RESUMO
The cephalic vein arises from the radial end of the dorsal venous arch. It turns around the radial border of the forearm and passes proximally along the arm to the shoulder, where it enters the axillary vein by penetrating the clavipectoral triangle. The cephalic vein is prone to vary at the antecubital fossa, where it forms numerous anastomoses. A male cadaver fixated with a 10% formalin solution was dissected during regular anatomy lessons. It was found that the cephalic vein crossed the upper third of the arm between two fasciculi of the deltoid muscle and reached the shoulder, where it passed above the acromion and crossed the posterior border of the clavicle in order to join the external jugular vein. The cephalic vein is one of the most used veins for innumerous activities, such as venipunctures and arteriovenous fistula creation. Furthermore, it is an anatomical landmark known for its consistent anatomy, as it possesses low rates of variability. Despite that, its anatomical variations are clinically and surgically significant and healthcare professionals must be aware of the variations of this vessel. We aim to report a rarely described variation of the cephalic vein and discuss its embryological, phylogenetic and clinical features.
Assuntos
Variação Anatômica , Veias Jugulares/anatomia & histologia , Extremidade Superior/irrigação sanguínea , Pontos de Referência Anatômicos , Veia Axilar/anatomia & histologia , Cadáver , Humanos , Masculino , FilogeniaRESUMO
Cryopreservation exposes spermatozoa to stressful conditions, leading to reduced cell viability. Several studies propose that overproduction of reactive oxygen species and decreased antioxidant capacity of semen may increase the damaging effects of the technique. The objective of this work was to evaluate the influence of a skim milk-egg yolk based semen extender on enzymatic and non-enzymatic antioxidant activity in equine semen cryopreservation. Fifteen ejaculates from six fertile Criollo stallions were cryopreserved using a commercial citrate-Hepes, egg yolk, skim milk and glycerol extender. Activities of catalase, glutathione peroxidase and superoxide dismutase and total radical-trapping antioxidant potential were assessed in raw semen, semen diluted in extender and thawed semen. All three enzymes showed higher activities in raw semen than in diluted or in thawed semen (P < 0.01), but enzyme activities did not differ significantly between diluted and thawed semen samples (P > 0.05). Non-enzymatic antioxidant defenses did not differ among any of the stages in the cryopreservation process (P > 0.05). In conclusion, the present study shows that dilution of semen with skim milk-egg yolk based extender after centrifugation compensates for the non-enzymatic antioxidant protection (but not enzymatic antioxidant defense) lost with seminal plasma removal. The absence of correlation between seminal and antioxidant parameters suggests that the compensation was enough for semen protection against oxidative stress, or antioxidant protection plays a minor role on semen from fertile stallions.(AU)
Assuntos
Animais , Preservação do Sêmen , Espermatozoides/citologia , Antioxidantes , Estresse Oxidativo/fisiologia , Cavalos/classificação , CriopreservaçãoRESUMO
Cryopreservation exposes spermatozoa to stressful conditions, leading to reduced cell viability. Several studies propose that overproduction of reactive oxygen species and decreased antioxidant capacity of semen may increase the damaging effects of the technique. The objective of this work was to evaluate the influence of a skim milk-egg yolk based semen extender on enzymatic and non-enzymatic antioxidant activity in equine semen cryopreservation. Fifteen ejaculates from six fertile Criollo stallions were cryopreserved using a commercial citrate-Hepes, egg yolk, skim milk and glycerol extender. Activities of catalase, glutathione peroxidase and superoxide dismutase and total radical-trapping antioxidant potential were assessed in raw semen, semen diluted in extender and thawed semen. All three enzymes showed higher activities in raw semen than in diluted or in thawed semen (P 0.05). Non-enzymatic antioxidant defenses did not differ among any of the stages in the cryopreservation process (P > 0.05). In conclusion, the present study shows that dilution of semen with skim milk-egg yolk based extender after centrifugation compensates for the non-enzymatic antioxidant protection (but not enzymatic antioxidant defense) lost with seminal plasma removal. The absence of correlation between seminal and antioxidant parameters suggests that the compensation was enough for semen protection against oxidative stress, or antioxidant protection plays a minor role on semen from fertile stallions.
