RESUMO
Chronic consumption of hyperpalatable and hypercaloric foods has been pointed out as a factor associated with cognitive decline and memory impairment in obesity. In this context, the integration between peripheral and central inflammation may play a significant role in the negative effects of an obesogenic environment on memory. However, little is known about how obesity-related peripheral inflammation affects specific neurotransmission systems involved with memory regulation. Here, we test the hypothesis that chronic exposure to a highly palatable diet may cause neuroinflammation, glutamatergic dysfunction, and memory impairment. For that, we exposed C57BL/6J mice to a high sugar and butter diet (HSB) for 12 weeks, and we investigated its effects on behavior, glial reactivity, blood-brain barrier permeability, pro-inflammatory features, glutamatergic alterations, plasticity, and fractalkine-CX3CR1 axis. Our results revealed that HSB diet induced a decrease in memory reconsolidation and extinction, as well as an increase in hippocampal glutamate levels. Although our data indicated a peripheral pro-inflammatory profile, we did not observe hippocampal neuroinflammatory features. Furthermore, we also observed that the HSB diet increased hippocampal fractalkine levels, a key chemokine associated with neuroprotection and inflammatory regulation. Then, we hypothesized that the elevation on glutamate levels may saturate synaptic communication, partially limiting plasticity, whereas fractalkine levels increase as a strategy to decrease glutamatergic damage.
Assuntos
Quimiocina CX3CL1 , Hipocampo , Animais , Camundongos , Quimiocina CX3CL1/metabolismo , Dieta Hiperlipídica/efeitos adversos , Hipocampo/metabolismo , Inflamação/complicações , Camundongos Endogâmicos C57BL , Obesidade/complicações , Fármacos Atuantes sobre Aminoácidos ExcitatóriosRESUMO
The treatment of major depressive disorder (MDD) is still a challenge. In the search for novel antidepressants, glutamatergic neuromodulators have been investigated as possible fast-acting antidepressants. Innovative studies suggest that the purine cycle and/or the purinergic signaling can be dysregulated in MDD, and the endogenous nucleoside guanosine has gained attention due to its extracellular effects. This study aimed to verify if guanosine produces fast-onset effects in the well-validated, reliable and sensitive olfactory bulbectomy (OBX) model of depression. The involvement of the mTOR pathway, a key target for the fast-onset effect of ketamine, was also investigated. Results show that a single i.p. injection of guanosine, or ketamine, completely reversed the OBX-induced anhedonic-like behavior 24 or 48 h post treatment, as well as the short-term recognition memory impairment 48 h post treatment. The antidepressant-like effects of guanosine and ketamine were completely abolished by rapamycin. This study shows, for the first time, that guanosine, in a way similar to ketamine, is able to elicit a fast antidepressant response in the OBX model in mice. The results support the notion that guanosine represents a new road for therapeutic improvement in MDD.
Assuntos
Antidepressivos/farmacologia , Transtorno Depressivo Maior/tratamento farmacológico , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , Guanosina/farmacologia , Anedonia/efeitos dos fármacos , Animais , Antidepressivos/efeitos adversos , Comportamento Animal/efeitos dos fármacos , Modelos Animais de Doenças , Guanosina/efeitos adversos , Ketamina/farmacologia , Masculino , Transtornos da Memória/induzido quimicamente , Camundongos , Camundongos Endogâmicos C57BL , Bulbo Olfatório/cirurgia , Serina-Treonina Quinases TOR/metabolismoRESUMO
We examined effects of Group I metabotropic glutamate receptors on the excitability of mouse medial nucleus of the trapezoid body (MNTB) neurons. The selective agonist, S-3,5-dihydroxyphenylglycine (DHPG), evoked a dose-dependent depolarization of the resting potential, increased membrane resistance, increased sag depolarization, and promoted rebound action potential firing. Under voltage-clamp, DHPG evoked an inward current, referred to as IDHPG , which was developmentally stable through postnatal day P56. IDHPG had low temperature dependence in the range 25-34°C, consistent with a channel mechanism. However, the I-V relationship took the form of an inverted U that did not reverse at the calculated Nernst potential for K+ or Cl- . Thus, it is likely that more than one ion type contributes to IDHPG and the mix may be voltage dependent. IDHPG was resistant to the Na+ channel blockers tetrodotoxin and amiloride, and to inhibitors of iGluR (CNQX and MK801). IDHPG was inhibited 21% by Ba2+ (500 µM), 60% by ZD7288 (100 µM) and 73% when the two antagonists were applied together, suggesting that KIR channels and HCN channels contribute to the current. Voltage clamp measurements of IH indicated a small (6%) increase in Gmax by DHPG with no change in the voltage dependence. DHPG reduced action potential rheobase and reduced the number of post-synaptic AP failures during high frequency stimulation of the calyx of Held. Thus, activation of post-synaptic Group I mGlu receptors modifies the excitability of MNTB neurons and contributes to the reliability of high frequency firing in this auditory relay nucleus.
