RESUMO
OBJECTIVE: Since no effective therapy exists, we aimed to test existing HIV antivirals for combination treatment of Coronavirus disease 19 (COVID-19). MATERIALS AND METHODS: The crystal structures of SARS-CoV-2 main protein (Mpro) (PDB ID: 6Y2F) and SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) (PDB ID: 7BV2) both available from Protein Data Bank were used in the study. Automated Docking by using blind and standard method both on Mpro and RdRp bound to the modified template-primer RNA was performed with AutoDock 4.2.6 program suite. Lamarckian genetic algorithm (LGA) was used for structures docking. All inhibitors were docked with all bonds completely free to rotate. RESULTS: Our molecular docking findings suggest that lopinavir, ritonavir, darunavir, and atazanavir activated interactions with the key binding sites of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) protease with a better inhibition constant (Ki) for lopinavir, ritonavir, and darunavir. Furthermore, we evidenced the ability of remdesivir, tenofovir, emtricitabine, and lamivudine to be incorporated in SARS-CoV-2 RdRp in the same protein pocket where poses the corresponding natural nucleoside substrates with comparable Ki and activating similar interactions. In principle, the four antiviral nucleotides might be used effectively against SARS-CoV-2. CONCLUSIONS: The combination of a protease inhibitor and two nucleoside analogues, drugs widely used to treat HIV infection, could be evaluated in clinical trials for the treatment of COVID-19.
Assuntos
Antivirais/farmacologia , Tratamento Farmacológico da COVID-19 , Quimioterapia Combinada/métodos , Nucleosídeos/uso terapêutico , Inibidores de Proteases/uso terapêutico , Monofosfato de Adenosina/análogos & derivados , Alanina/análogos & derivados , Sulfato de Atazanavir , Darunavir , Combinação de Medicamentos , Intervenção Médica Precoce , Emtricitabina , Humanos , Lamivudina , Lopinavir , Simulação de Acoplamento Molecular , Ritonavir , SARS-CoV-2RESUMO
Highly sensitive detection of ethanol concentrations in discrete brain regions of rats voluntarily accessing ethanol, with high temporal resolution, would represent a source of greatly desirable data in studies devoted to understanding the kinetics of the neurobiological basis of ethanol's ability to impact behavior. In the present study, we present a series of experiments aiming to validate and apply an original high-tech implantable device, consisting of the coupling, for the first time, of an amperometric biosensor for brain ethanol detection, with a sensor for detecting the microvibrations of the animal. This device allows the real-time comparison between the ethanol intake, its cerebral concentrations, and their effect on the motion when the animal is in the condition of voluntary drinking. To this end, we assessed in vitro the efficiency of three different biosensor designs loading diverse alcohol oxidase enzymes (AOx) obtained from three different AOx-donor strains: Hansenula polymorpha, Candida boidinii, and Pichia pastoris. In vitro data disclosed that the devices loading H. polymorpha and C. boidinii were similarly efficient (respectively, linear region slope [LRS]: 1.98 ± 0.07 and 1.38 ± 0.04 nA/mM) but significantly less than the P. pastoris-loaded one (LRS: 7.57 ± 0.12 nA/mM). The in vivo results indicate that this last biosensor design detected the rise of ethanol in the nucleus accumbens shell (AcbSh) after 15 minutes of voluntary 10% ethanol solution intake. At the same time, the microvibration sensor detected a significant increase in the rat's motion signal. Notably, both the biosensor and microvibration sensor described similar and parallel time-dependent U-shaped curves, thus providing a highly sensitive and time-locked high-resolution detection of the neurochemical and behavioral kinetics upon voluntary ethanol intake. The results overall indicate that such a dual telemetry unit represents a powerful device which, implanted in different brain areas, may boost further investigations on the neurobiological mechanisms that underlie ethanol-induced motor activity and reward.
