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1.
Saudi Pharm J ; 29(9): 1061-1069, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34588851

RESUMO

The medicinal uses of Calotropis procera are diverse, yet some of them are based on effects that still lack scientific support. Control of diabetes is one of them. Recently, latex proteins from C. procera latex (LP) have been shown to promote in vivo glycemic control by the inhibition of hepatic glucose production via AMP-activated protein kinase (AMPK). Glycemic control has been attributed to an isolated fraction of LP (CpPII), which is composed of cysteine peptidases (95%) and osmotin (5%) isoforms. Those proteins are extensively characterized in terms of chemistry, biochemistry and structural aspects. Furthermore, we evaluated some aspects of the mitochondrial function and cellular mechanisms involved in CpPII activity. The effect of CpPII on glycemic control was evaluated in fasting mice by glycemic curve and glucose and pyruvate tolerance tests. HepG2 cells was treated with CpPII, and cell viability, oxygen consumption, PPAR activity, production of lactate and reactive oxygen species, mitochondrial density and protein and gene expression were analyzed. CpPII reduced fasting glycemia, improved glucose tolerance and inhibited hepatic glucose production in control animals. Additionally, CpPII increased the consumption of ATP-linked oxygen and mitochondrial uncoupling, reduced lactate concentration, increased protein expression of mitochondrial complexes I, III and V, and activity of peroxisome-proliferator-responsive elements (PPRE), reduced the presence of reactive oxygen species (ROS) and increased mitochondrial density in HepG2 cells by activation of AMPK/PPAR. Our findings strongly support the medicinal use of the plant and suggest that CpPII is a potential therapy for prevention and/or treatment of type-2 diabetes. A common epitope sequence shared among the proteases and osmotin is possibly the responsible for the beneficial effects of CpPII.

2.
Sci Adv ; 6(49)2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33268375

RESUMO

MicroRNAs (miRNAs) have been implicated in oxidative metabolism and brown/beige adipocyte identity. Here, we tested whether widespread changes in miRNA expression promoted by treatment with the small-molecule enoxacin cause browning and prevent obesity. Enoxacin mitigated diet-induced obesity in mice, and this was associated with increased energy expenditure. Consistently, subcutaneous white and brown adipose tissues and skeletal muscle of enoxacin-treated mice had higher levels of markers associated with thermogenesis and oxidative metabolism. These effects were cell autonomous since they were recapitulated in vitro in murine and human cell models. In preadipocytes, enoxacin led to a reduction of miR-34a-5p expression and up-regulation of its target genes (e.g., Fgfr1, Klb, and Sirt1), thus increasing FGF21 signaling and promoting beige adipogenesis. Our data demonstrate that enoxacin counteracts obesity by promoting thermogenic signaling and inducing oxidative metabolism in adipose tissue and skeletal muscle in a mechanism that involves, at least in part, miRNA-mediated regulation.


Assuntos
Enoxacino , MicroRNAs , Tecido Adiposo Marrom/metabolismo , Animais , Metabolismo Energético , Enoxacino/metabolismo , Enoxacino/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , MicroRNAs/genética , MicroRNAs/metabolismo , Obesidade/etiologia , Obesidade/genética , Estresse Oxidativo , Termogênese/genética
3.
Front Endocrinol (Lausanne) ; 11: 561256, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33329381