Assuntos
Potenciais de Ação , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , Receptores de Glutamato Metabotrópico/metabolismo , Potenciais Sinápticos , Corpo Trapezoide/metabolismo , 6-Ciano-7-nitroquinoxalina-2,3-diona/farmacologia , Amilorida/farmacologia , Animais , Maleato de Dizocilpina/farmacologia , Feminino , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização/antagonistas & inibidores , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização/metabolismo , Masculino , Metoxi-Hidroxifenilglicol/análogos & derivados , Metoxi-Hidroxifenilglicol/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/fisiologia , Bloqueadores dos Canais de Potássio/farmacologia , Canais de Potássio Corretores do Fluxo de Internalização/antagonistas & inibidores , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Pirimidinas/farmacologia , Receptores de Glutamato Metabotrópico/agonistas , Receptores de Glutamato Metabotrópico/antagonistas & inibidores , Bloqueadores dos Canais de Sódio/farmacologia , Tetrodotoxina/farmacologia , Corpo Trapezoide/citologia , Corpo Trapezoide/efeitos dos fármacos , Corpo Trapezoide/fisiologiaRESUMO
The function of synaptic vesicle protein 2A (SV2A) has not been clearly identified, although it has an essential role in normal neurotransmission. Changes in SV2A expression have been linked to several diseases that could implicate an imbalance between excitation and inhibition, such as epilepsy. Although it is known that SV2A expression is necessary for survival, SV2A expression and its relationship with γ-aminobutyric acid (GABA) and glutamate neurotransmitter systems along development has not been addressed. This report follows SV2A expression levels in the rat hippocampus and their association with glutamatergic and GABAergic terminals along postnatal development. Total SV2A expression was assessed by real time PCR and western blot, while immunofluorescence was used to identify SV2A protein in the different hippocampal layers and its co-localization with GABA or glutamate vesicular transporters. SV2A was dynamically regulated along development and its association with GABA or glutamate transporters varied in the different hippocampal layers. In the principal cells layers (granular and pyramidal), SV2A protein was preferentially localized to GABAergic terminals, while in the hilus and stratum lucidum SV2A was associated mainly to glutamatergic terminals. Although SV2A was ubiquitously expressed in the entire hippocampus, it established a differential association with excitatory or inhibitory terminals, which could contribute to the maturation of excitatory/inhibitory balance.
Assuntos
Hipocampo/crescimento & desenvolvimento , Hipocampo/metabolismo , Glicoproteínas de Membrana/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Animais , Fármacos Atuantes sobre Aminoácidos Excitatórios/metabolismo , Neurônios GABAérgicos/metabolismo , Regulação da Expressão Gênica/genética , Ácido Glutâmico/metabolismo , Masculino , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/fisiologia , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/fisiologia , Período Pós-Parto/fisiologia , Terminações Pré-Sinápticas/metabolismo , Células Piramidais/metabolismo , Ratos , Ratos Sprague-Dawley , Transmissão Sináptica/fisiologia , Vesículas Sinápticas/metabolismo , Ácido gama-Aminobutírico/metabolismoRESUMO
The venom of Phoneutria nigriventer spider is a source of numerous bioactive substances, including some toxins active in insects. An example is PnTx4(5-5) that shows a high insecticidal activity and no apparent toxicity to mice, although it inhibited NMDA-evoked currents in rat hippocampal neurons. In this work the analgesic activity of PnTx4(5-5) (renamed Γ-ctenitoxin-Pn1a) was investigated. Methods: The antinociceptive activity was evaluated using the paw pressure test in rats, after hyperalgesia induction with intraplantar injection of carrageenan or prostaglandin E2 (PGE2). Results: PnTx4(5-5), subcutaneously injected, was able to reduce the hyperalgesia induced by PGE2 in rat paw, demonstrating a systemic effect. PnTx4(5-5) administered in the plantar surface of the paw caused a peripheral and dose-dependent antinociceptive effect on hyperalgesia induced by carrageenan or PGE2. The hyperalgesic effect observed in these two pain models was completely reversed with 5 µg of PnTx4(5-5). Intraplantar administration of L-glutamate induced hyperalgesic effect that was significantly reverted by 5 μg of PnTx4(5-5) injection in rat paw. Conclusion: The antinociceptive effect for PnTx4(5-5) was demonstrated against different rat pain models, i.e. induced by PGE2, carrageenan or glutamate. We suggest that the antinociceptive effect of PnTx4(5-5) may be related to an inhibitory activity on the glutamatergic system.(AU)
Assuntos
Venenos de Aranha , Dinoprostona , Fármacos Atuantes sobre Aminoácidos Excitatórios , Analgésicos/síntese químicaRESUMO
Neem fruit (Azadirachta indica A. Juss.) are popularly used to treat infections, diarrhea, fever, bronchitis, skin diseases, infected burns and hypertension. Although the antinociceptive and anti-inflammatory potential of A. indica has already been investigated in experimental models of pain and inflammation in mice, the current research is the first to report the evaluation of the capacity of A. indica fruit ethanolic extract (EtFrNeem) in acute pain attenuation using the adult zebrafish (Danio rerio) as an alternative model to the use in rodents. EtFrNeem was submitted to antioxidant action, preliminary chemical prospecting, FT-IR and determination of phenol and flavonoid content tests. Subsequently, EtFrNeem was tested for acute nociception and abdominal inflammation, locomotor activity, and acute toxicity in adult zebrafish. Possible neuromodulation mechanisms were also evaluated. EtFrNeem showed low antioxidant activity, but was shown to be rich in flavonoids. EtFrNeem showed no anti-inflammatory action, did not alter the locomotor system, and it was not toxic. However, EtFrNeem significantly reduced the nociceptive behavior induced by formalin, glutamate and acidic saline, when compared to the control group. These effects of EtFrNeem were significantly similar to those of morphine, used as a positive control. The antinociceptive effect of EtFrNeem was inhibited by naloxone, ketamine and amiloride. EtFrNeem has the pharmacological potential for acute pain treatment and this effect is modulated by the opioid system, NMDA receptors and ASICs channels. These results lead us to studies of isolation and characterization of EtFrNeem bioactive principles, using adult zebrafish as an experimental model.
