RESUMO
Alzheimer's Disease (AD) is a complex neurodegenerative disorder associated in some instances with dyshomeostasis of redox-active metal ions, such as copper and iron. In this work, we investigated whether the conjugation of various aromatic amines would improve the pharmacological efficacy of the iron chelator desferrioxamine (DFO). Conjugates of DFO with aniline (DFOANI), benzosulfanylamide (DFOBAN), 2-naphthalenamine (DFONAF) and 6-quinolinamine (DFOQUN) were obtained and their properties examined. DFOQUN had good chelating activity, promoted a significant increase in the inhibition of ß-amyloid peptide aggregation when compared to DFO, and also inhibited acetylcholinesterase (AChE) activity both in vitro and in vivo (Caenorhabditis elegans). These data indicate that the covalent conjugation of a strong iron chelator to an AChE inhibitor offers a powerful approach for the amelioration of iron-induced neurotoxicity symptoms.
Assuntos
Aminas/farmacologia , Antioxidantes/farmacologia , Caenorhabditis elegans/efeitos dos fármacos , Inibidores da Colinesterase/farmacologia , Desferroxamina/farmacologia , Quelantes de Ferro/farmacologia , Acetilcolinesterase/metabolismo , Aminas/química , Peptídeos beta-Amiloides/antagonistas & inibidores , Peptídeos beta-Amiloides/metabolismo , Animais , Antioxidantes/síntese química , Antioxidantes/química , Compostos de Bifenilo/antagonistas & inibidores , Caenorhabditis elegans/enzimologia , Inibidores da Colinesterase/síntese química , Inibidores da Colinesterase/química , Desferroxamina/química , Humanos , Quelantes de Ferro/síntese química , Quelantes de Ferro/química , Estrutura Molecular , Picratos/antagonistas & inibidores , Agregados Proteicos/efeitos dos fármacosRESUMO
Glutamatergic system and mTOR signaling pathway have been proposed to be important targets for pharmacological treatment of major depressive disorder. Previous studies have shown that inosine, an endogenous purine, is able to exert a remarkable antidepressant-like effect in mice. Nevertheless, the role of glutamatergic system and mTOR in this effect was not previously determined. This study was designed to investigate the possible modulation of NMDA receptors (NMDAR), AMPA receptors (AMPAR) and mTOR complex 1 (mTORC1) signaling pathway in the inosine anti-immobility effect in the tail suspension test (TST) in mice. Pre-treatment of mice with NMDA (0.1 pmol/mouse, NMDAR agonist, i.c.v.) and D-serine (30 µg/mouse, NMDAR co-agonist, i.c.v.) prevented inosine (10 mg/kg, i.p.) anti-immobility effect in the TST. In addition, a synergistic antidepressant-like effect was observed when a sub-effective dose of inosine (0.1 mg/kg, i.p.) was combined with sub-effective doses of NMDAR antagonists MK-801 (0.001 mg/kg, p.o.) or ketamine (0.1 mg/kg, i.p.). Conversely, the antidepressant-like effect elicited by inosine was not altered by pre-treatment with AMPAR antagonist, DNQX (2.5 µg/mouse, i.c.v.). The mTORC1 inhibitor rapamycin (0.2 nmol/mouse, i.c.v.) prevented the inosine anti-immobility effect in the TST. Noteworthy, inosine treatment did not change the immunocontent of the synaptic proteins PSD95, GluA1 and synapsin I. Mice locomotor activity assessed by open-field test, was not altered by treatments. Taken together, this study shows a pivotal role of NMDAR inhibition and mTORC1 activation for inosine antidepressant-like effect and extends the knowledge concerning the molecular mechanism and potential of inosine for antidepressant strategies.
