RESUMO
An amperometric biosensor for total biogenic amine determinations, using a carbon paste electrode modified with horseradish peroxidase (HRP) enzyme is described. The HRP immobilization on graphite was made using bovine serum albumin, carbodiimide and glutaraldehyde. The biosensor response was optimized using serotonin and it presented the best performance in 0.1 mol l(-1) phosphate buffer (pH=7.0) containing 10 micromol l(-1) of hydrogen peroxide. Under optimized operational conditions at -50 mV versus SCE, a linear response range from 40 to 470 ng ml(-1) was obtained. The detection limit was 17 ng ml(-1) and the response time was 0.5s. The proposed sensor presented a stable response during 4h under continuous monitoring. The difference of the response between six sensor preparations was <2%. The sensor was applied in the determination of total biogenic amines (neurotransmitters) in rat blood samples with success, obtaining a recovery average of 102%.
Assuntos
Monoaminas Biogênicas/análise , Técnicas Biossensoriais , Enzimas Imobilizadas/química , Peroxidase do Rábano Silvestre/química , Animais , Monoaminas Biogênicas/sangue , Soluções Tampão , Eletroquímica , Glutaral , Peróxido de Hidrogênio , Concentração de Íons de Hidrogênio , Indicadores e Reagentes , Ratos , Serotonina/sangue , Soroalbumina Bovina , SoluçõesRESUMO
The clinical and electroretinographic features of chronic methanol intoxication are scarce, and neurotransmitter studies have not been conducted. In addition, most of the studies in the field include results after acute administration. In the present work, a chronic methanol intoxication scheme (2 g/kg/day ip for 2 weeks) was carried out in Sprague-Dawley rats previously depleted of folates with methotrexate. Taurine (2%) in drinking water was also administered in two groups of animals. Blood formate levels were increased in methotrexate-methanol-treated animals with respect to controls (0.98 +/- 0.09 and 0.30 +/- 0.03 mM, respectively). Amino acids and monoamines were determined in plasma and in retina, optic nerve, hippocampus, and posterior cortex by HPLC with fluorescence or electrochemical detection. The main finding was an increased aspartate content in the optic nerve in methotrexate methanol-treated animals. Methanol alone increased glutamate, aspartate, glutamine, taurine, 5-hydroxytryptamine, and 5-hydroxyindoleacetic acid levels in the hippocampus and 5-hydroxytryptamine in the retina. Taurine administration had no significant effect on changes induced by methanol treatment. We concluded that chronic methanol administration produced accumulation of aspartate, an excitotoxic amino acid, in the optic nerve. These findings contribute to the understanding of methanol neurotoxicity and might indicate a relationship between chronic methanol consumption and the development of optic neuropathies.
Assuntos
Aminoácidos/metabolismo , Monoaminas Biogênicas/metabolismo , Encéfalo/metabolismo , Metanol/intoxicação , Neurotransmissores/metabolismo , Nervo Óptico/metabolismo , Retina/metabolismo , Aminoácidos/sangue , Animais , Monoaminas Biogênicas/sangue , Encéfalo/efeitos dos fármacos , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Formiatos/sangue , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Masculino , Metanol/administração & dosagem , Metanol/toxicidade , Metotrexato/farmacologia , Nervo Óptico/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Retina/efeitos dos fármacosRESUMO
OBJECTIVES: The purpose of the present study was to compare the plasma and serum monoamine levels in sedentary, untrained normotensive and hypertensive men at rest with levels measured after an acute bout of exercise and to compare similar measurements following a 12-week aerobic training program. PLACE OF STUDY: The data obtained for this study was collected from a clinic for the prevention of heart disease and cardiac rehabilitation (FITCOR) and analyzed in the Federal University of São Paulo (EPM), Laboratory of Experimental Neurology. SUBJECTS: Two groups of untrained male subjects, i.e., normotensive (N = 16) and hypertensive (N = 19), were submitted to an acute bout of exercise to analyze the acute effect of exercise on the monoamine levels. To study the chronic effect of exercise (physical training program), some individuals of each group were arranged in two other groups; normotensive (N = 11) and hypertensive (N = 8). MEASUREMENT: Plasma catecholamines and serum serotonin levels were determined by high performance liquid chromatography coupled with electrochemical detection. RESULTS: A significant reduction in diastolic blood pressure at rest was observed in the hypertensive group after the physical training program (p < 0.05). Only the mean plasma noradrenaline concentration increased significantly post-exercise in all groups of individuals (acute effect of exercise--p < 0.01 for untrained normotensive and hypertensive; chronic effect of exercise--p < 0.001 for untrained and trained normotensive, p < 0.01 for untrained and trained hypertensive). CONCLUSION: These data show the beneficial effect of physical exercise in reducing the blood pressure in hypertensive patients, which does not seem to be related to changes in circulating monoamines.
Assuntos
Monoaminas Biogênicas/sangue , Exercício Físico/fisiologia , Hipertensão/metabolismo , Monoaminas Biogênicas/metabolismo , Pressão Sanguínea , Teste de Esforço , Humanos , MasculinoRESUMO
Objetives: The purpose of the present study was to compare the plasma and serum monoamine levels in sedentary, untrained normotensive and hypertensive men at rest with levels measured after an acute bout of exercise and to compare similar measurements following a 12-week aerobic training program. Place of study: The data obtained for this study was collected from a clinic for the prevention of heart disease and cardiac rehabilitation (FITCOR) and analyzed in the Federal University of Sao Paulo (EPM), Laboratory of Experimental Neurology. Subjects: Two groups of untrained male subjects, i.e., normotensive (N=16) and hypertensive (N=19) were submitted to an acute bout of exercise to analyze the acute effect of exercise on the monoamine levels. To study the chronic effect of exercise (physical training program), some individuals of each group were arranged in two other groups; normotensive (N=11) and hypertensive (N=8). Measurement: Plasma catecholamines and serum serotonin levels were determined by high performance liquid chromatography coupled with electrochemical detection. Results: A significant reduction in diastolic blood pressure at rest was observed in the hypertensive group after the physical training program (p<0.05). Only the mean plasma noradrenaline concentration increased significantly post-exercise in all groups of individuals (acute effect of exercise - p < 0.01 for untrained normotensive and hypertensive; chronic effect of exercise - p < 0.001 for untrained and trained normotensive, p < 0.01 for untrained and trained hypertensive). Conclusion: These data show the beneficial effect of physical exercise in reducing the blood pressure in hypertensive patients, which does not seem to be related to changes in circulating monoamines.
Assuntos
Humanos , Masculino , Monoaminas Biogênicas/sangue , Exercício Físico/fisiologia , Hipertensão/metabolismo , Pressão Sanguínea , Monoaminas Biogênicas/metabolismo , Teste de EsforçoRESUMO
Este trabalho apresenta um método rápido para a quantificaçäo de catecolaminas utilizando a técnica de cromatografia líquida de fase reversa acoplada à detecçäo eletroquímica. Separaçäo isocrática rápida foi obtida empregando como fase móvel a soluçäo: 0,02M de fosfato de sódio dibásico, 0,02M de ácido nítrico, pH 2,64, metanol a 10 por cento, 0,12mM de EDTA sódico e 556 mg/L de ácido heptanosulfônico. Delineou-se o procedimento de preparaçäo das amostras com extraçäo das monoaminas em alumina, para melhorar a recuperaçäo e diminuir fatores de diluiçäo. O tempo total de análise é de 15 minutos, com boa separaçäo dos picos de monoaminas. O limite de detecçäo obtido para as monoaminas séricas é de 40 a 50 pg/mL, com uma taxa de recuperaçäo de 70-75 por cento.