RESUMO
The present method involves conversion of the aldehyde produced, as a result of serotonin deamination by monoamine oxidase, to its 2:4 dinitrophenyl hydrazone derivative which gives a stable, bright yellow colour in alkaline solution and can be measured colorimetrically. The derivative is however unstable in the acidic medium and has to be extracted into an organic solvent immediately. The details of the method and its standardization are discussed.
Assuntos
Monoaminoxidase/metabolismo , Serotonina/metabolismo , Animais , Colorimetria , Desaminação , Cobaias , Fígado/enzimologia , RatosRESUMO
The metabolic significance of indole-3-acetaldehyde in the process of in vitro pigment formation from tryptamine in the presence of guinea-pig liver mitochondria was investigated. Among the four type selective MAO inhibitors used, pargyline and deprenyl appear to be more effective in inhibiting pigment formation from tryptamine than serotonin, while in the presence of clorgyline and Lilly 51641, pigment formation from serotonin was preferentially inhibited. Reducing agents like ascorbic acid, cysteine and glutathione were found to block pigment formation significantly. Also, a reduction of pigment formation was noted in the presence of NADH and ethanol but not in the presence of NAD. It was observed that the amount of indole-3-acetaldehyde produced enzymatically from tryptamine under the present experimental conditions is not sufficient to account for the total amount of pigment formed in the standard incubation mixture and the generation of nascent aldehyde has greater contribution in pigment formation than that supplemented to the system exogenously. It appears that indole-3-acetaldehyde, tryptamine and MAO are associated with the process of pigment formation.
Assuntos
Indóis/metabolismo , Pigmentos Biológicos/biossíntese , Triptaminas/metabolismo , Animais , Ácido Ascórbico/farmacologia , Glutationa/farmacologia , Cobaias , Técnicas In Vitro , Mitocôndrias Hepáticas/metabolismo , Monoaminoxidase/análise , Inibidores da Monoaminoxidase/farmacologiaRESUMO
N-Carbamoyl-2-(2,6-dichlorophenyl)acetamidine HCl (LON 954), a tremorogenic drug, inhibited MAO activity in various tissue preparations in a reversible, competitive manner showing some degree of selectivity towards type-B MAO.
Assuntos
Inibidores da Monoaminoxidase , Ureia/análogos & derivados , Animais , Encéfalo/enzimologia , Dopamina/metabolismo , Cobaias , Técnicas In Vitro , Cinética , Mitocôndrias Hepáticas/enzimologia , Coelhos , Ratos , Tremor/induzido quimicamente , Ureia/farmacologiaRESUMO
The crude mitochondrial fraction of rat brain contains an active dehydrogenase involved in the direct oxidation of gamma-aminobutyric acid. INT (p-iodonitrotetrazolium violet) can serve as an efficient acceptor of electrons in this dehydrogenase reaction. During this oxidation of GABA, ammonia is not produced. In vitro the dehydrogenase activity is inhibited by certain MAO inhibitors. The effects of various inhibitors of GABA-T and GAD were also investigated. The dehydrogenase activity was found to be susceptible to various anti-convulsants and inhibitors of electron transport. The co-factors which may be involved in the transfer of electrons during GABA oxidation in the presence of INT are also discussed.
Assuntos
Encéfalo/enzimologia , Oxirredutases/metabolismo , Animais , Anticonvulsivantes/farmacologia , Transporte de Elétrons/efeitos dos fármacos , Masculino , Mitocôndrias/enzimologia , Inibidores da Monoaminoxidase/farmacologia , Ratos , Sais de Tetrazólio/metabolismoRESUMO
Reductase activity towards two aldose substrates has been examined in subcellular fractions prepared from rat brain. The reduction of glucuronate, which is sensitive to inhibition by the anticonvulsant drug sodium valproate, corresponds to the major high-Km aldehyde reductase in brain. Xylose reduction that is insensitive to valproate inhibition has characteristics consistent with the activity of aldose reductase (EC 1.1.1.21). Both enzymes are predominantly localized in the cytosolic fraction. The significance of the location of these two reductases is discussed in relation to the compartmentation of catecholamine metabolism in brain.
