Marcelo Gomes Pereira

Leucine Supplementation Improves Skeletal Muscle Regeneration after Cryolesion in Rats

This study was undertaken in order to provide further insight into the role of leucine supplementation in the skeletal muscle regeneration process, focusing on myofiber size and strength recovery. Young (2-month-old) rats were subjected or not to leucine supplementation (1.35 g/kg per day) started 3 days prior to cryolesion. Then, soleus muscles were cryolesioned and continued receiving leucine supplementation until 1, 3 and 10 days later. Soleus muscles from leucine-supplemented animals displayed an increase in myofiber size and a reduction in collagen type III expression on post-cryolesion day 10. Leucine was also effective in reducing FOXO3a activation and ubiquitinated protein accumulation in muscles at post-cryolesion days 3 and 10. In addition, leucine supplementation minimized the cryolesion-induced decrease in tetanic strength and increase in fatigue in regenerating muscles at post-cryolesion day 10. These beneficial effects of leucine were not accompanied by activation of any elements of the phosphoinositide 3-kinase/Akt/mechanistic target of rapamycin signalling pathway in the regenerating muscles. Our results show that leucine improves myofiber size gain and strength recovery in regenerating soleus muscles through attenuation of protein ubiquitination. In addition, leucine might have therapeutic effects for muscle recovery following injury and in some muscle diseases.

Angiotensin receptor blockade improves the net balance of cardiac Ca2+ handling-related proteins in sympathetic hyperactivity-induced heart failure

AIMS The clinical benefits of angiotensin II type 1 (AT1) receptor blockers (ARB) in heart failure (HF) include cardiac anti-remodeling and improved ventricular function. However, the cellular mechanisms underlying the benefits of ARB on ventricular function need to be better clarified. In the present manuscript, we evaluated the effects of AT1 receptor blockade on the net balance of Ca(2+) handling proteins in hearts of mice lacking α(2A) and α(2C) adrenoceptors (α(2A)/α(2C)ARKO), which develop sympathetic hyperactivity (SH) induced-HF. MAIN METHODS A cohort of male wild-type (WT) and congenic α(2A)/α(2C)ARKO mice in a C57BL6/J genetic background (5-7mo of age) was randomly assigned to receive either placebo or ARB (Losartan, 10mg/kg for 8wks). Ventricular function (VF) was assessed by echocardiography, and cardiac myocyte width and ventricular fibrosis by a computer-assisted morphometric system. Sarcoplasmic reticulum Ca(2+) ATPase (SERCA2), phospholamban (PLN), phospho-Ser(16)-PLN, phospho-Thr(17)-PLN, phosphatase 1 (PP1), Na(+)-Ca(2+) exchanger (NCX), Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and phospho-Thr(286)-CaMKII were analyzed by Western blot. KEY FINDINGS α(2A)/α(2C)ARKO mice displayed ventricular dysfunction, cardiomyocyte hypertrophy and cardiac fibrosis paralleled by decreased SERCA2 and increased phospho-Thr(17)-PLN, CaMKII, phospho-Thr(286)-CaMKII and NCX levels. ARB induced anti-cardiac remodeling effect and improved VF in α(2A)/α(2C)ARKO associated with increased SERCA2 and phospho-Ser(16)-PLN levels, and SERCA2:NCX ratio. Additionally, ARB decreased phospho-Thr(17)-PLN levels as well as reestablished NCX, CaMKII and phospho-Thr(286)-CaMKII toward WT levels. SIGNIFICANCE Altogether, these data provide new insights on intracellular Ca(2+) regulatory mechanisms underlying improved ventricular function by ARB therapy in HF.

