RESUMO
The aim of this study was to determine the effect of prolactin (PRL) on intracellular calcium (Ca2+) concentration and its neuroprotective role in a model of kainic acid (KA) excitotoxicity in primary cultures of hippocampal neurons. Cell viability and intracellular Ca2+ concentrations were determined by MTT and Fura-2 assays, respectively, either after induction by KA as an agonist or after treatment with NBQX antagonist alone or in combination with PRL administration. Expression of ionotropic glutamatergic receptors (iGluRs) subunits in neuronal cells was determined by RT-qPCR. Dose-response treatments with KA or glutamate (Glu), the latter used as endogenous agonist control, induced a significant increase in neuronal intracellular Ca2+ concentration followed by a significant decrease in hippocampal neuronal viability. Administration of PRL induced a significant increase in neuronal viability after treatment with KA. Furthermore, administration of PRL decreased intracellular Ca2+ concentrations induced by KA treatment. Independent administration of the AMPAR-KAR antagonist reversed cell death and reduced intracellular Ca2+ concentration in a similar manner as PRL. Additionally, mRNA expression of AMPAR, KAR and NMDAR subtypes were detected in hippocampal neurons; however, no significant changes in iGluRs subunit expression were observed due to excitotoxicity or PRL treatment. The results suggest that PRL inhibits the increase in intracellular Ca2+ concentration induced by KA, leading to neuroprotection.
Assuntos
Ácido Caínico , Prolactina , Prolactina/farmacologia , Ácido Caínico/toxicidade , Neuroproteção , Hipocampo/metabolismo , Neurônios/metabolismoRESUMO
BACKGROUND: Excitotoxicity-induced in vivo injury models are vital to reflect the pathophysiological features of acute spinal cord injury (SCI) in humans. The duration and concentration of chemical treatment controls the extent of neuronal cell damage. The extent of injury is explained in relation to locomotor and behavioural activity. Several SCI in vivo methods have been reported and studied extensively, particularly contusion, compression, and transection models. These models depict similar pathophysiology to that in humans but are extremely expensive (contusion) and require expertise (compression). Chemical excitotoxicity-induced SCI models are simple and easy while producing similar clinical manifestations. The kainic acid (KA) excitotoxicity model is a convenient, low-cost, and highly reproducible animal model of SCI in the laboratory. The basic impactor approximately cost between 10,000 and 20,000 USD, while the kainic acid only cost between 300 and 500 USD, which is quite cheap as compared to traditional SCI method. METHODS: In this study, 0.05 mM KA was administered at dose of 10 µL/100 g body weight, at a rate of 10 µL/min, to induce spinal injury by intra-spinal injection between the T12 and T13 thoracic vertebrae. In this protocol, detailed description of a dorsal laminectomy was explained to expose the spinal cord, following intra-spinal kainic acid administration at desired location. The dose, rate and technique to administer kainic acid were explained extensively to reflect a successful paraplegia and spinal cord injury in rats. The postoperative care and complication post injury of paraplegic laboratory animals were also explained, and necessary requirements to overcome these complications were also described to help researcher. RESULTS: This injury model produced impaired hind limb locomotor function with mild seizure. Hence this protocol will help researchers to induce spinal cord injury in laboratories at extremely low cost and also will help to determine the necessary supplies, methods for producing SCI in rats and treatments designed to mitigate post-injury impairment. CONCLUSIONS: Kainic acid intra-spinal injection at the concentration of 0.05 mM, and rate 10 µL/min, is an effective method create spinal injury in rats, however more potent concentrations of kainic acid need to be studied in order to create severe spinal injuries.