Assuntos
Analgésicos Opioides/farmacologia , Analgésicos/farmacologia , Azadirachta/química , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , Frutas/química , Meliaceae/química , Extratos Vegetais/farmacologia , Canais Iônicos Sensíveis a Ácido/metabolismo , Animais , Antioxidantes/metabolismo , Modelos Animais de Doenças , Etanol , Flavonoides/farmacologia , Locomoção/efeitos dos fármacos , Morfina/farmacologia , Dor/tratamento farmacológico , Dor/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Peixe-ZebraRESUMO
The role of spinal cord neurons in renal sympathoexcitation remains unclear in renovascular hypertension, represented by the 2-kidney, 1-clip (2K1C) model. Thus, we aimed to assess the influence of spinal glutamatergic and AT1 angiotensin II receptors on renal sympathetic nerve activity (rSNA) in 2K1C Wistar rats. Hypertension was induced by clipping the renal artery with a silver clip. After six weeks, a catheter (PE-10) was inserted into the subarachnoid space and advanced to the T10-11 vertebral level in urethane-anaesthetized rats. The effects of intrathecally (i.t.) injected kynurenic acid (KYN) or losartan (Los) on blood pressure (BP) and rSNA were analysed over 2 consecutive hours. KYN induced a significantly larger drop in rSNA among 2K1C rats than among control (CTL) rats (CTL vs. 2K1C: -8⯱â¯3 vs. -52⯱â¯9 spikes/s after 120'). Los also evoked a significantly larger drop in rSNA among 2K1C rats than among CTL rats starting at 80' after administration (CTL vs. 2K1C - 80â¯min: -10⯱â¯2 vs. -32⯱â¯6∗; 100â¯min: -15⯱â¯4 vs. -37⯱â¯9∗; 120â¯min: -12⯱â¯5 vs. -37⯱â¯8∗ spikes/s). KYN decreased BP similarly in the CTL and 2K1C groups; however, Los significantly decreased BP in the 2K1C group only. We found upregulation of AT1 gene expression in the T11-12 spinal segments in the 2K1C group but no change in gene expression for AT2 or ionotropic glutamate (NMDA, kainate and AMPA) receptors. Thus, our data show that spinal ionotropic glutamatergic and AT1 receptors contribute to increased rSNA in the 2K1C model, leading to the maintenance of hypertension; however, the participation of spinal AT1 receptors seems to be especially important in the establishment of sympathoexcitation in this model. The origins of those projections, i.e., the brain areas involved in establishing the activity of spinal glutamatergic and angiotensinergic pathways, remain unclear.
Assuntos
Hipertensão Renovascular/fisiopatologia , Rim/efeitos dos fármacos , Medula Espinal/fisiologia , Animais , Barorreflexo/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Fármacos Atuantes sobre Aminoácidos Excitatórios/metabolismo , Frequência Cardíaca/efeitos dos fármacos , Hipertensão Renovascular/metabolismo , Rim/inervação , Ácido Cinurênico/farmacologia , Losartan/farmacologia , Masculino , Neurotransmissores/farmacologia , Ratos , Ratos Wistar , Receptor Tipo 1 de Angiotensina/metabolismo , Sistema Nervoso Simpático/metabolismo , Sistema Nervoso Simpático/fisiopatologiaRESUMO
Drugs that lack the ability to cross the blood-brain barrier (BBB) need to be placed directly into the central nervous system. Our laboratory studies the involvement of the glutamatergic system in the aggressiveness of glioma, and some ligands of glutamate receptors cannot permeate the BBB. Here, glioma-implanted rats were treated by a technique that delivers ligands directly into the cerebrospinal fluid by puncture into the cisterna cerebellomedullaris. Rats were anesthetized and fixed in a rodent stereotactic device. The head was gently tilted downwards at an angle that allowed exposure of the cisterna. Injection into the cisterna was done freehand using a gingival needle coupled to a microsyringe. The efficiency of intracisternal injection was demonstrated using a methylene blue solution. This type of injection is adaptable for any rodent model using small volumes of a variety of other drugs, and is an interesting method for neuroscience studies.