Assuntos
Técnicas Biossensoriais/instrumentação , Etanol/farmacologia , Atividade Motora/efeitos dos fármacos , Núcleo Accumbens/efeitos dos fármacos , Administração Oral , Consumo de Bebidas Alcoólicas/metabolismo , Oxirredutases do Álcool/química , Animais , Espaço Extracelular , Técnicas In Vitro , Masculino , Núcleo Accumbens/ultraestrutura , Ratos , Ratos Sprague-Dawley , TelemetriaRESUMO
BACKGROUND: Translational studies investigating the effects of deep brain stimulation (DBS) on brain function up to now mainly relied on BOLD responses measured with fMRI. However, fMRI studies in rodents face technical and practical limitations (e.g., immobilization, sedation or anesthesia, spatial and temporal resolution of data). Direct measurement of oxygen concentration in the brain using electrochemical sensors is a promising alternative to the use of fMRI. Here, we tested for the first time if such measurements can be combined with DBS. NEW METHOD: We combined bilateral DBS in the internal capsule (IC-DBS) with simultaneous amperometric measurements of oxygen in the medial prefrontal cortex (prelimbic area) and striatum of freely moving mice. Using a two-day within-animal experimental design, we tested the effects of DBS on baseline oxygen concentrations, and on novelty- and restraint-induced increases in oxygen concentration. RESULTS: Basal oxygen levels were stable across the daily sampling periods. Exposure to novelty and immobilization reproducibly increased oxygen concentrations in both areas. IC-DBS did not significantly alter basal oxygen, but reduced the novelty-induced increase in the striatum. COMPARISON WITH EXISTING METHOD(S): Amperometric detection of brain oxygen concentration with high temporal and spatial resolution can be performed in a number of key brain areas to study the effects of DBS in animal models of disease. The method is easily implemented and does not require expensive equipment or complicated data analysis processes. CONCLUSIONS: Direct and simultaneous measurement of brain oxygen concentration in multiple brain areas can be used to study the effects of bilateral DBS neuromodulation on brain activity in freely moving mice.
Assuntos
Técnicas Biossensoriais/métodos , Corpo Estriado/metabolismo , Estimulação Encefálica Profunda , Oxigênio/análise , Córtex Pré-Frontal/metabolismo , Animais , Comportamento Animal , Técnicas Biossensoriais/instrumentação , Cápsula Interna/fisiologia , Masculino , Camundongos Endogâmicos C57BL , Oxigênio/metabolismoRESUMO
OBJECTIVE: The purpose of our review is an update about the burden of sexually transmitted infections (STIs) among various types of underserved populations, such as migrants, substance abusers, homeless and incarcerated inmates. First-line test and treatment based on the latest available evidence according to the revised guidelines of Centers for Disease Control and Prevention have also been considered. MATERIALS AND METHODS: We performed a comprehensive research using scientific databases such as Medline and Pubmed, followed by a review of citations and reference list. A consultation with other experts in the management of the various subpopulations was also conducted. RESULTS: Health-care is often influenced by social determinants, which play a vital role in the diffusion of STIs. The consequence is a socio-economical and ethnic disparity in the rate of STIs. Early screening and treatment of STIs should be implemented in clinical practice, starting from marginalized social groups, which are the most affected by this health problem. CONCLUSIONS: In the literature, there are very few papers containing information on STIs prevalence in various types of underserved populations, such as migrants, substance abusers, homeless and incarcerated inmates. The availability of more accurate epidemiological data is needed. In these groups, the most relevant barrier is the lower perception of health-care need, with an underestimation of risk and symptoms of STIs, causing a retard of diagnosis and health-care provision and use. For these populations, targeted interventions are needed, particularly on unaware people, responsible for most STIs transmissions.
Assuntos
Atenção à Saúde , Infecções Sexualmente Transmissíveis/patologia , Antibacterianos/uso terapêutico , Bases de Dados Factuais , Feminino , Pessoas Mal Alojadas , Humanos , Masculino , Comportamento Sexual , Infecções Sexualmente Transmissíveis/complicações , Infecções Sexualmente Transmissíveis/tratamento farmacológico , Transtornos Relacionados ao Uso de Substâncias/complicações , Transtornos Relacionados ao Uso de Substâncias/patologia , MigrantesRESUMO
OBJECTIVE: The purpose of the present multidisciplinary review is to give an updated insight into the most recent findings regarding the pathophysiology, diagnosis and therapeutics of HIV-associated neurocognitive disorder (HAND). MATERIALS AND METHODS: We performed a comprehensive search, through electronic databases (Pubmed - MEDLINE) and search engines (Google Scholar), of peer-reviewed publications (articles and reviews) and conferences proceedings on HAND pathophysiology, diagnosis, and therapy, from 1999 to 2016. RESULTS: It seems to be increasingly clear that neurodegeneration in HIV-1 affected patients is a multi-faceted disease involving numerous factors, from chronic inflammation to central nervous system (CNS) compartmentalization of HIV. Diagnosis of HAND may benefit from both laboratory analysis and advanced specific neuroimaging techniques. As regards HAND therapy, modified HAART combinations and simplification strategies have been tested, while novel exciting frontiers seem to involve the use of nanoparticles with the ability to cross the Blood-Brain Barrier (BBB). CONCLUSIONS: Albeit highly active antiretroviral therapy (HAART) allowed a major decrease in morbidity and mortality for AIDS patients, CNS involvement still represents a challenge in HIV patients even today, affecting up to 50% of patients with access to combination antiretroviral therapy (cART). Future studies will have to focus on CNS compartmentalization, drugs' ability to penetrate and suppress viral replication in this compartment, and on new approaches to reduce HIV-associated neuroinflammation.
