O propósito do presente estudo foi verificar os efeitos do overtraining (OT) nas proteínas relacionadas com a via de sinalização da mammalian target of the rapamycin complex 1 (mTORC1), no conteúdo proteico de sterol regulatory element binding protein-1 (SREBP-1) e nas características morfológicas do fígado de camundongos C57BL/6. Os animais foram divididos em grupo controle (CT), overtraining em declive (OTR/down), overtraining em aclive (OTR/up) e overtraining sem inclinação (OTR). Teste do rotarod, incremental, exaustivo e força de preensão foram utilizados para avaliação de performance. Após 36 horas o teste de força de preensão, os fígados foram removidos e utilizados para immunoblotting ou análises histológicas. A fosforilação da proteína kinase B (pAkt; Ser473), mammalian target of the rapamycin (pmTOR; Ser2448), 70-kDa ribosomal protein S6 kinase 1 (pS6K1; Thr389) e da AMP-activated protein kinase (pAMPK; Thr172) foram significativamente maiores no grupo OTR/down quando comparado com os grupos CT e OTR. A fosforilação da 4E-binding protein-1 (p4E-BP1; Thr37/46) foi significativamente maior no grupo OTR/down quando comparado com o grupo CT. Os níveis proteicos de sterol regulatory element binding protein- 1 (SREBP-1; p125 precursor) foram significativamente maiores nos grupos OTR/down e OTR/up quando comparados com o grupo CT. Enquanto o grupo OTR/down apresentou sinais de esteatose com inchaço celular acompanhado de inflamação aguda, os grupos OTR/up e OTR demonstraram evidências de injúria hepática, com a presença de núcleos picnóticos, hepatócitos em balão e vacúolos citoplasmáticos. Conclui-se que o protocolo de OTR/down aumenta a modulação da via de sinalização da mTOR e induz a sinais de esteatose hepática.

The purpose of this study was to verify the effects of overtraining (OT) on the proteins related to the mammalian target of the rapamycin complex 1 (mTORC1) signaling pathway, the protein content of the sterol regulatory element binding protein-1 (SREBP-1) and the morphological characteristics in the livers of C57BL/6 mice. Rodents were divided into control (CT), overtrained by downhill running (OTR/down), overtrained by uphill running (OTR/up) and overtrained by running without inclination (OTR) groups. Rotarod, incremental load, exhaustive and grip force tests were used to evaluate performance. Thirty-six hours after the grip force test, the livers were removed and used for immunoblotting or histological analysis. The phosphorylation of the protein kinase B (pAkt; Ser473), mammalian target of the rapamycin (pmTOR; Ser2448), 70-kDa ribosomal protein S6 kinase 1 (pS6K1; Thr389) and AMP-activated protein kinase (pAMPK; Thr172) were significantly higher in the OTR/down group when compared to the CT and OTR groups. The phosphorylation of the 4Ebinding protein-1 (p4E-BP1; Thr37/46) was significantly higher in the OTR/down group when compared to the CT group. The protein levels of the sterol regulatory element binding protein-1 (SREBP-1; p125 precursor) were significantly higher in the OTR/down and OTR/up groups when compared to the CT group. While the OTR/down group presented signs of steatosis with cell swelling accompanied by acute inflammation, the OTR/up and OTR groups demonstrated evidences of injury in liver, with the presence of pyknotic nuclei, ballooned hepatocytes and cytoplasmic vacuoles. In conclusion, the OTR/down protocol up-modulated the mTOR signaling pathway and induced signs of hepatic steatosis.