Assuntos
Traumatismos da Medula Espinal , Traumatismos da Coluna Vertebral , Humanos , Ratos , Animais , Ratos Sprague-Dawley , Ácido Caínico/uso terapêutico , Paraplegia/complicações , Traumatismos da Coluna Vertebral/complicações , Modelos Animais de DoençasRESUMO
Tiliaamericana var. mexicana (Tilia) possesses anticonvulsant, antioxidant, neuroprotective, and hepatoprotective activities. The spectrum of anticonvulsant activity in status epilepticus models has not been sufficiently explored. We evaluated the effects of ethyl acetate (EAc), and methanol (ME) extracts on kainic acid (KA)-induced seizures by measuring rats'behavior (severity and latency) and lipoperoxidation in different brain areas (cerebellum, brain hemispheres, cortex, and medulla), kidneys, and liver. Male Wistar rats were administered KA (10 mg/kg, i.p.) after three days of pretreatment with Tilia extract (100 mg/kg). The EAc and ME Tilia extracts significantly decreased the severity of phase 1 and phase 2 seizures, respectively. The ME Tilia extract increased the latency to seizure (27 ± 2 min) compared to the control (13 ± 2 min). The ME and EAc Tilia extracts significantly prevented the increased lipid peroxidation caused by KA-induced seizures in the cerebellum, brain hemispheres, cortex, medulla, liver, and kidneys. The vehicle olive oil (OO) also showed anticonvulsant effects, decreasing the severity of seizures to phase 3 and lipoperoxidation levels in the cerebellum, brain hemispheres, cortex, medulla, liver, and kidneys. The anticonvulsant activity of Tilia is mediated by antioxidant effects in central and systemic areas that involve synergistic interactions among the chemical constituents of these extracts (glucosides of quercetin and kaempferol), while vehicle OO showed the same effects, probably due to its constituent oleuropein.
RESUMO
BACKGROUND: Excitotoxicity-induced in vivo injury models are vital to reflect the pathophysiological features of acute spinal cord injury (SCI) in humans. The duration and concentration of chemical treatment controls the extent of neuronal cell damage. The extent of injury is explained in relation to locomotor and behavioural activity. Several SCI in vivo methods have been reported and studied extensively, particularly contusion, compression, and transection models. These models depict similar pathophysiology to that in humans but are extremely expensive (contusion) and require expertise (compression). Chemical excitotoxicity-induced SCI models are simple and easy while producing similar clinical manifestations. The kainic acid (KA) excitotoxicity model is a convenient, low-cost, and highly reproducible animal model of SCI in the laboratory. The basic impactor approximately cost between 10,000 and 20,000 USD, while the kainic acid only cost between 300 and 500 USD, which is quite cheap as compared to traditional SCI method. METHODS: In this study, 0.05 mM KA was administered at dose of 10 µL/100 g body weight, at a rate of 10 µL/min, to induce spinal injury by intra-spinal injection between the T12 and T13 thoracic vertebrae. In this protocol, detailed description of a dorsal laminectomy was explained to expose the spinal cord, following intra-spinal kainic acid administration at desired location. The dose, rate and technique to administer kainic acid were explained extensively to reflect a successful paraplegia and spinal cord injury in rats. The postoperative care and complication post injury of paraplegic laboratory animals were also explained, and necessary requirements to overcome these complications were also described to help researcher. RESULTS: This injury model produced impaired hind limb locomotor function with mild seizure. Hence this protocol will help researchers to induce spinal cord injury in laboratories at extremely low cost and also will help to determine the necessary supplies, methods for producing SCI in rats and treatments designed to mitigate post-injury impairment. CONCLUSIONS: Kainic acid intra-spinal injection at the concentration of 0.05 mM, and rate 10 µL/min, is an effective method create spinal injury in rats, however more potent concentrations of kainic acid need to be studied in order to create severe spinal injuries.
Assuntos
Humanos , Animais , Ratos , Traumatismos da Medula Espinal , Traumatismos da Coluna Vertebral/complicações , Paraplegia/complicações , Ratos Sprague-Dawley , Modelos Animais de Doenças , Ácido Caínico/uso terapêuticoRESUMO
OBJECTIVE: Brain metabolic processes are not fully characterized in the kainic acid (KA)-induced Status Epilepticus (KASE). Thus, we evaluated the usefulness of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) as an experimental strategy to evaluate in vivo, in a non-invasive way, the glucose consumption in several brain regions, in a semi-quantitative study to compare and to correlate with data from electroencephalography and histology studies. METHODS: Sixteen male Wistar rats underwent FDG-PET scans at basal state and after KA injection. FDG-PET images were normalized to an MRI-based atlas and segmented to locate regions. Standardized uptake values (SUV) were obtained at several time points. EEGs and cell viability by histological analysis, were also evaluated. RESULTS: FDG-PET data showed changes in regions such as: amygdala, hippocampus, accumbens, entorhinal cortex, motor cortex and hypothalamus. Remarkably, hippocampal hypermetabolism was found (mean SUV = 2.66 ± 0.057) 2 h after KA administration, while hypometabolism at 24 h (mean SUV = 1.83 ± 0.056) vs basal values (mean SUV = 2.19 ± 0.057). EEG showed increased spectral power values 2 h post-KA administration. Hippocampal viable-cell counting 24 h after KA was decreased, while Fluoro-Jade B-positive cells were increased, as compared to control rats, coinciding with the hypometabolism detected in the same region by semi-quantitative FDG-PET at 24 h after KASE. CONCLUSIONS: PET is suitable to measure metabolic brain changes in the rat model of status epilepticus induced by KA (KASE) at the first 24 h, compared to that of EEG; PET data may also be sensitive to cell viability.