Assuntos
Complexo AIDS Demência/tratamento farmacológico , Terapia Antirretroviral de Alta Atividade , Complexo AIDS Demência/diagnóstico , Complexo AIDS Demência/etiologia , Efeitos Psicossociais da Doença , HumanosRESUMO
A simple and rapid method was developed for in vivo simultaneous determination of ascorbic-acid and antioxidant capacity in microdialysates from cladodes of Opuntia ficus-indica (L.) Miller. The method is verified in water-stressed plants, as compared with a well-watered test controls. The microdialysis probe construction and insertion procedure was specifically developed to minimise the tissue trauma of the plant and to obtain optimal dialysis performance. Microdialysis was performed using a flow rate of 3 µL/min and the samples were analysed by HPLC coupled to electrochemical detection of ascorbic-acid and DPPH-determined antioxidant capacity. Our data indicate exponential decay of the concentrations of the analysed compounds as a function of microdialysis sampling time. Water-stressed Opuntia show decreased ascorbic acid levels and increased the others antioxidants.
Assuntos
Antioxidantes/análise , Ácido Ascórbico/análise , Diálise/métodos , Opuntia/química , Extratos Vegetais/análise , Cromatografia Líquida de Alta PressãoRESUMO
BACKGROUND: Microdialysis allows the in-vivo assessment of interstitial fluids. We studied the metabolic status of peripheral tissues (skeletal muscle) in patients undergoing coronary artery bypass surgery on- (CABG) or off-pump (OPCAB). METHODS: Twenty patients candidates to elective coronary bypass surgery were randomly assigned to undergo CABG or OPCAB. A microdialysis catheter was inserted in the left deltoid muscle before surgery and left in place for 24 hours, and metabolic markers of peripheral tissue perfusion (glucose, lactate, pyruvate, glycerol and lactate/pyruvate (L/P) ratio) were assessed before, at the end, and 24 hours after surgery. RESULTS: Preoperative clinical features were similar in both groups. Interstitial levels of glucose and lactate increased over time, being in both groups significantly higher than baseline 24 hours after surgery, whereas glycerol levels did not change over time and between groups. In addition, there was an increase over time of pyruvate levels which were significantly higher in CABG after surgery, whereas L/P ratio was significantly higher in OPCAB 24 hours after surgery. CONCLUSION: Metabolic changes after coronary bypass surgery occur with some differences related to CPB use. Overall, these changes suggest that, after coronary surgery, a certain degree of hypermetabolic state ensues, lasting up to 24 hours after surgery; the postoperative increase in pyruvate levels in CABG patients, together with the changes in L/P ratio occurring only in OPCAB patients implies an higher risk of tissue hypoperfusion/ischemia for patients submitted to OPCAB, although this does not lead to permanent cellular damage, as the markers of this complication (e.g., glycerol) do not change over time.
Assuntos
Ponte de Artéria Coronária sem Circulação Extracorpórea , Ponte de Artéria Coronária , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Anestesia , Biomarcadores , Glicemia/metabolismo , Feminino , Humanos , Ácido Láctico/sangue , Masculino , Metabolismo/fisiologia , Microdiálise , Pessoa de Meia-Idade , Músculo Esquelético/metabolismo , Período Perioperatório , Período Pós-Operatório , Ácido Pirúvico/sangue , Adulto JovemRESUMO
Emerging evidence points to reactive glia as a pivotal factor in Parkinson's disease (PD) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned mouse model of basal ganglia injury, but whether astrocytes and microglia activation may exacerbate dopaminergic (DAergic) neuron demise and/or contribute to DAergic repair is presently the subject of much debate. Here, we have correlated the loss and recovery of the nigrostriatal DAergic functionality upon acute MPTP exposure with extensive gene expression analysis at the level of the ventral midbrain (VM) and striata (Str) and found a major upregulation of pro-inflammatory chemokines and wingless-type MMTV integration site1 (Wnt1), a key transcript involved in midbrain DAergic neurodevelopment. Wnt signaling components (including Frizzled-1 [Fzd-1] and ß-catenin) were dynamically regulated during MPTP-induced DAergic degeneration and reactive glial activation. Activated astrocytes of the ventral midbrain were identified as candidate source of Wnt1 by in situ hybridization and real-time PCR in vitro. Blocking Wnt/Fzd signaling with Dickkopf-1 (Dkk1) counteracted astrocyte-induced neuroprotection against MPP(+) toxicity in primary mesencephalic astrocyte-neuron cultures, in vitro. Moreover, astroglial-derived factors, including Wnt1, promoted neurogenesis and DAergic neurogenesis from adult midbrain stem/neuroprogenitor cells, in vitro. Conversely, lack of Wnt1 transcription in response to MPTP in middle-aged mice and failure of DAergic neurons to recover were reversed by pharmacological activation of Wnt/ß-catenin signaling, in vivo, thus suggesting MPTP-reactive astrocytes in situ and Wnt1 as candidate components of neuroprotective/neurorescue pathways in MPTP-induced nigrostriatal DAergic plasticity.