Assuntos
Animais , Antioxidantes , Espermatozoides/citologia , Estresse Oxidativo/fisiologia , Preservação do Sêmen , Cavalos/classificação , CriopreservaçãoRESUMO
Phenylketonuria (PKU) is the most frequent disturbance of amino acid metabolism being caused by severe deficiency of phenylalanine hydroxylase activity. Untreated PKU patients present severe mental retardation whose pathophysiology is not completely estabilished. Despite the low-Phe diet, a considerable number of phenylketonuric patients present a mild to moderate psychomotor delay and decreased cognitive functions. In the present study we evaluated various parameters of oxidative stress namely thiobarbituric acid-reactive species (TBA-RS), total antioxidant reactivity (TAR) and activities of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) in two groups of treated PKU patients, one with well controlled and the other with high Phe blood levels in order to investigate whether blood Phe concentrations could be correlated with the extend of oxidative stress. We initially verified a marked increase of TBA-RS, and a decrease of TAR in plasma, as well as a reduction of erythrocyte GSH-Px activity which were similar in both groups of PKU patients, when compared to controls of similar ages. In contrast, CAT and SOD activities were not altered in PKU patients. These results show that oxidative stress occurs in PKU patients and that this pathogenic process is probably not directly correlated to Phe blood levels.
Assuntos
Estresse Oxidativo , Fenilcetonúrias/dietoterapia , Fenilcetonúrias/metabolismo , Catalase/metabolismo , Criança , Eritrócitos/enzimologia , Radicais Livres/sangue , Glutationa Peroxidase/metabolismo , Humanos , Peroxidação de Lipídeos , Fenilalanina/sangue , Superóxido Dismutase/metabolismo , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismoRESUMO
We have previously demonstrated that octanoic (OA) and decanoic acids (DA) inhibit Na+, K+ ATPase activity in synaptic plasma membranes from rat brain. The objective of the present study was to investigate the in vitro effects of the other metabolites that accumulate in tissues of medium-chain acyl-CoA dehydrogenase (MCAD)-deficient patients, namely cis-4-decenoic acid (cDA), octanoylcarnitine (OC), hexanoylcarnitine (HC), hexanoylglycine (HG), phenylpropionylglycine (PPG) and suberoylglycine (SG), on Na+, K+ ATPase activity in synaptic plasma membrane from cerebral cortex of 30-day-old rats. cDA, the pathognomonic compound found in this disorder, provoked the strongest inhibition on this enzyme activity at concentrations as low as 0.25 mM, whereas OC inhibited this activity at 1.0 mM and higher concentrations in a dose-dependent manner. In contrast, HC, HG, PPG and SG did not affect Na+, K+ ATPase activity. Furthermore, pre-treatment of cortical homogenates with the antioxidant enzymes catalase plus superoxide dismutase totally prevented cDA-induced Na+, K+ ATPase inhibition. We also provided evidence that cDA, as well as OA and DA, caused lipid peroxidation, which may explain, at least in part, the inhibitory properties of these compounds towards Na+, K+ ATPase. Considering that Na+, K+ ATPase is a critical enzyme for normal brain development and functioning, it is presumed that these findings, especially those regarding to the marked inhibitory effect of cDA, may be involved in the pathophysiology of the neurological dysfunction of MCAD-deficient patients.
Assuntos
Córtex Cerebral/enzimologia , Inibidores Enzimáticos , Ácidos Graxos Monoinsaturados/farmacologia , ATPase Trocadora de Sódio-Potássio/antagonistas & inibidores , Membranas Sinápticas/enzimologia , Acil-CoA Desidrogenase/deficiência , Animais , Antioxidantes/farmacologia , Carnitina/análogos & derivados , Carnitina/farmacologia , Córtex Cerebral/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos dos fármacos , Medições Luminescentes , Ratos , Ratos Wistar , Membranas Sinápticas/efeitos dos fármacos , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismoRESUMO
Phenylketonuria (PKU) is an autossomal recessive disease caused by phenylalanine-4-hydroxylase deficiency, which is a liver-specific enzyme that catalyzes the hydroxylation of l-phenylalanine (Phe) to l-tyrosine (Tyr). The deficiency of this enzyme leads to the accumulation of Phe in the tissues and plasma of patients. The clinical characterization of this disease is mental retardation and other neurological features. The mechanisms of brain damage are poorly understood. Oxidative stress is observed in some inborn errors of intermediary metabolism owing to the accumulation of toxic metabolites leading to excessive free radical production and may be a result of restricted diets on the antioxidant status. In the present study we evaluated various oxidative stress parameters, namely thiobarbituric acid-reactive species (TBA-RS) and total antioxidant reactivity (TAR) in the plasma of PKU patients. The activities of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were also measured in erythrocytes from these patients. It was observed that phenylketonuric patients present a significant increase of plasma TBA-RS measurement, indicating a stimulation of lipoperoxidation, as well as a decrease of plasma TAR, reflecting a deficient capacity to rapidly handle an increase of reactive species. The results also showed a decrease of erythrocyte GSH-Px activity. Therefore, it is presumed that oxidative stress is involved in the pathophysiology of the tissue damage found in PKU.
