RESUMO
Methylmercury (MeHg) is a ubiquitous environmental neurotoxicant whose mechanisms of action involve oxidation of endogenous nucleophilic groups (mainly thiols and selenols), depletion of antioxidant defenses, and disruption of neurotransmitter homeostasis. Diphenyl diselenide-(PhSe)2-a model diaryl diselenide, has been reported to display significant protective effects against MeHg-induced neurotoxicity under both in vitro and in vivo experimental conditions. In this study, we compared the protective effects of (PhSe)2 with those of RC513 (4,4'-diselanediylbis(2,6-di-tert-butylphenol), a novel diselenide-probucol-analog) against MeHg-induced toxicity in the neuronal (hippocampal) cell line HT22. Although both (PhSe)2 and RC513 significantly mitigated MeHg- and tert-butylhydroperoxide (t-BuOOH)-cytotoxicity, the probucol analog exhibited superior protective effects, which were observed earlier and at lower concentrations compared to (PhSe)2. RC513 treatment (at either 0.5 µM or 2 µM) significantly increased glutathione peroxidase (GPx) activity, which has been reported to counteract MeHg-toxicity. (PhSe)2 was also able to increase GPx activity, but only at 2 µM. Although both compounds increased the Gpx1 transcripts at 6 h after treatments, only RC513 was able to increase mRNA levels of Prx2, Prx3, Prx5, and Txn2, which are also involved in peroxide detoxification. RC513 (at 2 µM) significantly increased GPx-1 protein expression in HT22 cells, although (PhSe)2 displayed a minor (nonsignificant) effect in this parameter. In agreement, RC513 induced a faster and superior capability to cope with exogenously-added peroxide (t-BuOOH). In summary, when compared to the prototypical organic diaryl diselenide [(PhSe)2], RC513 displayed superior protective properties against MeHg-toxicity in vitro; this was paralleled by a more pronounced upregulation of defenses related to detoxification of peroxides, which are well-known MeHg-derived intermediate oxidant species.
Assuntos
Compostos de Metilmercúrio , Compostos Organosselênicos , Derivados de Benzeno/farmacologia , Compostos de Metilmercúrio/toxicidade , Compostos Organosselênicos/farmacologia , Peróxidos , Probucol/farmacologiaRESUMO
Folic acid has been reported to exert antidepressant effects, but its ability to abrogate the depressive-like behavior and signaling pathways alterations elicited by an inflammatory model of depression remains to be established. This study examined: a) the efficacy of folic acid in a mouse model of depression induced by tumor necrosis factor (TNF-α); b) whether the administration of subthreshold doses of folic acid and antidepressants (fluoxetine, imipramine, and bupropion), MK-801, or 7-nitroindazole cause antidepressant-like effects; c) the effects of TNF-α and/or folic acid on hippocampal p38MAPK, Akt, ERK, and JNK phosphorylation. Folic acid reduced the immobility time in the tail suspension test (TST) in control mice (10-50 mg/kg, p.o) and abolished the depressive-like behavior elicited by TNF-α (0.001 fg/site, i.c.v.) in this test (1-50 mg/kg, p.o). Coadministration of subthreshold doses of folic acid (1 mg/kg, p.o.) and fluoxetine, imipramine, bupropion, MK-801, or 7-nitroindazole produced an antidepressant-like effect in mice exposed or not to TNF-α. TNF-α-treated mice presented increased p38MAPK phosphorylation and decreased Akt phosphorylation, and the later effect was prevented by folic acid (10 mg/kg, p.o.). Additionally, ERK1 phosphorylation was increased in mice treated with TNF-α + folic acid (1 mg/kg), but no effects on ERK2 or JNK1/2/3 phosphorylation were found in any group. The results indicate the efficacy of folic acid to counteract the depressive-like behavior induced by a pro-inflammatory cytokine, an effect that might be associated with the activation of monoaminergic systems, inhibition of N-methyl-d-aspartate (NMDA) receptors and nitric oxide (NO) synthesis, as well as Akt modulation.
Assuntos
Antidepressivos/farmacologia , Comportamento Animal/efeitos dos fármacos , Depressão/induzido quimicamente , Depressão/tratamento farmacológico , Depressão/metabolismo , Ácido Fólico/farmacologia , Fator de Necrose Tumoral alfa/farmacologia , Complexo Vitamínico B/farmacologia , Animais , Antidepressivos/administração & dosagem , Modelos Animais de Doenças , Feminino , Ácido Fólico/administração & dosagem , Camundongos , Complexo Vitamínico B/administração & dosagemRESUMO
Guanosine is a purine nucleoside that has been shown to exhibit antidepressant effects, but the mechanisms underlying its effect are not well established. We investigated if the antidepressant-like effect induced by guanosine in the tail suspension test (TST) in mice involves the modulation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor, voltage-dependent calcium channel (VDCC), and brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB) pathway. We also evaluated if the antidepressant-like effect of guanosine is accompanied by an acute increase in hippocampal and prefrontocortical BDNF levels. Additionally, we investigated if the ability of guanosine to elicit a fast behavioral response in the novelty suppressed feeding (NSF) test is associated with morphological changes related to hippocampal synaptogenesis. The antidepressant-like effect of guanosine (0.05 mg/kg, p.o.) in the TST was prevented by DNQX (AMPA receptor antagonist), verapamil (VDCC blocker), K-252a (TrkBantagonist), or BDNF antibody. Increased P70S6K phosphorylation and higher synapsin I immunocontent in the hippocampus, but not in the prefrontal cortex, were observed 1 h after guanosine administration. Guanosine exerted an antidepressant-like effect 1, 6, and 24 h after its administration, an effect accompanied by increased hippocampal BDNF level. In the prefrontal cortex, BDNF level was increased only 1 h after guanosine treatment. Finally, guanosine was effective in the NSF test (after 1 h) but caused no alterations in dendritic spine density and remodeling in the ventral dentate gyrus (DG). Altogether, the results indicate that guanosine modulates targets known to be implicated in fast antidepressant behavioral responses (AMPA receptor, VDCC, and TrkB/BDNF pathway).