Assuntos
Fármacos do Sistema Nervoso Central/administração & dosagem , Líquido Cefalorraquidiano , Anestesia , Animais , Cisterna Magna , Meios de Contraste , Fármacos Atuantes sobre Aminoácidos Excitatórios/administração & dosagem , Glioma/tratamento farmacológico , Azul de Metileno , Modelos Animais , Ratos WistarRESUMO
The aims of the present study were to assess an interaction of corticotropin-releasing factor (CRF) neurotransmission within the bed nucleus of the stria terminalis (BNST) with local nitrergic signaling, as well as to investigate an involvement of activation of local NMDA glutamate receptor and nitric oxide (NO) signaling in control of cardiovascular responses to acute restraint stress by BNST CRF neurotransmission in rats. We observed that CRF microinjection into the BNST increased local NO release during restraint stress. Furthermore, bilateral microinjection of CRF into the BNST enhanced both the arterial pressure and heart rate increases evoked by restraint stress, but without affecting the sympathetically-mediated cutaneous vasoconstriction. The facilitation of both pressor and tachycardiac responses to restraint stress evoked by BNST treatment with CRF were completely inhibited by local pretreatment with either the selective NMDA glutamate receptor antagonist LY235959, the selective neuronal nitric oxide synthase (nNOS) inhibitor Nω-Propyl-l-arginine (NPLA), the soluble guanylate cyclase (sGC) inhibitor 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) or the protein kinase G (PKG) inhibitor KT5823. Taken together, these results provide evidence that BNST CRF neurotransmission facilitates local NMDA-mediated glutamatergic neurotransmission and activates nitrergic signaling, and this pathway is involved in control of cardiovascular responses to stress.
Assuntos
Hormônio Liberador da Corticotropina/metabolismo , Miocárdio/metabolismo , Núcleos Septais/metabolismo , Animais , Pressão Sanguínea/fisiologia , Sistema Cardiovascular/metabolismo , Fármacos Atuantes sobre Aminoácidos Excitatórios/metabolismo , Coração/fisiologia , Frequência Cardíaca/fisiologia , Masculino , N-Metilaspartato/metabolismo , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo I/metabolismo , Ratos , Ratos Wistar , Receptores de Glutamato/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Restrição Física/psicologia , Núcleos Septais/fisiologia , Transdução de Sinais , Estresse Psicológico/metabolismo , Transmissão Sináptica/fisiologiaRESUMO
Aloysia triphylla (Verbenaceae) is an aromatic medicinal plant, and it is used for the treatment of "nervous" problems as, "sadness" and "nervousness". While, there are no reports about its pharmacological activity in animal models. The objective of this work was to evaluate the anxiolytic effect of the extracts and fractions of this species and to measure the interaction of the most active fraction with serotonergic, glutamatergic and GABAergic drugs. An elevated plus maze test was carried ought where the methanol (AtM), dicloromethane (AtD) and hexanic (AtH) extracts presented anxiolytic activity in mice when exposed to the test. Also, different fractions obtained from the AtD were evaluated (AtF1, AtF2 and AtF3, 15mg/kg), and showed that fraction AtF1 possessed the anxiolytic activity, in the same model. Then, AtF1 was co-administered with different drugs, which act on GABAergic (bicuculline, picrotoxin, pentylenetetrazol, baclofen and phaclofen), or serotononinergic (DOI, 8-OH-DPAT, WAY 100635 and ketanserine) or glutamatergic (NMDA, MPEP and MK-801) systems. The anxiolytic activity of AtF1 was modified by GABAergic and serotoninergic drugs. Chemical analysis of this fraction by using GC-MS, showed that it contains hexadecanoic acid, hexadecanoic acid methyl ester, octadecanoic acid methyl ester, eicosanoic acid methyl ester, vitamin E, α-amiryn, campesterol, sitosterol, stigmastan-2,22, dien-3-ol (4) and stigmasta 5, 24 (28) dien-3-ol.