Assuntos
Oxirredutases do Álcool/metabolismo , Aldeído Redutase/metabolismo , Aldeídos/metabolismo , Encéfalo/enzimologia , Desidrogenase do Álcool de Açúcar/metabolismo , Ácido Valproico/farmacologia , Animais , Citosol/enzimologia , Masculino , NADP/farmacologia , Ratos , Ratos Endogâmicos , Xilose/metabolismoAssuntos
Mitocôndrias Hepáticas/enzimologia , Monoaminoxidase/metabolismo , Animais , Catecolaminas/metabolismo , Estabilidade de Medicamentos , Congelamento , Cobaias , Temperatura Alta , Técnicas In Vitro , Masculino , Monoaminoxidase/classificação , Inibidores da Monoaminoxidase/farmacologia , Desnaturação Proteica , Proteínas/metabolismo , Especificidade por SubstratoAssuntos
Encéfalo/enzimologia , Mitocôndrias/enzimologia , Inibidores da Monoaminoxidase/farmacologia , Monoaminoxidase/metabolismo , Animais , Encéfalo/efeitos dos fármacos , Harmalina/farmacologia , Harmina/farmacologia , Técnicas In Vitro , Masculino , Mitocôndrias/efeitos dos fármacos , Ratos , Selegilina/farmacologia , Serotonina/metabolismo , Especificidade por Substrato , Tiramina/metabolismoAssuntos
Ácidos Araquidônicos/farmacologia , Dextroanfetamina/farmacologia , Inibidores da Monoaminoxidase/farmacologia , Monoaminoxidase/metabolismo , Miocárdio/enzimologia , Ácidos Oleicos/farmacologia , Animais , Ácidos Araquidônicos/antagonistas & inibidores , Dextroanfetamina/antagonistas & inibidores , Técnicas In Vitro , Inibidores da Monoaminoxidase/antagonistas & inibidores , Ácidos Oleicos/antagonistas & inibidores , RatosAssuntos
Encéfalo/enzimologia , Clorgilina/farmacologia , Ciclopropanos/farmacologia , Mitocôndrias/enzimologia , Inibidores da Monoaminoxidase , Propilaminas/farmacologia , Animais , Encéfalo/efeitos dos fármacos , Técnicas In Vitro , Masculino , Mitocôndrias/efeitos dos fármacos , Éteres Fenílicos/farmacologia , Ratos , Serotonina/metabolismo , Frações Subcelulares/enzimologia , Tiramina/metabolismoAssuntos
Aminas Biogênicas/metabolismo , Encéfalo/metabolismo , Inibidores da Monoaminoxidase/farmacologia , Animais , Encéfalo/efeitos dos fármacos , Técnicas In Vitro , Monoaminoxidase/metabolismo , Oxirredução/efeitos dos fármacos , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/metabolismo , RatosRESUMO
Monoamine axodation has been studied in different organs of adult rats. Activity of monoamine dehydrogenase (MADH) has been measured both aerobically and anaerobically. Brain is the organ where maximum activity of MADH has been observed while in ovary the minimal enzyme activity has been noticed. In the absence of air, the activity proceeded at faster rate whereas MAO activity cannot take place in absence of oxygen. Oxygen can not be replaced by other electron acceptors like NTC. However, in some organs like pancreas, the formazan production was almost negligible. Aerobically moderate MADH activity was observed in case of ileum and testis. On the other hand, spleen, brain, testis and lung homogenates showed moderate amount of tetrazolium salts reduction in absence of air. This indicates the differential nature of the MADH activities in aerobic and anaerobic condition. High activity of monoamine oxidase (MAO) has been observed in liver. Brain and pancreas were also found good organs for MAO activity, but liver homogenate failed to reduce tetrazolium salt. Only dialysed liver homogenate in the presence of tryptamine, demonstrated moderate activity of MADH. Relative activity of both the enzymes has been studied. The organwise distribution pattern of MAO and MADH appeared quite different.