Assuntos
Antidepressivos/uso terapêutico , Depressão/tratamento farmacológico , Ácido Glutâmico/metabolismo , Inosina/uso terapêutico , Transdução de Sinais/efeitos dos fármacos , Serina-Treonina Quinases TOR/metabolismo , Análise de Variância , Animais , Depressão/diagnóstico , Modelos Animais de Doenças , Proteína 4 Homóloga a Disks-Large/metabolismo , Relação Dose-Resposta a Droga , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , Comportamento Exploratório/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Elevação dos Membros Posteriores/métodos , Masculino , Camundongos , Receptores de AMPA/metabolismoRESUMO
Organic selenium and tellurium compounds are known for their broad-spectrum effects in a variety of experimental disease models. However, these compounds commonly display high toxicity and the molecular mechanisms underlying these deleterious effects have yet to be elucidated. Thus, the need for an animal model that is inexpensive, amenable to high-throughput analyses, and feasible for molecular studies is highly desirable to improve organochalcogen pharmacological and toxicological characterization. Herein, we use Caenorhabdtis elegans (C. elegans) as a model for the assessment of pharmacological and toxicological parameters following exposure to two 4-phenylchalcogenil-7-chloroquinolines derivatives (PSQ for selenium and PTQ for tellurium-containing compounds). While non-lethal concentrations (NLC) of PTQ and PSQ attenuated paraquat-induced effects on survival, lifespan and oxidative stress parameters, lethal concentrations (LC) of PTQ and PSQ alone are able to impair these parameters in C. elegans. We also demonstrate that DAF-16/FOXO and SKN-1/Nrf2 transcription factors underlie the mechanism of action of these compounds, as their targets sod-3, gst-4 and gcs-1 were modulated following exposures in a daf-16- and skn-1-dependent manner. Finally, in accordance with a disturbed thiol metabolism in both LC and NLC, we found higher sensitivity of trxr-1 worm mutants (lacking the selenoprotein thioredoxin reductase 1) when exposed to PSQ. Finally, our study suggests new targets for the investigation of organochalcogen pharmacological effects, reinforcing the use of C. elegans as a powerful platform for preclinical approaches.
Assuntos
Antioxidantes/farmacologia , Caenorhabditis elegans/efeitos dos fármacos , Calcogênios/farmacologia , Compostos Organometálicos/farmacologia , Compostos Organosselênicos/farmacologia , Quinolinas/farmacologia , Telúrio/farmacologia , Animais , Antioxidantes/síntese química , Caenorhabditis elegans/genética , Caenorhabditis elegans/crescimento & desenvolvimento , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Calcogênios/síntese química , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Regulação da Expressão Gênica , Longevidade/efeitos dos fármacos , Fator 2 Relacionado a NF-E2/genética , Fator 2 Relacionado a NF-E2/metabolismo , Compostos Organometálicos/síntese química , Compostos Organosselênicos/síntese química , Oxidantes/antagonistas & inibidores , Oxidantes/toxicidade , Estresse Oxidativo , Paraquat/antagonistas & inibidores , Paraquat/toxicidade , Quinolinas/síntese química , Transdução de Sinais , Superóxido Dismutase/genética , Superóxido Dismutase/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
It has been demonstrated that variant vicilins are the main resistance factor of cowpea seeds (Vigna unguiculata) against attack by the cowpea beetle Callosobruchus maculatus. There is evidence that the toxic properties of these storage proteins may be related to their interaction with glycoproteins and other microvillar membrane constituents along the digestive tract of the larvae. New findings have shown that following interaction with the microvilli, the vicilins are absorbed across the intestinal epithelium and thus reach the internal environment of the larvae. In the present paper we studied the insecticidal activity of the variant vicilins purified from a resistant cowpea variety (IT81D-1053). Bioassays showed that the seeds of this genotype affected larval growth, causing developmental retardation and 100% mortality. By feeding C. maculatus larvae on susceptible and IT81D-1053 derived vicilins (FITC labelled or unlabelled), followed by fluorescence and immunogold cytolocalization, we were able to demonstrate that both susceptible and variant forms are internalized in the midgut cells and migrate inside vesicular structures from the apex to the basal portion of the enterocytes. However, when larvae were fed with the labelled vicilins for 24h and then returned to a control diet, the concentration of the variant form remained relatively high, suggesting that variant vicilins are not removed from the cells at the same rate as the non-variant vicilins. We suggest that the toxic effects of variant vicilins on midgut cells involve the binding of these proteins to the cell surface followed by internalization and interference with the normal physiology of the enterocytes, thereby affecting larval development in vivo.
Assuntos
Besouros/metabolismo , Fabaceae/metabolismo , Proteínas de Armazenamento de Sementes/metabolismo , Sementes/metabolismo , Animais , Sistema Digestório/metabolismo , Resistência à Doença , Epitélio/metabolismo , Larva/crescimento & desenvolvimento , Larva/metabolismo , Microvilosidades/metabolismo , Controle Biológico de VetoresRESUMO
The excitotoxicity induced by excessive activation of the glutamatergic neurotransmission pathway is involved in several neuropathologies. In this sense, molecules that prevent the release of glutamate or the excessive activation of its receptors can be useful in preventing the neuronal cell death observed in these diseases. Lectins are proteins capable of reversible binding to the carbohydrates in glycoconjugates, and some have been used in the study and purification of glutamate receptors. ConBr is a mannose/glucose-binding lectin purified from Canavalia brasiliensis seeds. In the present study, we aimed to evaluate the neuroprotective activity of ConBr against glutamate-induced excitotoxicity. Hippocampal slices were isolated from adult male mice and incubated for 6h in Krebs saline/DMEM buffer alone (control), in the presence of glutamate or glutamate plus ConBr. The phosphorylation of Akt and mitogen activated protein kinases (MAPKs) such as ERK1/2, p38(MAPK) and JNK1/2/3 was evaluated with western blotting. The results indicate that glutamate provoked a reduction in the hippocampal slice viability (-25%), diminished the phosphorylation of Akt and augmented p38(MAPK) and ERK1 phosphorylation. No changes were observed in the phosphorylation of JNK1/2/3 or ERK2. Notably, ConBr, through a mechanism dependent on carbohydrate interaction, prevented the reduction of cell viability and Akt phosphorylation induced by glutamate. Furthermore, in the presence of the PI3K inhibitor LY294002, ConBr was unable to reverse glutamate neurotoxicity. Taken together, our data suggest that the neuroprotective effect of ConBr against glutamate neurotoxicity requires oligosaccharide interaction and is dependent on the PI3K/Akt pathway.
