RESUMO
To investigate the precise mechanism of xenon (Xe), pharmacologically isolated AMPA/KA and NMDA receptor-mediated spontaneous (s) and evoked (e) excitatory postsynaptic currents (s/eEPSCAMPA/KA and s/eEPSCNMDA) were recorded from mechanically isolated single spinal sacral dorsal commissural nucleus (SDCN) neurons attached with glutamatergic nerve endings (boutons) using conventional whole-cell patch-clamp technique. We analysed kinetic properties of both s/eEPSCAMPA/KA and s/eEPSCNMDA by focal single- and/or paired-pulse electrical stimulation to compare them. The s/eEPSCNMDA showed smaller amplitude, slower rise time, and slower 1/e decay time constant (τDecay) than those of s/eEPSCAMPA/KA. We previously examined how Xe modulates s/eEPSCAMPA/KA, therefore, examined the effects on s/eEPSCNMDA in the present study. Xe decreased the frequency and amplitude of sEPSCNMDA, and decreased the amplitude but increased the failure rate and paired-pulse ratio of eEPSCNMDA without affecting their τDecay. It was concluded that Xe might suppress NMDA receptor-mediated synaptic transmission via both presynaptic and postsynaptic mechanisms.
Assuntos
Potenciais Pós-Sinápticos Excitadores , Neurônios , Receptores de N-Metil-D-Aspartato , Xenônio , Animais , Receptores de N-Metil-D-Aspartato/metabolismo , Xenônio/farmacologia , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/fisiologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/fisiologia , Ratos , Medula Espinal/efeitos dos fármacos , Medula Espinal/metabolismo , Medula Espinal/fisiologia , Sinapses/efeitos dos fármacos , Sinapses/fisiologia , Ratos Sprague-Dawley , Técnicas de Patch-Clamp , Receptores de AMPA/metabolismo , Receptores de AMPA/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Transmissão Sináptica/fisiologia , MasculinoRESUMO
Parkinson's disease (PD) is a significant health issue because it gradually damages the nervous system. α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors play a significant role in the development of PD. The current investigation employed hybrid benzodioxole-propanamide (BDZ-P) compounds to get information on AMPA receptors, analyze their biochemical and biophysical properties, and assess their neuroprotective effects. Examining the biophysical characteristics of all the subunits of the AMPA receptor offers insights into the impact of BDZ-P on the desensitization and deactivation rate. It demonstrates a partial improvement in the locomotor capacities in a mouse model of Parkinson's disease. In addition, the in vivo experiment assessed the locomotor activity by utilizing the open-field test. Our findings demonstrated that BDZ-P7 stands out with its remarkable potency, inhibiting the GluA2 subunit nearly 8-fold with an IC50 of 3.03 µM, GluA1/2 by 7.5-fold with an IC50 of 3.14 µM, GluA2/3 by nearly 7-fold with an IC50 of 3.19 µM, and GluA1 by 6.5-fold with an IC50 of 3.2 µM, significantly impacting the desensitization and deactivation rate of the AMPA receptor. BDZ-P7 showed an in vivo impact of partially reinstating locomotor abilities in a mouse model of PD. The results above suggest that the BDZ-P7 compounds show great promise as top contenders for the development of novel neuroprotective therapies.
Assuntos
Fármacos Neuroprotetores , Receptores de AMPA , Receptores de AMPA/metabolismo , Receptores de AMPA/efeitos dos fármacos , Animais , Fármacos Neuroprotetores/farmacologia , Camundongos , Doença de Parkinson/tratamento farmacológico , Doença de Parkinson/metabolismo , Camundongos Endogâmicos C57BL , Masculino , Humanos , Modelos Animais de DoençasRESUMO
Cerebral ischemia/reperfusion (I/R) injury is the main cause of death following trauma. The neuroprotective effect of sevoflurane (Sev) has been implicated in cerebral I/R injury. However, the mechanisms remain elusive. In this study, we aimed to explore its function in PC12 exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) and in rats challenged with I/R. Sev pretreatment reduced the damage of PC12 cells after OGD/R treatment. Moreover, Sev pretreatment ameliorated neurobehavioral deficits induced by I/R treatment, reduced brain infarct volume, and decreased apoptosis of neurons in hippocampal tissues. Sev pretreatment reduced the surface expression of glutamate receptor 1 (GRIA1) in neurons, while GRIA1 reduced the neuroprotective effects of Sev pretreatment in vitro and in vivo. There was no difference in the surface expression of GRIA2 in rats with I/R and PC12 cells exposed to OGD/R. The ratio of GRIA1/GRIA2 surface expression was reduced, and calcium permeable-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (CP-AMPAR) was blocked by Sev. Together, Sev might exert beneficial effects on cerebral I/R-induced neuronal injury through inhibiting the surface expression of GRIA1 and blocking CP-AMPAR.
