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Involvement of amygdalo-hippocampal substructures in patients with narcolepsy due to deficiencies in the orexinergic system, and the presence of hippocampus-dependent memory impairments in this disorder, have led us to investigate the effects of orexin 1 and 2 receptor antagonism in the basolateral amygdala (BLA) on long-term potentiation (LTP) of dentate gyrus (DG) granular cells. We used a 200-Hz high-frequency stimulation protocol in anesthetized rats. We studied the long-term synaptic plasticity of perforant path-dentate gyrus granule cells following the inactivation of orexin receptors before and after tetanic stimulation. LTP of the DG population spike was attenuated in the presence of orexin 1 and 2 receptor antagonism (treatment with SB-334867-A and TCS-OX2-29, respectively) in the BLA when compared to that observed following treatment with dimethyl sulfoxide (DMSO). However, the population excitatory post-synaptic potentials were not affected. Moreover, when orexin 1 and 2 receptors in the BLA were blocked after LTP induction, there were no differences between the DMSO and treatment groups. Our findings suggest that the orexinergic system of the BLA plays a modulatory role in the regulation of hippocampal plasticity in rats.
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Potenciais de Ação/efeitos dos fármacos , Complexo Nuclear Basolateral da Amígdala/efeitos dos fármacos , Giro Denteado/efeitos dos fármacos , Potenciação de Longa Duração/efeitos dos fármacos , Antagonistas dos Receptores de Orexina/farmacologia , Via Perfurante/efeitos dos fármacos , Potenciais de Ação/fisiologia , Animais , Complexo Nuclear Basolateral da Amígdala/fisiologia , Benzoxazóis/farmacologia , Giro Denteado/fisiologia , Estimulação Elétrica , Isoquinolinas/farmacologia , Potenciação de Longa Duração/fisiologia , Naftiridinas , Vias Neurais/efeitos dos fármacos , Vias Neurais/fisiologia , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Via Perfurante/fisiologia , Piridinas/farmacologia , Ratos , Ureia/análogos & derivados , Ureia/farmacologiaRESUMO
BACKGROUND: Oxidative stress has a pivotal role in the pathogenesis and development of diabetic peripheral neuropathy (DPN), the most common and debilitating complications of diabetes mellitus. There is accumulating evidence that Juglans regia L. (GRL) leaf extract, a rich source of phenolic components, has hypoglycemic and antioxidative properties. This study aimed to determine the protective effects of Juglans regia L. leaf extract against streptozotocin-induced diabetic neuropathy in rat. METHODS: The DPN rat model was generated by intraperitoneal injection of a single 55 mg/kg dose of streptozotocin (STZ). A subset of the STZ-induced diabetic rats intragastically administered with GRL leaf extract (200 mg/kg/day) before or after the onset of neuropathy, whereas other diabetic rats received only isotonic saline as the same volume of GRL leaf extract. To evaluate the effects of GRL leaf extract on the diabetic neuropathy various parameters, including histopathology and immunohistochemistry of apoptotic and inflammatory factors were assessed along with nociceptive and biochemical assessments. RESULTS: Degeneration of the sciatic nerves which was detected in the STZ-diabetic rats attenuated after GRL leaf extract administration. Greater caspase-3, COX-2, and iNOS expression could be detected in the STZ-diabetic rats, which were significantly attenuated after GRL leaf extract administration. Also, attenuation of lipid peroxidation and nociceptive response along with improved antioxidant status in the sciatic nerve of diabetic rats were detected after GRL leaf extract administration. In other word, GRL leaf extract ameliorated the behavioral and structural indices of diabetic neuropathy even after the onset of neuropathy, in addition to blood sugar reduction. CONCLUSION: Our results suggest that GRL leaf extract exert preventive and curative effects against STZ-induced diabetic neuropathy in rats which might be due to its antioxidant, anti-inflammatory, and antiapoptotic properties. Protection against neuropathy.
