RESUMO
Aging is a physiological decline process. The number of older adults is growing around the world; therefore, the incidence of cognitive impairment, dementia, and other diseases related to aging increases. The main cellular factors that converge in the aging process are mitochondrial dysfunction, antioxidant impairment, inflammation, and immune response decline, among others. In this context, these cellular changes have an influence on the kynurenine pathway (KP), the main route of tryptophan (Trp) catabolism. KP metabolites have been involved in the aging process and neurodegenerative diseases. Although there are changes in the metabolite levels with age, at this time, there is no study that has evaluated cognitive decline as a consequence of Trp catabolism fluctuation in aging. The aim of this study was to evaluate the relation between the changes in Trp catabolism and cognitive impairment associated with age through KP metabolites level alterations in women over 50 years of age. Seventy-seven nondemented women over 50 years old were examined with a standardized cognitive screening evaluation in Spanish language (Neuropsi), Beck anxiety inventory (BAI), and the geriatric depression scale (GDS). Also, serum levels of Trp, kynurenine (Kyn), kynurenic acid (KYNA), and 3-hydroykynurenine (3-HK) and the glutathione ratio (GSH/GSSG) were measured. Results showed a negative correlation between age and Trp levels and a positive correlation between age and KYNA/Trp and 3-HK/Trp ratios. The level of cognitive impairment showed a significant positive association with age and with kynurenine pathway activation and a significant negative correlation with Trp levels. The GSH/GSSG ratio correlated positively with Trp levels and negatively with Kyn/Trp and 3-HK/Trp ratios. The depression score correlated negatively with Trp and positively with the 3-HK/Trp ratio. We concluded that KP activation increases with age and it is strongly associated with the level of cognition performance in nondemented women over 50 years of age.
Assuntos
Cognição/fisiologia , Triptofano/sangue , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Ácido Cinurênico/sangue , Cinurenina/sangue , Pessoa de Meia-Idade , Ácido Quinolínico/sangueRESUMO
The catabolism of tryptophan has gained great importance in recent years due to the fact that the metabolites produced during this process, with neuroactive and redox properties, are involved in physiological and pathological events. One of these metabolites is kynurenic acid (KYNA), which is considered as a neuromodulator since it can interact with NMDA, nicotinic, and GPR35 receptors among others, modulating the release of neurotransmitters as glutamate, dopamine, and acetylcholine. Kynureninate production is attributed to kynurenine aminotransferases. However, in some physiological and pathological conditions, its high production cannot be explained just with kynurenine aminotransferases. This review focuses on the alternative mechanism whereby KYNA can be produced, either from D-amino acids or by means of other enzymes as D-amino acid oxidase or by the participation of free radicals. It is important to mention that an increase in KYNA levels in processes as brain development, aging, neurodegenerative diseases, and psychiatric disorders, which share common factors as oxidative stress, inflammation, immune response activation, and participation of gut microbiota that can also be related with the alternative routes of KYNA production, has been observed.
Assuntos
Encéfalo/metabolismo , Ácido Cinurênico/metabolismo , Animais , HumanosRESUMO
Oxido-reduction reactions are a fundamental part of the life due to support many vital biological processes as cellular respiration and glucose oxidation. In the redox reactions, one substance transfers one or more electrons to another substance. An important electron carrier is the coenzyme NAD+, which is involved in many metabolic pathways. De novo biosynthesis of NAD+ is through the kynurenine pathway, the major route of tryptophan catabolism, which is sensitive to redox environment and produces metabolites with redox capacity, able to alter biological functions that are controlled by redox-responsive signaling pathways. Kynurenine pathway metabolites have been implicated in the physiology process and in the physiopathology of many diseases; processes that also share others factors as dysregulation of calcium homeostasis, mitochondrial dysfunction, oxidative stress, inflammation and cell death, which impact the redox environment. This review examines in detail the available evidence in which kynurenine pathway metabolites participate in redox reactions and their effect on cellular redox homeostasis, since the knowledge of the main factors and mechanisms that lead to cell death in many neurodegenative disorders and other pathologies, such as mitochondrial dysfunction, oxidative stress and kynurenines imbalance, will allow to develop therapies using them as targets. This article is part of the Special Issue entitled 'The Kynurenine Pathway in Health and Disease'.