RESUMO

The nuclear receptor PPARγ is essential to maintain whole-body glucose homeostasis and insulin sensitivity, acting as a master regulator of adipogenesis, lipid, and glucose metabolism. Its activation through natural or synthetic ligands induces the recruitment of coactivators, leading to transcription of target genes such as cytokines and hormones. More recently, post translational modifications, such as PPARγ phosphorylation at Ser273 by CDK5 in adipose tissue, have been linked to insulin resistance trough the dysregulation of expression of a specific subset of genes. Here, we investigate how this phosphorylation may disturb the interaction between PPARγ and some coregulator proteins as a new mechanism that may leads to insulin resistance. Through cellular and in vitro assays, we show that PPARγ phosphorylation inhibition increased the activation of the receptor, therefore the increased recruitment of PGC1-α and TIF2 coactivators, whilst decreases the interaction with SMRT and NCoR corepressors. Moreover, our results show a shift in the coregulators interaction domains preferences, suggesting additional interaction interfaces formed between the phosphorylated PPARγ and some coregulator proteins. Also, we observed that the CDK5 presence disturb the PPARγ-coregulator's synergy, decreasing interaction with PGC1-α, TIF2, and NCoR, but increasing coupling of SMRT. Finally, we conclude that the insulin resistance provoked by PPARγ phosphorylation is linked to a differential coregulators recruitment, which may promote dysregulation in gene expression.


Assuntos
Resistência à Insulina/fisiologia , PPAR gama/metabolismo , Serina/metabolismo , Células 3T3 , Adipócitos/metabolismo , Animais , Células COS , Chlorocebus aethiops , Quinase 5 Dependente de Ciclina/genética , Quinase 5 Dependente de Ciclina/metabolismo , Células HEK293 , Humanos , Camundongos , PPAR gama/genética , Fosforilação/fisiologia , Serina/genética
4.
Proteome Sci ; 18: 4, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32368190

RESUMO

BACKGROUND: Members of the family of NEK protein kinases (NIMA-related kinases) were described to have crucial roles in regulating different aspects of the cell cycle. NEK10 was reported to take part in the maintenance of the G2/M checkpoint after exposure to ultraviolet light. NEK1, NEK5, NEK2 and NEK4 proteins on the other hand have been linked to mitochondrial functions. METHODS: HEK293T cells were transfected with FLAG empty vector or FLAG-NEK10 and treated or not with Zeocin. For proteomic analysis, proteins co-precipitated with the FLAG constructs were digested by trypsin, and then analyzed via LC-MS/MS. Proteomic data retrieved were next submitted to Integrated Interactome System analysis and differentially expressed proteins were attributed to Gene Ontology biological processes and assembled in protein networks by Cytoscape. For functional, cellular and molecular analyses two stable Nek10 silenced HeLa cell clones were established. RESULTS: Here, we discovered the following possible new NEK10 protein interactors, related to mitochondrial functions: SIRT3, ATAD3A, ATAD3B, and OAT. After zeocin treatment, the spectrum of mitochondrial interactors increased by the proteins: FKBP4, TXN, PFDN2, ATAD3B, MRPL12, ATP5J, DUT, YWHAE, CS, SIRT3, HSPA9, PDHB, GLUD1, DDX3X, and APEX1. We confirmed the interaction of NEK10 and GLUD1 by proximity ligation assay and confocal microscopy. Furthermore, we demonstrated that NEK10-depleted cells showed more fragmented mitochondria compared to the control cells. The knock down of NEK10 resulted further in changes in mitochondrial reactive oxygen species (ROS) levels, decreased citrate synthase activity, and culminated in inhibition of mitochondrial respiration, affecting particularly ATP-linked oxygen consumption rate and spare capacity. NEK10 depletion also decreased the ratio of mtDNA amplification, possibly due to DNA damage. However, the total mtDNA content increased, suggesting that NEK10 may be involved in the control of mtDNA content. CONCLUSIONS: Taken together these data place NEK10 as a novel regulatory player in mitochondrial homeostasis and energy metabolism.