Assuntos
Estresse Oxidativo , Fenilcetonúrias/etiologia , Adolescente , Adulto , Criança , Pré-Escolar , Enzimas/sangue , Eritrócitos/enzimologia , Humanos , Peroxidação de Lipídeos , Fenilalanina/sangue , Fenilcetonúrias/sangue , Substâncias Reativas com Ácido Tiobarbitúrico/análiseRESUMO
Mitochondrial beta-ketothiolase and 2-methyl-3-hydroxybutyryl-CoA dehydrogenase (MHBD) deficiencies are inherited neurometabolic disorders affecting isoleucine catabolism. Biochemically, beta-ketothiolase deficiency is characterized by intermittent ketoacidosis and urinary excretion of 2-methyl-acetoacetate (MAA), 2-methyl-3-hydroxybutyrate (MHB) and tiglylglycine (TG), whereas in MHBD deficiency only MHB and tiglylglycine accumulate. Lactic acid accumulation and excretion are also observed in these patients, being more pronounced in MHBD-deficient individuals, particularly during acute episodes of decompensation. Patients affected by MHBD deficiency usually manifest severe mental retardation and convulsions, whereas beta-ketothiolase-deficient patients present encephalopathic crises characterized by metabolic acidosis, vomiting and coma. Considering that the pathophysiological mechanisms responsible for the neurological alterations of these disorders are unknown and that lactic acidosis suggests an impairment of energy production, the objective of the present work was to investigate the in vitro effect of MAA and MHB, at concentrations varying from 0.01 to 1.0 mmol/L, on several parameters of energy metabolism in cerebral cortex from young rats. We observed that MAA markedly inhibited CO2 production from glucose, acetate and citrate at concentrations as low as 0.01 mmol/L. In addition, the activities of the respiratory chain complex II and succinate dehydrogenase were mildly inhibited by MAA. MHB, at 0.01 mmol/L and higher concentrations, strongly inhibited CO2 production from all tested substrates, as well as the respiratory chain complex IV activity. The other activities of the respiratory chain were not affected by these metabolites. The data indicate a marked blockage in the Krebs cycle and a mild inhibition of the respiratory chain caused by MAA and MHB. Furthermore, MHB inhibited total and mitochondrial creatine kinase activities, which was prevented by the use of the nitric-oxide synthase inhibitor L-NAME and glutathione (GSH). These data indicate that the effect of MHB on creatine kinase was probably mediated by oxidation or other modification of essential thiol groups of the enzyme by nitric oxide and other by-products derived from this organic acid. In contrast, MAA did not affect creatine kinase activity. Taken together, these observations indicate that aerobic energy metabolism is inhibited by MAA and to a greater extent by MHB, a fact that may be related to lactic acidaemia occurring in patients affected by MHBD and beta-ketothiolase deficiencies. If the in vitro effects detected in the present study also occur in vivo, it is tempting to speculate that they may contribute, at least in part, to the neurological dysfunction found in these disorders.