Assuntos
Astrócitos/metabolismo , Astrócitos/patologia , Transtornos Parkinsonianos/metabolismo , Transtornos Parkinsonianos/patologia , Transdução de Sinais/genética , Substância Negra/metabolismo , Substância Negra/patologia , Proteína Wnt1/genética , Animais , Astrócitos/efeitos dos fármacos , Células Cultivadas , Técnicas de Cocultura , Regulação da Expressão Gênica/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Regeneração Nervosa/efeitos dos fármacos , Regeneração Nervosa/genética , Vias Neurais/efeitos dos fármacos , Vias Neurais/metabolismo , Vias Neurais/patologia , Transdução de Sinais/efeitos dos fármacos , Substância Negra/efeitos dos fármacosRESUMO
The final step in the physiological synthesis of 17beta estradiol (E(2)) is aromatization of precursor testosterone by a CYP19 gene product, cytochrome P450 estrogen aromatase in the C19 steroid metabolic pathway. Within the central nervous system (CNS) the presence, distribution, and activity of aromatase have been well characterized. Developmental stage and injury are known modulators of brain enzyme activity, where both neurons and glial cells reportedly have the capability to synthesize this key estrogenic enzyme. The gonadal steroid E(2) is a critical survival, neurotrophic and neuroprotective factor for dopaminergic neurons of the substantia nigra pars compacta (SNpc), the cells that degenerate in Parkinson's disease (PD). In previous studies we underlined a crucial role for the estrogenic status at the time of injury in dictating vulnerability to the parkinsonian neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Our ongoing studies address the contribution of brain aromatase and extragonadal E(2) as vulnerability factors for PD pathology in female brain, by exposing aromatase knockout (ArKO, -/-) female mice which are unable to synthesize estrogens to MPTP. Our initial results indicate that aromatase deficiency from early embryonic life significantly impairs the functional integrity of SNpc tyrosine hydroxylase-positive neurons and dopamine transporter innervation of the caudate-putamen in adulthood. In addition, ArKO females exhibited a far greater vulnerability to MPTP-induced nigrostriatal damage as compared to their Wt type gonadally intact and gonadectomized counterparts. Characterization of this novel implication of P450 aromatase as determining factor for PD vulnerability may unravel new avenues for the understanding and development of novel therapeutic approaches for Parkinson's disease.
Assuntos
Aromatase/metabolismo , Encéfalo/enzimologia , Estradiol/metabolismo , Doença de Parkinson/enzimologia , Animais , Encéfalo/patologia , Exposição Ambiental , Feminino , Predisposição Genética para Doença , Humanos , Camundongos , Camundongos Knockout , Doença de Parkinson/etiologia , Doença de Parkinson/patologia , Fatores de RiscoRESUMO
Post-menopausal estrogen deficiency is recognized to play a pivotal role in the pathogenesis of a number of age-related diseases in women, such as osteoporosis, coronary heart disease and Alzheimer's disease. There are also sexual differences in the progression of diseases associated with the nigrostriatal dopaminergic system, such as Parkinson's disease, a chronic progressive degenerative disorder characterized by the selective degeneration of mesencephalic dopaminergic neurons in the substancia nigra pars compacta. The mechanism(s) responsible for dopaminergic neuron degeneration in Parkinson's disease are still unknown, but oxidative stress and neuroinflammation are believed to play a key role in nigrostriatal dopaminergic neuron demise. Estrogen neuroprotective effects have been widely reported in a number of neuronal cell systems including the nigrostriatal dopaminergic neurons, via both genomic and non-genomic effects, however, little is known on estrogen modulation of astrocyte and microglia function in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine model of Parkinson's disease. We here highlight estrogen modulation of glial neuroinflammatory reaction in the protection of mesencephalic dopaminergic neurons and emphasize the cardinal role of glia-neuron crosstalk in directing neuroprotection vs neurodegeneration. In particular, the specific role of astroglia and its pro-/anti-inflammatory mechanisms in estrogen neuroprotection are presented. This study shows that astrocyte and microglia response to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine injury vary according to the estrogenic status with direct consequences for dopaminergic neuron survival, recovery and repair. These findings provide a new insight into the protective action of estrogen that may possibly contribute to the development of novel therapeutic treatment strategies for Parkinson's disease.