Assuntos
Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Antagonistas de Aminoácidos Excitatórios/farmacologia , Ácido Caínico/farmacologia , Animais , Encéfalo/efeitos dos fármacos , Eletroencefalografia , Fluordesoxiglucose F18 , Hipocampo/metabolismo , Hipocampo/patologia , Masculino , Tomografia por Emissão de Pósitrons , Compostos Radiofarmacêuticos , Ratos , Ratos Wistar , Estado Epiléptico/induzido quimicamente , Estado Epiléptico/metabolismo , Estado Epiléptico/patologiaRESUMO
Prolactin (PRL) is known to exert neuroprotective effects against excitotoxic damage in the hippocampus of female rats, both in vitro and in vivo. It is still unknown whether this effect can be seen in the male hippocampus and intracellular signaling mediating such action. To assess this, adult male CD-1 mice were subjected to excitotoxic damage with kainic acid (KA; i.c.v.), after a) no manipulation (control group), b) treatment with saline, and c) treatment with PRL (8 µg of PRL/100 µl of saline s.c.). Treatments consisted of one daily injection of the mentioned dosage for seven consecutive days until the day of the excitotoxic lesion. Neurodegeneration (Fluoro-Jade C), neuronal survival (NeuN) and astrogliosis (GFAP) markers were identified with immunohistochemistry in the CA1, CA3 and CA4 areas of the dorsal hippocampus, as well as PRL-related protein levels by Western blot in the whole hippocampus 48 h after excitotoxicity. Anatomical measurements revealed a preferential protective effect of PRL against excitotoxic damage in the CA3 hippocampal subfield, with lower levels of cell death and neurodegeneration, compared to controls. In CA4, the results were not conclusive, and no damage was observed in CA1 after KA administration. PRL treatment provoked an upregulation of active Akt, a well-known cell survival pathway, after KA administration. PRL also caused downregulation of active MAPK, independently of the excitotoxic damage. The present results indicate a neuroprotective role for PRL preferentially located in the CA3 area of the hippocampus of male mice, possibly mediated by Akt-related survival mechanisms.
Assuntos
Lesões Encefálicas/tratamento farmacológico , Hipocampo/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Prolactina/farmacologia , Animais , Lesões Encefálicas/induzido quimicamente , Lesões Encefálicas/metabolismo , Lesões Encefálicas/patologia , Morte Celular/efeitos dos fármacos , Modelos Animais de Doenças , Hipocampo/diagnóstico por imagem , Hipocampo/patologia , Humanos , Ácido Caínico/toxicidade , Camundongos , Neurônios/efeitos dos fármacos , Neurônios/patologia , Neurotoxinas/toxicidade , RatosRESUMO
Cell lineage in the adult hippocampus comprises multipotent and neuron-committed progenitors. In the present work, we fate-mapped neuronal progenitors using Dcx-CreERT2 and CAG-CAT-EGFP double-transgenic mice (cDCX/EGFP). We show that 3 days after tamoxifen-mediated recombination in cDCX/EGFP adult mice, GFP+ cells in the dentate gyrus (DG) co-expresses DCX and about 6% of these cells are proliferative neuronal progenitors. After 30 days, 20% of GFP+ generated from these progenitors differentiate into GFAP+ astrocytes. Unilateral intrahippocampal administration of the chemoconvulsants kainic acid (KA) or pilocarpine (PL) triggered epileptiform discharges and led to a significant increase in the number of GFP+ cells in both ipsi and contralateral DG. However, while PL favored the differentiation of neurons in both ipsi- and contralateral sides, KA stimulated neurogenesis only in the contralateral side. In the ipsilateral side, KA injection led to an unexpected increase of astrogliogenesis in the Dcx-lineage. We also observed a small number of GFP+/GFAP+ cells displaying radial-glia morphology ipsilaterally 3 days after KA administration, suggesting that some Dcx-progenitors could regress to a multipotent stage. The boosted neurogenesis and astrogliogenesis observed in the Dcx-lineage following chemoconvulsants administration correlated, respectively, with preservation or degeneration of the parvalbuminergic plexus in the DG. Increased inflammatory response, by contrast, was observed both in the DG showing increased neurogenesis or astrogliogenesis. Altogether, our data support the view that cell lineage progression in the adult hippocampus is not unidirectional and could be modulated by local network activity and GABA-mediated signaling.