Assuntos
Antidepressivos/farmacologia , Fator Neurotrófico Derivado do Encéfalo/efeitos dos fármacos , Guanosina/farmacologia , Glicoproteínas de Membrana/efeitos dos fármacos , Proteínas Tirosina Quinases/efeitos dos fármacos , Receptores de AMPA/agonistas , Transdução de Sinais/efeitos dos fármacos , Animais , Fator Neurotrófico Derivado do Encéfalo/biossíntese , Canais de Cálcio/efeitos dos fármacos , Espinhas Dendríticas/efeitos dos fármacos , Comportamento Alimentar/efeitos dos fármacos , Feminino , Elevação dos Membros Posteriores , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Glicoproteínas de Membrana/biossíntese , Camundongos , Neurogênese/efeitos dos fármacos , Córtex Pré-Frontal/efeitos dos fármacos , Córtex Pré-Frontal/metabolismo , Proteínas Tirosina Quinases/biossíntese , Sinapses/efeitos dos fármacosRESUMO
Fluoxetine is the foremost prescribed antidepressant. Drugs acting on monoaminergic system may also regulate glutamatergic system. Indeed, the investigation of proteins associated with this system, such as Narp (neuronal activity-dependent pentraxin) and GluA4 subunit of AMPA receptor may reveal poorly explored modulations triggered by conventional antidepressants. This study aimed to uncover neurochemical mechanisms underlying the chronic fluoxetine treatment, mainly by evaluating these protein targets in the prefrontal cortex and in the hippocampus. Mice received a daily administration of fluoxetine (0.1, 1 or 10 mg/kg, p.o.) or potable water (vehicle group) for 21 days. These animals were submitted to the forced swim test (FST) to verify antidepressant-like responses and the open-field test (OFT) to assess locomotor activity. Modulation of signaling proteins was analyzed by western blot. Chronic treatment with fluoxetine (1 and 10 mg/kg) was effective, since it reduced the immobility time in the FST, without altering locomotor activity. Fluoxetine 10 mg/kg increased CREB phosphorylation and BDNF expression in the prefrontal cortex and hippocampus. Noteworthy, in the hippocampus fluoxetine also promoted Akt activation and augmented Narp expression. In the prefrontal cortex, a significant decrease in the expression of the GluA4 subunit and Narp were observed following fluoxetine administration (10 mg/kg). The results provide evidence of novel molecular targets potentially involved in the antidepressant effects of fluoxetine, since in mature rodents Narp and GluA4 are mainly expressed in the GABAergic parvalbumin-positive (PV+) interneurons. This may bring new insights into the molecular elements involved in the mechanisms underlying the antidepressant effects of fluoxetine.
Assuntos
Antidepressivos de Segunda Geração/administração & dosagem , Proteína C-Reativa/antagonistas & inibidores , Sistemas de Liberação de Medicamentos/métodos , Fluoxetina/administração & dosagem , Proteínas do Tecido Nervoso/antagonistas & inibidores , Receptores de AMPA/antagonistas & inibidores , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Proteína C-Reativa/metabolismo , Relação Dose-Resposta a Droga , Masculino , Camundongos , Proteínas do Tecido Nervoso/metabolismo , Receptores de AMPA/metabolismoRESUMO
Glioblastoma multiforme is the most aggressive type of glioma, with limited treatment and poor prognosis. Despite some advances over the last decade, validation of novel and selective antiglioma agents remains a challenge in clinical pharmacology. Prior studies have shown that leguminous lectins may exert various biological effects, including antitumor properties. Accordingly, this study aimed to evaluate the mechanisms underlying the antiglioma activity of ConBr, a lectin extracted from the Canavalia brasiliensis seeds. ConBr at lower concentrations inhibited C6 glioma cell migration while higher levels promoted cell death dependent upon carbohydrate recognition domain (CRD) structure. ConBr increased p38MAPK and JNK and decreased ERK1/2 and Akt phosphorylation. Moreover, ConBr inhibited mTORC1 phosphorylation associated with accumulation of autophagic markers, such as acidic vacuoles and LC3 cleavage. Inhibition of early steps of autophagy with 3-methyl-adenine (3-MA) partially protected whereas the later autophagy inhibitor Chloroquine (CQ) had no protective effect upon ConBr cytotoxicity. ConBr also augmented caspase-3 activation without affecting mitochondrial function. Noteworthy, the caspase-8 inhibitor IETF-fmk attenuated ConBr induced autophagy and C6 glioma cell death. Finally, ConBr did not show cytotoxicity against primary astrocytes, suggesting a selective antiglioma activity. In summary, our results indicate that ConBr requires functional CRD lectin domain to exert antiglioma activity, and its cytotoxicity is associated with MAPKs and Akt pathways modulation and autophagy- and caspase-8- dependent cell death.
