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Objective: This study investigated the chronic (oral) and acute (hypothalamic infusion) effects of L-arginine supplementation on feed intake, body composition, and behavioral changes in rats. Methods: Twenty rats were divided into two groups treated orally for 60 days; one group received L-arginine (1 g/kg body weight) and one group received saline (1 mL/NaCl 0.9%). Daily consumption of water and food were evaluated, and weight monitored. After the oral treatment, the rats underwent stereotactic biopsy and a group was injected with 2 µL of L-arginine (0.5 mM) and another received an injection of saline (0.9% NaCl), in the hypothalamic route, through micro infusion. Immediately after micro infusion, the animal behavior was evaluated through tests in the open field. Food and water consumption were evaluated at 12 and 24 hours after the micro infusion. Daily water consumption and weight gain evolution were evaluated. At the end of treatments, rats were euthanized and blood was collected for glucose, glycerol, and cholesterol evaluation, and histological analysis of vital organs. Results: Oral supplementation with L-arginine increased water intake (11%, p<0.05) and promoted weight gain (3%, p<0.05). However, hypothalamic infusion promoted a significant increase in chow intake (30%, p<0.05) after 24 hours of L-arginine administration. Conclusion: Chronic oral treatment with L-arginine was not effective on appetite modulation; however, an effect was observed when L-arginine was administered directly into the hypothalamus, suggesting a central regulation on appetite through nNOS sensitization. Chronic use of L-arginine did not cause substantial changes in anthropometric, biochemical, behavioral, or histological variables. .

Objetivo: Este estudo investigou os efeitos da suplementação crônica (oral) e aguda (infusão no hipotálamo) com L-arginina sobre a saciedade, composição corporal e mudanças comportamentais em ratos. Métodos: Vinte ratos foram divididos em dois grupos e tratados por via oral durante 60 dias; um grupo recebeu uma dose de L-arginina (1 g/kg de peso corporal), outro grupo recebeu uma dose de solução salina (1 mL/NaCl 0.9%). O consumo diário de água e comida e a evolução do ganho de peso foram avaliados. Após o tratamento por via oral, os ratos foram submetidos à estereotaxia: um grupo recebeu uma injeção com 2 µl de L-Arginina (0.5 mM) e outro recebeu uma injeção de solução salina (NaCl 0,9%), no hipotálamo, através de microinfusão. Imediatamente após a microinfusão, foi avaliado o comportamento dos animais através do teste em campo aberto. O consumo de água e de comida foi avaliado nas 12 e 24 horas seguintes à microinfusão. No final dos tratamentos, os ratos foram eutanasiados para coleta de amostras para dosagem de glicose, glicerol e colesterol, além da análise histológica dos órgãos. Resultados: A suplementação oral com L-arginina promoveu aumento do consumo de água (11%, p<0,05) e ganho de peso (3%, p<0,05). Além disso, a infusão hipotalâmica promoveu um aumento significativo do consumo alimentar (30%, p<0,05) após 24 horas da administração de L-arginina. Conclusão: O tratamento oral crônico com L-arginina não obteve efeitos na modulação do apetite. No entanto, ocorreu aumento da ingestão de alimento quando a L-arginina foi administrada diretamente no hipotálamo, sugerindo que exista uma estimulação do apetite através da sensibilização da nNOS nessa região. O uso crônico de L-arginina não causou mudanças substanciais nos dados antropométricos, bioquímicos, comportamentais ou histológicos. .

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OBJETIVO: O presente estudo verificou os efeitos da suplementação com cafeína associada ao exercício físico agudo sobre a resposta glicêmica em ratos diabéticos. MÉTODOS: Foram utilizados 32 animais, com 60 dias de idade, e 238±3 g de peso, divididos em quatro grupos: controle, controle cafeína, diabetes e diabetes/cafeína. O modelo de diabetes foi induzido pela administração intraperitoneal de 60 mg/kg de estreptozotocina. De forma aguda, os animais receberam 6 mg de cafeína ou salina para os grupos-controles 60 minutos antes do exercício físico. Os animais realizaram um protocolo de natação de 60 minutos de exercício físico, com sobrecarga de 6% do peso corporal com lactacidemia compatível com a máxima produção de lactato em estado estável (5,5 mmol/L). Após o exercício físico agudo, foi realizada a eutanásia dos animais para coleta de sangue e análises glicêmicas. Antes e após a prescrição das suplementações, ocorreu a aferição das respostas cardiovasculares por meio de um pletismógrafo de cauda. Foi realizado o teste estatístico Analise de Variância one way com post hoc de Student-Newman-Keuls para analisar as diferenças estatísticas entre as suplementações, sendo considerado p<0,05. RESULTADOS: A prescrição de cafeína na dose de 6 mg/kg não alterou respostas cardiovasculares. No entanto, a cafeína promoveu uma significante redução na glicemia sanguínea (42%; p<0,05) após 60 minutos do protocolo de exercício nos ratos diabéticos em relação aos grupos-controles. CONCLUSÃO: A ingestão aguda de cafeína associada ao exercício físico agudo pode aumentar a captação de glicose sem alterar as respostas ...