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Antioxidantes/farmacologia , Neuropatias Diabéticas/metabolismo , Juglans/química , Nervos Periféricos/efeitos dos fármacos , Extratos Vegetais/farmacologia , Animais , Antioxidantes/química , Glicemia/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Neuropatias Diabéticas/induzido quimicamente , Hipoglicemiantes/farmacologia , Masculino , Nervos Periféricos/patologia , Extratos Vegetais/química , Folhas de Planta/química , Ratos , Ratos Sprague-Dawley , Estreptozocina/efeitos adversosRESUMO
PURPOSE: The aim of this study was to assess the various doses of oral oxybutynin on cardiac autonomic modulation by measuring short-term heart rate variability (HRV) indexes during supine rest position. METHODS: Eight male healthy subjects (20-23 years) participated in the double-blind crossover randomized study. The single dose of oxybutynin (2.5, 5 and 10 mg) or placebo was given to the volunteers in four sessions within 5-day intervals. Before and minutes of 30, 60, 90 and 120 after administration, lead II electrocardiogram (ECG) was recorded for 5 min. ECG extracted RR intervals data became the base of the calculation of time domain and frequency domain HRV parameters, which indicate cardiac autonomic activity. Statistical analysis was done by using the nonparametric Wilcoxon and Kruskal-Wallis tests. RESULTS: The data analysis has revealed that MNN (P < 0.001), SDNN (P < 0.05), PNN50% (P < 0.01), RMSSD (P < 0.001), HFnu (P < 0.05) and LF/HF ratio (P < 0.05) values were significantly increased relative to baseline at various time points in all the groups except in placebo group. LFnu (P < 0.05) values were significantly increased relative to baseline at various time points in all the groups except in placebo group. CONCLUSIONS: Our findings have revealed that acute consumption of 2.5, 5 and 10 mg oxybutynin (an anticholinergic compound) in the juvenile healthy male subjects produces a cholinergic effect according to time and frequency domain of HRV indexes.
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Sistema Nervoso Autônomo/efeitos dos fármacos , Coração/efeitos dos fármacos , Coração/inervação , Ácidos Mandélicos/farmacologia , Parassimpatolíticos/farmacologia , Estudos Cross-Over , Método Duplo-Cego , Eletrocardiografia/efeitos dos fármacos , Voluntários Saudáveis , Frequência Cardíaca/efeitos dos fármacos , Humanos , Masculino , Valores de Referência , Adulto JovemRESUMO
AIMS: Vaccination has played an important role in protecting against death and the severity of COVID-19. The recombinant protein vaccine platform has a long track record of safety and efficacy. Here, we fused the SARS-CoV-2 spike S1 subunit to the Fc region of IgG and investigated immunogenicity, reactivity to human vaccinated sera, and neutralizing activity as a candidate protein vaccine. MATERIALS AND METHOD: We evaluated the immunogenicity of CHO-expressed S1-Fc fusion protein and tag-free S1 protein in rabbits via the production of S1-specific polyclonal antibodies. We subsequently compared the neutralizing activities of sera from immunized rabbits and human-vaccinated individuals using a surrogate Virus Neutralization Test (sVNT). KEY FINDINGS: The results indicate that S1-specific polyclonal antibodies were induced in all groups; however, antibody levels were higher in rabbits immunized with S1-Fc fusion protein than tag-free S1 protein. Moreover, the reactivity of human vaccinated sera against S1-Fc fusion protein was significantly higher than tag-free S1 protein. Lastly, the results of the virus-neutralizing activity revealed that vaccination with S1-Fc fusion protein induced the highest level of neutralizing antibody response against SARS-CoV-2. SIGNIFICANCE: Our results demonstrate that the S1 protein accompanied by the Fc fragment significantly enhances the immunogenicity and neutralizing responses against SARS-CoV-2. It is hoped that this platform can be used for human vaccination.
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COVID-19 , Vacinas , Animais , Humanos , Coelhos , Glicoproteína da Espícula de Coronavírus , COVID-19/prevenção & controle , Fragmentos Fc das Imunoglobulinas/genética , Anticorpos Antivirais , SARS-CoV-2 , Anticorpos Neutralizantes , Proteínas RecombinantesRESUMO
Spinal cord ischemia-reperfusion injury (IR) is a terrible non-traumatic injury that occurs after abdominal aortic occlusion and causes serious damage to neurological function. Several treatment strategies have been suggested for IR, but they were not unable to effectively improve these conditions. Herein we investigated whether exosomes derived from human placental mesenchymal stem cells (hpMSCs-Exos) in combination with hyperbaric oxygen (HBO) could alleviate injury and promote recovery in IR rats. Eighty male Sprague-Dawley rats were randomly allocated into five equal groups. In addition to the control group that only underwent laparotomy, IR animals were planned into four groups as follows: IR group; IR-Exos group; IR-HBO group; and IR-Exos + HBO group. Neurological function evaluated before, 6 h, 12 h, 24 h, and 48 h after injury. After the last neurological evaluation, tissue samples were obtained for stereological, biochemical, and molecular assessments. Our results indicated that the neurological function scores (MDI), the numerical density of neurons, the levels of antioxidative factors (GSH, SOD, and CAT), and anti-inflammatory cytokine (IL-10) were considerably greater in treatment groups than in the IR group, and these changes were more obvious in the IR-Exos + HBO ones. This is while the numerical density of glial cells, the levels of an oxidative factor (MDA) and inflammatory cytokines (IL-1ß, TNF-α, and IL-18), as well as the expression of an apoptotic protein (caspase-3) were meaningfully decreased in treatment groups, especially IR-Exos + HBO group, compared to the IR group. Generally, it was found that co-administration of hpMSCs-Exos and HBO has synergistic neuroprotective effects in the rats undergoing IR.