Assuntos
Estrogênios/fisiologia , Degeneração Neural/fisiopatologia , Neuroglia/fisiologia , Doença de Parkinson/fisiopatologia , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina , Animais , Modelos Animais de Doenças , Humanos , Inflamação/fisiopatologia , Modelos Neurológicos , Degeneração Neural/prevenção & controle , Sistema Nervoso/fisiopatologia , Neurônios/patologia , Neurônios/fisiologia , Estresse OxidativoRESUMO
1. We showed previously that interaction between NO and iron (II), both released following the decomposition of sodium nitroprusside (SNP), accounted for the late SNP-induced dopamine (DA) increase in dialysates from the striatum of freely moving rats; in addition, we showed that co-infusion of iron (II) with the NO-donor S-nitroso-N-acetylpenicillamine mimicked SNP effects on striatal DA release. 2. In the present study, intrastriatal co-infusion of iron (II) (given as FeSO(4), 1 mM for 40 min) with the NO-donor and potential peroxynitrite generator 3-morpholinosydnonimine (SIN-1) (0.2, 0.5, 1.0 or 5.0 mM for 180 min), potentiated the SIN-1-induced increase in DA concentration in dialysates from the striatum of freely moving rats. Neither alone nor associated with iron (II) did SIN-1 induce changes in dialysate ascorbic acid or uric acid concentrations. 3. Neither co-infusion of a superoxide dismutase mimetic nor uric acid affected SIN-1-induced increases in dialysate DA concentration. 4. Infusion of the iron chelator deferoxamine (0.2 mM for 180 min) decreased dialysate DA and attenuated SIN-1-induced increases in dialysate DA concentrations. 5. These results suggest that iron plays a key role in SIN-1-induced release of striatal DA and do not support any role for either peroxynitrite or superoxide anion in SIN-1-induced release of striatal DA.
Assuntos
Corpo Estriado/efeitos dos fármacos , Dopamina/metabolismo , Ferro/farmacologia , Molsidomina/análogos & derivados , Molsidomina/farmacologia , Doadores de Óxido Nítrico/farmacologia , Óxido Nítrico/fisiologia , Ácido 3,4-Di-Hidroxifenilacético/metabolismo , Acetilcisteína/farmacologia , Animais , Ácido Ascórbico/metabolismo , Corpo Estriado/metabolismo , Desferroxamina/farmacologia , Soluções para Diálise/química , Relação Dose-Resposta a Droga , Sequestradores de Radicais Livres/farmacologia , Ácido Homovanílico/metabolismo , Masculino , Metaloporfirinas/farmacologia , Movimento , Ratos , Ratos Wistar , Ácido Úrico/metabolismo , Ácido Úrico/farmacologiaRESUMO
1. We showed previously that interaction between NO and iron(II), both released following decomposition of sodium nitroprusside (SNP), accounted for the late SNP-induced dopamine (DA) increase in dialysates from the striatum of freely moving rats. 2. In this study, intrastriatal infusion of the NO-donor S-nitroso-N-acetylpenicillamine (SNAP) (0.2 mM for 180 min) induced a moderate increase in dialysate DA and decreases in ascorbic acid dialysate concentrations; in contrast, SNAP 1 mM infusion induced a long-lasting decrease in both DA and ascorbic acid dialysate concentrations. 3-Methoxy-tyramine (3-MT), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and uric acid levels were unaffected. 3. Co-infusion of ferrous sulphate [iron(II), 1 mM for 40 min] with SNAP either 1 or 0.2 mM (for 180 min), produced a significant increase in both DA and 3-MT dialysate concentrations, but it did not affect decreases in dialysate ascorbic acid levels. All other dialysate neurochemicals were unaffected. 4. Co-infusion of ascorbic acid (0.1 mM) with SNAP (1 mM) for 180 min did not modify SNAP-induced decreases in dialysate DA levels. In contrast, co-infusion of uric acid (1 mM) reversed SNAP-induced decreases in dialysate DA; co-infusion of a superoxide dismutase mimetic delayed SNAP-induced DA decreases for a short period, while co-infusion of the antioxidant N-acetylcysteine (NAC, 0.1 mM) significantly increased dialysate DA. 5. The results of this study show that SNAP induces concentration-related changes in DA dialysate levels. At higher concentrations, SNAP induces non-enzymatic DA oxidation, which is inhibited by uric acid and NAC; ascorbic acid failed to protect dialysate DA from oxidation, probably owing to its promoting effect on SNAP decomposition; exogenous iron(II) may react with NO generated from SNAP decomposition, with a consequent increase in dialysate DA and 3-MT, therefore mimicking SNP effects on striatal DA release.