Assuntos
Canavalia/química , Antagonistas de Aminoácidos Excitatórios , Ácido Glutâmico/toxicidade , Hipocampo/efeitos dos fármacos , Fármacos Neuroprotetores , Proteína Oncogênica v-akt/fisiologia , Fosfatidilinositol 3-Quinases/fisiologia , Lectinas de Plantas/farmacologia , Transdução de Sinais/efeitos dos fármacos , Animais , Western Blotting , Metabolismo dos Carboidratos/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Cromonas/farmacologia , Inibidores Enzimáticos/farmacologia , Hipocampo/patologia , Técnicas In Vitro , Masculino , Camundongos , Proteínas Quinases Ativadas por Mitógeno/fisiologia , Morfolinas/farmacologia , Fosforilação , Lectinas de Plantas/química , Lectinas de Plantas/isolamento & purificação , Sais de Tetrazólio , TiazóisRESUMO
While manganese (Mn) is essential for proper central nervous system (CNS) development, excessive Mn exposure may lead to neurotoxicity. Mn preferentially accumulates in the basal ganglia, and in adults it may cause Parkinson's disease-like disorder. Compared to adults, younger individuals accumulate greater Mn levels in the CNS and are more vulnerable to its toxicity. Moreover, the mechanisms mediating developmental Mn-induced neurotoxicity are not completely understood. The present study investigated the developmental neurotoxicity elicited by Mn exposure (5, 10 and 20 mg/kg; i.p.) from postnatal day 8 to PN27 in rats. Neurochemical analyses were carried out on PN29, with a particular focus on striatal alterations in intracellular signaling pathways (MAPKs, Akt and DARPP-32), oxidative stress generation and cell death. Motor alterations were evaluated later in life at 3, 4 or 5 weeks of age. Mn exposure (20 mg/kg) increased p38(MAPK) and Akt phosphorylation, but decreased DARPP-32-Thr-34 phosphorylation. Mn (10 and 20 mg/kg) increased caspase activity and F2-isoprostane production (a biological marker of lipid peroxidation). Paralleling the changes in striatal biochemical parameters, Mn (20 mg/kg) also caused motor impairment, evidenced by increased falling latency in the rotarod test, decreased distance traveled and motor speed in the open-field test. Notably, the antioxidant Trolox™ reversed the Mn (20 mg/kg)-dependent augmentation in p38(MAPK) phosphorylation and reduced the Mn (20 mg/kg)-induced caspase activity and F2-isoprostane production. Trolox™ also reversed the Mn-induced motor coordination deficits. These findings are the first to show that long-term exposure to Mn during a critical period of neurodevelopment causes motor coordination dysfunction with parallel increment in oxidative stress markers, p38(MAPK) phosphorylation and caspase activity in the striatum. Moreover, we establish Trolox™ as a potential neuroprotective agent given its efficacy in reversing the Mn-induced neurodevelopmental effects.