Assuntos
Isquemia Encefálica , Neurônios , Fármacos Neuroprotetores , Receptores de AMPA , Traumatismo por Reperfusão , Animais , Ratos , Apoptose , Isquemia Encefálica/complicações , Infarto Cerebral/complicações , Glucose/metabolismo , Neurônios/metabolismo , Neurônios/patologia , Fármacos Neuroprotetores/farmacologia , Fármacos Neuroprotetores/uso terapêutico , Fármacos Neuroprotetores/metabolismo , Oxigênio , Reperfusão/efeitos adversos , Traumatismo por Reperfusão/tratamento farmacológico , Traumatismo por Reperfusão/metabolismo , Sevoflurano/farmacologia , Receptores de AMPA/efeitos dos fármacos , Receptores de AMPA/metabolismoRESUMO
Finding from animal models of depression indicated that Toll-like receptor 4 (TLR4) is associated with the pathophysiology of depression. Herein, the TLR4 antagonists TAK-242 and baicalin induced antidepressant-like effects in a rat learned helplessness model of depression. The antidepressant-like effects of both TLR4 antagonists were blocked by the TrkB inhibitor ANA-12. Also, the antidepressant-like effects of TAK-242 were blocked by the treatment with AMPA receptor antagonist NBQX. The antidepressant-like effects of the TLR4 antagonist TAK-242 involves BDNF-TrkB signaling and AMPA receptor activation.
Assuntos
Antidepressivos/farmacologia , Fator Neurotrófico Derivado do Encéfalo/efeitos dos fármacos , Depressão/tratamento farmacológico , Desamparo Aprendido , Receptor trkB/efeitos dos fármacos , Receptores de AMPA/efeitos dos fármacos , Sulfonamidas/farmacologia , Receptor 4 Toll-Like/antagonistas & inibidores , Animais , Comportamento Animal/efeitos dos fármacos , Modelos Animais de Doenças , Flavonoides/farmacologia , Masculino , Ratos , Ratos Sprague-Dawley , Receptor trkB/antagonistas & inibidores , Receptores de AMPA/antagonistas & inibidores , Transdução de Sinais/efeitos dos fármacosRESUMO
Although the pharmacological and behavioural interactions between cocaine and alcohol are well established, less is known about how polyconsumption of these drugs affects the neurotransmitter systems involved in their psychoactive effects and in particular, in the process of addiction. Here, rats of both sexes at two stages of development were studied under a chronic regime of intravenous cocaine and/or alcohol administration. Brain samples from the medial prefrontal cortex, nucleus accumbens, hippocampus and amygdala were extracted to analyse the mRNA expression of genes encoding subunits of the GABA, NMDA and AMPA receptors, as well as the expression of the CB1 receptor, and that of enzymes related to the biosynthesis and degradation of endocannabinoids. Moreover, two synaptic scaffold proteins related to GABA and NMDA receptors, gephyrin and PSD-95, were quantified in Western blots. Significant interactions between cocaine and alcohol were common, affecting the GABAergic and endocannabinoid systems in the medial prefrontal cortex and amygdala of young adults, whereas such interactions were evident in the glutamatergic and endocannabinoid systems in adults, as well as a more pronounced sex effect. Significant interactions between these drugs affecting the scaffold proteins were evident in the medial prefrontal cortex and nucleus accumbens of young adults, and in the nucleus accumbens and amygdala of adults, but not in the hippocampus. These results highlight the importance of considering the interactions between cocaine and alcohol on neurotransmitter systems in the context of polyconsumption, specifically when treating problems of abuse of these two substances.
Assuntos
Depressores do Sistema Nervoso Central/farmacologia , Cérebro/efeitos dos fármacos , Cocaína/farmacologia , Inibidores da Captação de Dopamina/farmacologia , Etanol/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Receptores de AMPA/efeitos dos fármacos , Receptores de Canabinoides/efeitos dos fármacos , Receptores de GABA/efeitos dos fármacos , Receptores de N-Metil-D-Aspartato/efeitos dos fármacos , Fatores Etários , Animais , Depressores do Sistema Nervoso Central/administração & dosagem , Cocaína/administração & dosagem , Inibidores da Captação de Dopamina/administração & dosagem , Interações Medicamentosas , Etanol/administração & dosagem , Feminino , Masculino , Ratos , Caracteres SexuaisRESUMO
Ampakines are synthetic molecules that allosterically modulate AMPA-type glutamate receptors. We tested the hypothesis that delivery of ampakines to the intrathecal space could stimulate neural drive to the diaphragm. Ampakine CX717 (20 mM, dissolved in 10 % HPCD) or an HPCD vehicle solution were delivered via a catheter placed in the intrathecal space at the fourth cervical segment in urethane-anesthetized, mechanically ventilated adult male Sprague-Dawley rats. The electrical activity of the phrenic nerve was recorded for 60-minutes following drug application. Intrathecal application of CX717 produced a gradual and sustained increase in phrenic inspiratory burst amplitude (n = 10). In contrast, application of HPCD (n = 10) caused no sustained change in phrenic motor output. Phrenic burst rate, heart rate, and mean arterial pressure were similar between CX717 and HPCD treated rats. We conclude that intrathecally delivered ampakines can modulate phrenic motor output. This approach may have value for targeted induction of spinal neuroplasticity in the context of neurorehabiliation.