RESUMO
BACKGROUND: Neuroinflammation induced in response to damage caused by status epilepticus (SE) activates the interleukin (IL)1-ß pathway and proinflammatory proteins that increase vulnerability to the development of spontaneous seizure activity and/or epilepsy. OBJECTIVES: The study aimed to assess the short-term anti-inflammatory and neuroprotective effects of Magnolia officinalis (MO) on recurrent SE in immature rats. METHODS: Sprague-Dawley rats at PN day 10 were used; n = 60 rats were divided into two control groups, SHAM and KA, and two experimental groups, MO (KA-MO) and Celecoxib (KA-Clbx). The anti-inflammatory effect of a single dose of MO was evaluated at 6 and 24 hr by Western blotting and on day 30 PN via a subchronic administration of MO to assess neuronal preservation and hippocampal gliosis by immunohistochemistry for NeunN and GFAP, respectively. RESULTS: KA-MO caused a decrease in the expression of IL1-ß and Cox-2 at 6 and 24 h post-treatment, a reduction in iNOS synthase at 6 and 24 hr post-treatment and reduced neuronal loss and gliosis at postnatal day 30, similar to Clbx. CONCLUSION: The results indicating that Magnolia officinalis is an alternative preventive treatment for early stages of epileptogenesis are encouraging.
Assuntos
Magnolia , Estado Epiléptico , Animais , Modelos Animais de Doenças , Hipocampo/fisiologia , Inflamação/tratamento farmacológico , Ácido Caínico , Ratos , Ratos Sprague-Dawley , Estado Epiléptico/induzido quimicamente , Estado Epiléptico/tratamento farmacológicoRESUMO
Status epilepticus (SE) is one of the most significant complications in pediatric neurology. Clinical studies have shown positive effects of electroacupuncture (EA) as a therapeutic alternative in the control of partial seizures and secondary generalized clonic seizures. EA promotes the release of neurotransmitters such as GABA and some opioids. The present study aimed to evaluate the anticonvulsive and neuromodulatory effects of Shui Gou DM26 (SG_DM26) acupuncture point electrostimulation on the expression of the glutamate decarboxylase 67 (GAD67) enzyme and the glutamate transporter EAAC1 in an early SE model. At ten postnatal days (10-PD), male rats weighing 22-26 g were divided into 16 groups, including control and treatment groups: Simple stimulation, electrostimulation, anticonvulsant drug treatment, and combined treatment-electrostimulation and pentobarbital (PB). SE was induced with kainic acid (KA), and the following parameters were measured: Motor behavior, and expression of GAD67 and EAAC1. The results suggest an antiepileptic effect derived from SG DM26 point EA. The possible mechanism is most likely the increased production of the inhibitory neurotransmitter GABA, which is observed as an increase in the expression of both GAD67 and EAAC1, as well as the potential synergy between the neuromodulator effects of EA and PB.
RESUMO
Neuroprotective effects of short prolactin (PRL) pre-treatment against kainic acid (KA)-induced damage include neuron loss avoidance in all hippocampal regions and attenuation of seizures. Recent evidence points PRL receptor (PRL-R) as mediator of such neuroprotective effects and seizures as regulators of neuronal marker transcript expression in the hippocampus. Here, we investigated if a daily PRL dose of 100 µg or vehicle for 14 days in ovariectomized rats (OVX) prevents neuron loss induced by KA administered on the third day of PRL treatment in a systemic single dose of 7.5 mg/kg or vehicle, and promotes PRL-R, vesicular glutamate transporter 1 (VGLUT1) and glutamic acid decarboxylase 65 (GAD65) expression changes in the hippocampus of sacrificed rats 27 days after the KA administration. Immunostaining for Neu-N and PRL-R revealed significant neuron number and PRL-R expression reduction induced by KA that was prevented and turned into overexpression respectively in all hippocampal regions when PRL was added; while VGLUT1,and GAD65 immunostaining displayed expression decrease in the CA1 of injured rats, prevented in the last case and turned into VGLUT1, overexpression when administered PRL. These data indicate that chronic PRL administration before damage induces hippocampal neuroprotection associated with PRL-R and VGLUT1 overexpression, the latter in a regiondependent way.