5.
Int J Food Sci Nutr ; 71(5): 529-539, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31694434

RESUMO

Studies have shown synergistic and independent effects of leucine and resveratrol (RSV) as possible therapeutic agents to ameliorate metabolic disorders. Thus, the objective of this study was to investigate the effects of supplementation with leucine and RSV, alone and in combination, on metabolic changes in white adipose tissue of neonatally STZ-induced diabetic rats. After weaning, the rats were treated with trans-resveratrol (0.6 mg/kg/dose) and/or leucine (1.35 mg/kg/dose) administered orally. The animals were euthanized at age 16 weeks for blood analyses. Subcutaneous (SC), periepididymal (PE) and retroperitoneal (RP) fat pads were weighed. Adipocytes from PE and RP pads were isolated for morphometric analysis. Long-term supplementation with RSV promoted adiposity recovery, prevented hypoinsulinemia and improved the metabolic profile of the diabetic rats. However, some of these effects were impaired when RSV was associated with leucine. The diabetic rats supplemented with leucine alone showed no significant improvement in metabolic disorders.


Assuntos
Tecido Adiposo Branco/metabolismo , Glicemia/metabolismo , Diabetes Mellitus Experimental/metabolismo , Interações Medicamentosas , Hipoglicemiantes/farmacologia , Leucina/farmacologia , Resveratrol/farmacologia , Adipócitos , Tecido Adiposo , Adiposidade , Animais , Antioxidantes/farmacologia , Antioxidantes/uso terapêutico , Diabetes Mellitus Experimental/tratamento farmacológico , Suplementos Nutricionais , Frutas/química , Hipoglicemiantes/uso terapêutico , Insulina/sangue , Resistência à Insulina , Leucina/uso terapêutico , Masculino , Fitoterapia , Ratos , Resveratrol/uso terapêutico
6.
Sci Rep ; 9(1): 15529, 2019 10 29.
Artigo em Inglês | MEDLINE | ID: mdl-31664147

RESUMO

Leucine can stimulate protein synthesis in skeletal muscle, and recent studies have shown an increase in leucine-related mitochondrial biogenesis and oxidative phosphorylation capacity in muscle cells. However, leucine-related effects in tumour tissues are still poorly understood. Thus, we described the effects of leucine in both in vivo and in vitro models of a Walker-256 tumour. Tumour-bearing Wistar rats were randomly distributed into a control group (W; normoprotein diet) and leucine group (LW; leucine-rich diet [normoprotein + 3% leucine]). After 20 days of tumour evolution, the animals underwent 18-fludeoxyglucose positron emission computed tomography (18F-FDG PET-CT) imaging, and after euthanasia, fresh tumour biopsy samples were taken for oxygen consumption rate measurements (Oroboros Oxygraph), electron microscopy analysis and RNA and protein extraction. Our main results from the LW group showed no tumour size change, lower tumour glucose (18F-FDG) uptake, and reduced metastatic sites. Furthermore, leucine stimulated a shift in tumour metabolism from glycolytic towards oxidative phosphorylation, higher mRNA and protein expression of oxidative phosphorylation components, and enhanced mitochondrial density/area even though the leucine-treated tumour had a higher number of apoptotic nuclei with increased oxidative stress. In summary, a leucine-rich diet directed Walker-256 tumour metabolism to a less glycolytic phenotype profile in which these metabolic alterations were associated with a decrease in tumour aggressiveness and reduction in the number of metastatic sites in rats fed a diet supplemented with this branched-chain amino acid.


Assuntos
Carcinoma 256 de Walker/metabolismo , Glucose/metabolismo , Glicólise/efeitos dos fármacos , Leucina/farmacologia , Fosforilação Oxidativa/efeitos dos fármacos , Animais , Carcinoma 256 de Walker/dietoterapia , Carcinoma 256 de Walker/patologia , Feminino , Alimentos Formulados , Metástase Neoplásica , Ratos , Ratos Wistar
7.
Free Radic Biol Med ; 143: 203-208, 2019 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-31408725

RESUMO

The ability to respond to fluctuations of reactive oxygen species (ROS) within the cell is a central aspect of mammalian physiology. This dynamic process depends on the coordinated action of transcriptional factors to promote the expression of genes encoding for antioxidant enzymes. Here, we demonstrate that the transcriptional coregulators, PGC-1α and NCoR1, are essential mediators of mitochondrial redox homeostasis in skeletal muscle cells. Our findings reveal an antagonistic role of these coregulators in modulating mitochondrial antioxidant induction through Sod2 transcriptional control. Importantly, the activation of this mechanism by either PGC-1α overexpression or NCoR1 knockdown attenuates mitochondrial ROS levels and prevents cell death caused by lipid overload in skeletal muscle cells. The opposing actions of coactivators and corepressors, therefore, exert a commanding role over cellular antioxidant capacity.