Assuntos
Acetoacetatos/farmacologia , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/embriologia , Metabolismo Energético , Hidroxibutiratos/farmacologia , 3-Hidroxiacil-CoA Desidrogenases , Acetatos/metabolismo , Acetil-CoA C-Aciltransferase/metabolismo , Acidose/metabolismo , Oxirredutases do Álcool/metabolismo , Animais , Encéfalo/metabolismo , Dióxido de Carbono/química , Dióxido de Carbono/metabolismo , Córtex Cerebral/metabolismo , Citratos/metabolismo , Creatina Quinase/metabolismo , Relação Dose-Resposta a Droga , Transporte de Elétrons , Glucose/metabolismo , Glutationa/metabolismo , Glicina/análogos & derivados , Glicina/metabolismo , Técnicas In Vitro , Deficiência Intelectual , Ácido Láctico/metabolismo , NG-Nitroarginina Metil Éster/metabolismo , NG-Nitroarginina Metil Éster/farmacologia , Oxigênio/metabolismo , Ratos , Ratos Wistar , Fatores de TempoRESUMO
The pathophysiology of the striatum degeneration characteristic of patients affected by the inherited neurometabolic disorder glutaryl-CoA dehydrogenase deficiency (GDD), also known as glutaric aciduria type I, is still in debate. We have previously reported that 3-hydroxyglutaric acid (3-OH-GA) considered the main neurotoxin in this disorder, induces oxidative stress in rat cerebral cotex. In the present work, we extended these studies by investigating the in vitro effect of 3-OH-GA, at concentrations ranging from 0.01 to 1.0 mmol/L on the brain antioxidant defences by measuring total radical-trapping antioxidant potential (TRAP), total antioxidant reactivity (TAR) and glutathione (GSH) levels, and on the production of hydrogen peroxide (H(2)O(2)), nitric oxide (NO) and malondialdehyde in striatum homogenates from young rats. We observed that TRAP, TAR and GSH levels were markedly reduced (by up to 50%) when striatum homogenates were treated with 3-OH-GA. In contrast, H(2)O(2) (up to 44%), NO (up to 95%) and malondialdehyde levels (up to 28%) were significantly increased by 3-OH-GA. These data indicate that total nonenzymatic antioxidant defences (TRAP) and the tissue capacity to handle an increase of reactive species (TAR) were reduced by 3-OH-GA in the striatum. Furthermore, the results also reflect an increase of lipid peroxidation, probably secondary to 3-OH-GA-induced free radical production. Thus, it may be presumed that oxidative stress is involved in the neuropathology in GDD.
Assuntos
Corpo Estriado/metabolismo , Glutaratos/metabolismo , Estresse Oxidativo , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/deficiência , Animais , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Relação Dose-Resposta a Droga , Glutaril-CoA Desidrogenase , Glutationa/metabolismo , Peróxido de Hidrogênio/metabolismo , Peróxido de Hidrogênio/farmacologia , Metabolismo dos Lipídeos , Peroxidação de Lipídeos , Masculino , Malondialdeído/farmacologia , Óxido Nítrico/metabolismo , Ratos , Ratos Wistar , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismo , Fatores de TempoRESUMO
Organic acidurias represent a group of inherited disorders resulting from deficient activity of specific enzymes of the catabolism of amino acids, carbohydrates or lipids, leading to tissue accumulation of one or more carboxylic (organic) acids. Patients affected by organic acidurias predominantly present neurological symptoms and structural brain abnormalities, of which the aetiopathogenesis is poorly understood. However, in recent years increasing evidence has emerged suggesting that oxidative stress is possibly involved in the pathology of some organic acidurias and other inborn errors of metabolism. This review addresses some of the recent developments obtained mainly from animal studies indicating oxidative damage as an important determinant of the neuropathophysiology of some organic acidurias. Recent data showing that various organic acids are capable of inducing free radical generation and decreasing brain antioxidant defences is presented. The discussion focuses on the relatively low antioxidant defences of the brain and the vulnerability of this tissue to reactive species. This offers new perspectives for potential therapeutic strategies for these disorders, which may include the early use of appropriate antioxidants as a novel adjuvant therapy, besides the usual treatment based on removing toxic compounds and using special diets and pharmacological agents, such as cofactors and L-carnitine.
Assuntos
Ácidos Carboxílicos/urina , Erros Inatos do Metabolismo/urina , Doenças do Sistema Nervoso/etiologia , Estresse Oxidativo , Animais , Antioxidantes/uso terapêutico , Química Encefálica , Encefalopatias/etiologia , Encefalopatias/patologia , Encefalopatias/fisiopatologia , Radicais Livres , Doenças do Sistema Nervoso/prevenção & controle , Doenças Neurodegenerativas/etiologia , Doenças Neurodegenerativas/prevenção & controleRESUMO
Histidinemia is an inherited metabolic disorder caused by deficiency of histidase activity, which leads to tissue accumulation of histidine and its derivatives. Affected patients usually present with speech delay and mental retardation, although asymptomatic patients have been reported. Considering that the pathophysiology of the neurological dysfunction of histidinemia is not yet understood and since histidine has been considered a pro-oxidant agent, in the present study we investigated the effect of histidine and one of its derivatives, l-beta-imidazolelactic acid, at concentrations ranging from 0.1 to 10 mM, on various parameters of oxidative stress in cerebral cortex of 30-day-old Wistar rats. Chemiluminescence, total radical-trapping antioxidant potential (TRAP), thiobarbituric acid reactive substances (TBA-RS), and the activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were measured in tissue homogenates in the presence of l-histidine or l-beta-imidazolelactic acid. We observed that l-histidine provoked an increase of chemiluminescence and a reduction of TRAP at concentrations of 2.5 mM and higher, while TBA-RS measurement, GSH-Px, CAT and SOD activities were not affected. Furthermore, l-beta-imidazolelactic acid provoked antioxidant effects at high concentrations (5-10 mM) as observed by the reduction of chemiluminescence, although this compound enhanced chemiluminescence at low concentrations (0.5-1 mM). These results suggest that in vitro oxidative stress is elicited by histidine but only at supraphysiological concentrations.