Assuntos
Hipocampo/efeitos dos fármacos , Ácido Caínico/toxicidade , Neurônios/efeitos dos fármacos , Fármacos Neuroprotetores/administração & dosagem , Prolactina/administração & dosagem , Receptores da Prolactina/metabolismo , Proteína Vesicular 1 de Transporte de Glutamato/metabolismo , Animais , Agonistas de Aminoácidos Excitatórios/toxicidade , Feminino , Glutamato Descarboxilase/metabolismo , Hipocampo/metabolismo , Hipocampo/patologia , Neurônios/metabolismo , RatosRESUMO
Status epilepticus (SE) is a serious medical condition, as it may trigger epileptogenesis. SE produces continuous generalized seizures resulting in irreversible brain damage. Therefore, the use of neuroprotective agents to prevent cell damage, may reduce the impact of SE. The use of diazepam (DZP), has shown limited neuroprotective effect in SE patients. According to previous reports, dapsone (DDS) is able to reduce both cell damage and seizures, when administered 30â¯min before the onset of seizures. This study is aimed to evaluate the ability of DDS, alone or in combination with DZP starting their administration once the SE is onset to evaluate the control of seizures in rats. Results showed a reduced convulsive electrical activity after 30â¯min, 1 and 2â¯h after SE induced by kainic acid (KA) administration, in the animals treated with DZP alone or in combination with DDS. At 24â¯h, we observed electrical activity similar to baseline in all groups receiving treatment. The animals treated with DDS and DZP alone or in combination showed an increase in the number of viable pyramidal cells but only the combination showed a lower number of damaged pyramidal neurons of hippocampal CA3. In conclusion, DDS plus DZP was able to control SE and to prevent SE-induced damage, when administered in combination with DZP. As DDS is already in use for patients with leprosy, that combination may be a safe, good option for human cases of SE.
Assuntos
Dapsona/farmacologia , Estado Epiléptico/tratamento farmacológico , Animais , Anticonvulsivantes/farmacologia , Diazepam/farmacologia , Eletroencefalografia , Hipocampo/efeitos dos fármacos , Ácido Caínico/efeitos adversos , Masculino , Neurônios/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Células Piramidais/efeitos dos fármacos , Ratos , Ratos Wistar , Convulsões/induzido quimicamente , Estado Epiléptico/induzido quimicamenteRESUMO
The dentate gyrus (DG) is a neurogenic structure that exhibits functional and structural reorganization after injury. Neurogenesis and functional recovery occur after brain damage, and the possible relation between both processes is a matter of study. We explored whether neurogenesis and the activation of new neurons correlated with DG recovery over time. We induced a DG lesion in young adult rats through the intrahippocampal injection of kainic acid and analyzed functional recovery and the activation of new neurons after animals performed a contextual fear memory task (CFM) or a control spatial exploratory task. We analyzed the number of BrdU+ cells that co-localized with doublecortin (DCX) or with NeuN within the damaged DG and evaluated the number of cells in each population that were labelled with the activity marker c-fos after either task. At 10 days post-lesion (dpl), a region of the granular cell layer was devoid of cells, evidencing the damaged area, whereas at 30 dpl this region was significantly smaller. At 10 dpl, the number of BrdU+/DCX+/c-fos positive cells was increased compared to the sham-lesion group, but CFM was impaired. At 30 dpl, a significantly greater number of BrdU+/NeuN+/c-fos positive cells was observed than at 10 dpl, and activation correlated with CFM recovery. Performance in the spatial exploratory task induced marginal c-fos immunoreactivity in the BrdU+/NeuN+ population. We demonstrate that neurons born after the DG was damaged survive and are activated in a time- and task-dependent manner and that activation of new neurons occurs along functional recovery.