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Introduction: It has long been known that Methamphetamine (MA), as a psychostimulant, leads to long-lasting cognitive deficits. Previous studies have shown that lithium, a mood stabilizer, could facilitate cognitive ability in most of brain diseases. In current study the effects of lithium on spatial memory, hippocampal apoptosis and brain edema in METH-exposed rats are investigated. Methods: The present study 32 Wistar rats were used to examine the effects of lithium on spatial memory by the Morris water maze, hippocampal apoptosis using the TUNEL assay, and brain edema following MA administrations. Results: The findings indicated that treatment with lithium significantly ameliorated spatial learning and memory impairment in MA-treated rats. In addition, the findings showed that treatment with lithium significantly reduced brain edema and apoptosis in the CA1 neurons in MA -exposed rats. Conclusion: The results show that treatment with lithium can partially ameliorate the MA-induced neurocognitive deficits in rats, which may be related to its protective effect in the hippocampus.
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Spinal cord injury (SCI) is a critical medical condition during which sensorimotor function is lost. Current treatments are still unable to effectively improve these conditions, so it is important to pay attention to other effective approaches. Currently, we investigated the combined effects of human placenta mesenchymal stem cells (hPMSCs)-derived exosomes along with hyperbaric oxygen (HBO) in the recovery of SCI in rats. Ninety male mature Sprague-Dawley (SD) rats were allocated into five equal groups, including; sham group, SCI group, Exo group (underwent SCI and received hPMSCs-derived exosomes), HBO group (underwent SCI and received HBO), and Exo+HBO group (underwent SCI and received hPMSCs-derived exosomes plus HBO). Tissue samples at the lesion site were obtained for the evaluation of stereological, immunohistochemical, biochemical, molecular, and behavioral characteristics. Findings showed a significant increase in stereological parameters, biochemical factors (GSH, SOD, and CAT), IL-10 gene expression and behavioral functions (BBB and EMG Latency) in treatment groups, especially Exo+HBO group, compared to SCI group. In addition, MDA levels, the density of apoptotic cells and gliosis, as well as expression of inflammatory genes (TNF-α and IL-1ß) were considerably reduced in treatment groups, especially Exo+HBO group, compared to SCI group. We conclude that co-administration of hPMSCs-derived exosomes and HBO has synergistic neuroprotective effects in animals undergoing SCI.
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Exossomos , Oxigenoterapia Hiperbárica , Células-Tronco Mesenquimais , Traumatismos da Medula Espinal , Gravidez , Ratos , Humanos , Masculino , Feminino , Animais , Ratos Sprague-Dawley , Exossomos/metabolismo , Placenta/metabolismo , Placenta/patologia , Traumatismos da Medula Espinal/terapia , Oxigênio , Células-Tronco Mesenquimais/metabolismo , Medula EspinalRESUMO
BACKGROUND AND PURPOSE: Following traumatic brain injury, inflammation, mitochondrial dysfunction, oxidative stress, ischemia, and energy crisis can cause mortality or long-term morbidity. As an activator of AMP-activated protein kinase, metformin reduces the secondary injuries of traumatic brain injury by compensating for the lack of energy in damaged cells. But the blood-brain barrier prevents a hydrophilic drug such as metformin from penetrating the brain tissue. Solid lipid nanoparticles with their lipid nature can cross the blood-brain barrier and solve this challenge. so This study aimed to investigate the effect of metformin-loaded lipid nanoparticles (NanoMet) for drug delivery to the brain and reduce complications from traumatic brain injury. METHOD: Different formulations of NanoMet were designed by Box-Behnken, and after formulation, particle size, zeta potential, and entrapment efficiency were investigated. For in vivo study, Male rats were divided into eight groups, and except for the intact and sham groups, the other groups underwent brain trauma by the Marmarou method. After the intervention, the Veterinary Coma Scale, Vestibular Motor function, blood-brain barrier integrity, cerebral edema, level of inflammatory cytokines, and histopathology of brain tissue were assessed. RESULTS: The optimal formula had a size of 282.2 ± 9.05 nm, a zeta potential of -1.65 ± 0.33 mV, and entrapment efficiency of 60.61 ± 6.09% which released the drug in 1400 min. Concentrations of 5 and 10 mg/kg of this formula improved the consequences of trauma. CONCLUSION: This study showed that nanoparticles could help target drug delivery to the brain and apply the desired result.