Assuntos
Ácido Ascórbico/fisiologia , Corpo Estriado/efeitos dos fármacos , Dopamina/metabolismo , Doadores de Óxido Nítrico/farmacologia , Estresse Oxidativo , Penicilamina/farmacologia , Acetilcisteína/farmacologia , Animais , Corpo Estriado/metabolismo , Ferro/metabolismo , Masculino , Microdiálise , Penicilamina/análogos & derivados , Ratos , Ratos Wistar , S-Nitroso-N-AcetilpenicilaminaRESUMO
The degradation of high-energy phosphates was recently shown to precede manganese-induced cellular death. We evaluated hypoxanthine, xanthine, uric acid and glutamate levels in the striatum and brainstem of 3- and 20-month-old rats after subchronic oral exposure to manganese (MnCl2, 200 mg/kg/day in young rats, and 50-100 or 200 mg/kg/day in aged rats). Aged rats had higher basal levels of hypoxanthine, xanthine, and glutamate both in the striatum and brainstem than young rats; conversely, basal uric acid levels were lower in the striatum, but higher in the brainstem. Manganese induced a significantly greater increase in hypoxanthine, xanthine, uric acid and glutamate levels in aged rats than in young rats in both brain regions. These findings depict a greater manganese-induced energetic impairment (increases in hypoxanthine and xanthine levels), xanthine oxidase-induced free radical generation (increases in xanthine and uric acid levels), and excitotoxic status (increases in glutamate levels) in aged rats than in young rats. In addition, these findings may also account for a greater manganese toxicity to the nigro-striatal dopaminergic system in aged than in young rats, as shown in a previous work.
Assuntos
Envelhecimento/metabolismo , Tronco Encefálico/metabolismo , Corpo Estriado/metabolismo , Metabolismo Energético/efeitos dos fármacos , Ácido Glutâmico/metabolismo , Manganês/farmacologia , Fosfatos/metabolismo , Animais , Tronco Encefálico/efeitos dos fármacos , Corpo Estriado/efeitos dos fármacos , Hipoxantina/metabolismo , Masculino , Concentração Osmolar , Ratos , Ratos Wistar , Fatores de Tempo , Ácido Úrico/metabolismo , Xantina/metabolismoRESUMO
The effects of intrastriatal infusion of 3-morpholinosydnonimine (SIN-1) or sodium nitroprusside (SNP) on dopamine (DA), 3-methoxytyramine (3-MT), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), L-dihydroxyphenylalanine (L-DOPA), ascorbic acid and uric acid concentrations in dialysates from the striatum of freely moving rats were evaluated using microdialysis. SIN-1 (1 mM) infusion for 180 min increased microdialysate DA and 3-MT concentrations, while L-DOPA, DOPCA+HVA, ascorbic acid and uric acid levels were unaffected. Co-infusion with ascorbic acid (0.1 mM) inhibited SIN-1-induced increases in DA and 3-MT dialysate concentration. SNP (1 mM) infusion for 180 min increased greatly the dialysate DA concentration to a peak (2950% of baseline) at the end of the infusion, while increases in 3-MT were negligible. In addition, SNP decreased ascorbic acid and L-DOPA but increased uric acid concentration in the dialysate. Co-infusion with deferoxamine (0.2 mM) inhibited the late SNP-induced increase in DA dialysate concentration, but did not affect the decrease in ascorbic acid and increase uric acid dialysate concentrations. SNP (1 mM) infusion for 20 min moderately increased uric acid, DA and 3-MT, but decreased L-DOPA levels in the dialysate. Ascorbic acid concentration increased at the end of SNP infusion. Co-infusion with ascorbic acid (0.1 mM) inhibited the SNP-induced increase in DA and 3-MT, but did not affect the decrease in L-DOPA and increase in uric acid dialysate concentrations. These results suggest that NO released from SIN-1 may account for the increase in the dialysate DA concentration. NO released following decomposition of SNP may account for the early increase in dialysate DA, while late changes in microdialysate composition following SNP may result from an interaction between NO and the ferrocyanide moiety of SNP. Exogenous ascorbic acid inhibits the effect of exogenous NO on DA release probably by scavenging NO, suggesting that endogenous ascorbic acid may modulate the NO control of DA release from 300 striatal dopaminergic terminals.