Assuntos
Giro Denteado/lesões , Giro Denteado/patologia , Rememoração Mental/fisiologia , Neurogênese/fisiologia , Neurônios/fisiologia , Animais , Mapeamento Encefálico , Bromodesoxiuridina , Condicionamento Psicológico/efeitos dos fármacos , Condicionamento Psicológico/fisiologia , Giro Denteado/diagnóstico por imagem , Proteína Duplacortina , Agonistas de Aminoácidos Excitatórios/toxicidade , Comportamento Exploratório/fisiologia , Medo/efeitos dos fármacos , Medo/fisiologia , Ácido Caínico/toxicidade , Masculino , Rememoração Mental/efeitos dos fármacos , Microscopia Confocal , Proteínas do Tecido Nervoso/metabolismo , Neurogênese/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Ratos , Ratos Wistar , Comportamento Espacial/efeitos dos fármacos , Comportamento Espacial/fisiologia , Estatísticas não Paramétricas , Fatores de TempoRESUMO
The lateral wings subnucleus of the dorsal raphe nucleus (lwDR) has been implicated in the modulation of panic-like behaviors, such as escape. Infusion of non- excitotoxic doses of the excitatory amino acid kainic acid into this subnucleus promptly evokes a vigorous escape response. In addition, rats exposed to panic-inducing situations show an increase in Fos protein expression in neurons within the lwDR. In the present study, we first investigated whether key structures associated with the mediation of escape behavior are recruited after chemical stimulation of the lwDR with kainic acid. We next investigated whether the infusion of the GABAA receptor antagonist bicuculline into the lwDR also evoked escape responses measured both in a circular arena and in the rat elevated T-maze. The effects of bicuculline in the circular arena were compared to those caused by the infusion of this antagonist into the ventrolateral periaqueductal gray (vlPAG), an area in close vicinity to the lwDR. The results showed that kainic acid infusion into the lwDR increased Fos protein immunostaining in brain structures deeply involved in panic-like defensive behaviors, such as the periaqueductal gray and hypothalamus, but not the amygdala. As observed with kainic acid, bicuculline evoked a pronounced escape response in the circular arena when microinjected in the lwDR, but not in the vlPAG. The escape-promoting effect of bicuculline in the lwDR was also evidenced in the elevated T-maze. These findings strength the view that dysfunction in mechanisms controlling escape in the lwDR is critically implicated in the pathophysiology of panic disorder.
Assuntos
Comportamento Animal/efeitos dos fármacos , Bicuculina/farmacologia , Núcleo Dorsal da Rafe/efeitos dos fármacos , Reação de Fuga/efeitos dos fármacos , Agonistas de Aminoácidos Excitatórios/farmacologia , Antagonistas de Receptores de GABA-A/farmacologia , Ácido Caínico/farmacologia , Pânico/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-fos/efeitos dos fármacos , Animais , Bicuculina/administração & dosagem , Agonistas de Aminoácidos Excitatórios/administração & dosagem , Antagonistas de Receptores de GABA-A/administração & dosagem , Imuno-Histoquímica , Ácido Caínico/administração & dosagem , Masculino , Substância Cinzenta Periaquedutal/efeitos dos fármacos , Ratos , Ratos Wistar , Estimulação QuímicaRESUMO
It is known that growth hormone (GH) is expressed in extrapituitary tissues, including the nervous system and ocular tissues, where it is involved in autocrine/paracrine actions related to cell survival and anti-apoptosis in several vertebrates. Little is known, however, in reptiles, so we analyzed the expression and distribution of GH in the eye of green iguana and its potential neuroprotective role in retinas that were damaged by the intraocular administration of kainic acid (KA). It was found, by Western blotting, that GH-immunoreactivity (GH-IR) was expressed as two isoforms (15 and 26kDa, under reducing conditions) in cornea, vitreous, retina, crystalline, iris and sclera, in varying proportions. Also, two bands for the growth hormone receptor (GHR)-IR were observed (70 and 44kDa, respectively) in the same tissues. By immunofluorescence, GH-IR was found in neurons present in several layers of the neuroretina (inner nuclear [INL], outer nuclear [ONL] and ganglion cell [GCL] layers) as determined by its co-existence with NeuN, but not in glial cells. In addition, GH and GHR co-expression was found in the same cells, suggesting paracrine/autocrine interactions. KA administration induced retinal excitotoxic damage, as determined by a significant reduction of the cell density and an increase in the appearance of apoptotic cells in the INL and GCL. In response to KA injury, both endogenous GH and Insulin-like Growth Factor I (IGF-I) expression were increased by 70±1.8% and 33.3±16%, respectively. The addition of exogenous GH significantly prevented the retinal damage produced by the loss of cytoarchitecture and cell density in the GCL (from 4.9±0.79 in the control, to 1.45±0.2 with KA, to 6.35±0.49cell/mm(2) with KA+GH) and in the INL (19.12±1.6, 10.05±1.9, 21.0±0.8cell/mm(2), respectively) generated by the long-term effect of 1mM KA intraocular administration. The co-incubation with a specific anti-GH antibody, however, blocked the protective effect of GH in GCL (1.4±0.23cell/mm(2)) and INL (11.35±1.06), respectively. Furthermore, added GH induced an increase of 90±14% in the retinal IGF-I concentration and the anti-GH antibody also blocked this effect. These results indicate that GH and GHR are expressed in the iguana eye and may be able to exert, either directly of mediated by IGF-I, a protective mechanism in neuroretinas that suffered damage by the administration of kainic acid.