Assuntos
Pressão Arterial/efeitos dos fármacos , Diafragma/efeitos dos fármacos , Frequência Cardíaca/efeitos dos fármacos , Isoxazóis/farmacologia , Plasticidade Neuronal/efeitos dos fármacos , Nervo Frênico/efeitos dos fármacos , Receptores de AMPA/efeitos dos fármacos , Animais , Injeções Espinhais , Isoxazóis/administração & dosagem , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
Drugs of abuse, such as cocaine, produce aberrant changes in synaptic transmission and plasticity that emerge throughout withdrawal. One region of the brain that displays a high degree of synaptic plasticity, as well as connectivity with mesolimbic structures such as the nucleus accumbens, is the ventral hippocampus (vH). Here, we investigated the effects of an escalating cocaine dosing schedule on vH CA1 excitatory transmission by measuring place preference and recording excitatory postsynaptic currents (EPSCs) at three different withdrawal time points: withdrawal day (WD) 2, 9 or 28. Behaviourally, this escalating cocaine-conditioning protocol was capable of producing conditioned place preference that persisted through WD28. Physiologically, cocaine conditioning produced an increase in vH excitatory transmission on WD2 that appeared to be the result of an increase in calcium-impermeable (CI)-AMPA receptor density. Excitatory transmission was still enhanced in cocaine-treated animals on WD9; however, a significant increase in the contribution of calcium-permeable (CP)-AMPA receptors to EPSCs was detected as compared with WD2. By WD28, these CP-AMPA receptors provided a major contribution to vH CA1 excitatory transmission, resulting in synaptic responses distinct from WD2 and WD9. Taken together, these results highlight progressive changes in vH synaptic transmission during withdrawal that may enhance cocaine contextual associations.
Assuntos
Cocaína/farmacologia , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Hipocampo/efeitos dos fármacos , Receptores de AMPA/efeitos dos fármacos , Síndrome de Abstinência a Substâncias/fisiopatologia , Animais , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Plasticidade Neuronal/efeitos dos fármacos , Fatores de TempoRESUMO
Respiratory compromise after cervical spinal cord injury (SCI) is a leading cause of mortality and morbidity. Most SCIs are incomplete, and spinal respiratory motoneurons as well as proprio- and bulbospinal synaptic pathways provide a neurological substrate to enhance respiratory output. Ampakines are allosteric modulators of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, which are prevalent on respiratory neurons. We hypothesized that low dose ampakine treatment could safely and effectively increase diaphragm electromyography (EMG) activity that has been impaired as a result of acute- or sub-acute cervical SCI. Diaphragm EMG was recorded using chronic indwelling electrodes in unanesthetized, freely moving rats. A spinal hemi-lesion was induced at C2 (C2Hx), and rats were studied at 4 and 14 days post-injury during room air breathing and acute respiratory challenge accomplished by inspiring a 10% O2, 7% CO2 gas mixture. Once a stable baseline recording was established, one of two different ampakines (CX717 or CX1739, 5 mg/kg, intravenous) or a vehicle (2-hydroxypropyl-beta-cyclodextrin [HPCD]) was delivered. At 4 days post-injury, both ampakines increased diaphragm EMG output ipsilateral to C2Hx during both baseline breathing and acute respiratory challenge. Only CX1739 treatment also led to a sustained (15 min) increase in ipsilateral EMG output. At 14 days post-injury, both ampakines produced sustained increases in ipsilateral diaphragm EMG output and enabled increased output during the respiratory challenge. We conclude that low dose ampakine treatment can increase diaphragm EMG activity after cervical SCI, and therefore may provide a pharmacological strategy that could be useful in the context of respiratory rehabilitation.