Assuntos
Ansiolíticos/farmacologia , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , Ácidos Graxos/farmacologia , GABAérgicos/farmacologia , Serotoninérgicos/farmacologia , Terpenos/farmacologia , Verbenaceae , Animais , Ansiolíticos/isolamento & purificação , Fármacos Atuantes sobre Aminoácidos Excitatórios/isolamento & purificação , Ácidos Graxos/isolamento & purificação , GABAérgicos/isolamento & purificação , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Aprendizagem em Labirinto/fisiologia , Camundongos , Camundongos Endogâmicos ICR , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Folhas de Planta , Caules de Planta , Serotoninérgicos/isolamento & purificação , Terpenos/isolamento & purificaçãoRESUMO
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
A growing body of evidence demonstrates that quinoline compounds have attracted much attention in the field of drug development. Accordingly, 4-phenylselenyl-7-chloroquinoline (4-PSQ) is a new quinoline derivative containing selenium, which showed a potential antioxidant, antinociceptive and anti-inflammatory effect. The present study was undertaken to evaluate the anxiolytic-like properties of 4-PSQ. Mice were orally pretreated with 4-PSQ (5-50 mg/kg) or vehicle, 30 min prior to the elevated plus-maze (EPM), light-dark (LDT) or open field (OFT) tests. A time-response curve was carried out by administration of 4-PSQ (50 mg/kg) at different times before the EPM test. The involvement of glutamate uptake/release and Na+, K+-ATPase activity in the anxiolytic-like effect was investigated in cerebral cortices. In addition, the effectiveness of acute treatment with 4-PSQ was evaluated in a model of kainate (KA)-induced anxiety-related behavior. Finally, acute toxicity of this compound was investigated. 4-PSQ produced an anxiolytic-like action, both in EPM and LDT. In OFT, 4-PSQ did not affect locomotor and exploratory activities. 4-PSQ anxiolytic-like effect started at 0.5 h and remained significant up to 72 h after administration. Treatment with 4-PSQ reduced [3H] glutamate uptake, but the [3H] glutamate release and Na+, K+-ATPase activity were not altered. KA-induced anxiety-related behavior was protected by 4-PSQ pretreatment. Additionally, 4-PSQ exposure did not alter urea levels, aspartate (AST) and alanine aminotrasferase (ALT) activities in plasma. Parameters of oxidative stress in brain and liver of mice were not modified by 4-PSQ. Taken together these data demonstrated that the anxiolytic-like effect caused by 4-PSQ seems to be mediated by involvement of the glutamatergic system.
Assuntos
Ansiolíticos/farmacologia , Ansiedade/tratamento farmacológico , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , Compostos Organosselênicos/farmacologia , Quinolinas/farmacologia , Administração Oral , Animais , Ansiolíticos/química , Ansiolíticos/toxicidade , Ansiedade/metabolismo , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Fármacos Atuantes sobre Aminoácidos Excitatórios/química , Fármacos Atuantes sobre Aminoácidos Excitatórios/toxicidade , Comportamento Exploratório/efeitos dos fármacos , Comportamento Exploratório/fisiologia , Ácido Glutâmico/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Camundongos , Estrutura Molecular , Atividade Motora/efeitos dos fármacos , Atividade Motora/fisiologia , Compostos Organosselênicos/química , Compostos Organosselênicos/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/fisiologia , Testes Psicológicos , Quinolinas/química , Quinolinas/toxicidade , ATPase Trocadora de Sódio-Potássio/metabolismo , Fatores de Tempo , TrítioRESUMO
The mesocorticolimbic circuit projects to the prefrontal cortex, hippocampus, amygdala, and nucleus accumbens, among others, and it originates in the dopaminergic neurons of the ventral tegmental area (VTA). The VTA receives glutamatergic inputs from the prefrontal cortex and several subcortical regions. The glutamate released activates dopaminergic neurons and its action depends on the activation of ionotropic and metabotropic glutamate receptors. VTA dopaminergic neurons release dopamine (DA) from axon terminals in the innervated regions and somatodendritically in the VTA itself. DA release in the VTA is directly correlated with the activity of dopaminergic neurons. We hypothesized that metabotropic glutamate 5 receptors (mGlu5) directly regulate the activity of VTA dopaminergic neurons. To test this hypothesis, the extracellular levels of VTA DA and glutamate were studied by in-vivo microdialysis after an intra-VTA perfusion of (R,S)-2-chloro-5-hydroxyphenylglycine (CHPG), selective mGlu5 agonist. We observed that CHPG induced a significant increase in VTA DA and glutamate extracellular levels. To determine whether the effect of CHPG on DA levels is because of the increase in glutamate release, we perfused kynurenic acid, an ionotropic glutamate receptor antagonist, through the probe. Our results showed that kynurenic acid did not block the ability of CHPG to cause DA release. Thus, our results suggest that CHPG acts directly on mGlu5 in dopaminergic neurons to induce the release of DA.