Assuntos
Antineoplásicos/farmacologia , Caspase 8/metabolismo , Ativação Enzimática/efeitos dos fármacos , Glioma/tratamento farmacológico , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Lectinas de Plantas/farmacologia , Animais , Apoptose/efeitos dos fármacos , Astrócitos/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Caspase 3/metabolismo , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Glioma/metabolismo , Glioma/patologia , Humanos , Camundongos , Mitocôndrias/efeitos dos fármacos , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Simulação de Acoplamento Molecular , Polissacarídeos/metabolismo , Domínios Proteicos/fisiologia , Estrutura Quaternária de Proteína/fisiologia , Estrutura Terciária de Proteína/fisiologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , RatosRESUMO
Lectins are a group of proteins of non-immune origin recognized for their ability to bind reversibly to carbohydrates. Researchers have been intrigued by oligosaccharides and glycoconjugates for their involvement as mediators of complex cellular events and then many biotechnological applications of lectins are based on glycocode decoding and their activities. Here, we report a structural and biological study of a ConA-like mannose/glucose-specific lectin from Canavalia bonariensis seeds, CaBo. More specifically, we evaluate the binding of CaBo with α-methyl-D-mannoside (MMA) and mannose-1,3-α-D-mannose (M13) and the resultant in vivo effects on a rat model of acute inflammation. A virtual screening was also carried out to cover a larger number of possible bindings of CaBo. In silico analysis demonstrated the stability of CaBo interaction with mannose-type ligands, and the lectin was able to induce acute inflammation in rats with the participation of the carbohydrate recognition domain (CRD) and histamine release. These results confirm the ability of CaBo to interact with hybrid and high-mannose N-glycans, supporting the hypothesis that CaBo's biological activity occurs primarily through its interaction with cell surface glycosylated receptors.
Assuntos
Carboidratos/química , Inflamação/tratamento farmacológico , Lectinas de Ligação a Manose/farmacologia , Lectinas de Plantas/farmacocinética , Animais , Sítios de Ligação , Histamina/farmacologia , Humanos , Inflamação/induzido quimicamente , Inflamação/patologia , Manose/química , Lectinas de Ligação a Manose/química , Manosídeos/química , Lectinas de Plantas/química , Lectinas de Plantas/farmacologia , Polissacarídeos/química , RatosRESUMO
Lectins from Diocleinae subtribe species (family Leguminosae) are of special interest since they present a wide spectrum of biological activities, despite their high structural similarity. During their synthesis in plant cells, these proteins undergo post-translational processing resulting in the formation of three chains (α, ß, γ), which constitute the lectins' subunits. Furthermore, such wild-type proteins are presented as isolectins or with different combinations of these chains, which undermine their biotechnological potential. Thus, the present study aimed to produce a recombinant form of the lectin from Dioclea sclerocarpa seeds (DSL), exclusively constituted by α-chain. The recombinant DSL (rDSL) was successfully expressed in E. coli BL21 (DE3) and purified by affinity chromatography (Sephadex G-50), showing a final yield of 74 mg of protein per liter of culture medium and specificity for D-mannose, α-methyl-mannoside and melibiose, unlike the wild-type protein. rDSL presented an effective vasorelaxant effect in rat aortas up to 100% and also interacted with glioma cells C6 and U87. Our results demonstrated an efficient recombinant production of rDSL in a bacterial system that retained some biochemical properties of the wild-type protein, showing wider versatility in sugar specificities and better efficacy in its activity in the biological models evaluated in this work.
Assuntos
Dioclea/química , Lectinas de Plantas/química , Animais , Aorta/efeitos dos fármacos , Linhagem Celular Tumoral , Cromatografia de Afinidade , Escherichia coli/genética , Escherichia coli/metabolismo , Glioma/metabolismo , Hemaglutinação , Manose/química , Lectinas de Plantas/metabolismo , Estrutura Secundária de Proteína , Ratos , Proteínas Recombinantes/análise , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/farmacologia , Sementes/química , Vasodilatadores/químicaRESUMO
Although guanosine is an endogenous nucleoside that displays antidepressant-like properties in several animal models, the mechanism underlying its antidepressant-like effects is not well characterized. The present study aimed at investigating the involvement of ERK/GSK-3ß and Nrf2/HO-1 signaling pathways in the antidepressant-like effect of guanosine in the mouse tail suspension test (TST). The immobility time in the TST was taken as an indicative of antidepressant-like responses and the locomotor activity was assessed in the open-field test. Biochemical analyses were performed by Western blotting in the hippocampus and prefrontal cortex (PFC). The combined treatment with sub-effective doses of guanosine (0.01 mg/kg, p.o.) and lithium chloride (a non-selective GSK-3ß inhibitor, 10 mg/kg, p.o.) or AR-A014418 (selective GSK-3ß inhibitor, 0.01 µg/site, i.c.v.) produced a synergistic antidepressant-like effect in the TST. The antidepressant-like effect of guanosine (0.05 mg/kg, p.o.) was completely prevented by the treatment with MEK1/2 inhibitors U0126 (5 µg/site, i.c.v.), PD98059 (5 µg/site, i.c.v.), or zinc protoporphyrin IX (ZnPP) (HO-1 inhibitor, 10 µg/site, i.c.v). Guanosine administration (0.05 mg/kg, p.o.) increased the immunocontent of ß-catenin in the nuclear fraction and Nrf2 in the cytosolic fraction in the hippocampus and PFC. The immunocontent of HO-1 was also increased in the hippocampus and PFC. Altogether, the results provide evidence that the antidepressant-like effect of guanosine in the TST involves the inhibition of GSK-3ß, as well as activation of MAPK/ERK and Nrf2/HO-1 signaling pathways, highlighting the relevance of these molecular targets for antidepressant responses.