Assuntos
Medula Cervical/lesões , Diafragma/efeitos dos fármacos , Diafragma/fisiopatologia , Isoxazóis/uso terapêutico , Traumatismos da Medula Espinal/complicações , Animais , Vértebras Cervicais , Eletromiografia , Feminino , Masculino , Ratos , Ratos Sprague-Dawley , Receptores de AMPA/efeitos dos fármacos , Traumatismos da Medula Espinal/fisiopatologia , Traumatismos da Medula Espinal/terapiaRESUMO
Available evidence indicates that dopamine D2 receptor modulates the neurotoxic effects induced by glutamate. However, neurotoxicity mediated by AMPA-subtype glutamate receptor has rarely been studied in the olfactory bulb. This study mainly explores the neuroprotective effects of dopamine D2 receptor agonist on AMPA receptor-mediated neurotoxicity in the olfactory bulb in a mouse model of allergic rhinitis (AR) with olfactory dysfunction (OD). In our study, we found that AR with OD was closely associated with increased surface expression of the AMPA receptor GluR1, reduced surface expression of GluR2, and apoptosis damage in the olfactory bulb in vivo. Quinpirole (a dopamine D2 receptor agonist) improved olfactory function in mice, ameliorated apoptosis injury in the olfactory bulb but not in the olfactory mucosa, and inhibited the internalization of GluR2-containing AMPA receptor in vitro and in vivo. In addition, phosphorylation plays a crucial role in the regulation of AMPA receptor trafficking. Our results showed that quinpirole reduced the phosphorylation of GluR1 S845 and GluR2 S880 in olfactory bulb neurons in vitro, but it had no obvious effect on GluR1 S831. Therefore, dopamine D2 receptor agonist may inhibit the phosphorylation of GluR1 S845 and GluR2 S880, thereby reducing AMPA receptor-mediated neurotoxicity and alleviating neurotoxic injury to the olfactory bulb caused by AR.
Assuntos
Doenças Neuroinflamatórias/tratamento farmacológico , Fármacos Neuroprotetores/uso terapêutico , Bulbo Olfatório/efeitos dos fármacos , Receptores de Dopamina D2/agonistas , Rinite Alérgica/tratamento farmacológico , Animais , Western Blotting , Técnicas de Cocultura , Modelos Animais de Doenças , Ensaio de Imunoadsorção Enzimática , Feminino , Imunofluorescência , Marcação In Situ das Extremidades Cortadas , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microglia/efeitos dos fármacos , Doenças Neuroinflamatórias/etiologia , Doenças Neuroinflamatórias/patologia , Neurônios/efeitos dos fármacos , Bulbo Olfatório/patologia , Quimpirol/uso terapêutico , Receptores de AMPA/efeitos dos fármacos , Rinite Alérgica/complicações , Rinite Alérgica/patologia , Olfato/efeitos dos fármacosRESUMO
Repeated short episodes of hypoxia produce a sustained increase in phrenic nerve output lasting well beyond acute intermittent hypoxia (AIH) exposure (i.e., phrenic long-term facilitation; pLTF). Pretreatment with ampakines, drugs which allosterically modulate AMPA receptors, enables a single brief episode of hypoxia to produce pLTF, lasting up to 90 min after hypoxia. Here, we tested the hypothesis that ampakine pretreatment would enhance the magnitude of pLTF evoked by repeated bouts of hypoxia. Phrenic nerve output was recorded in urethane-anesthetized, mechanically ventilated, and vagotomized adult male Sprague-Dawley rats. Initial experiments demonstrated that ampakine CX717 (15 mg/kg iv) caused an acute increase in phrenic nerve inspiratory burst amplitude reaching 70 ± 48% baseline (BL) after 2 min (P = 0.01). This increased bursting was not sustained (2 ± 32% BL at 60 min, P = 0.9). When CX717 was delivered 2 min before a single episode of isocapnic hypoxia (5 min, [Formula: see text] = 44 ± 9 mmHg), facilitation of phrenic nerve burst amplitude occurred (96 ± 62% BL at 60 min, P < 0.001). However, when CX717 was given 2 min before three, 5-min hypoxic episodes ([Formula: see text] = 45 ± 6 mmHg) pLTF was attenuated and did not reach statistical significance (24 ± 29% BL, P = 0.08). In the absence of CX717 pretreatment, pLTF was observed after three (74 ± 33% BL at 60 min, P < 0.001) but not one episode of hypoxia (1 ± 8% BL at 60 min, P = 0.9). We conclude that pLTF is not enhanced when ampakine pretreatment is followed by repeated bouts of hypoxia. Rather, the combination of ampakine and a single hypoxic episode appears to be ideal for producing sustained increase in phrenic motor output.NEW & NOTEWORTHY Pretreatment with ampakine CX717 created conditions that enabled an acute bout of moderate hypoxia to evoke phrenic motor facilitation, but this response was not observed when ampakine pretreatment was followed by intermittent hypoxia. Thus, in anesthetized and spinal intact rats, the combination of ampakine and one bout of hypoxia appears ideal for triggering respiratory neuroplasticity.