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Lesões Encefálicas Traumáticas , Metformina , Fármacos Neuroprotetores , Masculino , Animais , Ratos , Fármacos Neuroprotetores/farmacologia , Projetos de Pesquisa , Lesões Encefálicas Traumáticas/tratamento farmacológicoRESUMO
Introduction: The Basolateral Amygdala (BLA) substantially affects neuronal transmission and synaptic plasticity processes through the dentate gyrus. Orexin neuropeptides play different roles in the sleep/wakefulness cycle, feeding, learning, and memory. The present study aimed to investigate the function of the orexin receptors of the BLA in the hippocampal local interneuron circuits. Methods: For this, the region's paired-pulse responses from the Dentate Gyrus (DG) were recorded. Within the procedure, SB-334867-A (12µg/0.5µL) and TCS-OX2-29 (10µg/0.5µL (orexin 1 & 2 receptors antagonists, respectively), were administered into both sides of the BLA areas of the rat brain. Dimethyl Sulfoxide (DMSO) was used as the solvent in the control animals with a volume of 0.5µL. Results: Our data indicated that the Paired-pulse (PP) responses were not affected by the inactivation of the orexin receptors of the BLA. Conclusion: Due to not observing any significant changes in the short form of synaptic plasticity, after inactivation of the orexin system of the BLA, we hypothesize that the orexinergic fibers to the basolateral part of the amygdala influence the long-term synaptic efficacy; however, the primary processing of information in short-term plasticity model is not affected by the same system. The elementary processing of the data by the amygdala might happen through the action of other neurotransmitter systems. Highlights: The neuronal transmission of DG following orexin receptors antagonism of the BLA.Paired-pulse responses were not affected by the orexin 1 receptors antagonism.Paired-pulse responses were not affected by the orexin 2 receptors antagonism. Plain Language Summary: The orexinergic system has modulatory effects by sending projection fibers to several parts of the brain, such as the hippocampus and amygdala. Orexin neuropeptides activate basolateral amygdala neural circuits during different arousal states. Although, this system plays a vital role in creating appropriate behavioral reactions, the primary processing of the information in short-term plasticity model is not affected by it.
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The dorsal raphe nucleus (DRN) is a brainstem nucleus involved in the pathophysiology of the depression, through its serotoninergic innervation. Furthermore, depressive symptoms in patients are also associated with some memory and sleep complaints. Anatomical evidence confirmed the presence of projections from the lateral hypothalamus to serotonergic neurons of the dorsal raphe nucleus (DRN). These projection fibers release orexin neuropeptides which play roles in the spatial memory. Both of the orexinergic receptors are widely distributed in dorsal raphe nucleus. Therefore, the present work was aimed to assess the probable roles of orexin 1 and 2 receptors using an orexin 1 receptor antagonist, SB-334867-A, and an orexin 2 receptor antagonist, TCS-OX2-29 in the DRN on the retrieval, and consolidation phases of spatial reference memory in the Morris water maze (MWM) task. The results demonstrated that blocking orexin 1 receptors in the DRN impairs the process of memory consolidation in the spatial MWM via increasing in the time of the escape latency of the probe day. Blocking these receptors did not affect the retrieval phase of MWM learning. Furthermore, blocking of the orexin 2 receptors in this area did not affect neither consolidation nor retrieval phases of the memory. In conclusion, orexin 1 receptors in the DRN play major roles in the consolidation of the spatial reference memory in rats.