Assuntos
Hormônio do Crescimento/metabolismo , Ácido Caínico/metabolismo , Neurônios/metabolismo , Retina/metabolismo , Animais , IguanasRESUMO
Fast ripples (FR, 250-600 Hz) are field potentials that occur only in those areas capable of generating seizures, such as the hippocampus, and modulation of FR by serotonin has been reported. Therefore, we hypothesized that the receptor antagonists 5HT1A and 5HT2A, B, C will increase FR in rats treated with kainic acid (KA, 0.8 µg/0.5 µl). For this purpose, the intracranial EEG recordings of the hippocampus from animals treated with KA and the serotonin antagonists WAY100135 and ritanserin (dose 0.2mg/Kg, i.p) were analyzed. In addition, morphologic parameters were analyzed after staining samples with cresyl violet, Timm stain, NeuN and GFAP and observing immunofluorescence. The results showed an increase in the number of events of FR (p<0.0001) and duration of each FR event after the administration of WAY100135 (p<0.030). Additionally, there was an increase in the number of events of FR (p<0.0001) and amplitude of FR after ritanserin administration (p<0.014). In relation to changes in unspecified cells, there was a significant decrement in the width of the CA3 pyramidal layer of the hippocampus (p<0.001), and there were no significant changes in reactive glia and fiber sprouting. However, a slight gain of astrocytes marked with GFAP and larger astrocytes with more projections were observed. In conclusion, these results support the modulation of FR by serotonin with participation of the 5HT1A receptor as a possible mediator of the effect. However the exact mechanisms resulting in such effect is not known.
Assuntos
Ondas Encefálicas/efeitos dos fármacos , Agonistas de Aminoácidos Excitatórios/farmacologia , Ácido Caínico/farmacologia , Convulsões/induzido quimicamente , Convulsões/fisiopatologia , Antagonistas da Serotonina/farmacologia , Análise de Variância , Animais , Relação Dose-Resposta a Droga , Eletroencefalografia , Proteína Glial Fibrilar Ácida/metabolismo , Masculino , Fosfopiruvato Hidratase/metabolismo , Piperazinas/farmacologia , Ratos , Ratos Wistar , Ritanserina/farmacologiaRESUMO
Epilepsy is a neurological disorder that has been associated with oxidative stress therefore epilepsy models have been develop such as kainic acid and pentylenetetrazol are usually used to understanding of the molecular mechanisms of this disease. We examined the metallothionein expression in rat brains of treated with kainic acid and pentylenetetrazol. Increase in metallothionein and nitrotirosyne immunoreactivity of both seizures epilepsy models was observed. Moreover, we show a significant increase on levels of MT expression. These results suggest that the increase of metallothionein expression is related with kainic acid and pentylenetetrazol treatments as response to damage mediated by oxidative stress.
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Encéfalo/efeitos dos fármacos , Epilepsia/metabolismo , Ácido Caínico/toxicidade , Metalotioneína/metabolismo , Pentilenotetrazol/toxicidade , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Modelos Animais de Doenças , Epilepsia/induzido quimicamente , Epilepsia/patologia , Ácido Caínico/administração & dosagem , Masculino , Estresse Oxidativo , Pentilenotetrazol/administração & dosagem , Ratos , Ratos Wistar , Tirosina/análogos & derivados , Tirosina/metabolismoRESUMO
The long-term effects of status epilepticus (SE) include severe clinical conditions that result in disorders of various organs and systems as well as neurological damage that could lead to death. Sparteine is a quinolizidine alkaloid synthesized from most Lupine species, and its anticonvulsive effect was evaluated in the pentylenetetrazole model of SE. However, efforts to clearly determine the anticonvulsive effect of sparteine have not been made previously. For this reason, we consider it important to study the anticonvulsant effects of sparteine at the level of behavior and EEG activity in three different SE models. The animals of the control groups, which received intraperitoneal pentylenetetrazole (90 mg/kg), kainic acid (9 mg/kg) or pilocarpine (370 mg/kg), exhibited convulsive behavior and epileptiform activity. After sparteine pretreatment (13 mg/kg, administered 30 min before the convulsive drug), the animals administered pentylenetetrazole and pilocarpine exhibited reduced mortality rates compared with the corresponding control groups, while the animals administered kainic acid exhibited a delayed onset of convulsive behavior and decreased seizure duration compared with the corresponding control group. In the three models of SE, a significant reduction in the amplitude and frequency of discharge trains was observed. These results support the anticonvulsant effect of low doses of sparteine and allow us to direct our efforts to other new anticonvulsant strategies for seizure treatment. However, it is necessary to perform more experiments to determine the precise mechanism through which sparteine produces an anticonvulsant effect at this concentration.