Assuntos
Hipóxia/fisiopatologia , Isoxazóis/farmacologia , Plasticidade Neuronal/efeitos dos fármacos , Nervo Frênico/efeitos dos fármacos , Nervo Frênico/fisiologia , Receptores de AMPA/efeitos dos fármacos , Animais , Isoxazóis/administração & dosagem , Masculino , Ratos , Ratos Sprague-Dawley , Fatores de TempoRESUMO
Glutamatergic transmission is widely implicated in neuropsychiatric disorders, and the discovery that ketamine elicits rapid-acting antidepressant effects by modulating α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) signaling has spurred a resurgence of interest in the field. This review explores agents in various stages of development for neuropsychiatric disorders that positively modulate AMPARs, both directly and indirectly. Despite promising preclinical research, few direct and indirect AMPAR positive modulators have progressed past early clinical development. Challenges such as low potency have created barriers to effective implementation. Nevertheless, the functional complexity of AMPARs sets them apart from other drug targets and allows for specificity in drug discovery. Additional effective treatments for neuropsychiatric disorders that work through positive AMPAR modulation may eventually be developed.
Assuntos
Desenvolvimento de Medicamentos/métodos , Transtornos Mentais/tratamento farmacológico , Receptores de AMPA/efeitos dos fármacos , Animais , Antidepressivos/farmacologia , Descoberta de Drogas/métodos , Humanos , Ketamina/farmacologia , Transtornos Mentais/fisiopatologia , Receptores de AMPA/metabolismoRESUMO
Recent studies have reported that melamine can accumulate in several regions of the brain including the medial prefrontal cortex (mPFC). Although melamine accumulation in the hippocampus has been verified to induce cognitive impairments, whether it can cause mPFC-dependent working memory deficits is still unknown. After chronic treatment with melamine (150 (Mel(150)) or 300 (Mel(300)) mg/kg), rats were tested during both delay nonmatching-to-sample spatial and odor discrimination tasks. Levels of AMPA receptor subunits in the mPFC were detected using western blotting. To further explore the mechanism at the cellular level, prefrontal activity was recorded during the odor discrimination. The working memory of Mel(150) rats was found to be significantly impaired in a 3-minute delay odor discrimination task (control: n = 6, Mel(150): n = 6; P < 0.05). Compared with the control group (n = 6), rats in the 300 mg/kg Mel(300)-treated group (n = 8) displayed working memory deficits in 60-second delay Y-maze task (P < 0.05), 1-minute and 3-minute delay odor discrimination tasks (both P < 0.05). The levels of AMPA receptor mGluR2/3 subunit were significantly decreased in rats of the Mel(150) (n = 7) and Mel(300) (n = 7) groups (both P < 0.05). Exposure to 150 (n = 7) or 300 mg/kg (n = 7) melamine resulted in significant inhibition of the regular-spiking neuron activity during the delay period of the memory test (both P < 0.05). Intraperitoneal (n = 7) and intra-mPFC (n = 6) infusions of GluR2/3 agonists, effectively enhanced the neural correlate (both P < 0.05) while rescuing cognitive deficits in Mel(300)-treated rats (both P < 0.05). Collectively, these findings suggested that melamine could induce prefrontal dysfunction and cause cognitive impairments.
Assuntos
Memória de Curto Prazo/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Córtex Pré-Frontal/efeitos dos fármacos , Receptores de AMPA/efeitos dos fármacos , Receptores de AMPA/metabolismo , Triazinas/toxicidade , Animais , Relação Dose-Resposta a Droga , Exposição Ambiental , Humanos , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Modelos Animais , Ratos , Ratos Sprague-DawleyRESUMO
Obesity is characterized by a condition of low-grade chronic inflammation that facilitates development of numerous comorbidities and dysregulation of brain homeostasis. It is reported that obesity can lead to behavioral alterations such as cognitive decline and depression-like behaviors both in humans and rodents. Saponins from panax japonicus (SPJ) have been reported to exhibit anti-inflammatory action in mouse model of diet-induced obesity. We evaluated the neuroprotection of SPJ on high fat diet (HFD) induced impaired behaviors such as memory deficit and depressive-like behaviors, and explored the underlying mechanisms. 6-week male Balb/c mice were divided into normal control group (NC, 17% total calories from fat), HFD group (60% total calories from fat), and HFD treated with SPJ groups (orally gavaged with dosages of 15 mg/kg and 45 mg/kg), respectively. After treatment for 16 weeks, behavioral tests were performed to evaluate the cognition and depression-like behaviors of the mice. The underling mechanisms of SPJ on HFD-induced impaired behaviors were investigated through histopathological observation, Western blot analysis and immunofluorescence. Our results showed that HFD-fed mice caused behavioral disorders, neuronal degeneration as well as elevated neuroinflammation, which was partly involved in NLRP3 inflammasome that finally resulted in decreased protein levels of AMPA receptors and down-regulated phosphorylated levels of CaMKII and CREB in cortex and hippocampus. All the above changes in cortex and hippocampus induced by HFD were mitigated by SPJ treatment. SPJ treatment alleviated HFD-induced recognitive impairment and depression-like behaviors of mice, which could be partly due to the capacity of SPJ to mitigate neuroinflammation through inhibition of NLRP3 inflammasome and upregulation of AMPA receptors signaling pathway.