Assuntos
Glicogênio Sintase Quinase 3 beta/efeitos dos fármacos , Guanosina/farmacologia , Heme Oxigenase-1/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Animais , Antidepressivos/farmacologia , Depressão/tratamento farmacológico , Depressão/metabolismo , Modelos Animais de Doenças , Comportamento Exploratório/efeitos dos fármacos , Feminino , Heme Oxigenase-1/metabolismo , Elevação dos Membros Posteriores/métodos , Hipocampo/metabolismo , Masculino , Ratos Wistar , Transdução de Sinais/fisiologiaRESUMO
Neuronal hippocampal death can be induced by exacerbated levels of cortisol, a condition usually observed in patients with Major depressive disorder (MDD). Previous in vitro and in vivo studies showed that ursolic acid (UA) elicits antidepressant and neuroprotective properties. However, the protective effects of UA against glucocorticoid-induced cytotoxicity have never been addressed. Using an in vitro model of hippocampal cellular death induced by elevated levels of corticosterone, we investigated if UA prevents corticosterone-induced cytotoxicity in HT22 mouse hippocampal derived cells. Concentrations lower than 25 µM UA did not alter cell viability. Co-incubation with UA for 48 h was able to protect HT22 cells from the reduction on cell viability and from the increase in apoptotic cells induced by corticosterone. Inhibition of protein kinase A (PKA), protein kinase C (PKC) and, Ca2+/calmodulin-dependent protein kinase II (CaMKII), but not phosphoinositide 3-kinase(PI3K), by using the pharmacological the inhibitors: H-89, chelerythrine, KN-62, and LY294002, respectively totally abolished the cytoprotective effects of UA. Finally, UA abrogated the reduction in phospho-extracellular signal-regulated kinases 1 and 2 (ERK1/2) but not in phospho-c-Jun kinases induced by corticosterone. These results indicate that the protective effect of UA against the cytotoxicity induced by corticosterone in HT22 cells may involve PKA, PKC, CaMKII, and ERK1/2 activation. The cytoprotective potential of UA against corticosterone-induced cytotoxicity and its ability to modulate intracellular signaling pathways involved in cell proliferation and survival suggest that UA may be a relevant strategy to manage stress-related disorders such as MDD.
RESUMO
The antitumor activity of DVL, a lectin purified from Dioclea violacea seeds, on the U87 human glioma cell line was evaluated and compared with Canavalia ensiformis lectin (ConA). Treatment with DVL (10-100⯵g/mL; 24-96â¯h) induced alterations in cell morphology, decreased cell numbers and clonogenic survival in a time- and concentration-dependent manner. DVL caused significant decreases in cell viability and impaired cell migration. Mechanistically, DVL treatment (12â¯h) disrupted mitochondrial electrochemical gradient, without ROS accumulation or caspase activation. In the absence of apoptosis, DVL (30-100⯵g/mL), instead, induced autophagy, as detected by acridine orange staining and cleavage of LC3I. Inhibition of autophagy with 3-Methyladenine (3-MA) and Chloroquine partially abrogated DVL, but not ConA, cytotoxicity. The modulation of signaling pathways that orchestrate autophagic and cell survival processes were analyzed. DVL (30-100⯵g/mL) decreased Akt, mTORC1 and ERK1/2 phosphorylation and augmented JNK(p54) and p38MAPK phosphorylation. DVL was more potent than ConA for most parameters analyzed. Even though both lectins showed cytotoxicity to glioma cells, they spared primary astrocyte cultures. The results suggest a selective antiglioma activity of DVL by inhibiting U87 glioma cell migration and proliferation and inducing cell death, partially associated with autophagy, and likely involving Akt and mTORC1 dephosphorylation.
Assuntos
Autofagia/efeitos dos fármacos , Dioclea/química , Lectinas de Plantas/farmacologia , Animais , Astrócitos/efeitos dos fármacos , Astrócitos/metabolismo , Caspase 3/metabolismo , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Glioma/genética , Glioma/metabolismo , Humanos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias/metabolismo , Lectinas de Plantas/química , Lectinas de Plantas/isolamento & purificação , Ratos , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
Plant lectins have been studied owing to their structural properties and biological effects that include agglutinating activity, antidepressant-like effect and antitumor property. The results from this work showed the effects of the lectin extracted from the Dioclea violacea plant (DVL) on the C6 rat glioma cell line. DVL treatment was able to induce caspase-3 activation, apoptotic cell death and cellular membrane damage. Furthermore, DVL decreased mitochondrial membrane potential and increased the number of acidic vesicles and cleavage of LC3, indicating activation of autophagic processes. DVL also significantly inhibited cell migration. Compared to ConA, a well-studied lectin extracted from Canavalia ensiformes seeds, some effects of DVL were more potent, including decreasing C6 glioma cell viability and migration ability. Taken together, the results suggest that DVL can induce glioma cell death, autophagy and inhibition of cell migration, displaying potential anti-glioma activity.