Assuntos
Cinurenina/metabolismo , Redes e Vias Metabólicas/fisiologia , Oxirredução , Estresse Oxidativo/fisiologia , Animais , HumanosRESUMO
The kynurenines 3-hydroxyanthranilic acid (3-HANA) and its precursor 3-hydroxykynurenine (3-HK) are metabolites derived from tryptophan degradation. 3-HK, has been related to diverse neurodegenerative diseases including Huntington's, Alzheimer's and Parkinson's diseases that share mitochondrial metabolic dysregulation. Nevertheless, the direct effect of these kynurenines on mitochondrial function has not been investigated despite it could be regulated by their redox properties that are controversial. A body of literature has suggested a ROS mediated cell death induced by 3-HK and 3-HANA. On the other hand, some works have supported that both kynurenines have antioxidant effects. Therefore, the aim of this study was to investigate 3-HK and 3-HANA effects on mitochondrial and cellular function in rat cultured cortical astrocytes (rCCA) and in animals intrastriatally injected with these kynurenines as well as to determinate the ROS role on these effects. First, we evaluated 3-HK and 3-HANA effect on cellular function, ROS production and mitochondrial membrane potential in vivo and in vitro in rCCA. Our results show that both kynurenines decreased MTT reduction in a concentration-dependent manner together with mitochondrial membrane potential. These observations were accompanied with increased cell death in rCCA and in circling behavior and morphological changes of injected animals. Interestingly, we found that ROS production was not increased in both in vitro and in vivo experiments, and accordingly lipid peroxidation (LP) was neither increased in striatal tissue of animals injected with both kynurenines. The lack of effect on these oxidative markers is in agreement with the ·OH and ONOO(-) scavenging capacity of both kynurenines detected by chemical combinatorial assays. Altogether, these data indicate that both kynurenines exert toxic effects through mechanisms that include impairment of cellular energy metabolism which are not related to early ROS production.
Assuntos
Ácido 3-Hidroxiantranílico/toxicidade , Sequestradores de Radicais Livres/farmacologia , Cinurenina/análogos & derivados , Doenças Mitocondriais/induzido quimicamente , Espécies Reativas de Oxigênio/metabolismo , Animais , Astrócitos/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Células Cultivadas , Córtex Cerebral/citologia , Modelos Animais de Doenças , Metabolismo Energético/efeitos dos fármacos , Cinurenina/toxicidade , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Oxirredução/efeitos dos fármacos , Ratos , Ratos Wistar , Comportamento Estereotipado/efeitos dos fármacos , Succinato Desidrogenase/metabolismoRESUMO
BACKGROUND: l-Kynurenine has antinociceptive effects in acute and inflammatory pain. This study determined the effect of l-kynurenine and its metabolite (kynurenic acid) on rats subjected to neuropathic pain. METHODS: L5/L6 spinal nerve ligation induced tactile allodynia as measured with von Frey filaments using the up-down method. High-performance liquid chromatography and Western blot analysis determined kynurenic acid levels and expression of kynurenine amino transferase II (KAT II), respectively. RESULTS: l-Kynurenine (50-200 mg/kg, i.p.) or probenecid (100 mg/kg, i.p.) did not affect allodynia in neuropathic rats. In contrast, l-kynurenine (50-200 mg/kg, i.p.) in combination with probenecid (100 mg/kg, i.p.), an inhibitor of organic anion transport, reversed allodynia. Furthermore, intrathecal kynurenic acid (1-30 µg) reversed allodynia. Probenecid (100 mg/kg, i.p.) supplementation enhanced the maximal antiallodynic effect of intrathecal kynurenic acid (10 µg). Only the combined administration of l-kynurenine (200 mg/kg)/probenecid (100 mg/kg) increased the kynurenic acid concentration in cerebrospinal fluid. KAT II is expressed in dorsal root ganglia and dorsal spinal cord. KAT II expression was unchanged by the spinal nerve ligation or l-kynurenine/probenecid combination. The kynurenine/probenecid combination did not affect motor activity. CONCLUSIONS: l-Kynurenine produces its antiallodynic effect in the central nervous system through kynurenic acid. This effect may result from blockade of N-methyl-d-aspartate receptors. KAT II is expressed in dorsal root ganglion and dorsal spinal cord. Combined l-kynurenine and probenecid therapy has the potential to reduce neuropathic pain in humans.
Assuntos
Hiperalgesia/tratamento farmacológico , Cinurenina/uso terapêutico , Neuralgia/tratamento farmacológico , Probenecid/uso terapêutico , Animais , Quimioterapia Combinada , Feminino , Cinurenina/farmacologia , Atividade Motora/efeitos dos fármacos , Medição da Dor , Probenecid/farmacologia , Ratos , Ratos Wistar , Medula Espinal/efeitos dos fármacosRESUMO
OBJECTIVES: To determine a population pharmacokinetic model of the antihelmintic drug, albendazole, and identify the factors influencing the pharmacokinetic parameters in patients with neurocysticercosis. METHODS: A prospective study was performed in 90 patients receiving 30 mg/kg/day of albendazole for 8 days. Blood samples were collected at steady state. Plasma concentrations of albendazole sulfoxide, the main active metabolite of albendazole, were determined by HPLC. The population pharmacokinetics analysis was performed using non-linear mixed-effect modeling (NONMEM). A one-compartment model with first order absorption and elimination was used. RESULTS: Body weight was included empirically on CL/F and V/F using an allometric relationship. Although none of the investigated covariates had a significant influence on the pharmacokinetic parameters of albendazole, the final model identified two subpopulations on the bioavailability parameter. One subpopulation comprising of 27% of the total population had a bioavailability of 28%, with the remaining subpopulation defined to have complete bioavailability. The CL/F and V/F for a standard 70 kg individual was determined to be 51.6 l/h and 4560 l, respectively. Interindividual variability in CL/F was 32%; the residual unexplained variability was 32%. CONCLUSIONS: The considerable variability reported in albendazole pharmacokinetics and plasma concentrations is likely due to issues related to bioavailability. With one-fourth of the population absorbing as little as 30% of the drug relative to others, low drug exposures might be responsible for treatment failures. Therapeutic drug monitoring may be warranted to optimize the eradication of the infecting parasite.