Assuntos
Regulação da Expressão Gênica , Mitocôndrias/metabolismo , Correpressor 1 de Receptor Nuclear/metabolismo , Oxirredução/efeitos dos fármacos , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Animais , Antioxidantes/metabolismo , Caenorhabditis elegans , Sobrevivência Celular , Proteínas de Fluorescência Verde/metabolismo , Homeostase , Lipídeos/química , Camundongos , Músculo Esquelético/metabolismo , Palmitatos/farmacologia , Propídio/farmacologia , RNA Interferente Pequeno/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/metabolismo , Transativadores/metabolismo , Transcrição Genética
8.
J Cell Physiol ; 234(5): 6313-6323, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30317568

RESUMO

Nutrient malnutrition, during the early stages of development, may facilitate the onset of metabolic diseases later in life. However, the consequences of nutritional insults, such as a high-fat diet (HFD) after protein restriction, are still controversial. We assessed overall glucose homeostasis and molecular markers of mitochondrial function in the gastrocnemius muscle of protein-restricted mice fed an HFD until early adulthood. Male C57BL/6 mice were fed a control (14% protein-control diet) or a protein-restricted (6% protein-restricted diet) diet for 6 weeks. Afterward, mice received an HFD or not for 8 weeks (mice fed a control diet and HFD [CH] and mice fed a protein-restricted diet and HFD [RH]). RH mice showed lower weight gain and fat accumulation and did not show an increase in fasting plasma glucose and insulin levels compared with CH mice. RH mice showed higher energy expenditure, increased citrate synthase, peroxisome-proliferator-activated receptor gamma coactivator 1-alpha protein content, and higher levels of malate and α-ketoglutarate compared with CH mice. Moreover, RH mice showed increased AMPc-dependent kinase and acetyl coenzyme-A (CoA) carboxylase phosphorylation, lower intramuscular triacylglycerol content, and similar malonyl-CoA levels. In conclusion, protein undernourishment after weaning does not potentiate fat accumulation and insulin resistance in adult young mice fed an HFD. This outcome seems to be associated with increased skeletal muscle mitochondrial oxidative capacity and reduced lipids accumulation.


Assuntos
Dieta Hiperlipídica/efeitos adversos , Glucose/metabolismo , Homeostase/fisiologia , Músculo Esquelético/metabolismo , Deficiência de Proteína/metabolismo , Animais , Metabolismo Energético/fisiologia , Resistência à Insulina/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/metabolismo
9.
Cell Stress Chaperones ; 21(5): 793-804, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27278803