Assuntos
Autofagia/efeitos dos fármacos , Dioclea/química , Expressão Gênica/efeitos dos fármacos , Neuroglia/efeitos dos fármacos , Lectinas de Plantas/farmacologia , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Autofagia/genética , Canavalia/química , Caspase 3/genética , Caspase 3/metabolismo , Ciclo Celular/efeitos dos fármacos , Ciclo Celular/genética , Linhagem Celular Tumoral , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Membrana Celular/ultraestrutura , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Concanavalina A/isolamento & purificação , Concanavalina A/farmacologia , L-Lactato Desidrogenase/metabolismo , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Neuroglia/metabolismo , Neuroglia/patologia , Lectinas de Plantas/isolamento & purificação , RatosRESUMO
Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is one of the most robust neurobiological findings in the pathophysiology of major depressive disorder (MDD) over the last 40 years. The persistent increase in glucocorticoids levels induces morphological and anatomical changes in the brain, especially in the hippocampus. Ketamine represents a major advance for the treatment of MDD, however the psychotomimetic effects of this compound limit its widespread use. Agmatine is a neuromodulator that has been shown to be a putative novel and well-tolerated antidepressant/augmenter drug. In this study, the exposure of HT22 hippocampal neuronal cell line to corticosterone (50⯵M) induced a significant neuronal cell death. Interestingly, the incubation of HT22 cells with the fast-acting antidepressant drug ketamine (1⯵M) prevented the corticosterone-induced toxicity. Similarly, agmatine caused a significant cytoprotection at the concentration of 0.1⯵M against corticosterone (50⯵M) cell damage. Notably, the incubation with a subthreshold concentration of ketamine (0.01⯵M) in combination with a subthreshold concentration of agmatine (0.001⯵M) prevented the neuronal damage elicited by corticosterone (50⯵M). A 24â¯h co-incubation with subthreshold concentrations of ketamine (0.01⯵M) and agmatine (0.001⯵M) was able to cause a significant increase in the phosphorylation levels of Akt (Ser473) and p70S6 kinase (Thr389) as well as PSD95 immunocontent. Neither glycogen synthase kinase-3ß (Ser9) phosphorylation nor ß catenin immunocontent were altered by a 24â¯h co-incubation period. Finally, the co-incubation of cells for 30â¯min did not produce any effect in the phosphorylation or immunocontent of any protein investigated. Taken together, our results support the notion that the combination of subthreshold concentrations of ketamine and agmatine has cytoprotective effects against corticosterone-induced cell death. This effect is accompanied by its ability to activate Akt and mTOR/S6 kinase signaling pathway, and increase the expression of synaptic proteins.
Assuntos
Agmatina/administração & dosagem , Ketamina/administração & dosagem , Fármacos Neuroprotetores/administração & dosagem , Proteínas Quinases S6 Ribossômicas/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Analgésicos/administração & dosagem , Animais , Morte Celular/efeitos dos fármacos , Morte Celular/fisiologia , Linhagem Celular Transformada , Corticosterona/toxicidade , Relação Dose-Resposta a Droga , Sinergismo Farmacológico , Camundongos , Transdução de Sinais/efeitos dos fármacosRESUMO
N-methyl D-aspartate (NMDA) preconditioning is evoked by the administration of a subtoxic dose of NMDA and is protective against neuronal excitotoxicity. This effect may involve a diversity of targets and cell signaling cascades associated to neuroprotection. Phosphatidylinositol-3 kinase/protein kinase B (PI3K/Akt) and mitogen-activated protein kinases (MAPKs) such as extracellular regulated protein kinase 1/2 (ERK1/2) and p38MAPK pathways play a major role in neuroprotective mechanisms. However, their involvement in NMDA preconditioning was not yet fully investigated. The present study aimed to evaluate the effect of NMDA preconditioning on PI3K/Akt, ERK1/2, and p38MAPK pathways in the hippocampus of mice and characterize the involvement of PI3K on NMDA preconditioning-evoked prevention of seizures and hippocampal cell damage induced by quinolinic acid (QA). Thus, mice received wortmannin (a PI3K inhibitor) and 15 min later a subconvulsant dose of NMDA (preconditioning) or saline. After 24 h of this treatment, an intracerebroventricular QA infusion was administered. Phosphorylation levels and total content of Akt, glycogen synthase protein kinase-3ß (GSK-3ß), ERK1/2, and p38MAPK were not altered after 24 h of NMDA preconditioning with or without wortmmanin pretreatment. Moreover, after QA administration, behavioral seizures, hippocampal neuronal degeneration, and Akt activation were evaluated. Inhibition of PI3K pathway was effective in abolishing the protective effect of NMDA preconditioning against QA-induced seizures, but did not modify neuronal protection promoted by preconditioning as evaluated by Fluoro-Jade B staining. The study confirms that PI3K participates in the mechanism of protection induced by NMDA preconditioning against QA-induced seizures. Conversely, NMDA preconditioning-evoked protection against neuronal degeneration is not altered by PI3K signaling pathway inhibition. These results point to differential mechanisms regarding protection against a behavioral and cellular manifestation of neural damage.