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Núcleo Dorsal da Rafe/fisiologia , Receptores de Orexina/fisiologia , Memória Espacial/fisiologia , Animais , Benzoxazóis/farmacologia , Núcleo Dorsal da Rafe/efeitos dos fármacos , Masculino , Teste do Labirinto Aquático de Morris/efeitos dos fármacos , Teste do Labirinto Aquático de Morris/fisiologia , Naftiridinas/farmacologia , Antagonistas dos Receptores de Orexina/farmacologia , Receptores de Orexina/efeitos dos fármacos , Receptores de Orexina/metabolismo , Ratos , Memória Espacial/efeitos dos fármacos , Ureia/análogos & derivados , Ureia/farmacologiaRESUMO
Orexin receptors expressed in basolateral amygdala (BLA) have been proposed for memory processing and hippocampal plasticity. There are several investigations about the effect of the adrenergic system in BLA on memory enhancement. However, there is no information about the molecular basis of this effect. Adrenergic and orexinergic fibers are found in BLA. In this study, the effects of both adrenergic and orexinergic systems were investigated on the amygdala function. To this end, the selective beta 2 adrenergic agonist (clenbuterol) and orexin receptors' antagonists (OX1R and OX2R, SB-334867-A and TCS-OX2-29, respectively) were administered into the BLA, then the high frequency stimulation (200-Hz) was applied to the perforant pathway and the synaptic plasticity of the dentate granular cells was studied in anaesthetized rats. Clenbuterol injection into the BLA enhanced the population spike (PS) component of LTP in the dentate gyrus (DG), as compared to that observed after dimethyl sulfoxide treatment. In addition, after orexin 1 or 2 receptor antagonists (SB-334867-A and TCS-OX2-29, respectively) injecting into the BLA, the enhancing effect of clenbuterol on PS was reduced. Moreover, the population excitatory post-synaptic potential also decreased in the SB-clenbuterol and TCS- clenbuterol experimental groups. However, the PS amplitude was also decreased in the group treated only by SB or TCS relative to the clenbuterol treated group. The PS amplitude or EPSP slope in the groups treated by both application of orexin receptors' antagonists and clenbuterol was considerably lower relative to the groups treated only by orexin receptors' antagonists. It is concluded that the BLA orexinergic system modulates hippocampal plasticity in relation with the adrenergic system.
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Complexo Nuclear Basolateral da Amígdala , Animais , Giro Denteado , Potenciação de Longa Duração , Masculino , Plasticidade Neuronal/fisiologia , Receptores de Orexina , Ratos , Receptores AdrenérgicosRESUMO
The orexinergic system supposedly plays a role in stress circuits for arousing behaviors during anxiety, suggesting that it may play a role also in neural circuits mediating the compulsive behavior characteristic of obsessive-compulsive disorder (OCD). This study aims to investigate the roles of the orexinergic system in the development of OCD behaviors, using as preparation the induction of compulsive checking by chronic treatment with the D2/D3 agonist, quinpirole. Repeated injections of quinpirole (0.5 mg/kg, twice per week for a total of 10 injections) were used to induce compulsive checking. In separate groups of rats, OX1R (SB334867-A; 10 µg i.c.v) and OX2R (TCS-OX2-29; 10 µg i.c.v) receptor antagonists were co-administered together with quinpirole. Checking behavior in a large open field was measured after the first, fifth, and tenth injections of the drugs. SB334867-A attenuated checking behavior and the level of anxiety. TCS-OX2-29 administration ameliorated anxiety but did not block the development of compulsive checking. Orexin 1 receptors seem to play a more critical role than orexin 2 receptors in the induction of compulsive checking. Considering that the quinpirole sensitization model of OCD involves activation of dopamine systems and sensitization to quinpirole, it is suggested that neural interaction between orexigenic and dopamine systems may be important in the pathogenesis of OCD.