Assuntos
Ácido Ascórbico/farmacologia , Corpo Estriado/metabolismo , Dopamina/metabolismo , Ferro/fisiologia , Molsidomina/análogos & derivados , Doadores de Óxido Nítrico/farmacologia , Óxido Nítrico/fisiologia , Nitroprussiato/farmacologia , Animais , Desferroxamina/farmacologia , Masculino , Microdiálise , Molsidomina/farmacologia , Ratos , Ratos WistarRESUMO
We have previously shown that manganese enhances L-dihydroxyphenylanine (L-DOPA) toxicity to PC12 cells in vitro. The supposed mechanism of manganese enhancing effect [an increase in L-DOPA and dopamine (DA) auto-oxidation] was studied using microdialysis in the striatum of freely moving rats. Systemic L-DOPA [25 mg kg(-1) intraperitoneally (i.p.) twice in a 12 h interval] significantly increased baseline dialysate concentrations of L-DOPA, dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and uric acid, compared to controls. Conversely, DA and ascorbic acid concentrations were significantly decreased. A L-DOPA oxidation product, presumptively identified as L-DOPA semiquinone, was detected in the dialysate. The L-DOPA semiquinone was detected also following intrastriatal infusion of L-DOPA. In rats given L-DOPA i.p. , intrastriatal infusion of N-acetylcysteine (NAC) significantly increased DA and L-DOPA dialysate concentrations and lowered those of L-DOPA semiquinone; in addition, NAC decreased DOPAC+HVA and uric acid dialysate concentrations. In rats given L-DOPA either systemically or intrastriatally, intrastriatal infusion of manganese decreased L-DOPA dialysate concentrations and greatly increased those of L-DOPA semiquinone. These changes were inhibited by NAC infusion. These findings demonstrate that auto-oxidation of exogenous L-DOPA occurs in vivo in the rat striatum. The consequent reactive oxygen species generation may account for the decrease in dialysate DA and ascorbic acid concentrations and increase in enzymatic oxidation of xanthine and DA. L-DOPA auto-oxidation is inhibited by NAC and enhanced by manganese. These results may be of relevance to the L-DOPA long-term therapy of Parkinson's disease.
Assuntos
Corpo Estriado/efeitos dos fármacos , Levodopa/metabolismo , Manganês/farmacologia , Ácido 3,4-Di-Hidroxifenilacético/metabolismo , Acetilcisteína/farmacologia , Animais , Ácido Ascórbico/metabolismo , Cloretos/farmacologia , Cromatografia Líquida de Alta Pressão , Corpo Estriado/metabolismo , Soluções para Diálise/química , Dopamina/metabolismo , Ácido Homovanílico/metabolismo , Bombas de Infusão , Levodopa/farmacologia , Levodopa/uso terapêutico , Masculino , Compostos de Manganês/farmacologia , Microdiálise , Movimento , Oxirredução/efeitos dos fármacos , Doença de Parkinson/tratamento farmacológico , Ratos , Ratos Wistar , Fatores de Tempo , Ácido Úrico/metabolismoRESUMO
1. The effects of systemic, intrastriatal or intranigral administration of d-amphetamine on glutamate, aspartate, ascorbic acid (AA), uric acid, dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) concentrations in dialysates from the striatum of freely-moving rats were evaluated using microdialysis. 2. d-Amphetamine (2 mg kg-1) given subcutaneously (s.c.) increased DA, AA and uric acid and decreased DOPAC + HVA, glutamate and aspartate dialysate concentrations over a 3 h period after d-amphetamine. 5-HIAA concentrations were unaffected. Individual changes in glutamate and AA dialysate concentrations were negatively correlated. 3. d-Amphetamine (0.2 mM), given intrastriatally, increased DA and decreased DOPAC + HVA and aspartate dialysate concentrations, but failed to change those of glutamate, AA uric acid or 5-HIAA, over a 2 h period after d-amphetamine. Haloperidol (0.1 mM), given intrastriatally, increased aspartate concentrations without affecting those of glutamate or AA. 4. d-Amphetamine (0.2 mM), given intranigrally, increased AA and uric acid dialysate concentrations and decreased those of glutamate, aspartate and DA; DOPAC + HVA and 5-HIAA concentrations were unaffected. 5. These results suggest that d-amphetamine-induced increases in AA and uric acid and decreases in glutamate concentrations are triggered at nigral sites. The changes in aspartate levels may be evoked by at least two mechanisms: striatal (mediated by inhibitory dopaminergic receptors) and nigral (activation of amino acid carrier-mediated uptake).
Assuntos
Ácido Ascórbico/metabolismo , Dextroanfetamina/farmacologia , Inibidores da Captação de Dopamina/farmacologia , Ácido Glutâmico/metabolismo , Neostriado/metabolismo , Ácido Úrico/metabolismo , Ácido 3,4-Di-Hidroxifenilacético/metabolismo , Animais , Dextroanfetamina/administração & dosagem , Dopamina/metabolismo , Antagonistas de Dopamina/farmacologia , Inibidores da Captação de Dopamina/administração & dosagem , Haloperidol/farmacologia , Técnicas In Vitro , Injeções , Masculino , Microdiálise , Atividade Motora/efeitos dos fármacos , Neostriado/efeitos dos fármacos , Oxirredução , Ratos , Ratos Wistar , Técnicas Estereotáxicas , Comportamento Estereotipado/efeitos dos fármacosRESUMO
Aging is a factor known to increase neuronal vulnerability to oxidative stress, which is widely accepted as a mechanism of manganese-induced neuronal damage. We previously showed that subchronic exposure to manganese induced greater energy impairment (as revealed by increases in hypoxanthine, xanthine and uric acid levels) in the striatum and brainstem of aged rats vs young rats. This study shows that inhibition of glutathione (GSH) synthesis, by means of buthionine (SR) sulfoximine, decreased GSH levels and increased the ascorbic acid oxidation status in the striatum and limbic forebrain of both young and aged rats. In addition, inhibition of GSH synthesis greatly potentiated the manganese-induced increase in inosine, hypoxanthine, xanthine and uric acid levels in both regions of aged rats; moreover, inhibition of GSH synthesis significantly increased inosine, hypoxanthine, xanthine and uric acid levels in both regions of young rats, compared with the manganese-treated group. These results suggest that an impairment in the neuronal antioxidant system renders young rats susceptible to manganese-induced energetic impairment, and further support the hypothesis that an impairment in this system plays a permissive role in the increase of neuronal vulnerability that occurs with aging.