Assuntos
Anticonvulsivantes/uso terapêutico , Convulsivantes/toxicidade , Esparteína/uso terapêutico , Estado Epiléptico/induzido quimicamente , Estado Epiléptico/tratamento farmacológico , Animais , Ondas Encefálicas/efeitos dos fármacos , Modelos Animais de Doenças , Eletroencefalografia , Ácido Caínico/toxicidade , Masculino , Pentilenotetrazol/toxicidade , Pilocarpina/toxicidade , Ratos , Ratos WistarRESUMO
Kainic acid (KA) or pilocarpine (PILO) have been used in rats to model human temporal lobe epilepsy (TLE) but the distribution and severity of structural lesions between these two models may differ. Magnetic resonance imaging (MRI) studies have used quantitative measurements of hippocampal T2 (T2HP) relaxation time and volume, but simultaneous comparative results have not been reported yet. The aim of this study was to compare the MRI T2HP and volume with histological data and frequency of seizures in both models. KA- and PILO-treated rats were imaged with a 2 T MRI scanner. T2HP and volume values were correlated with the number of cells, mossy fiber sprouting, and spontaneous recurrent seizures (SRS) frequency over the 9 months following status epilepticus (SE). Compared to controls, KA-treated rats had unaltered T2HP, pronounced reduction in hippocampal volume and concomitant cell reduction in granule cell layer, CA1 and CA3 at 3 months post SE. In contrast, hippocampal volume was unchanged in PILO-treated animals despite detectable increased T2HP and cell loss in granule cell layer, CA1 and CA3. In the following 6 months, MRI hippocampal volume remained stable with increase of T2HP signal in the KA-treated group. The number of CA1 and CA3 cells was smaller than age-matched CTL group. In contrast, PILO group had MRI volumetric reduction accompanied by reduction in the number of CA1 and CA3 cells. In this group, T2HP signal was unaltered at 6 or 9 months after status. Reductions in the number of cells were not progressive in both models. Notably, the SRS frequency was higher in PILO than in the KA model. The volumetry data correlated well with tissue damage in the epileptic brain, suggesting that MRI may be useful for tracking longitudinal hippocampal changes, allowing the assessment of individual variability and disease progression. Our results indicate that the temporal changes in hippocampal morphology are distinct for both models of TLE and that these are not significantly correlated to the frequency of SRS.
RESUMO
During brain development, the electrical disturbance promoted by a seizure can have several consequences, because it can disturb a set of steps extremely regulated needed to the correct brain maturation. Animal modeling of seizure is invaluable to contribute to the mechanistic understanding of punctual seizure event, and those that triggered in an immature neural network could alter the mature brain physiology. In the present study we observed that the exposure to kainic acid diluted directly in water of zebrafish decreased the locomotor activity at 7 days post-fertilization (dpf) animals and increased at 15 dpf, despite the absence of more specific seizure features. Pre-exposure to kainic acid (500 µM) diluted in water at 7 dpf animals reduced the susceptibility to a second exposure 2 months later by intraperitoneal injection. The current data suggest that these different responses are associated with neuronal maturation process and open a question about the window of development that are crucial to long lasting effects related to seizure in this animal model.
Assuntos
Encéfalo/efeitos dos fármacos , Encéfalo/crescimento & desenvolvimento , Tolerância a Medicamentos/fisiologia , Ácido Caínico/toxicidade , Convulsões/induzido quimicamente , Animais , Encéfalo/fisiopatologia , Relação Dose-Resposta a Droga , Injeções Intraperitoneais , Atividade Motora/efeitos dos fármacos , Atividade Motora/fisiologia , Convulsões/fisiopatologia , Peixe-ZebraRESUMO
The brain has a central role in the regulation of energy stability of the organism. It is the organ with the highest energetic demands, the most susceptible to energy deficits, and is responsible for coordinating behavioral and physiological responses related to food foraging and intake. Dietary interventions have been shown to be a very effective means to extend lifespan and delay the appearance of age-related pathological conditions, notably those associated with brain functional decline. The present review focuses on the effects of these interventions on brain metabolism and cerebral redox state, and summarizes the current literature dealing with dietary interventions on brain pathology.