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Comportamento Compulsivo/fisiopatologia , Antagonistas dos Receptores de Orexina/administração & dosagem , Receptores de Orexina/fisiologia , Quimpirol/administração & dosagem , Animais , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Comportamento Compulsivo/induzido quimicamente , Agonistas de Dopamina/administração & dosagem , Masculino , Ratos WistarRESUMO
The beta-adrenergic receptors of the basolateral amygdala (BLA) are involved in modulating emotional memory formation in the hippocampus. The molecular mechanisms of this involvement are still unclear. In this study, we investigate the effects of the beta-adrenergic receptors of the BLA involvements during the major cellular mechanisms that underlie memory formation in hippocampal sub-regions. Wistar rats were injected with the selective beta receptor agonist, clenbuterol (15 ng/0.5 µl) bilaterally into the BLA. Then, the long-term potentiation (LTP) and the paired-pulse responses were recorded. Control rats were injected by saline at the same volume. Our data indicated that the injection of clenbuterol into the BLA area enhanced the amplitude of the population spike (PS) but not the slope of the excitatory postsynaptic potential (EPSP). In addition, short-term plasticity in the dentate gyrus (DG) region was significantly changed at 500 ms inter-pulse interval. These results suggest that the activation of the beta-adrenergic receptors of the BLA can improve LTP induction, which depends on the short-term plasticity with a mechanism related to the GABAergic transmission. Thus, it can be concluded that the adrenergic system of the BLA engages with long-term and short-term plasticity.
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Agonistas Adrenérgicos beta/administração & dosagem , Complexo Nuclear Basolateral da Amígdala/fisiologia , Giro Denteado/citologia , Giro Denteado/fisiologia , Plasticidade Neuronal/fisiologia , Receptores Adrenérgicos beta/fisiologia , Animais , Complexo Nuclear Basolateral da Amígdala/efeitos dos fármacos , Giro Denteado/efeitos dos fármacos , Potenciação de Longa Duração/efeitos dos fármacos , Potenciação de Longa Duração/fisiologia , Masculino , Microinjeções/métodos , Plasticidade Neuronal/efeitos dos fármacos , Ratos , Ratos WistarRESUMO
OBJECTIVES: Cisplatin-induced peripheral neuropathy is a debilitating side effect in patients receiving this drug. Recent studies suggest hyperbaric oxygen (HBO) therapy as a new treatment approach for models of neural injury. The aim of the current study was to determine the protective effects of HBO preconditioning against peripheral neuropathy induced by Cisplatin (CDDP). MATERIALS AND METHODS: The present study was conducted on 4 groups of rats: Sham group; HBO group (60 min/d); Control group (CDDP 2 mg/kg/d); Precondition group (HBO+CDDP). Mechanical threshold testing was weekly carried out using von Frey filament. Sciatic nerve and associated ganglia were removed five weeks after the first CDDP injection for biochemical evaluation of malondialdehyde (MDA) content and myeloperoxidase (MPO) activity, immunohistochemistry of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), TNF-α, caspase-3 and iNOS, and transmission electron microscopic (TEM) assessments. RESULTS: MDA levels and MPO activities were significantly decreased in preconditioned rats. Attenuated TUNEL reaction along with attenuated caspase-3, TNF-α, and iNOS expression could be significantly detected in preconditioned rats. Also, HBO preconditioning improved the nociceptive threshold. CONCLUSION: The results suggest that HBO preconditioning can attenuate peripheral neuropathy caused by cisplatin in rats.
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The hippocampal formation plays an essential role in associative learning like passive avoidance (PA) learning. It has been shown; orexin-containing terminals and orexin receptors densely are distributed in the hippocampal formation. We have previously demonstrated that antagonization of orexin 1 receptor (OX1R) in CA1 region of hippocampus and dentate gyrus (DG) impaired spatial memory processing. Although, there are few studies concerning function of orexinergic system on memory processing in PA task, but there is no study about physiological function of OX1R on this process. To address this, the OX1R antagonist, SB-334867-A, was injected into DG or CA1 regions of hippocampus and evaluated the influence of OX1R antagonization on acquisition, consolidation and retrieval in PA task. Our results show that, SB-334867-A administration into CA1 region impaired memory retrieval but not PA acquisition and consolidation. However, SB-334867-A administration into DG region impaired acquisition and consolidation but not PA memory retrieval. Therefore, it seems that endogenous orexins play an important role in learning and memory in the rat through OX1Rs.