Assuntos
Envelhecimento/metabolismo , Encéfalo/metabolismo , Metabolismo Energético/efeitos dos fármacos , Glutationa/deficiência , Manganês/farmacologia , Fosfatos/metabolismo , Animais , Antimetabólitos/farmacologia , Ácido Ascórbico/metabolismo , Butionina Sulfoximina/farmacologia , Ácido Desidroascórbico/metabolismo , Sinergismo Farmacológico , Glutationa/antagonistas & inibidores , Glutationa/metabolismo , Hipoxantina/metabolismo , Inosina/metabolismo , Masculino , Ratos , Ratos Wistar , Distribuição Tecidual , Ácido Úrico/metabolismo , Xantina/metabolismoRESUMO
L-DOPA and manganese both induce oxidative stress-mediated apoptosis in catecholaminergic PC12 cells. In this study, exposure of PC12 cells to 0.2 mM MnCl2 or 10-20 microM L-DOPA neither affected cell viability, determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, nor induced apoptosis, tested by flow cytometry, fluorescence microscopy, and the TUNEL technique. L-DOPA (50 microM) induced decreases in both cell viability and apoptosis. When 0.2 mM MnCl2 was associated with 10, 20, or 50 microM L-DOPA, a concentration-dependent decrease in cell viability was observed. Apoptotic cell death also occurred. In addition, manganese inhibited L-DOPA effects on dopamine (DA) metabolism (i.e., increases in DA and its acidic metabolite levels in both cell lysate and incubation medium). The antioxidant N-acetyl-L-cysteine significantly inhibited decreases in cell viability, apoptosis, and changes in DA metabolism induced by the manganese association with L-DOPA. An increase in autoxidation of L-DOPA and of newly formed DA is suggested as a mechanism of manganese action. These data show that agents that induce oxidative stress-mediated apoptosis in catecholaminergic cells may act synergistically.
Assuntos
Apoptose/efeitos dos fármacos , Dopaminérgicos/toxicidade , Levodopa/toxicidade , Intoxicação por Manganês , Estresse Oxidativo/fisiologia , Acetilcisteína/farmacologia , Animais , Antioxidantes/farmacologia , Ácido Ascórbico/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Dopamina/biossíntese , Sinergismo Farmacológico , Citometria de Fluxo , Estresse Oxidativo/efeitos dos fármacos , Células PC12 , RatosRESUMO
In the present study in vivo and ex vivo experiments were combined to evaluate the effects of allopurinol on the neurochemical changes induced by an acute morphine challenge (2 mg kg-1, s.c.). In samples from rat striatum, levels of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), 3-methoxytyramine (3-MT), ascorbate (AA), dehydroascorbate (DHAA), hypoxanthine, xanthine and uric acid (UA) were measured. Brain microdialysis experiments were carried out in freely moving rats. Striatal dialysate levels were assayed for DA, DOPAC + HVA, AA and UA using liquid chromatography followed by electrochemical detection. Morphine administration increased the striatal levels of DA metabolites, UA and DHAA and the extracellular concentrations of DA, DOPAC + HVA, UA and AA. Allopurinol (50 mg kg-1 by gavage), an inhibitor of xanthine oxidase which catalyses oxidation of xanthine to UA, decreased basal UA and AA concentrations and the morphine-induced increase in DA metabolites and AA oxidation. Since oxidation of DA and xanthines generates reactive oxygen species (ROS) and AA and UA are the main cellular antioxidants, these findings suggest that: (a) single morphine administration increases DA and xanthine oxidative metabolism with a consequent increase in ROS production, which may account for changes in concentrations of extracellular AA and tissue DHAA; (b) allopurinol decreases morphine-induced DA and xanthine oxidation; (c) UA and AA may act in concert to regulate levels of ROS in the brain.