Assuntos
Erros Inatos do Metabolismo dos Aminoácidos/metabolismo , Encefalopatias Metabólicas Congênitas/metabolismo , Córtex Cerebral/metabolismo , Histidina/metabolismo , Estresse Oxidativo/fisiologia , Erros Inatos do Metabolismo dos Aminoácidos/fisiopatologia , Animais , Encefalopatias Metabólicas Congênitas/fisiopatologia , Catalase/efeitos dos fármacos , Catalase/metabolismo , Córtex Cerebral/crescimento & desenvolvimento , Córtex Cerebral/fisiopatologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Feminino , Radicais Livres/metabolismo , Glutationa Peroxidase/efeitos dos fármacos , Glutationa Peroxidase/metabolismo , Histidina/farmacologia , Imidazóis/farmacologia , Lactatos/farmacologia , Medições Luminescentes , Oxidantes/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Wistar , Superóxido Dismutase/efeitos dos fármacos , Superóxido Dismutase/metabolismoRESUMO
Propionic and methylmalonic acidemic patients have severe neurologic symptoms whose etiopathogeny is still obscure. Since increase of lactic acid is detected in the urine of these patients, especially during metabolic decompensation when high concentrations of methylmalonate (MMA) and propionate (PA) are produced, it is possible that cellular respiration may be impaired in these individuals. Therefore, we investigated the effects of MMA and PA (1, 2.5 and 5mM), the principal metabolites which accumulate in these conditions, on the mitochondrial respiratory chain complex activities succinate: 2,6-dichloroindophenol (DCIP) oxireductase (complex II); succinate: cytochrome c oxireductase (complexII+CoQ+III); NADH: cytochrome c oxireductase (complex I+CoQ+complex III); and cytochrome c oxidase (COX) (complex IV) from cerebral cortex homogenates of young rats. The effect of MMA on ubiquinol: cytochrome c oxireductase (complex III) and NADH: ubiquinone oxireductase (complex I) activities was also tested. Control groups did not contain MMA and PA in the incubation medium. MMA significantly inhibited complex I+III (32-46%), complex I (61-72%), and complex II+III (15-26%), without affecting significantly the activities of complexes II, III and IV. However, by using 1mM succinate in the assay instead of the usual 16mM concentration, MMA was able to significantly inhibit complex II activity in the brain homogenates. In contrast, PA did not affect any of these mitochondrial enzyme activities. The effect of MMA and PA on succinate: phenazine oxireductase (soluble succinate dehydrogenase (SDH)) was also measured in mitochondrial preparations. The results showed significant inhibition of the soluble SDH activity by MMA (11-27%) in purified mitochondrial fractions. Thus, if the in vitro inhibition of the oxidative phosphorylation system is also expressed under in vivo conditions, a deficit of brain energy production might explain some of the neurological abnormalities found in patients with methylmalonic acidemia (MMAemia) and be responsible for the lactic acidemia/aciduria identified in some of them.
Assuntos
Córtex Cerebral/efeitos dos fármacos , Transporte de Elétrons/efeitos dos fármacos , Ácido Metilmalônico/farmacologia , Mitocôndrias/efeitos dos fármacos , Animais , Córtex Cerebral/enzimologia , Córtex Cerebral/metabolismo , Metabolismo Energético , Mitocôndrias/enzimologia , Ratos , Ratos WistarRESUMO
Neurological dysfunction is common in patients with methylmalonic and propionic acidemias. However, the mechanisms underlying the neuropathology of these disorders are far from understood. In the present study we investigated the in vitro effects of methylmalonic (MMA) and propionic (PA) acids at various concentrations (1 microM-5 mM) on three parameters of the glutamatergic system, namely the basal and potassium-induced release of L-[3H]glutamate by synaptosomes, Na+-dependent L-[3H]glutamate uptake by synaptosomes and Na+-independent L-[3H]glutamate uptake by synaptic vesicles from cerebral cortex of male adult Wistar rats. The results showed that MMA significantly increased potassium-induced but not basal L-[3H]glutamate release from synaptosomes with no alteration in synaptosomal L-[3H]glutamate uptake. A significant reduction of L-[3H]glutamate incorporation into vesicles caused by MMA was also detected. In contrast, PA had no effect on these parameters. These findings indicate that MMA alters the glutamatergic system. Although additional studies are necessary to evaluate the importance of these observations for the neuropathology of methylmalonic acidemia, it is possible that the effects elicited by MMA may lead to excessive glutamate concentrations at the synaptic cleft, a fact that may explain previous in vivo and in vitro findings associating MMA with excitotoxicity.