Assuntos
Agonistas de Aminoácidos Excitatórios/administração & dosagem , Hipocampo/patologia , N-Metilaspartato/administração & dosagem , Doenças Neurodegenerativas/induzido quimicamente , Fosfatidilinositol 3-Quinase/metabolismo , Ácido Quinolínico/toxicidade , Transdução de Sinais/efeitos dos fármacos , Animais , Modelos Animais de Doenças , Esquema de Medicação , Inibidores Enzimáticos/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Masculino , Camundongos , Doenças Neurodegenerativas/patologia , Neurônios/efeitos dos fármacos , Neurônios/patologia , Fatores de TempoRESUMO
Agmatine is an endogenous neuromodulator that has been shown to have antidepressant-like properties. We have previously demonstrated that it can induce a rapid increase in BDNF levels after acute administration, suggesting that agmatine may be a fast-acting antidepressant. To investigate this hypothesis, the present study evaluated the effects of a single administration of agmatine in mice subjected to chronic unpredictable stress (CUS), a model of depression responsive only to chronic treatment with conventional antidepressants. The ability of agmatine to reverse CUS-induced behavioral and biochemical alterations was evaluated and compared with those elicited by the fast-acting antidepressant (ketamine) and the conventional antidepressant (fluoxetine). After exposed to CUS for 14days, mice received a single oral dose of agmatine (0.1mg/kg), ketamine (1mg/kg) or fluoxetine (10mg/kg), and were submitted to behavioral evaluation after 24h. The exposure to CUS caused an increased immobility time in the tail suspension test (TST) but did not change anhedonic-related parameters in the splash test. Our findings provided evidence that, similarly to ketamine, agmatine is able to reverse CUS-induced depressive-like behavior in the TST. Western blot analyses of prefrontal cortex (PFC) demonstrated that mice exposed to CUS and/or treated with agmatine, fluoxetine or ketamine did not present alterations in the immunocontent of synaptic proteins [i.e. GluA1, postsynaptic density protein 95 (PSD-95) and synapsin]. Altogether, our findings indicate that a single administration of agmatine is able to reverse behavioral alterations induced by CUS in the TST, suggesting that this compound may have fast-acting antidepressant-like properties. However, there was no alteration in the levels of synaptic proteins in the PFC, a result that need to be further investigated in other time points.
Assuntos
Agmatina/farmacologia , Antidepressivos/farmacologia , Transtorno Depressivo/tratamento farmacológico , Ketamina/farmacologia , Estresse Psicológico/complicações , Animais , Feminino , Elevação dos Membros Posteriores , Camundongos , Atividade Motora/efeitos dos fármacos , Córtex Pré-Frontal/químicaRESUMO
Carboxypeptidase A6 (CPA6) is an extracellular matrix metallocarboxypeptidase that modulates peptide and protein function by removal of hydrophobic C-terminal amino acids. Mutations in the human CPA6 gene that reduce enzymatic activity in the extracellular matrix are associated with febrile seizures, temporal lobe epilepsy, and juvenile myoclonic epilepsy. The characterization of these human mutations suggests a dominant mode of inheritance by haploinsufficiency through loss of function mutations, however the total number of humans with pathologic mutations in CPA6 identified to date remains small. To better understand the relationship between CPA6 and seizures we investigated the effects of morpholino knockdown of cpa6 mRNA in zebrafish (Danio rerio) larvae. Knockdown of cpa6 mRNA resulted in resistance to the effect of seizure-inducing drugs pentylenetetrazole and pilocarpine on swimming behaviors. Knockdown of cpa6 mRNA also reduced the levels of mRNAs encoding neuropeptide precursors (bdnf, npy, chga, pcsk1nl, tac1, nts, edn1), a neuropeptide processing enzyme (cpe), transcription factor (c-fos), and molecules implicated in glutamatergic signaling (grin1a and slc1a2b). Treatment of zebrafish embryos with 60 mM pilocarpine for 1 hour led to reductions in levels of many of the same mRNAs when measured 1 day after pilocarpine exposure, except for c-fos which was elevated 1 day after pilocarpine treatment. Pilocarpine treatment, like cpa6 knockdown, led to a reduced sensitivity to pentylenetetrazole when tested 1 day after pilocarpine treatment. Taken together, these results add to mounting evidence that peptidergic systems participate in the biological effects of seizure-inducing drugs, and are the first in vivo demonstration of the molecular and behavioral consequences of cpa6 insufficiency.