Assuntos
Albendazol/farmacocinética , Anti-Helmínticos/farmacocinética , Modelos Biológicos , Neurocisticercose/tratamento farmacológico , Adolescente , Adulto , Idoso , Albendazol/análogos & derivados , Albendazol/uso terapêutico , Anti-Helmínticos/uso terapêutico , Disponibilidade Biológica , Cromatografia Líquida de Alta Pressão , Monitoramento de Medicamentos/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Dinâmica não Linear , Estudos Prospectivos , Adulto JovemRESUMO
Thirty-six patients with subarachnoid and intraventricular cysticercosis were randomly assigned to receive albendazole at 15 or 30 mg/kg/day plus dexamethasone for 8 days. Results favored a higher dose, with larger cyst reduction on MRI at 90 and 180 days and higher albendazole sulfoxide levels in plasma. An albendazole course at 30 mg/kg/day combined with corticosteroids is safe and more effective than the usual dose. A single treatment was insufficient in intraventricular and giant cysts.
Assuntos
Albendazol/administração & dosagem , Anticestoides/administração & dosagem , Ventrículos Cerebrais/parasitologia , Dexametasona/administração & dosagem , Neurocisticercose/tratamento farmacológico , Espaço Subaracnóideo/parasitologia , Adulto , Albendazol/efeitos adversos , Albendazol/uso terapêutico , Anticestoides/efeitos adversos , Anticestoides/uso terapêutico , Dexametasona/uso terapêutico , Relação Dose-Resposta a Droga , Esquema de Medicação , Quimioterapia Combinada , Feminino , Cefaleia/induzido quimicamente , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do TratamentoRESUMO
BACKGROUND: Despite the wide use of oxcarbazepine (OXC) there is little data concerning the usefulness of plasma level monitoring with this drug in Mexican patients with epilepsy. The purpose of the present study was to determine whether OXC levels correlate with dose, age, weight, or drugs used concomitantly. METHODS: Plasma levels of the antiepileptic drug OXC were evaluated in 214 patients with epilepsy. In each patient, plasma MHD (10-hydroxycarbazepine, the main metabolite of OXC) concentration was determined. Additionally, plasma protein binding was determined in 30 patients and affinity to red blood cells (RBCs) was evaluated in 50 patients. RESULTS: Our results showed that the mean plasma level of MHD was 15.34 microg/mL, mean protein binding ranged between 30-40%, and the mean RBC concentration was 18.38 microg/mL. A relationship between dose/weight and plasma concentration was found (r = 0.5149, p <0.001). In addition, a linear relationship between plasma and RBC concentration was established (r = 0.8806, p <0.0001). CONCLUSIONS: These results suggest that for OXC, routine RBC concentrations are not necessary to make drug adjustments.
Assuntos
Anticonvulsivantes/sangue , Carbamazepina/análogos & derivados , Epilepsia/tratamento farmacológico , Adolescente , Adulto , Fatores Etários , Idoso , Anticonvulsivantes/administração & dosagem , Anticonvulsivantes/farmacocinética , Anticonvulsivantes/farmacologia , Proteínas Sanguíneas/metabolismo , Peso Corporal , Carbamazepina/administração & dosagem , Carbamazepina/sangue , Carbamazepina/farmacocinética , Criança , Pré-Escolar , Interações Medicamentosas , Monitoramento de Medicamentos , Quimioterapia Combinada , Epilepsia/sangue , Eritrócitos/metabolismo , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Oxcarbazepina , Ligação ProteicaRESUMO
To evaluate two different dosage regimens for albendazole (7.5 mg/kg twice a day or 5.0 mg/kg three times a day), a study was performed in 10 patients with a diagnosis of parenchymal brain cysticercosis. Each patient received both regimens sequentially according to a randomized, crossover design. Blood and urine samples were taken once the drug steady state had been reached. Plasma levels of albendazole sulfoxide at steady state were determined using a HPLC method. In spite of a great intersubject variability observed with both regimens in the area under the curve (AUC) and in the minimum steady-state plasma concentration (Cp min ss), no statistically significant differences were found in these parameters. We suggest that a regimen of 7.5 mg/kg every 12 h can favorably replace the currently used regimen of 5 mg/kg every 8 h.