Assuntos
Córtex Cerebral/metabolismo , Ácido Glutâmico/metabolismo , Ácido Metilmalônico/farmacologia , Propionatos/farmacologia , Vesículas Sinápticas/metabolismo , Sinaptossomos/metabolismo , Animais , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/enzimologia , L-Lactato Desidrogenase/metabolismo , Masculino , Proteínas do Tecido Nervoso/metabolismo , Potássio/farmacologia , Ratos , Ratos Wistar , Vesículas Sinápticas/efeitos dos fármacos , Vesículas Sinápticas/enzimologia , Sinaptossomos/efeitos dos fármacos , Sinaptossomos/enzimologiaRESUMO
The exact mechanisms by which 3-nitropropionic acid (3-NP), a naturally occurring plant and fungal neurotoxin, exerts its neurotoxic effects are not fully understood. However, blockage of ATP synthesis by the irreversible inhibition of succinate dehydrogenase activity, increased production of free radicals, and secondary excitotoxicity have been implicated in its actions. In the present study, synaptic vesicle preparations from brain of adult rats were incubated with 3-NP at final concentrations ranging from 0.01 to 10 mM for the determination of glutamate uptake. The effect of 3-NP on gamma-aminobutyric acid (GABA) and glycine uptake was also studied. Glutamate incorporation into vesicles was inhibited by 3-NP in a dose-dependent manner, whereas doses of up to 10 mM neurotoxin did not affect GABA or glycine uptake. Moreover, 3-NP did not inhibit the ATPase activity of synaptic vesicles. These findings indicate that low concentrations of 3-NP are able to selectively prevent vesicular glutamate storage, and this may represent at least one of the mechanisms responsible for the neurotoxic effects of 3-NP.
Assuntos
Química Encefálica , Ácido Glutâmico/farmacocinética , Propionatos/farmacologia , Vesículas Sinápticas/efeitos dos fármacos , Vesículas Sinápticas/metabolismo , Adenosina Trifosfatases/metabolismo , Animais , Relação Dose-Resposta a Droga , Ativação Enzimática/efeitos dos fármacos , Glicina/farmacocinética , Masculino , Neurotoxinas/farmacologia , Nitrocompostos , Ratos , Ratos Wistar , Vesículas Sinápticas/química , Ácido gama-Aminobutírico/farmacocinéticaRESUMO
In the present study we investigated the effect of acute administration of L-arginine on Na(+),K(+)-ATPase and Mg(2+)-ATPase activities and on some parameters of oxidative stress (chemiluminescence and total radical-trapping antioxidant parameter-TRAP) in midbrain of adult rats. We also tested the effect of L-NAME on the effects produced by arginine. Sixty-day-old rats were treated with an acute intraperitoneal injection of saline (group I, control), arginine (0.8 g/kg) (group II), L-NAME (2 mg/kg) (group III) or arginine (0.8 g/kg) plus L-NAME (2 mg/kg) (group IV). Na(+),K(+)-ATPase activity was significantly reduced in the arginine-treated rats, but was not affected by other treatments. In contrast, Mg(2+)-ATPase activity was not altered by any treatment. Furthermore, chemiluminescence was significantly increased and TRAP was significantly decreased in arginine-treated rats, whereas the simultaneous injection of L-NAME prevented these effects. These results demonstrate that in vivo arginine administration reduces Na(+),K(+)-ATPase activity possibly through free radical generation induced by NO formation.
