RESUMO
Abnormal patterns of brain connectivity characterize epilepsy. However, little is known about these patterns during the stages preceding a seizure induced by pentylenetetrazol (PTZ). To investigate brain connectivity in male Wistar rats during the preictal phase of PTZ-induced seizures (60 mg/kg), we recorded local field potentials in the primary motor (M1) cortex, the ventral anterior (VA) nucleus of the thalamus, the hippocampal CA1 area, and the dentate gyrus (DG) during the baseline period and after PTZ administration. While there were no changes in power density between the baseline and preictal periods, we observed an increase in directional functional connectivity in theta from the hippocampal formation to M1 and VA, as well as in middle gamma from DG to CA1 and from CA1 to M1, and also in slow gamma from M1 to CA1. These findings are supported by increased phase coherence between DG-M1 in theta and CA1-M1 in middle gamma, as well as enhanced phase-amplitude coupling of delta-middle gamma in M1 and delta-fast gamma in CA1. Interestingly, we also noted a slight decrease in phase synchrony between CA1 and VA in slow gamma. Together, these results demonstrate increased functional connectivity between brain regions during the PTZ-induced preictal period, with this increase being particularly driven by the hippocampal formation.
Assuntos
Encéfalo , Pentilenotetrazol , Ratos Wistar , Convulsões , Animais , Pentilenotetrazol/farmacologia , Masculino , Convulsões/induzido quimicamente , Convulsões/fisiopatologia , Encéfalo/efeitos dos fármacos , Encéfalo/fisiopatologia , Ratos , Vias Neurais/fisiopatologia , Vias Neurais/efeitos dos fármacos , Modelos Animais de Doenças , Eletroencefalografia/métodos , Região CA1 Hipocampal/efeitos dos fármacos , Região CA1 Hipocampal/fisiopatologia , Convulsivantes/toxicidade , Convulsivantes/farmacologia , Ondas Encefálicas/efeitos dos fármacos , Ondas Encefálicas/fisiologia , Córtex Motor/efeitos dos fármacos , Córtex Motor/fisiopatologiaRESUMO
Few data are available in the literature describing the long-term effects of envenoming in the perinatal period. In this study, the relationship between envenoming of lactating rats and possible behavioral changes in the mother and in her offspring were investigated. Lactating Wistar rats received a single dose of T. serrulatus crude venom on postnatal days 2 (V2), 10 (V10) or 16 (V16), and had their maternal behavior evaluated. The seizure threshold was evaluated in adulthood offspring. A decrease in maternal care during envenoming was observed in V2 and V10 groups. The retrieval behavior was absent in the V2 group, and a lower seizure threshold in the adult offspring of all groups was observed. During envenoming, mothers stayed away from their offspring for a relatively long time. Maternal deprivation during the early postnatal period is one of the most potent stressors for pups and could be responsible, at least in part, for the decrease in the convulsive threshold of the offspring since stress is pointed to as a risk factor for epileptogenesis. Furthermore, the scorpionic accident generates an intense immune response, and inflammation in neonates increases the susceptibility to seizures in adulthood. Therefore, maternal envenoming during lactation can have adverse effects on offspring in adulthood.
Assuntos
Lactação , Comportamento Materno/efeitos dos fármacos , Venenos de Escorpião/toxicidade , Convulsões/induzido quimicamente , Animais , Animais Recém-Nascidos , Comportamento Animal/efeitos dos fármacos , Convulsivantes/administração & dosagem , Feminino , Masculino , Exposição Materna/efeitos adversos , Pentilenotetrazol/administração & dosagem , Ratos WistarRESUMO
OBJECTIVES: The erythrinan alkaloids erythravine and 11α-hydroxy-erythravine from Erythrina verna (Vell.) have been extensively investigated for their anxiolytic and anticonvulsant effects. Both are structurally similar to the erythrartine that also exhibit anxiolytic effects, but there is no report on its anticonvulsant potential. Since some anxiolytic drugs can be useful in the management of epileptic seizures, we investigated whether erythrartine could prevent seizures induced by different chemoconvulsants. METHODS: Experiments were performed using different concentrations of erythrartine injected via intracerebroventricular in rats submitted to pilocarpine, kainic acid, pentylenetetrazol or picrotoxin-induced seizures. Moreover, the rotarod test was performed to verify the effects of erythrartine on animal motor coordination. RESULTS: Our data showed for the first time that erythrartine prevented the occurrence of seizures induced by all of the chemoconvulsants tested and did not affect locomotor performance neither produced sedative effect on animals. CONCLUSION: Obtained results validate the ethnopharmacological significance of E. verna and provide new information on erythrartine, another erythrinian alkaloid of biotechnological and medicinal interest.