RESUMO

This study aims to evaluate the effect of regular post-exercise cold water immersion (CWI) on intramuscular markers of cellular stress response and signaling molecules related to mitochondria biogenesis and exercise performance after 4 weeks of high intensity interval training (HIIT). Seventeen healthy subjects were allocated into two groups: control (CON, n = 9) or CWI (n = 8). Each HIIT session consisted of 8-12 cycling exercise stimuli (90-110 % of peak power) for 60 s followed by 75 s of active recovery three times per week, for 4 weeks (12 HIIT sessions). After each HIIT session, the CWI had their lower limbs immersed in cold water (10 °C) for 15 min and the CON recovered at room temperature. Exercise performance was evaluated before and after HIIT by a 15-km cycling time trial. Vastus lateralis biopsies were obtained pre and 72 h post training. Samples were analyzed for heat shock protein 72 kDa (Hsp72), adenosine monophosphate-activated protein kinase (AMPK), and phosphorylated p38 mitogen-activated protein kinase (p-p38 MAPK) assessed by western blot. In addition, the mRNA expression of heat shock factor-1 (HSF-1), peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α), nuclear respiratory factor 1 and 2 (NRF1 and 2), mitochondrial transcription factor A (Tfam), calcium calmodulin-dependent protein kinase 2 (CaMK2) and enzymes citrate synthase (CS), carnitine palmitoyltransferase I (CPT1), and pyruvate dehydrogenase kinase (PDK4) were assessed by real-time PCR. Time to complete the 15-km cycling time trial was reduced with training (p < 0.001), but was not different between groups (p = 0.33). The Hsp72 (p = 0.01), p38 MAPK, and AMPK (p = 0.04) contents increased with training, but were not different between groups (p > 0.05). No differences were observed with training or condition for mRNA expression of PGC-1α (p = 0.31), CPT1 (p = 0.14), CS (p = 0.44), and NRF-2 (p = 0.82). However, HFS-1 (p = 0.007), PDK4 (p = 0.03), and Tfam (p = 0.03) mRNA were higher in CWI. NRF-1 decrease in both groups after training (p = 0.006). CaMK2 decreased with HIIT (p = 0.003) but it was not affected by CWI (p = 0.99). Cold water immersion does not alter HIIT-induced Hsp72, AMPK, p38 MAPK, and exercise performance but was able to increase some markers of cellular stress response and signaling molecules related to mitochondria biogenesis.


Assuntos
Proteínas de Choque Térmico HSP72/metabolismo , Músculo Esquelético/metabolismo , Adaptação Fisiológica , Adulto , Biomarcadores/metabolismo , Temperatura Baixa , Treinamento Intervalado de Alta Intensidade , Humanos , Masculino , Mitocôndrias Musculares/metabolismo , Proteínas Mitocondriais/metabolismo , Condicionamento Físico Humano , Adulto Jovem
10.
J Endocrinol ; 208(3): 257-64, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21212094

RESUMO

Endurance exercise is known to enhance peripheral insulin sensitivity and reduce insulin secretion. However, it is unknown whether the latter effect is due to the reduction in plasma substrate availability or alterations in ß-cell secretory machinery. Here, we tested the hypothesis that endurance exercise reduces insulin secretion by altering the intracellular energy-sensitive AMP-activated kinase (AMPK) signaling pathway. Male Wistar rats were submitted to endurance protocol training one, three, or five times per week, over 8 weeks. After that, pancreatic islets were isolated, and glucose-induced insulin secretion (GIIS), glucose transporter 2 (GLUT2) protein content, total and phosphorylated calmodulin kinase kinase (CaMKII), and AMPK levels as well as peroxisome proliferator-activated receptor-γ coactivator-1-α (PGC-1α) and uncoupling protein 2 (UCP2) content were measured. After 8 weeks, chronic endurance exercise reduced GIIS in a dose-response manner proportionally to weekly exercise frequency. Contrariwise, increases in GLUT2 protein content, CaMKII and AMPK phosphorylation levels were observed. These alterations were accompanied by an increase in UCP2 content, probably mediated by an enhancement in PGC-1α protein expression. In conclusion, chronic endurance exercise induces adaptations in ß-cells leading to a reduction in GIIS, probably by activating the AMPK signaling pathway.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Insulina/metabolismo , Canais Iônicos/metabolismo , Ilhotas Pancreáticas/metabolismo , Proteínas Mitocondriais/metabolismo , Condicionamento Físico Animal , Resistência Física , Animais , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Transportador de Glucose Tipo 2/metabolismo , Secreção de Insulina , Masculino , Músculo Esquelético/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Proteínas de Ligação a RNA/metabolismo , Ratos , Ratos Wistar , Fatores de Transcrição/metabolismo , Proteína Desacopladora 2
11.
Eur J Appl Physiol ; 110(4): 825-32, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20614130