Assuntos
Antioxidantes/farmacologia , Gânglios da Base/efeitos dos fármacos , Comportamento Animal/efeitos dos fármacos , Cromanos/farmacologia , Intoxicação por Manganês/tratamento farmacológico , Atividade Motora/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Fatores Etários , Animais , Animais Recém-Nascidos , Gânglios da Base/metabolismo , Gânglios da Base/fisiopatologia , Caspases/metabolismo , Modelos Animais de Doenças , Ativação Enzimática , Feminino , Masculino , Intoxicação por Manganês/etiologia , Intoxicação por Manganês/metabolismo , Intoxicação por Manganês/fisiopatologia , Intoxicação por Manganês/psicologia , Fosforilação , Ratos , Ratos Wistar , Teste de Desempenho do Rota-Rod , Transdução de Sinais/efeitos dos fármacos , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
BACKGROUND: Tuberculosis, caused by Mycobacterium tuberculosis or Mycobacterium bovis, remains one of the leading infectious diseases worldwide. The ability of mycobacteria to rapidly grow in host macrophages is a factor contributing to enhanced virulence of the bacteria and disease progression. Bactericidal functions of phagocytes are strictly dependent on activation status of these cells, regulated by the infecting agent and cytokines. Pathogenic mycobacteria can survive the hostile environment of the phagosome through interference with activation of bactericidal responses. To study the mechanisms employed by highly virulent mycobacteria to promote their intracellular survival, we investigated modulating effects of two pathogenic M. bovis isolates and a reference M. tuberculosis H37Rv strain, differing in their ability to multiply in macrophages, on activation phenotypes of the cells primed with major cytokines regulating proinflammatory macrophage activity. RESULTS: Bone marrow- derived macrophages obtained from C57BL/6 mice were infected by mycobacteria after a period of cell incubation with or without treatment with IFN-γ, inducing proinflammatory type-1 macrophages (M1), or IL-10, inducing anti-inflammatory type-2 cells (M2). Phenotypic profiling of M1 and M2 was then evaluated. The M. bovis strain MP287/03 was able to grow more efficiently in the untreated macrophages, compared with the strains B2 or H37Rv. This strain induced weaker secretion of proinflammatory cytokines, coinciding with higher expression of M2 cell markers, mannose receptor (MR) and arginase-1 (Arg-1). Treatment of macrophages with IFN-γ and infection by the strains B2 and H37Rv synergistically induced M1 polarization, leading to high levels of inducible nitric oxide synthase (iNOS) expression, and reduced expression of the Arg-1. In contrast, the cells infected with the strain MP287/03 expressed high levels of Arg-1 which competed with iNOS for the common substrate arginine, leading to lower levels of NO production. CONCLUSIONS: The data obtained demonstrated that the strain, characterized by increased growth in macrophages, down- modulated classical macrophage activation, through induction of an atypical mixed M1/M2 phenotype.
Assuntos
Ativação de Macrófagos , Macrófagos/imunologia , Macrófagos/microbiologia , Mycobacterium bovis/imunologia , Mycobacterium bovis/patogenicidade , Animais , Citocinas/biossíntese , Evasão da Resposta Imune , Camundongos , Camundongos Endogâmicos C57BL , Viabilidade Microbiana , Mycobacterium tuberculosis/imunologia , Mycobacterium tuberculosis/patogenicidade , Fagossomos/microbiologiaRESUMO
Manganese (Mn) is an essential metal for development and metabolism. However, exposures to high Mn levels may be toxic, especially to the central nervous system (CNS). Neurotoxicity is commonly due to occupational or environmental exposures leading to Mn accumulation in the basal ganglia and a Parkinsonian-like disorder. Younger individuals are more susceptible to Mn toxicity. Moreover, early exposure may represent a risk factor for the development of neurodegenerative diseases later in life. The present study was undertaken to investigate the developmental neurotoxicity in an in vivo model of immature rats exposed to Mn (5, 10 and 20 mg/kg; i.p.) from postnatal day 8 (PN8) to PN12. Neurochemical analysis was carried out on PN14. We focused on striatal alterations in intracellular signaling pathways, oxidative stress and cell death. Moreover, motor alterations as a result of early Mn exposure (PN8-12) were evaluated later in life at 3-, 4- and 5-weeks-of-age. Mn altered in a dose-dependent manner the activity of key cell signaling elements. Specifically, Mn increased the phosphorylation of DARPP-32-Thr-34, ERK1/2 and AKT. Additionally, Mn increased reactive oxygen species (ROS) production and caspase activity, and altered mitochondrial respiratory chain complexes I and II activities. Mn (10 and 20 mg/kg) also impaired motor coordination in the 3(rd), 4(th) and 5(th) week of life. Trolox™, an antioxidant, reversed several of the Mn altered parameters, including the increased ROS production and ERK1/2 phosphorylation. However, Trolox™ failed to reverse the Mn (20 mg/kg)-induced increase in AKT phosphorylation and motor deficits. Additionally, Mn (20 mg/kg) decreased the distance, speed and grooming frequency in an open field test; Trolox™ blocked only the decrease of grooming frequency. Taken together, these results establish that short-term exposure to Mn during a specific developmental window (PN8-12) induces metabolic and neurochemical alterations in the striatum that may modulate later-life behavioral changes. Furthermore, some of the molecular and behavioral events, which are perturbed by early Mn exposure are not directly related to the production of oxidative stress.