Assuntos
Alcaloides/uso terapêutico , Anticonvulsivantes/uso terapêutico , Erythrina/química , Fitoterapia , Extratos Vegetais/uso terapêutico , Convulsões/prevenção & controle , Alcaloides/farmacologia , Animais , Ansiolíticos/farmacologia , Ansiolíticos/uso terapêutico , Anticonvulsivantes/farmacologia , Convulsivantes , Modelos Animais de Doenças , Epilepsia/tratamento farmacológico , Masculino , Extratos Vegetais/farmacologia , Ratos Wistar , Convulsões/induzido quimicamenteRESUMO
Ureases are microbial virulence factors either because of the enzymatic release of ammonia or due to many other non-enzymatic effects. Here we studied two neurotoxic urease isoforms, Canatoxin (CNTX) and Jack Bean Urease (JBU), produced by the plant Canavalia ensiformis, whose mechanisms of action remain elusive. The neurotoxins provoke convulsions in rodents (LD50 â¼2 mg/kg) and stimulate exocytosis in cell models, affecting intracellular calcium levels. Here, electrophysiological and brain imaging techniques were applied to elucidate their mode of action. While systemic administration of the toxins causes tonic-clonic seizures in rodents, JBU injected into rat hippocampus induced spike-wave discharges similar to absence-like seizures. JBU reduced the amplitude of compound action potential from mouse sciatic nerve in a tetrodotoxin-insensitive manner. Hippocampal slices from CNTX-injected animals or slices treated in vitro with JBU failed to induce long term potentiation upon tetanic stimulation. Rat cortical synaptosomes treated with JBU released L-glutamate. JBU increased the intracellular calcium levels and spontaneous firing rate in rat hippocampus neurons. MicroPET scans of CNTX-injected rats revealed increased [18]Fluoro-deoxyglucose uptake in epileptogenesis-related areas like hippocampus and thalamus. Curiously, CNTX did not affect voltage-gated sodium, calcium or potassium channels currents, neither did it interfere on cholinergic receptors, suggesting an indirect mode of action that could be related to the ureases' membrane-disturbing properties. Understanding the neurotoxic mode of action of C. ensiformis ureases could help to unveil the so far underappreciated relevance of these toxins in diseases caused by urease-producing microorganisms, in which the human central nervous system is affected.
Assuntos
Canavalia/química , Síndromes Neurotóxicas/etiologia , Proteínas de Plantas/toxicidade , Toxinas Biológicas/toxicidade , Urease/toxicidade , Animais , Convulsivantes/isolamento & purificação , Convulsivantes/toxicidade , Feminino , Masculino , Camundongos , Sistema Nervoso/efeitos dos fármacos , Sistema Nervoso/patologia , Síndromes Neurotóxicas/fisiopatologia , Proteínas de Plantas/isolamento & purificação , Ratos , Ratos Wistar , Toxinas Biológicas/isolamento & purificação , Urease/isolamento & purificação , Xenopus laevisRESUMO
ß-Lactam antibiotics such as ceftriaxone, are potent stimulators of the expression of l-glutamate transporter GLT-1 and may exert neuroprotective effects when chronically used in rats and mice. In this study, we used two animal models to test the neurological effect of subchronic treatment with ceftriaxone: experimental acute glaucoma in Wistar rats and induction of acute seizures with pentylenetetrazole in mice. We also assessed the performance of mice in the rotarod to calculate therapeutic indexes and exploratory activity in the open field. Our results showed that subchronic use of ceftriaxone was neuroprotective in both models, reducing injury in acute ischemia and ischemia/reperfusion in specific layers of retina and leading to a decrease in the seizure severity score. In behavioral experiments, we observed that ceftriaxone increased hyperactivity followed by a decrease in exploratory behavior in the open field, and there was no motor impairment in the rotarod test. We conclude that ceftriaxone may be useful as a tool in the development of new neuroprotective drugs targeting diseases which present a possible dysfunction in the balance of glutamatergic neurotransmission.
Assuntos
Antibacterianos/administração & dosagem , Ceftriaxona/administração & dosagem , Convulsivantes/farmacologia , Glaucoma/fisiopatologia , Fármacos Neuroprotetores/administração & dosagem , Convulsões/prevenção & controle , Tetrazóis/farmacologia , Doença Aguda , Animais , Comportamento Animal/efeitos dos fármacos , Masculino , Camundongos , Ratos , Ratos WistarRESUMO
Stress during gestation has been shown to affect susceptibility and intensity of seizures in offspring. Environmental stimuli, such as maternal physical exercise, have shown to be beneficial for brain development. Although studies have demonstrated the deleterious influence of stress during pregnancy on seizure manifestation in offspring, very little is known on how to minimize these effects. This study verified whether physical exercise during the pregnancy associated with prenatal stress minimizes seizure susceptibility in offspring at the beginning of postnatal development. Pregnant rats and male pups were divided into the following groups: control, stress, stress/forced exercise, and stress/voluntary exercise. Behavioral manifestations were analyzed after injection of pentylenetetrazol (PTZ; 45 and 60 mg/kg) at ages P15 and P25. Increased behavioral manifestations and seizure severity was observed in the stress group compared with the control group at both ages. At the dose of 45 mg/kg, offspring of stressed mothers who performed both physical exercise models showed an increase in latency for the first manifestation and decrease in the seizures severity at both ages compared with the mothers groups who were only stressed. Prenatal restraint stress potentiated PTZ-induced seizure behavior, and both forced and voluntary exercise during gestation attenuates the negative effects of PTZ-induced offspring.