Assuntos
Carboxipeptidases A/genética , Técnicas de Silenciamento de Genes , Larva/enzimologia , Proteínas de Peixe-Zebra/genética , Peixe-Zebra/crescimento & desenvolvimento , Animais , Convulsivantes/administração & dosagem , Mutação , Pilocarpina/administração & dosagem , RNA Mensageiro/genética , Transcrição Gênica , Peixe-Zebra/embriologiaRESUMO
Creatine has been proposed to exert beneficial effects in the management of depression, but the cell signaling pathways implicated in its antidepressant effects are not well established. This study investigated the involvement of PI3K/Akt signaling pathway and its downstream intracellular targets in the antidepressant-like effect of creatine. The acute treatment of mice with creatine (1 mg/kg, po) increased the Akt and P70S6K phosphorylation, and HO-1, GPx and PSD95 immunocontents. The pretreatment of mice with LY294002 (10 nmol/mouse, icv, PI3K inhibitor), wortmannin (0.1 µg/mouse, icv, PI3K inhibitor), ZnPP (10 µg/mouse, icv, HO-1 inhibitor), or rapamycin (0.2 nmol/mouse, icv, mTOR inhibitor) prevented the antidepressant-like effect of creatine (1 mg/kg, po) in the TST. In addition, the administration of subeffective dose of either the selective GSK3 inhibitor AR-A014418 (0.01 µg/mouse, icv), the nonselective GSK3 inhibitor lithium chloride (10 mg/kg, po), or the HO-1 inductor CoPP (0.01 µg/mouse, icv), in combination with a subeffective dose of creatine (0.01 mg/kg, po) reduced the immobility time in the TST as compared with either drug alone. No treatment caused significant changes in the locomotor activity of mice. These results indicate that the antidepressant-like effect of creatine in the TST depends on the activation of Akt, Nrf2/HO-1, GPx, and mTOR, and GSK3 inhibition.
Assuntos
Antidepressivos/farmacologia , Creatina/farmacologia , Espaço Intracelular/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Animais , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Proteína 4 Homóloga a Disks-Large/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Quinase 3 da Glicogênio Sintase/antagonistas & inibidores , Quinase 3 da Glicogênio Sintase/metabolismo , Heme Oxigenase-1/metabolismo , Hipocampo/metabolismo , Masculino , Camundongos , Fosforilação/efeitos dos fármacos , Proteína Quinase C/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Proteínas Quinases S6 Ribossômicas 70-kDa/metabolismo , Transdução de Sinais/efeitos dos fármacos , Especificidade por Substrato/efeitos dos fármacos , Serina-Treonina Quinases TOR/metabolismoRESUMO
Mitogen-activated protein kinases (MAPKs) are a group of serine-threonine kinases, including p38(MAPK), ERK 1/2 and JNK p54/p46, activated by phosphorylation in response to extracellular stimuli. The early postnatal period is characterized by significant changes in brain structure as well as intracellular signaling. In the hippocampus MAPKs have been involved in the modulation of development and neural plasticity. However, the temporal profile of MAPK activation throughout the early postnatal development is incomplete. An understanding of this profile is important since slight changes in the activity of these enzymes, in response to environmental stress in specific developmental windows, might alter the course of development. The present study was undertaken to investigate the hippocampal differential activation of MAPK during postnatal period. MAPK activation and total content were evaluated by Western blotting of hippocampal tissue obtained from male Wistar rats at postnatal days (P) 1, 4, 7, 10, 14, 21, 30 and 60. The total content and phosphorylation of each MAPK was expressed as mean ± SEM and then calculates as a percentile compared to P1 (set at 100 %). The results showed: (1) phosphorylation peaks of p38(MAPK) at PN4 (p = 0.036) and PN10 to PN60; (2) phosphorylation of ERK1 and ERK2 were increased with age (ERK1 p = 0.0000005 and ERK2 p = 0.003); (3) phosphorylation profile of JNK p54/p46 was not changed during the period analyzed (JNKp56 p = 0.716 and JNKp46 p = 0.192). Therefore, the activity profile of ERK 1/2 and p38(MAPK) during postnatal development of rat hippocampus are differentially regulated. Our results demonstrate that ERK 1/2 and p38(MAPK) are dynamically regulated during postnatal neurodevelopment, suggesting temporal correlation of MAPK activity with critical periods when programmed cell death and synaptogenesis are occurring. This suggests an important role for these MAPKs in postnatal development of rat hippocampus.
Assuntos
Hipocampo/enzimologia , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo , Animais , Animais Recém-Nascidos , Ativação Enzimática , Hipocampo/crescimento & desenvolvimento , Isoenzimas/metabolismo , Masculino , Fosforilação , Ratos WistarRESUMO
Considering that intracellular signaling pathways that modulate brain BDNF are implicated in antidepressant responses, this study investigated whether signaling pathway inhibitors upstream to BDNF might influence the antidepressant-like effect of zinc, a metal that has been shown to display antidepressant properties. To this end, the influence of i.c.v. administration of H-89 (1µg/site, PKA inhibitor), KN-62 (1µg/site, CAMKII inhibitor), chelerythrine (1µg/site, PKC inhibitor), PD98059 (5µg/site, MEK1/2 inhibitor), U0126 (5µg/site, MEK1/2 inhibitor), LY294002 (10nmol/site, PI3K inhibitor) on the reduction of immobility time in the tail suspension test (TST) elicited by ZnCl2 (10mg/kg, p.o.) was investigated. Moreover, the effect of the combination of sub-effective doses of ZnCl2 (1mg/kg, p.o.) and AR-A014418 (0.001µg/site, GSK-3ß inhibitor) was evaluated. The occurrence of changes in CREB phosphorylation and BDNF immunocontent in the hippocampus and prefrontal cortex of mice following ZnCl2 treatment was also investigated. The anti-immobility effect of ZnCl2 in the TST was prevented by treatment with PKA, PKC, CAMKII, MEK1/2 or PI3K inhibitors. Furthermore, ZnCl2 in combination with AR-A014418 caused a synergistic anti-immobility effect in the TST. None of the treatments altered locomotor activity of mice. ZnCl2 treatment caused no alteration in CREB phosphorylation and BDNF immunocontent. The results extend literature data regarding the mechanisms underlying the antidepressant-like action of zinc by indicating that its antidepressant-like effect may be dependent on the activation of PKA, CAMKII, PKC, ERK, and PI3K/GSK-3ß pathways. However, zinc is not able to acutely increase BDNF in the hippocampus and prefrontal cortex.