Assuntos
Comportamento Animal/efeitos dos fármacos , Dieta Hiperlipídica/efeitos adversos , Inflamassomos/efeitos dos fármacos , Proteína 3 que Contém Domínio de Pirina da Família NLR/antagonistas & inibidores , Panax/química , Receptores de AMPA/biossíntese , Receptores de AMPA/efeitos dos fármacos , Saponinas/farmacologia , Animais , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/biossíntese , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/biossíntese , Depressão/induzido quimicamente , Depressão/psicologia , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Masculino , Transtornos da Memória/induzido quimicamente , Transtornos da Memória/psicologia , Camundongos , Camundongos Endogâmicos BALB C , Transdução de Sinais/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacosRESUMO
Cognitive deficits are the core feature of schizophrenia and effective treatment strategies are still missing. Previous studies have reported that fisetin promotes long-term potentiation (LTP) and cognitive function in normal rodents and other model animals of neurological diseases. The aim of this study was to assess the effect of fisetin on synaptic plasticity and cognitive deficits caused by a brief disruption of N-methyl-D-aspartate receptors (NMDARs) with dizocilpine (MK-801) during early development in rats. The cognitive performance was examined by the Morris water maze task and a fear conditioning test. Hippocampal synaptic plasticity was investigated by field potential recording. The expression of α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs) and cognition-related proteins was measured by western blotting. We found that intraperitoneal administration of fisetin rescued hippocampus-dependent spatial and contextual fear memory in MK-801 rats. In parallel with these behavioral results, fisetin treatment in MK-801 rats reversed the impairment of hippocampal LTP. At the molecular level, fisetin treatment selectively increased the phosphorylation and surface expression of AMPA receptor subunit 1 (GluA1) in MK-801-treated rats. Moreover, fisetin restored the phosphorylation levels of calcium-calmodulin-dependent kinaseII (CaMKII), cAMP response element-binding protein (CREB), and the extracellular signal-regulated kinase (ERK1/2) in MK-801-treated rats. Collectively, our findings demonstrate that fisetin treatment can reverse the deficits of hippocampal synaptic plasticity and memory in a male rat model of schizophrenia by restoring the phosphorylation and surface expression of AMPAR GluA1 subunit, suggesting fisetin as a promising therapeutic candidate for schizophrenia-associated cognitive deficits.
Assuntos
Cognição/efeitos dos fármacos , Flavonóis/farmacologia , Plasticidade Neuronal/efeitos dos fármacos , Receptores de AMPA/efeitos dos fármacos , Esquizofrenia/tratamento farmacológico , Sinapses/efeitos dos fármacos , Animais , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/efeitos dos fármacos , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Maleato de Dizocilpina/farmacologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Medo/efeitos dos fármacos , Medo/psicologia , Injeções Intraperitoneais , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Desempenho Psicomotor/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Psicologia do EsquizofrênicoRESUMO
BACKGROUND: The chronic mild stress (CMS) procedure is a widely used animal model of depression, and its application in Wistar-Kyoto (WKY) rats has been validated as a model of antidepressant-refractory depression. While not responding to chronic treatment with antidepressant drugs, WKY rats do respond to acute deep brain stimulation (DBS) of the medial prefrontal cortex (mPFC). In antidepressant-responsive strains there is evidence suggesting a role for AMPA subtype of glutamate receptor in the action mechanism of both antidepressants and DBS. METHODS: Animals were subjected to CMS for 6 to 8 weeks; sucrose intake was monitored weekly and novel object recognition (NOR) test was conducted following recovery from CMS. Wistars were treated chronically with venlafaxine (VEN), while WKY were treated acutely with either DBS, optogenetic stimulation (OGS) of virally-transduced (AAV5-hSyn-ChR2-EYFP) mPFC or ventral hippocampus, or acute intra-mPFC injection of the AMPA receptor positive allosteric modulator CX-516. The AMPA receptor antagonist NBQX was administered, at identical sites in mPFC, immediately following the exposure trial in the NOR. RESULTS: Sucrose intake and NOR were suppressed by CMS, and restored by VEN in Wistars and by DBS, OGS, or CX-516 in WKY. However, OGS of the ventral hippocampal afferents to mPFC was ineffective. A low dose of NBQX selectively blocked the procognitive effect of VEN, DBS and OGS. CONCLUSIONS: These results suggest that activation of AMPA receptors in the mPFC represents a common pathway for the antidepressant effects of both conventional (VEN) and novel (DBS, OGS) antidepressant modalities, in both antidepressant responsive (Wistar) and antidepressant-resistant (WKY) rats.