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Aprendizagem da Esquiva/fisiologia , Giro Denteado/fisiologia , Hipocampo/fisiologia , Memória/fisiologia , Receptores Acoplados a Proteínas G/antagonistas & inibidores , Receptores de Neuropeptídeos/antagonistas & inibidores , Animais , Benzoxazóis/farmacologia , Interpretação Estatística de Dados , Dimetil Sulfóxido/farmacologia , Masculino , Microinjeções , Naftiridinas , Receptores de Orexina , Desempenho Psicomotor/fisiologia , Ratos , Ratos Wistar , Ureia/análogos & derivados , Ureia/farmacologiaRESUMO
Pain control in opioid-dependent individuals is a clinical complication. The present study investigated the effects of different doses of amitriptyline in the three stages of the formalin test in morphine-dependent rats (MDRs). Morphine dependency was induced using the oral method, and then, amitriptyline-induced antinociceptive effects were measured at 4 doses (2.5, 5, 10, and 20 mg/kg) and compared with the control group in a formalin-based model of pain. There was no observed antinociceptive effect in the MDRs and morphine-naïve rats (MNRs) in phase I. In the interphase, amitriptyline induced pain suppression at doses of 5 and 20 mg/kg. In phase II, at doses of 5, 10, and 20 mg/kg, the hypoalgesic effect on pain-related behaviors was seen in the MNRs. In MDRs, amitriptyline at doses of 2.5 and 5 mg/kg caused the hyperalgesic effect, whereas at 10 and 20 mg/kg doses, it induced a hypoalgesic effect. A significant attenuation was observed in the latency to fall from the accelerating rotarod at doses of 10 and 20 mg/kg in the MDRs, and at a dose of 20 mg/kg in the MNRs. Data showed that amitriptyline dose-dependently induced paradoxical hypo- and hyper-algesic effects in MDRs.
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Amitriptilina/uso terapêutico , Analgésicos não Narcóticos/uso terapêutico , Hiperalgesia/tratamento farmacológico , Dependência de Morfina/tratamento farmacológico , Medição da Dor/efeitos dos fármacos , Dor/tratamento farmacológico , Amitriptilina/farmacologia , Analgésicos não Narcóticos/farmacologia , Analgésicos Opioides/efeitos adversos , Animais , Relação Dose-Resposta a Droga , Hiperalgesia/patologia , Hiperalgesia/psicologia , Masculino , Morfina/efeitos adversos , Dependência de Morfina/patologia , Dependência de Morfina/psicologia , Dor/patologia , Dor/psicologia , Medição da Dor/métodos , Ratos , Ratos Wistar , Resultado do TratamentoRESUMO
The novel neuropeptides orexin-A and orexin-B derive from a common 130-amino acid precursor molecule (prepro-orexin), are mainly localized to neurons within and around the lateral hypothalamus, and exhibit high affinity to the closely related G-Protein-coupled receptors orexin 1 and 2 receptor (OX1R, OX2R). Orexinergic neurons send their axons to the hippocampal formation (CA1, CA2 and dentate gyrus), which expresses OX1Rs. Recent studies have shown that central administration of orexin-A and orexin-B have effects on learning and memory but literature concerning the role of orexinergic system in cognition remains controversial. More recently, antagonists have been described. The most potent and selective is SB-334867-A, which has an affinity of 40 nM at OX1R which is at least 50-fold selective over OX2R. It is likely that the intracerebroventricular (i.c.v.) administration may block OX1Rs in many brain regions. Previously we have shown that intra-CA1 injection of SB-334867-A impairs acquisition, consolidation and retrieval of spatial memory in MWM task. In the present study, the effect of pre-training, post-training and pre-probe of trial intra-DG (dentate gyrus) administration of SB-334867-A (1.5, 3, 6 microg/0.5 microl) on acquisition, consolidation and retrieval in a single-day testing version of MWM (Morris water maze) task was examined. Our results show impaired acquisition and consolidation of MWM task for SB-334867-A as compared with the control group. However, SB-334867-A had no effect on retrieval in spatial memory. Also, this antagonist had no effect on escape latency of a non-spatial visual discrimination task. Therefore, it seems that endogenous orexin-A and orexin-B, through DG OX1Rs, play an important role in spatial learning and memory in the rat.
