Tryptophan and tyrosine catabolic pattern in neuropsychiatric disorders.

Catabolism of tryptophan and tyrosine in relation to the isoprenoid pathway was studied in neurological and psychiatric disorders. The concentration of trytophan, quinolinic acid, kynurenic acid, serotonin and 5-hydroxyindoleacetic acid was found to be higher in the plasma of patients with all these disorders; while that of tyrosine, dopamine, epinephrine and norepinephrine was lower. There was increase in free fatty acids and decrease in albumin (factors modulating tryptophan transport) in the plasma of these patients. Concentration of digoxin, a modulator of amino acid transport, and the activity of HMG CoA reductase, which synthesizes digoxin, were higher in these patients; while RBC membrane Na+-K+ ATPase activity showed a decrease. Concentration of plasma ubiquinone (part of which is synthesised from tyrosine) and magnesium was also lower in these patients. No morphine could be detected in the plasma of these patients except in MS. On the other hand, strychnine and nicotine were detectable. These results indicate hypercatabolism of tryptophan and hypocatabolism of tyrosine in these disorders, which could be a consequence of the modulating effect of hypothalamic digoxin on amino acid transport.

Monoamine responses to acute and chronic aerobic exercise in mormotensive and hypertensive subjects

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.

Serum catecholamine levels determined by high performance liquid chromatography coupled with electrochemical detection

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.

Effect of interaction between the tricyclic antidepressant [Doxepin] and the B-adrenoceptor blocker [timolol] on the brain monoamines and systemic arterial blood pressure. [Experimental and clinical study]

Daily oral administration of timolol 5 mg/kgm for 2 weeks in albino rats produced significant increase in whole brain [A] and [NA] concentration while [5-HT] was significantly reduced. Doxepin administration 10 mg/kgm/day orally for 2 weeks induced significant increase of rat whole brain [A] and significant reduction of [NA] and [5-HT]. The effects of concurrent timolol and doxepin administration on brain [A], [NA] and [5-HT] were similar to effects of timolol but of less magnitude. In patients with mild to moderate hypertension timolol oral therapy [10 mg b.i.d.] induced a highly significant reduction of both diastolic and systolic pressures, while doxepin therapy 25 mg b.i.d. orally for 2 weeks alone or concurrently with timolol [10 mg b.i.d.] induced just significant reduction of diastolic pressure but the systolic pressure was insignificantly lowered, these effects were significantly less than the effects of timolol therapy alone. The effects of timolol or doxepin therapy as well as the effects of interaction between them on the arterial blood pressure could be partly explained by the changes induced by these druge in the brain monoamines estimated in the present work