Assuntos
Dopamina/metabolismo , Líquido Extracelular/metabolismo , Receptor de Glutamato Metabotrópico 5/metabolismo , Área Tegmentar Ventral/metabolismo , Animais , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , Líquido Extracelular/efeitos dos fármacos , Ácido Glutâmico/metabolismo , Glicina/análogos & derivados , Glicina/farmacologia , Ácido Cinurênico/farmacologia , Masculino , Microdiálise , Fenilacetatos/farmacologia , Piridinas/farmacologia , Ratos , Ratos Sprague-Dawley , Tiazóis/farmacologia , Área Tegmentar Ventral/efeitos dos fármacosRESUMO
During memory retrieval, consolidated memories are expressed and destabilized in order to maintain or update information through a memory reconsolidation process. Despite the key role of the amygdala during memory acquistion and consolidation, the participation of neurotransmitter signals in memory retrieval is poorly understood. Hence, we used conditioned taste aversion and in vivo microdialysis to evaluate changes in glutamate, norepinephrine and dopamine concentrations within the amygdala during memory retrieval. We observed that exposure to an aversive-conditioned stimulus induced an augmentation in glutamate, norepinephrine and dopamine levels within the amygdala, while exposure to a familiar and safe stimulus did not induce changes in these neurotransmitters levels. Also, we evaluated the amygdalar blockade of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), N-methyl-d-aspartate (NMDA), ß-adrenergic and dopamine D1 receptors in memory retrieval and updating. Results showed that during retrieval, behavioural expression was impaired by intra-amygdalar blockade of AMPA and ß-adrenergic receptors, whereas NMDA, D1 and ß-adrenergic receptors blockade hindered memory updating. In summary, during conditioned taste aversion retrieval there was an increase in the extracellular levels of glutamate, norepinephrine and dopamine within the amygdala, and their receptors activity were differentially involved in the behavioural expression and memory updating during retrieval.
Assuntos
Tonsila do Cerebelo/metabolismo , Aprendizagem da Esquiva/fisiologia , Catecolaminas/metabolismo , Ácido Glutâmico/metabolismo , Rememoração Mental/fisiologia , Paladar/fisiologia , Tonsila do Cerebelo/efeitos dos fármacos , Animais , Aprendizagem da Esquiva/efeitos dos fármacos , Cobalto/farmacologia , Condicionamento Psicológico/efeitos dos fármacos , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , Comportamento Exploratório/efeitos dos fármacos , Resposta de Imobilidade Tônica/efeitos dos fármacos , Masculino , Rememoração Mental/efeitos dos fármacos , Microdiálise , N-Metilaspartato/farmacologia , Óxido Nítrico Sintase Tipo I/metabolismo , Ratos , Ratos Wistar , Natação/psicologia , Paladar/efeitos dos fármacos , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/farmacologiaRESUMO
The endocannabinoid system (ECS) is involved in a considerable number of physiological processes in the Central Nervous System. Recently, a modulatory role of cannabinoid receptors (CBr) and CBr agonists on the reduction of the N-methyl-d-aspartate receptor (NMDAr) activation has been demonstrated. Quinolinic acid (QUIN), an endogenous analog of glutamate and excitotoxic metabolite produced in the kynurenine pathway (KP), selectively activates NMDAr and has been shown to participate in different neurodegenerative disorders. Since the early pattern of toxicity exerted by this metabolite is relevant to explain the extent of damage that it can produce in the brain, in this work we investigated the effects of the synthetic CBr agonist WIN 55,212-2 (WIN) and other agonists (anandamide or AEA, and CP 55,940 or CP) on early markers of QUIN-induced toxicity in rat striatal cultured cells and rat brain synaptosomes. WIN, AEA and CP exerted protective effects on the QUIN-induced loss of cell viability. WIN also preserved the immunofluorescent signals for neurons and CBr labeling that were decreased by QUIN. The QUIN-induced early mitochondrial dysfunction, lipid peroxidation and reactive oxygen species (ROS) formation were also partially or completely prevented by WIN pretreatment, but not when this CBr agonist was added simultaneously with QUIN to brain synaptosomes. These findings support a neuroprotective and modulatory role of cannabinoids in the early toxic events elicited by agents inducing excitotoxic processes.