Assuntos
Arginina/farmacologia , Inibidores Enzimáticos/farmacologia , Mesencéfalo/efeitos dos fármacos , Mesencéfalo/enzimologia , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico Sintase/antagonistas & inibidores , ATPase Trocadora de Sódio-Potássio/metabolismo , Animais , Ratos , Ratos Wistar , ATPase Trocadora de Sódio-Potássio/antagonistas & inibidoresRESUMO
Na(+), K(+)-ATPase activity was determined in erythrocyte membranes from 12 phenylketonuric patients of both sexes, aged 8.8 +/- 5.0 y, with plasma phenylalanine levels of 0.64 +/- 0.31 mM. The in vitro effects of phenylalanine and alanine on the enzyme activity in erythrocyte membranes from healthy individuals were also investigated. We observed that Na(+), K(+)-ATPase activity was decreased by 31% in erythrocytes from phenylketonuric patients compared with normal age-matched individuals (p < 0.01). We also observed a significant negative correlation between erythrocyte Na(+), K(+)-ATPase activity and plasma phenylalanine levels (r = -0.65; p < 0.05). All PKU patients with plasma phenylalanine levels higher than 0.3 mM had erythrocyte Na(+), K(+)-ATPase activity below the normal range. Phenylalanine inhibited in vitro erythrocyte Na(+), K(+)-ATPase activity by 22 to 34%, whereas alanine had no effect on this activity. However, when combined with phenylalanine, alanine prevented Na(+) K(+)-ATPase inhibition. Considering that reduction of Na(+), K(+)-ATPase activity occurs in various neurodegenerative disorders leading to neuronal loss, our previous observations showing a significant reduction of Na(+), K(+)-ATPase activity in brain cortex of rats subjected to experimental phenylketonuria and the present results, it is proposed that determination of Na(+), K(+)-ATPase activity in erythrocytes may be a useful peripheral marker for the neurotoxic effect of phenylalanine in phenylketonuria.
Assuntos
Membrana Eritrocítica/enzimologia , Fenilcetonúrias/sangue , Fenilcetonúrias/enzimologia , ATPase Trocadora de Sódio-Potássio/sangue , Adolescente , Estudos de Casos e Controles , Criança , Pré-Escolar , Feminino , Humanos , MasculinoRESUMO
2-Hydroxybutyric acid appears at high concentrations in situations related to deficient energy metabolism (e.g., birth asphyxia) and also in inherited metabolic diseases affecting the central nervous system during neonatal development, such as "cerebral" lactic acidosis, glutaric aciduria type II, dihydrolipoyl dehydrogenase (E3) deficiency, and propionic acidemia. The present study was carried out to determine the effect of 2-hydroxybutyric acid at various concentrations (1-10 mM) on CO2 production and lipid synthesis from labeled substrates in cerebral cortex of 30-day-old Wistar rats in vitro. CO2 production was significantly inhibited (30-70 percent) by 2-hydroxybutyric acid in cerebral cortex prisms, in total homogenates and in the mitochondrial fraction. We also demonstrated a significant inhibition of lipid synthesis (20-45 percent) in cerebral cortex prisms and total homogenates in the presence of 2-hydroxybutyric acid. However, no inhibition of lipid synthesis occurred in homogenates free of nuclei and mitochondria. The results indicate an impairment of mitochondrial energy metabolism caused by 2-hydroxybutyric acid, a fact that may secondarily lead to reduction of lipid synthesis. It is possible that these findings may be associated with the neuropathophysiology of the situations where 2-hydroxybutyric acid is accumulated
Assuntos
Animais , Ratos , Dióxido de Carbono/metabolismo , Córtex Cerebral/efeitos dos fármacos , Metabolismo Energético , Hidroxibutiratos/farmacologia , Lipídeos/síntese química , Análise de Variância , Hidroxibutiratos/química , Mitocôndrias/metabolismo , Ratos WistarAssuntos
Ruptura Cardíaca/diagnóstico , Ferimentos não Penetrantes/diagnóstico , Fenômenos Biomecânicos , Tubos Torácicos , Pré-Escolar , Drenagem , Ecocardiografia , Tratamento de Emergência/métodos , Feminino , Ruptura Cardíaca/complicações , Ruptura Cardíaca/cirurgia , Humanos , Derrame Pericárdico/etiologia , Derrame Pleural/etiologia , Toracostomia , Tomografia Computadorizada por Raios X , Ferimentos não Penetrantes/complicações , Ferimentos não Penetrantes/cirurgiaRESUMO
2-Hydroxybutyric acid appears at high concentrations in situations related to deficient energy metabolism (e.g., birth asphyxia) and also in inherited metabolic diseases affecting the central nervous system during neonatal development, such as "cerebral" lactic acidosis, glutaric aciduria type II, dihydrolipoyl dehydrogenase (E3) deficiency, and propionic acidemia. The present study was carried out to determine the effect of 2-hydroxybutyric acid at various concentrations (1-10 mM) on CO2 production and lipid synthesis from labeled substrates in cerebral cortex of 30-day-old Wistar rats in vitro. CO2 production was significantly inhibited (30-70%) by 2-hydroxybutyric acid in cerebral cortex prisms, in total homogenates and in the mitochondrial fraction. We also demonstrated a significant inhibition of lipid synthesis (20-45%) in cerebral cortex prisms and total homogenates in the presence of 2-hydroxybutyric acid. However, no inhibition of lipid synthesis occurred in homogenates free of nuclei and mitochondria. The results indicate an impairment of mitochondrial energy metabolism caused by 2-hydroxybutyric acid, a fact that may secondarily lead to reduction of lipid synthesis. It is possible that these findings may be associated with the neuropathophysiology of the situations where 2-hydroxybutyric acid is accumulated.