Assuntos
Benzoxazóis/farmacologia , Memória/efeitos dos fármacos , Receptores Acoplados a Proteínas G/antagonistas & inibidores , Receptores de Neuropeptídeos/antagonistas & inibidores , Ureia/análogos & derivados , Animais , Benzoxazóis/administração & dosagem , Giro Denteado/efeitos dos fármacos , Giro Denteado/fisiologia , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Aprendizagem em Labirinto/fisiologia , Memória/fisiologia , Microinjeções , Naftiridinas , Receptores de Orexina , Ratos , Ratos Wistar , Receptores Acoplados a Proteínas G/fisiologia , Receptores de Neuropeptídeos/fisiologia , Comportamento Espacial/efeitos dos fármacos , Comportamento Espacial/fisiologia , Natação , Ureia/administração & dosagem , Ureia/farmacologiaRESUMO
There is an extensive evidence concerning basolateral amygdala (BLA) function to hippocampal memory processing. However, few researches have addressed the orexinergic system roles in this modulation. Then, the present study aims at investigating the action of orexin 1 and 2 receptors in BLA on passive avoidance (PA) learning. Wistar male rats (n=79) were trained to avoid foot shock in one type of PA task. The rats were injected bilaterally into BLA, a selective orexin 1 receptor antagonist, SB-334867-A (3, 6, 12µg/0.5µl), and an orexin 2 receptor antagonist, TCS-OX2-29 (2.5, 5, 10µg/0.5µl), after training or before retrieval of the inhibitory avoidance task. Control rats received dimethyl sulfoxide at the same volume. The amount of learning was assessed 24h later. The time of the first entrance to the dark compartment and the total time spending in the light compartment were measured as criteria for the avoidance memory. The results showed that consolidation and retrieval were significantly impaired by SB-334867-A administration into BLA in 3, 6 and 12µg/0.5µl. However, TCS-OX2-29 in 2.5µg/0.5µl could not influence neither consolidation nor retrieval. The TCS-OX2-29 administration into BLA impaired memory retrieval in 5 and 10µg/0/5µl but not the consolidation. It gives the impression that orexinergic system of the BLA plays an important role in regulation of memory processing and learning in the rats.
Assuntos
Complexo Nuclear Basolateral da Amígdala/efeitos dos fármacos , Benzoxazóis/farmacologia , Isoquinolinas/farmacologia , Memória/efeitos dos fármacos , Antagonistas dos Receptores de Orexina/farmacologia , Piridinas/farmacologia , Ureia/análogos & derivados , Animais , Aprendizagem da Esquiva/fisiologia , Complexo Nuclear Basolateral da Amígdala/fisiologia , Relação Dose-Resposta a Droga , Masculino , Rememoração Mental/efeitos dos fármacos , Naftiridinas , Ratos , Ratos Wistar , Tempo de Reação/efeitos dos fármacos , Ureia/farmacologiaRESUMO
Oxidative stress and mitochondrial dysfunction are the main suggested mechanisms for neurodegenerative diseases. In this study, we have evaluated the effects of epicatechin (EC) on mitochondrial damage induced by homocycteine (Hcy) using isolated rat hippocampus mitochondria in vivo. EC (50 mg/kg) was gavaged daily for a period of 10 days, starting 5 days prior to Hcy (0.5 µmol/µL) intra hippocampus injection in rats. Mitochondria were isolated from brain by different centrifuge techniques. Mitochondrial function was assayed by MTT test. Also, mitochondrial swelling and oxidative stress markers, such as reactive oxygen species (ROS), lipid peroxidation and glutathione (GSH), were assayed. Hcy induced mitochondrial dysfunction and swelling. Increase in ROS formation, lipid peroxidation, and decreased GSH were observed after Hcy treatment in isolated brain mitochondria. Furthermore, oral administration of EC significantly decreased the lipid peroxidation and ROS levels and also increased GSH levels. Also, EC treatment significantly improved mitochondrial function. As EC indicated protective effects against oxidative stress and mitochondrial damage induced by Hcy, it is suggested for further trials for prevention or treatments of neurodegenerative disorders such as Alzheimer disease.
RESUMO
Orexin containing neurons in the lateral hypothalamic area (LHA) produce orexin-A (hypocretin-1) and orexin-B (hypocretin-2) and send their axons to the hippocampus, which predominantly expresses orexin 1 receptors (OX1Rs) showing a higher affinity to orexin-A. Recent studies have shown that central administration of orexin-A has an effect on learning and memory but literature concerning the role of orexinergic system in cognition remains controversial. Therefore, we examined the effect of pre-training, post-training and pre-probe trial intrahippocampal CA1 administration of a selective OX1R the orexin 1 receptor antagonist SB-334867-A (1.5, 3, 6 microg/0.5 microl) on acquisition, consolidation and retrieval in a single-day testing version of Morris water maze (MWM) task. Our results show that, SB-334867-A impaired acquisition, consolidation and retrieval of MWM task as compared with the control group. This drug had no effect on escape latency of a non-spatial visual discrimination task. Therefore, it seems that endogenous orexins, especially orexin-A, play an important role in spatial learning and memory in the rat.