Assuntos
Encéfalo/efeitos dos fármacos , Agonistas de Receptores de Canabinoides/farmacologia , Fármacos Atuantes sobre Aminoácidos Excitatórios/toxicidade , Mitocôndrias/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Ácido Quinolínico/toxicidade , Animais , Ácidos Araquidônicos/farmacologia , Benzoxazinas/farmacologia , Encéfalo/fisiopatologia , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Células Cultivadas , Cicloexanóis/farmacologia , Endocanabinoides/farmacologia , Peroxidação de Lipídeos/efeitos dos fármacos , Peroxidação de Lipídeos/fisiologia , Masculino , Mitocôndrias/metabolismo , Morfolinas/farmacologia , Naftalenos/farmacologia , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Estresse Oxidativo/fisiologia , Alcamidas Poli-Insaturadas/farmacologia , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Receptores de Canabinoides/metabolismo , Sinaptossomos/efeitos dos fármacos , Sinaptossomos/fisiologiaRESUMO
BACKGROUND: Traumatic memories have been resilient to therapeutic approaches targeting their permanent attenuation. One of the potentially promising pharmacological strategies under investigation is the search for safe reconsolidation blockers. However, preclinical studies focusing on this matter have scarcely addressed abnormal aversive memories and related outcomes. METHODS: By mimicking the enhanced noradrenergic activity reported after traumatic events in humans, here we sought to generate a suitable condition to establish whether some clinically approved drugs able to disrupt the reconsolidation of conditioned fear memories in rodents would still be effective. RESULTS: We report that the α2-adrenoceptor antagonist yohimbine was able to induce an inability to restrict behavioral (fear) and cardiovascular (increased systolic blood pressure) responses to the paired context when administered immediately after acquisition, but not 6h later, indicating the formation of a generalized fear memory, which endured for over 29 days and was less susceptible to suppression by extinction. It was also resistant to reconsolidation disruption by the α2-adrenoceptor agonist clonidine or cannabidiol, the major non-psychotomimetic component of Cannabis sativa. Since signaling at N-methyl-D-aspartate (NMDA) receptors is important for memory labilization and because a dysfunctional memory may be less labile than is necessary to trigger reconsolidation on its brief retrieval and reactivation, we then investigated and demonstrated that pre-retrieval administration of the partial NMDA agonist D-cycloserine allowed the disrupting effects of clonidine and cannabidiol on reconsolidation. CONCLUSIONS: These findings highlight the effectiveness of a dual-step pharmacological intervention to mitigate an aberrant and enduring aversive memory similar to that underlying the post-traumatic stress disorder.
Assuntos
Medo/efeitos dos fármacos , Memória/efeitos dos fármacos , Psicotrópicos/farmacologia , Agonistas de Receptores Adrenérgicos alfa 2/farmacologia , Antagonistas de Receptores Adrenérgicos alfa 2/farmacologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Canabidiol/farmacologia , Clonidina/farmacologia , Ciclosserina/farmacologia , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , Extinção Psicológica/efeitos dos fármacos , Medo/fisiologia , Masculino , Distribuição Aleatória , Ratos Wistar , Transtornos de Estresse Pós-Traumáticos/tratamento farmacológico , Ioimbina/farmacologiaRESUMO
Evidence corroborates the role of the anterior cingulate cortex (ACC) in the modulation of cognitive and emotional functions. Its involvement in the motivational-affective component of pain has been widely investigated using different methods to elucidate the specific role of different neurotransmitter systems. We used the peripheral noxious stimulus-induced vocalization algesimetric test to verify glutamatergic and GABAergic neurotransmission in the guinea pig ACC. Microinjection of homocysteic acid (DLH; 30 nmol) in the left guinea pig ACC increased the amplitude of vocalizations (pronociception) compared to controls injected with saline. Moreover, microinjection of MK-801 (3.6 nmol), an NMDA receptor antagonist, did not alter the amplitude of vocalizations, but its microinjection prior to DLH prevented the increase in vocalizations induced by this drug. Regarding the GABAergic system, blockade of GABAA receptors with bicuculline (1 nmol) increased the amplitude of vocalizations, while three different doses of the GABAA agonist muscimol (0.5, 1 and 2 nmol) did not influence nociceptive vocalization responses. Finally, a combination of MK-801 (3.6 nmol) and muscimol (1 nmol) reduced the amplitude of vocalizations (antinociception), suggesting that a combination of glutamate and GABA in the ACC modulates the expression of affective-motivational pain response. We suggest that activation of NMDA receptors or blockade of GABAergic neurotransmission promotes pronociception and that the antinociceptive effect of muscimol depends on the blockade of NMDA receptors.
Assuntos
Ácido Glutâmico/metabolismo , Giro do Cíngulo/metabolismo , Dor/patologia , Dor/fisiopatologia , Vocalização Animal/fisiologia , Ácido gama-Aminobutírico/metabolismo , Animais , Bicuculina/análogos & derivados , Bicuculina/farmacologia , Maleato de Dizocilpina/farmacologia , Relação Dose-Resposta a Droga , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , GABAérgicos/farmacologia , Cobaias , Giro do Cíngulo/efeitos dos fármacos , Homocisteína/análogos & derivados , Homocisteína/farmacologia , Masculino , Microinjeções , Muscimol/farmacologia , Dor/induzido quimicamente , Fatores de Tempo , Vocalização Animal/efeitos dos fármacosRESUMO
BACKGROUND: The effect of the agonism on γ-aminobutyric acid (GABA) receptors was studied within medial prefrontal cortex (mPFC), amygdala (AMY) and ventral hipocampus (VH) in the plus-maze test in male rats bilaterally cannulated. These structures send glutamatergic projections to the nucleus accumbens septi (NAS), in which interaction and integration between these afferent pathways has been described. In a previous study of our group, blockade of glutamatergic transmission within NAS induced an anxiolytic like effect. METHODS: Three rat groups received either saline or dipotassium chlorazepate (1 or 2 µg/1 µl solution) 15 min before testing. Time spent in the open arms (TSOA), time per entry (TPE), extreme arrivals (EA), open and closed arms entries (OAE, CAE) and relationship between open- and closed-arms quotient (OCAQ) were recorded. RESULTS: In the AMY injected group TSOA, OAE and EA were increased by the higher doses of dipotassium chlorazepate (p < 0.01). In the mPFC, TPE was decreased by both doses (p < 0.05). Injection within ventral hippocampus (VH) decreased TSOA, OAE and OCAQ with lower doses (p < 0.05). When the three studied saline groups were compared, TSOA, OAE, EA and OCAQ were enhanced in the VH group when compared to mPFC and AMY (p < 0.001). Insertion of inner canula (p < 0.001, p < 0.01, p < 0.01) and saline injection showed an increasing significant difference (p < 0.001 in all cases) with the action of guide cannula alone within VH in TSOA, OAE and EA. CONCLUSION: We conclude that the injection of dipotassium chlorazepate has a differential effect depending of the brain area, leading to facilitatory and inhibitory effects on anxiety processing.