Assuntos
Dióxido de Carbono/metabolismo , Córtex Cerebral/efeitos dos fármacos , Metabolismo Energético , Hidroxibutiratos/farmacologia , Lipídeos/síntese química , Análise de Variância , Animais , Hidroxibutiratos/química , Mitocôndrias/metabolismo , Ratos , Ratos WistarRESUMO
Neurological dysfunction is common in patients with maple syrup urine disease (MSUD). However, the mechanisms underlying the neuropathology of this disorder are poorly known. In the present study we investigated the effect of acute hyperleucinemia on plasma and brain concentrations of amino acids. Fifteen-day-old rats were injected subcutaneously with 6 micromol L-leucine per gram body weight. Controls received saline in the same volumes. The animals were sacrificed 30--120 min after injection, blood was collected and their brain rapidly removed and homogenized. The amino acid concentrations were determined by HPLC using orthophtaldialdehyde for derivatization and fluorescence for detection. The results showed significant reductions of the large neutral amino acids (LNAA) L-phenylalanine, L-tyrosine, L-isoleucine, L-valine and L-methionine, as well as L-alanine, L-serine and L-histidine in plasma and of L-phenylalanine, L-isoleucine, L-valine and L-methionine in brain, as compared to controls. In vitro experiments using brain slices to study the influence of leucine on amino acid transport and protein synthesis were also carried out. L-Leucine strongly inhibited [14C]-L-phenylalanine transport into brain, as well as the incorporation of the [14C]-amino acid mixture, [14C]-L-phenylalanine and [14C]-L-lysine into the brain proteins. Although additional studies are necessary to evaluate the importance of these effects for MSUD, considering previous findings of reduced levels of LNAA in plasma and CSF of MSUD patients during crises, it may be speculated that a decrease of essential amino acids in brain may lead to reduction of protein and neurotransmiter synthesis in this disorder.
Assuntos
Aminoácidos/metabolismo , Leucina/sangue , Doença da Urina de Xarope de Bordo/metabolismo , Aminoácidos/sangue , Animais , Glicemia/análise , Cromatografia Líquida de Alta Pressão , Feminino , Insulina/sangue , Masculino , Doença da Urina de Xarope de Bordo/sangue , Ratos , Ratos WistarRESUMO
Levels of methylmalonic acid (MMA) comparable to those of human methylmalonic acidemia were achieved in blood (2-2.5 mmol/l) and brain (1.35 umol/g) of rats by administering buffered MMA, pH 7.4, subcutaneously twice a day from the 5th to the 28th day of life. MMA doses ranged from 0.76 to 1.67 umol/g as a function of animal age. Control rats were treated with saline in the same volumes. The animals were sacrificed by decapitation on the 28th day of age. Blood was taken and the brain was rapidly removed. Medulla, pons, the olfactory lobes and cerebellum were discarded and the rest of the brain ("cerebrum") was isolated. Body and "cerebrum" weight were measured, as well as the cholesterol and triglyceride concentrations in blood and the content of myelin, total lipids, and the concentrations of the lipid fractions (cholesterol, glycerolipids, phospholipids and ganglioside N-acetylneuraminic acid (ganglioside-NANA)) in the "cerebrum". Chronic MMA administration had no effect on body or "cerebrum" weight, suggesting that the metabolites per se neither affect the appetite of the rats nor cause malnutrition. In contrast, MMA caused a significant reduction of plasma triglycerides, but not of plasma cholesterol levels. A significant diminution of myelin content and of ganglioside-NANA concentration was also observed in the "cerebrum". We propose that the reduction of myelin content and ganglioside-NANA caused by MMA may be related to the delayed myelination/cerebral atrophy and neurological dysfunction found in methylmalonic acidemic children.