Assuntos
Antidepressivos de Segunda Geração/farmacologia , Estimulação Encefálica Profunda , Transtorno Depressivo Resistente a Tratamento/metabolismo , Transtorno Depressivo Resistente a Tratamento/terapia , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , Optogenética , Córtex Pré-Frontal , Receptores de AMPA/metabolismo , Cloridrato de Venlafaxina/farmacologia , Animais , Antidepressivos de Segunda Geração/administração & dosagem , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Transtorno Depressivo Resistente a Tratamento/tratamento farmacológico , Modelos Animais de Doenças , Fármacos Atuantes sobre Aminoácidos Excitatórios/administração & dosagem , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Masculino , Córtex Pré-Frontal/efeitos dos fármacos , Córtex Pré-Frontal/metabolismo , Ratos , Ratos Endogâmicos WKY , Ratos Wistar , Receptores de AMPA/efeitos dos fármacos , Estresse Psicológico/complicações , Cloridrato de Venlafaxina/administração & dosagemRESUMO
OBJECTIVE: The purpose of the current analysis was to investigate the direct inhibitory effects of perampanel and other anti-seizure medications (ASMs) on the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), N-methyl-D-aspartic acid (NMDA), and kainate glutamate receptor subtypes using electrophysiological assessments. METHODS: AMPA receptor subunit-expressing cell lines (hGluA1-4, including two kinds of Q/R RNA-editing variants of hGluA2), NMDA receptor-expressing cells (hNR1/hNR2B), and kainate receptor-expressing cells (hGluK2) were developed in house. The effects of perampanel, and other ASMs including topiramate, phenobarbital, lamotrigine, gabapentin, carbamazepine, valproate, levetiracetam, and lacosamide, on AMPA, NMDA, and kainate receptors were evaluated by automated patch-clamp technique. In the same way, 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline (NBQX) and GYKI 52466 were evaluated as reference compounds of AMPA receptor antagonists. For the AMPA receptor functional assay, AMPA currents were elicited by AMPA in the presence of cyclothiazide. NMDA with glycine was used as a stimulant for the NMDA receptor assays, while glutamate was used for the kainate receptor assays. The mean 50 % inhibitory concentration (IC50) values were determined based on sigmoidal-curve fitting using GraphPad Prism software. RESULTS: Perampanel inhibited functions of hGluA1-4, but did not inhibit hNR1/hNR2B and hGluK2 up to 25 µM, the maximum soluble concentration. The IC50 values were 660 nM for hGluA1, 780 nM for hGluA2(R), 1200 nM for hGluA2(Q), 1200 nM for hGluA3, and 1800 nM for hGluA4. NBQX and GYKI 52466 also inhibited the function of all AMPA receptor subunits, but did not inhibit hNR1/hNR2B and hGluK2. The IC50 values for NBQX were 880 nM for hGluA1, 290 nM for hGluA2(R), 310 nM for hGluA2(Q), 330 nM for hGluA3, and 630 nM for hGluA4. For GYKI 52466, IC50 values were 25,000 nM for hGluA1, 30,000 nM for hGluA2(R), 42,000 nM for hGluA2(Q), 28,000 nM for hGluA3, and 53,000 nM for hGluA4. Phenobarbital inhibited hGluA2(R) at an IC50 value of 730,000 nM. The majority of other ASMs evaluated in this study did not show a direct inhibitory effect on almost any of the glutamate receptor functions examined up to 1 M. However, lamotrigine and carbamazepine inhibited hNR1/hNR2B function at IC50 values of 930,000 and 1,000,000 nM, respectively. SIGNIFICANCE: Only a few ASMs evaluated in this study showed direct interaction with ionotropic glutamate receptors. Perampanel is the only ASM that had a potent inhibitory effect on all AMPA receptor subtypes, but did not inhibit NMDA or kainate receptor subunits; while phenobarbital inhibited GluA2(R), and carbamazepine and lamotrigine inhibited the NMDA receptor at high concentration ranges.