Assuntos
Tonsila do Cerebelo/efeitos dos fármacos , Comportamento Animal/efeitos dos fármacos , Clorazepato Dipotássico/administração & dosagem , Fármacos Atuantes sobre Aminoácidos Excitatórios/administração & dosagem , Hipocampo/efeitos dos fármacos , Núcleo Accumbens/efeitos dos fármacos , Córtex Pré-Frontal/efeitos dos fármacos , Animais , Ansiolíticos/administração & dosagem , Ansiedade/tratamento farmacológico , Agonistas GABAérgicos/administração & dosagem , Masculino , RatosRESUMO
The interest in the behavioral features of zebrafish has significantly increased over the past two decades. However, most available protocols have used longer training periods and have been based on reinforcement/reward or avoidance. The Y-Maze memory task has the advantage of using a simple and rapid training session, but it has not been established in zebrafish. Here, we have characterized this task for zebrafish, with the addition of pharmacological interventions in the acquisition and consolidation memory phases. The results show that zebrafish spend more time in the novel arm than in the other arms of the Y-Maze, both in response to novelty and spatial memory training-test intervals (TTIs). We have also studied the involvement of the glutamatergic and cholinergic systems with pre- and post-training treatments with the NMDA receptor antagonist MK-801 (20 µM) and the cholinergic blocker scopolamine (200 µM). After 1h of TTI, pre-training MK-801 and scopolamine-treated fish reduced their exploration of the novel arm when compared to the control group, with no changes in their locomotor activity. Post-training of MK-801 treatment also impaired their Y-Maze performance, while post-training of any scopolamine treatment failed to affect novel arm exploration. In conclusion, the Y-Maze memory task can be reliably used for zebrafish, providing a new, rapid, and preference/avoidance independent task for the study of memory in this teleost. In addition, our results highlight the implication of the glutamatergic and cholinergic systems in the memory of zebrafish.
Assuntos
Neurônios Colinérgicos/fisiologia , Comportamento Exploratório/fisiologia , Ácido Glutâmico/metabolismo , Aprendizagem em Labirinto/fisiologia , Peixe-Zebra , Acetilcolina/metabolismo , Animais , Aprendizagem da Esquiva/efeitos dos fármacos , Aprendizagem da Esquiva/fisiologia , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Pesquisa Comportamental/métodos , Colinérgicos/farmacologia , Discriminação Psicológica/efeitos dos fármacos , Discriminação Psicológica/fisiologia , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , Comportamento Exploratório/efeitos dos fármacos , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Vias Neurais/efeitos dos fármacos , Vias Neurais/metabolismo , Distribuição Aleatória , Reconhecimento Psicológico/efeitos dos fármacos , Reconhecimento Psicológico/fisiologiaRESUMO
In mice, repeated ethanol administration may induce behavioral sensitization - a process of progressive potentiation of its stimulant effects, associated with neuroadaptations in the brain reward system. Few studies have directly investigated the subsequent neuroadaptations in the nucleus accumbens (NAc), the central area of the brain reward system, after chronic ethanol administration. The goal of the present study was to analyze the involvement of accumbal glutamate NMDA receptors in the locomotion behavioral response to an NMDA agonist or to an NMDA antagonist in mice previously treated with ethanol. Swiss Albino mice received repeated daily administrations of 2.2 g/kg ethanol or saline for 21 days. According to their locomotor response on the last day of treatment, ethanol-treated mice were classified into sensitized or non-sensitized groups. They were then submitted to a surgical procedure to implement intra-NAc cannulae. After recovery, mice were challenged with intra-NAc administration of saline and, two days later, with NMDA (NMDA agonist) or MK-801 (NMDA antagonist), having their locomotor activity recorded for 1 h. The administration of NMDA induced similar locomotor behavior in all groups. On the other hand, the administration of 3 µg/side MK-801 induced a significant stimulant effect which was more prominent during the first 15 min in the sensitized group than in the non-sensitized or saline groups. Despite no effect of the agonist administration, only in sensitized mice did we observe cross-sensitization between repeated ethanol treatment and the intra-NAc administration of MK-801.