RESUMO

The polymorphisms of endothelial nitric oxide synthase (eNOS) are associated with reduced eNOS activity. Aerobic exercise training (AEX) may influence resting nitric oxide (NO) production, oxidative stress and blood pressure. The purpose of this study was to investigate the effect of AEX on the relationship among blood pressure, eNOS gene polymorphism and oxidative stress in pre-hypertensive older people. 118 pre-hypertensive subjects (59 ± 6 years) had blood samples collected after a 12 h overnight fast for assessing plasma NO metabolites (NOx) assays, thiobarbituric acid reactive substances (T-BARS) and superoxide dismutase activity (ecSOD). eNOS polymorphism (T-786C and G-894T) was done by standard PCR methods. All people were divided according to the genotype results (G1: TT/GG, G2: TT/GT + TT, G3: TC + CC/GG, G4: TC + CC/GT + TT). All parameters were measured before and after 6 months of AEX (70% of VO(2 max)). At baseline, no difference was found in systolic and diastolic blood pressure, ecSOD and T-BARS activity. Plasma NOx levels were significantly different between G1 (19 ± 1 µM) and G4 (14.2 ± 0.6 µM) and between G2 (20.1 ± 1.7 µM) and G4 (14.2 ± 0.6 µM). Therefore, reduced NOx concentration in G4 group occurred only when the polymorphisms were associated, suggesting that these results are more related to genetic factors than NO-scavenging effect. After AEX, the G4 increased NOx values (17.2 ± 1.2 µM) and decreased blood pressure. G1, G3 and G4 decreased T-BARS levels. These results suggest the AEX can modulate the NOx concentration, eNOS activity and the relationship among eNOS gene polymorphism, oxidative stress and blood pressure especially in C (T-786C) and T (G-894T) allele carriers.


Assuntos
Envelhecimento/fisiologia , Exercício Físico/fisiologia , Óxido Nítrico Sintase Tipo III/genética , Estresse Oxidativo/fisiologia , Pré-Hipertensão , Idoso , Pressão Sanguínea/fisiologia , Humanos , Pessoa de Meia-Idade , Nitratos/sangue , Consumo de Oxigênio/fisiologia , Polimorfismo Genético/fisiologia , Pré-Hipertensão/genética , Pré-Hipertensão/metabolismo , Pré-Hipertensão/fisiopatologia
12.
Metabolism ; 59(6): 911-3, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20015523

RESUMO

Low-protein diet impairs insulin secretion in response to nutrients and may induce several metabolic disorders including diabetes, obesity, and cardiovascular disease. In the present study, the influence of leucine supplementation on glutamate dehydrogenase (GDH) expression and glucose-induced insulin secretion (GIIS) was investigated in malnourished rats. Four groups were fed with different diets for 12 weeks: a normal-protein diet (17%) without or with leucine supplementation or a low (6%)-protein diet without (LP) or with leucine supplementation (LPL). Leucine (1.5%) was supplied in the drinking water. Western blotting analysis revealed reduced GDH expression in LP, whereas LPL displayed improved GDH expression, similar to control. The GIIS and leucine-induced insulin release were also enhanced in LPL compared with LP and similar to those observed in rats fed a normal-protein diet without leucine supplementation. In addition, GDH allosteric activators produced an increased insulin secretion in LPL. These findings indicate that leucine supplementation was able to increase GDH expression leading to GIIS restoration, probably by improved leucine metabolic pathways.