Assuntos
Comportamento Animal/efeitos dos fármacos , Epilepsia/prevenção & controle , Condicionamento Físico Animal , Efeitos Tardios da Exposição Pré-Natal/prevenção & controle , Convulsões/prevenção & controle , Convulsões/fisiopatologia , Estresse Psicológico/terapia , Animais , Convulsivantes/administração & dosagem , Modelos Animais de Doenças , Feminino , Masculino , Pentilenotetrazol/administração & dosagem , Gravidez , Ratos , Ratos Wistar , Convulsões/induzido quimicamente , VoliçãoRESUMO
Deficits in cognitive functions are often observed in epileptic patients, particularly in temporal lobe epilepsy (TLE). Evidence suggests that this cognitive decline can be associated with the occurrence of focal brain lesions, especially on hippocampus and cortex regions. We previously demonstrated that the erythrinian alkaloids, (+)-erythravine and (+)-11α-hydroxy-erythravine, inhibit seizures evoked in rats by different chemoconvulsants. AIMS: The current study evaluated if these alkaloids would be acting in a neuroprotective way, reducing hippocampal sclerosis, and consequently, improving learning/memory performance. MAIN METHODS: Here we confirmed the anticonvulsant effect of both alkaloids by means of the pilocarpine seizure-induced model and also showed that they enhanced spatial learning of rats submitted to the Morris Water Maze test reverting the cognition deficit. Additionally, immunohistochemistry assays showed that neuronal death and glial activation were prevented by the alkaloids in the hippocampus CA1, CA3 and dentate gyrus regions at both hemispheres indistinctly 15 days after status epilepticus induction. KEY FINDINGS: Our results show, for the first-time, the improvement on memory/learning elicited by these erythrinian alkaloids. Furthermore, data presented herein explain, at least partially, the cellular mechanism of action of these alkaloids. Together, (+)-erythravine and (+)-11α-hydroxy-erythravine seem to be a promising protective strategy against TLE, comprising three main aspects: neuroprotection, control of epileptic seizures and cognitive improvement. SIGNIFICANCE: Moreover, our findings on neuroprotection corroborate the view that seizure frequency and severity, hippocampal lesions and memory deficits are interconnected events.
Assuntos
Alcaloides/uso terapêutico , Epilepsia/tratamento farmacológico , Epilepsia/psicologia , Compostos Heterocíclicos de 4 ou mais Anéis/uso terapêutico , Transtornos da Memória/tratamento farmacológico , Transtornos da Memória/psicologia , Fármacos Neuroprotetores/uso terapêutico , Transtorno de Aprendizagem Específico/tratamento farmacológico , Transtorno de Aprendizagem Específico/psicologia , Animais , Convulsivantes , Epilepsia/induzido quimicamente , Hipocampo/patologia , Imuno-Histoquímica , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Pilocarpina , Ratos , Ratos Wistar , Esclerose/prevenção & controle , Estado Epiléptico/induzido quimicamente , Estado Epiléptico/psicologiaRESUMO
OBJECTIVE: We aimed to explore the effects of neuropeptides ghrelin, obestatin, and vasoactive intestinal peptide (VIP) on seizures and plasma concentrations of neuroinflammation biomarkers including calcitonin gene-related peptide (CGRP), substance-P (SP), and interleukin-1 beta (IL-1ß) in pentylenetetrazol-induced seizures in rats. METHODS: Ghrelin (80 µg/kg), obestatin (1 µg/kg), VIP (25 ng/kg) or saline were administered to rats intraperitoneally 30 min before pentylenetetrazole (PTZ, 50 mg/kg) injections. Stages of epileptic seizures were evaluated by Racine's scale, and plasma CGRP, SP, and IL-1ß concentrations were measured using ELISA. RESULTS: Both obestatin and VIP shortened onset-time of generalized tonic-clonic seizure, respectively, moreover VIP also shortened the onset-time of first myoclonic-jerk induced by PTZ. While PTZ increased plasma CGRP, SP and IL-1ß concentrations, ghrelin reduced the increases evoked by PTZ. While VIP further increased PTZ-evoked CGRP levels, it diminished IL-1ß concentrations. However, obestatin did not change CGRP, SP, and IL-1ß concentrations. CONCLUSION: Our results suggest that ghrelin acts as an anticonvulsant, obestatin acts as a proconvulsant, and VIP has dual action on epilepsy. Receptors of those neuropeptides may be promising targets for epilepsy treatment.
Assuntos
Convulsivantes , Neuropeptídeos , Pentilenotetrazol , Hormônios Peptídicos , Convulsões , Animais , Masculino , Biomarcadores/sangue , Peptídeo Relacionado com Gene de Calcitonina/sangue , Peptídeo Relacionado com Gene de Calcitonina/efeitos dos fármacos , Convulsivantes/efeitos adversos , Modelos Animais de Doenças , Grelina/farmacologia , Inflamação , