). The acute exercise decreased the glycogen reserves, while animals treated with metformin showed an increase in their muscle and liver glycogen reserves (p>0,05). Additionally, the drug showed no increase glucose and corticosterone concentration compared to the control and treated with metformin groups (p>0,05). Treatment with metformin improved energy conditions and lowers the stress response, suggesting that an important pharmacological tool for the potentiation of performance.

Efeito dos aminoácidos de cadeia ramificada no músculo imobilizado e no músculo desnervado

Objetivo: Este trabalho teve como objetivo avaliar histologicamente o musculo soleo imobilizado e desnervado de ratos suplementados com aminoacidos de cadeia ramificada. Materiais e Metodos: Para a realizacao da pesquisa foram utilizados 30 ratos navergicus albinus machos, variedade Wistar, com 3 a 4 meses de vida, divididos em 6 grupos (n=5) e denominados: controle (C), desnervado 7 dias (D), imobilizado 7 dias (I), suplementado com aminoacidos de cadeia ramificada 7 dias (BCAA), desnervado suplementado com aminoacidos de cadeia ramificada (D+BCAA) e imobilizado suplementado com aminoacidos de cadeia ramificada (I+BCAA). Os animais desnervados passaram pelo seccionamento do nervo ciatico (1 cm). Os animais dos grupos imobilizados receberam uma ortese de resina acrilica acoplada na pata posterior promovendo a imobilizacao. Apos a fase experimental os animais foram eutanasiados e os musculos foram analisados histologicamente. O teste de Shapiro-Wilk avaliou a normalidade dos dados, seguido da analise de variância e, posteriormente, Tukey-Kramer com nivel de significância menor de 5%. Resultados: A suplementacao aumentou a area de seccao transversa da fibra muscular em 74,94% no grupo I+BCAA e 90,37% no grupo D+BCAA em relacao aos grupos I e D, respectivamente. Houve aumento de 97,21% na densidade de area de tecido conjuntivo no grupo BCAA em relacao ao grupo C, porem a suplementacao promoveu reducao de 34,44% no grupo D+BCAA em relacao ao grupo D, no entanto, nao houve diferenca significativa entre os grupos I+BCAA e I. Conclusao: Observa-se que a utilizacao dos aminoacidos de cadeia ramificada pode diminuir a atrofia provocada pelo desuso muscular, tanto na condicao de desnervacao quanto na condicao de imobilizacao.