Assuntos
Antidepressivos/uso terapêutico , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Cloretos/uso terapêutico , Depressão/tratamento farmacológico , Transdução de Sinais/fisiologia , Compostos de Zinco/uso terapêutico , Animais , Antidepressivos/farmacologia , Proteína de Ligação a CREB/metabolismo , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Cloretos/farmacologia , Depressão/patologia , Depressão/fisiopatologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/farmacologia , Comportamento Exploratório/efeitos dos fármacos , Feminino , Elevação dos Membros Posteriores , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Camundongos , Fosforilação/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Estatísticas não Paramétricas , Compostos de Zinco/farmacologiaRESUMO
In the central nervous system, many receptors, ion channels and neurotransmitter transporters are glycoproteins, where the glycan chains are modulator elements. Lectins are proteins, which recognize and bind carbohydrate complexes. We have previously shown that ConBr, a lectin purified from Canavalia brasiliensis seeds, produced antidepressant-like effect and blocked hippocampal neurotoxicity induced by quinolinic acid and glutamate. Noteworthy, all these effects occurred in a dependence of its carbohydrate recognition domain. Therefore, the present study was undertaken in order to elucidate intracellular signaling pathways regulated by ConBr that may be potentially associated with the antidepressant and neuroprotective effects previously reported to be dependent on carbohydrate interaction. ConBr (10 µg/site) was injected into the ventricle (i.c.v.) of mice, and the hippocampi were removed 0.5, 1, 3, 6, 8, 12, 18, and 24 h after treatment. Our results showed that in the period of 0.5-3 h, ConBr induced activation of the protein kinases Akt, ERK1, and PKA. Furthermore, the phosphorylation of CREB-Ser133 was stimulated by ConBr (1-6 h), while brain-derived neurotrophic factor (BDNF) mRNA was increased at 12 h and BDNF protein at 18-24 h. Our data suggest that an early activation of protein kinases may trigger CREB-dependent BDNF transcription, resulting in a subsequent increase of BDNF protein in response to ConBr. Later, increment of Akt phosphorylation was observed 24 h after ConBr administration, possibly due to BDNF/TrkB-dependent activation of Akt. Our findings indicate that ConBr is a multifunctional molecule capable to activate signaling pathways involved in neuroplasticity and neuroprotection.
Assuntos
Fator Neurotrófico Derivado do Encéfalo/genética , Canavalia/química , Lectinas de Plantas/farmacologia , Sementes/química , Transdução de Sinais/efeitos dos fármacos , Animais , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Glicosilação/efeitos dos fármacos , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Injeções Intraventriculares , Masculino , Camundongos , Modelos Biológicos , Fosforilação/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Fatores de TempoRESUMO
Agmatine is an endogenous neuromodulator which, based on animal and human studies, is a putative novel antidepressant drug. In this study, we investigated the ability of sub-chronic (21 days) p.o. agmatine administration to produce an antidepressant-like effect in the tail suspension test and examined the hippocampal cell signaling pathways implicated in such an effect. Agmatine at doses of 0.01 and 0.1 mg/kg (p.o.) produced a significant antidepressant-like effect in the tail suspension test and no effect in the open-field test. Additionally, agmatine (0.001-0.1 mg/kg, p.o.) increased the phosphorylation of protein kinase A substrates (237-258% of control), protein kinase B/Akt (Ser(473)) (116-127% of control), glycogen synthase kinase-3ß (Ser(9)) (110-113% of control), extracellular signal-regulated kinases 1/2 (119-137% and 121-138% of control, respectively) and cAMP response elements (Ser(133)) (127-152% of control), and brain-derived-neurotrophic factor (137-175% of control) immunocontent in a dose-dependent manner in the hippocampus. Agmatine (0.001-0.1 mg/kg, p.o.) also reduced the c-jun N-terminal kinase 1/2 phosphorylation (77-71% and 65-51% of control, respectively). Neither protein kinase C nor p38(MAPK) phosphorylation was altered under any experimental conditions. Taken together, the present study extends the available data on the mechanisms that underlie the antidepressant action of agmatine by showing an antidepressant-like effect following sub-chronic administration. In addition, our results are the first to demonstrate the ability of agmatine to elicit the activation of cellular signaling pathways associated with neuroplasticity/cell survival and the inhibition of signaling pathways associated with cell death in the hippocampus.