Leucine Supplementation Accelerates Connective Tissue Repair of Injured Tibialis Anterior Muscle

This study investigated the effect of leucine supplementation on the skeletal muscle regenerative process, focusing on the remodeling of connective tissue of the fast twitch muscle tibialis anterior (TA). Young male Wistar rats were supplemented with leucine (1.35 g/kg per day); then, TA muscles from the left hind limb were cryolesioned and examined after 10 days. Although leucine supplementation induced increased protein synthesis, it was not sufficient to promote an increase in the cross-sectional area (CSA) of regenerating myofibers (p > 0.05) from TA muscles. However, leucine supplementation reduced the amount of collagen and the activation of phosphorylated transforming growth factor-β receptor type I (TβR-I) and Smad2/3 in regenerating muscles (p < 0.05). Leucine also reduced neonatal myosin heavy chain (MyHC-n) (p < 0.05), increased adult MyHC-II expression (p < 0.05) and prevented the decrease in maximum tetanic strength in regenerating TA muscles (p < 0.05). Our results suggest that leucine supplementation accelerates connective tissue repair and consequent function of regenerating TA through the attenuation of TβR-I and Smad2/3 activation. Therefore, future studies are warranted to investigate leucine supplementation as a nutritional strategy to prevent or attenuate muscle fibrosis in patients with several muscle diseases.

BIOLOGIA MOLECULAR COMO FERRAMENTA NO ESPORTE DE ALTO RENDIMENTO: possibilidades e perspectivas

Varias estrategias tem sido pensadas com o proposito de se utilizar a biologia molecular como ferramenta na pre-selecao e na selecao de talentos esportivos, na manipulacao genetica visando ao aumento ou a diminuicao da producao de determinadas substâncias pelo organismo, na prescricao do treinamento e na recuperacao de lesoes. Portanto, o objetivo desta revisao e apresentar o DNA como regulador do funcionamento do organismo e de que forma alteracoes no perfil genetico, tanto espontâneas como induzidas artificialmente, podem modular respostas fisiologicas e morfologicas por alterar a expressao de determinadas proteinas. Sera dada especial atencao a descricao dos procedimentos utilizados para a manipulacao genetica, nos baixos riscos associados e nas estrategias que tem sido desenvolvidas com o objetivo de detecta-la. Com base em conhecimentos cientificos, coerencia e bom senso, diversas visoes devem ser expostas e amplamente discutidas para ser definido o que e permitido e o que e proibido nas competicoes esportivas.

La biología molecular como una herramienta de alto ingreso deportes: posibilidades y perspectivas

Varias estrategias tem sido pensadas com o proposito de se utilizar a biologia molecular como ferramenta na pre-selecao e na selecao de talentos esportivos, na manipulacao genetica visando ao aumento ou a diminuicao da producao de determinadas substâncias pelo organismo, na prescricao do treinamento e na recuperacao de lesoes. Portanto, o objetivo desta revisao e apresentar o DNA como regulador do funcionamento do organismo e de que forma alteracoes no perfil genetico, tanto espontâneas como induzidas artificialmente, podem modular respostas fisiologicas e morfologicas por alterar a expressao de determinadas proteinas. Sera dada especial atencao a descricao dos procedimentos utilizados para a manipulacao genetica, nos baixos riscos associados e nas estrategias que tem sido desenvolvidas com o objetivo de detecta-la. Com base em conhecimentos cientificos, coerencia e bom senso, diversas visoes devem ser expostas e amplamente discutidas para ser definido o que e permitido e o que e proibido nas competicoes esportivas.

Molecular biology as an instrument in the high performance sport: possibilities and perspectives

Varias estrategias tem sido pensadas com o proposito de se utilizar a biologia molecular como ferramenta na pre-selecao e na selecao de talentos esportivos, na manipulacao genetica visando ao aumento ou a diminuicao da producao de determinadas substâncias pelo organismo, na prescricao do treinamento e na recuperacao de lesoes. Portanto, o objetivo desta revisao e apresentar o DNA como regulador do funcionamento do organismo e de que forma alteracoes no perfil genetico, tanto espontâneas como induzidas artificialmente, podem modular respostas fisiologicas e morfologicas por alterar a expressao de determinadas proteinas. Sera dada especial atencao a descricao dos procedimentos utilizados para a manipulacao genetica, nos baixos riscos associados e nas estrategias que tem sido desenvolvidas com o objetivo de detecta-la. Com base em conhecimentos cientificos, coerencia e bom senso, diversas visoes devem ser expostas e amplamente discutidas para ser definido o que e permitido e o que e proibido nas competicoes esportivas.