Assuntos
Nitrilas/farmacologia , Piridonas/farmacologia , Receptores de AMPA/efeitos dos fármacos , Receptores Ionotrópicos de Glutamato/efeitos dos fármacos , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/farmacologia , Animais , Antagonistas de Aminoácidos Excitatórios/farmacologia , Ácido Glutâmico/efeitos dos fármacos , Ácido Glutâmico/metabolismo , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Humanos , N-Metilaspartato/farmacologia , Receptores de AMPA/metabolismo , Receptores Ionotrópicos de Glutamato/metabolismo , Receptores de Ácido Caínico/antagonistas & inibidores , Receptores de Ácido Caínico/metabolismo , Receptores de N-Metil-D-Aspartato/efeitos dos fármacos , Receptores de N-Metil-D-Aspartato/metabolismo , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico/metabolismoRESUMO
Transmembrane AMPA receptor regulatory proteins (TARPs) are auxiliary AMPA receptor subunits that play a key role in receptor trafficking and in modulating receptor gating. The ability of TARPs to slow both deactivation and desensitization is isoform specific. However, TARP isoform-specific modulation of receptor properties remains uncharacterized. Here, we compare the isoform-specific effects of γ-2, γ-3, γ-4, and γ-8 TARPs on recovery from desensitization and responses to pairs of brief applications of glutamate. All four isoforms were able to reduce receptor-mediated paired-pulse depression and significantly speed recovery from desensitization in an isoform-specific manner. In the presence of TARPs, recovery time courses were observed to contain two components, fast and slow. The proportion of fast and slow components was determined by the TARP isoform. The time constant of recovery was also altered by the duration of glutamate application. When studies with TARP chimeras were performed, TARP extracellular loops were found to play a vital role in TARP modulation of recovery. Thus, isoform-specific differences in TARP modulation of recovery from desensitization influence receptor responses to repeated brief applications of glutamate, and these differences may impact frequency-dependent synaptic signaling in the mammalian central nervous system.SIGNIFICANCE STATEMENT AMPA receptors are major determinants of excitatory synaptic strength. The channel kinetics of AMPA receptors contribute to the kinetics of synaptic transmission. Transmembrane AMPA receptor regulatory proteins (TARPs) auxiliary subunits can modulate the decay kinetics of AMPA receptors. However, whether TARP isoforms specifically modulate receptor recovery is unclear. Here, we investigated the recovery kinetics of AMPA receptors by expressing various TARP isoforms and chimeras. We observed that the TARP isoforms and duration of glutamate application uniquely modulate time constants and the proportion of fast and slow components through a previously unidentified TARP domain. Given the impact of recovery kinetics on receptor responses to repetitive stimulation such as synaptic transmission, this work will be of great interest in the field of excitatory synaptic transmission research.
Assuntos
Proteínas Nucleares/fisiologia , Receptores de AMPA/fisiologia , Linhagem Celular , Espaço Extracelular/fisiologia , Ácido Glutâmico/farmacologia , Humanos , Isomerismo , Cinética , Proteínas Mutantes Quiméricas , Proteínas Nucleares/química , Técnicas de Patch-Clamp , Receptores de AMPA/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Sinapses/efeitos dos fármacos , Sinapses/fisiologia , Transmissão Sináptica/fisiologiaRESUMO
Centella asiatica is notable for its wide range of biological activities beneficial to human health, particularly its cognitive enhancement and neuroprotective effects. The α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors are ionotropic glutamate receptors mediating fast excitatory neurotransmission essential in long-term potentiation widely thought to be the cellular mechanism of learning and memory. The method of whole-cell patch-clamp was used to study the effect of the acute application of Centella asiatica extract on the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor-mediated spontaneous excitatory postsynaptic currents in the entorhinal cortex of rat brain slices. The respective low dose of test compounds significantly increased the amplitude of spontaneous excitatory postsynaptic currents while having no significant effects on the frequency. The findings suggested that Centella asiatica extract increased the response of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors at the postsynaptic level, revealing the potential role of Centella asiatica in modulating the glutamatergic responses in the entorhinal cortex of rat brain slices to produce cognitive enhancement effects.
Assuntos
Córtex Entorrinal/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Nootrópicos/farmacologia , Receptores de AMPA/efeitos dos fármacos , Triterpenos/farmacologia , Animais , Centella , Nootrópicos/administração & dosagem , Técnicas de Patch-Clamp , Extratos Vegetais , Ratos , Triterpenos/administração & dosagemRESUMO
Conventional antidepressant drugs elevate the availability of monoamine neurotransmitters. However, these pharmacological therapies have limited efficacy and a slow onset of action as main limitations. New glutamatergic drugs such as ketamine have shown promise as a rapid-acting antidepressant drugs although with adverse effects. The mechanism of action of ketamine is hypothesized to involve a dis-inhibition of cortical pyramidal neurons produced by an stimulation of AMPA receptors by glutamate. In this context, low-impact positive allosteric modulators of the AMPA receptors (a.k.a. ampakines) have been regarded as potential antidepressant drugs. Here, we have examined the behavioral, biochemical, and molecular effects of a low-impact ampakine, CX717. Our results show that CX717 has a rapid (30 min) but short-lasting (up to 24 h) antidepressant-like effect in the forced swim test. Intra-cortical infusion of CX717 increases the efflux of noradrenaline, dopamine, and serotonin, but not glutamate. However, systemic CX717 does not alter these neurotransmitters. CX717 also produced a rapid (up to 1 h) increase of brain-derived neurotrophic factor (BDNF) and a more sustained (up to 6 h) increase of p11. Overall, CX717 appears to possess a rapid but not sustained antidepressant action possibly caused by rapid increases of BDNF and p11.