OBJECTIVE: The present study investigated the effects of caffeine supplementation combined with acute physical exercise on the glycemic response of diabetic rats. METHODS: Thirty-two 60-day-old rats with a mean weight of 238±3 g were divided into four groups: control, control caffeine, diabetes, and diabetes/caffeine. Diabetes was induced by 60 mg/kg of streptozotocin intraperitoneally. The control groups received an acute dose of caffeine (6 mg) or saline 60 minutes before exercise. The animals were then forced to swim for 60 minutes carrying a ballast weighing 6% of their body weight, producing lactacidemia compatible with the maximum lactate production during the steady state (5.5 mmol/L). After the acute exercise session, the animals were sacrificed and their blood collected for glucose analysis. The cardiovascular responses were measured before and after supplementation by tail cuff plethysmography. The one-way Analysis of Variance (Anova) was realized with post hoc of Student-Newman-Keuls to analyse the statistical differences between the supplementations, considering p<0.05. RESULTS: Caffeine at a dose of 6 mg/kg did not change the cardiovascular responses. However, compared with the control groups, caffeine reduced the blood glucose (42%, p<0.05) of diabetic rats after 60 minutes of exercise. CONCLUSION: Acute caffeine ingestion together with exercise can increase glucose uptake without changing cardiovascular responses in animal models. .

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CONTEXT: Caffeine can stimulate insulin secretion by attenuating hyperglycemia in diabetes models with significant reduction of pancreatic functional ß cells. Knowledge of these mechanisms could contribute to new strategies for treating diabetes. OBJECTIVE: This study evaluated the effects of caffeine and physical exercise on glycemic and insulin responses in diabetic rats. MATERIALS AND METHODS: The diabetes model was induced by intraperitoneal administration of 60 mg/kg of streptozotocin (STZ). Animals were divided into six groups: control, caffeine, STZ control, STZ caffeine, STZ sulfonylurea, and STZ caffeine + sulfonylurea. Acutely, control animals received 6 mg of caffeine and 10 mg/kg sulfonylurea or 10 mg/kg saline. Animals were sacrificed after physical exercise; blood samples were collected for glucose, glycerol, lactate, and insulin analyses. Cardiovascular responses were recorded before and after treatments. A one-way ANOVA and the post hoc Student-Newman-Keuls test were used to analyze statistical differences between treatments (p < 0.05). RESULTS: About 6 mg/kg of caffeine did not alter cardiovascular responses, but promoted blood glucose reduction after 60 min of exercise when compared to animals in the control groups (387-187 mg/dL; p < 0.05). Insulin levels increased significantly (0.6-10 µU/mL; p < 0.05) in rats that received acute caffeine treatment associated with sulfonylurea compared to rats in the other groups. DISCUSSION AND CONCLUSION: Acute caffeine intake with exercise can increase glucose uptake enhancing insulin secretion stimulated by sulfonylurea in ß cells-deficient pancreas. The results indicate the potential use of caffeine as a strategy for glycemic and insulin control in diabetes.

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The essential hypertension has been associated with membrane cell damage. The aim of the present study is investigate the relationship between erythrocyte Na(+),K(+)-ATPase and lipoperoxidation in prehypertensive patients compared to normotensive status. The present study involved the prehypertensive patients (systolic: 136 ± 7 mmHg; diastolic: 86.8 ± 6.3 mmHg; n = 8) and healthy men with normal blood pressure (systolic: 110 ± 6.4 mmHg; diastolic: 76.1 ± 4.2 mmHg; n = 8) who were matched for age (35 ± 4 years old). The venous blood samples of antecubital vein (5 mL) were collected into a tube containing sodium heparin as anticoagulant (1000 UI), and erythrocyte ghosts were prepared for quantifying Na(+),K(+)-ATPase activity. The extent of the thiobarbituric acid reactive substances (TBARS) was determined in plasma. The statistical analysis was carried out by Student's t-test and Pearson's correlation coefficient. A P < 0.05 was considered significant. The Na(+),K(+)-ATPase activity was lower in prehypertensive patients compared with normotensive subjects (4.9 versus 8.0 nmol Pi/mg protein/min; P < 0.05). The Na(+),K(+)-ATPase activity correlated negatively with TBARS content (r = -0.6; P < 0.05) and diastolic blood pressure (r = -0.84; P < 0.05). The present study suggests that Na(+),K(+)-ATPase activity reduction and elevation of the TBARS content may underlie the pathophysiological aspects linked to the prehypertensive status.

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