Assuntos
Glucose/farmacologia , Glutamato Desidrogenase/biossíntese , Insulina/metabolismo , Leucina/uso terapêutico , Desnutrição Proteico-Calórica/tratamento farmacológico , Desnutrição Proteico-Calórica/metabolismo , Animais , Western Blotting , Glutamato Desidrogenase/genética , Técnicas In Vitro , Ilhotas Pancreáticas/efeitos dos fármacos , Ilhotas Pancreáticas/metabolismo , Masculino , Desnutrição Proteico-Calórica/enzimologia , Ratos
13.
Rev. bras. ciênc. mov ; 12(3): 21-26, 2004. graf
Artigo em Português | LILACS | ID: lil-524506

RESUMO

Uma elevada taxa na oxidação de ácidos graxos reduz a oxidação de glicose em músculo esquelético. Esse efeito seria importante durante o exercício intermitente intenso, uma vez que, baixos níveis de glicogênio ou altos níveis de lactato muscular estão diretamente envolvidos com o mecanismo de fadiga muscular. Nosso objetivo foi examinar se uma maior disponibilidade de ácidos graxos induz uma redução nos níveis de lactato e glicose sanguínea, seguido de um aumento no tempo de exaustão (TE) durante o exercício intermitente intenso. 10 ciclistas masculinos foram submetidos a testes para determinação do limiar anaeróbio (LA), potência anaeróbia máxima (P.A.M.) e índice de fadiga (I.F.). Após 48 h, foram submetidos a uma sessão de exercício intermitente no ciclo-ergômetro a uma intensidade de 30% acima do LA. Os participantes ingeriram cafeína (CF) (5 mg.kg-1) ou placebo (PL) (5 mg.kg-1) 60 min antes do exercício. Amostras de sangue para determinação de cafeína e ácidos graxos livres (AGL) foram coletadas antes do exercício (0 min) e para determinação de glicose e lactato foram coletadas a cada 5 min durante o exercício. Entre as diferentes variáveis coletadas houve uma diferença significativa no tempo de exaustão (TE) após a ingestão de CF comparado a mesma situação após ingesta de PL (82,4 ± 28 vs 56,2 ± 17 min) (p < 0,05). A ingesta de CF também aumentou as concentrações de AGL antes de exercício (0,183 ± 0,097 vs 0,110 ± 0,052 g.dL-1) (p < 0,05). As concentrações de glicose sanguínea aumentaram significantemente com CF apenas nos instantes finais do exercício (p < 0,05), ao passo que as concentrações de lactato não sofreram alterações (p > 0,05). Os valores de percepção subjetiva de esforço (PSE) foram estatisiticamente significativos apenas no final do exercício quando as análises foram realizadas dentro de cada grupo isoladamente (p < 0,05).


This study examined the influence of caffeine on changes in selected blood and performance variables in response to intermittent exercise. 10 male cyclists withdrew all dietary sources of caffeine for 72 h before two tests. One hour before exercise they ingested placebo (PL) or caffeine (CF) capsules (5 mg.kg-1), rested quietly and then cycled at 30% above the anaerobic threshold (AT) until voluntary exhaustion. Blood samples for caffeine and free fatty acids (FFA) analysis were taken immediately before the exercise and samples for glucose and lactate analysis were taken during exercise. The variables rating perceived exertion (RPE), heart rate (HR) and time to exhaustion (TE) were also measured during exercise. There was a significant difference in CF compared with PL trial for TE (82,4 ± 28 vs 56,2 ± 17 min) and FFA (0,183 ± 0,097 vs 0,110 ± 0,052 g.dL-1) (p < 0,05). Glucose blood concentrations also significantly increased in CF trial in the end of exercise (p < 0,05), whereas lactate concentrations did not change during the exercise for both trial (p > 0,05). The RPE values just show significance toward the end of exercise when the result were compared separately into the same group (p < 0,05), but failed for significance when CF and PL were compared (p > 0,05). Therefore, our results suggest that an increased caffeine-induced lipolysis may contributed with a reduced consume of glucose by skeletal muscle following by a marked increase in the performance during intermittent exercise.


Assuntos
Humanos , Masculino , Adulto , Cafeína , Exercício Físico , Glucose/metabolismo , Lipólise
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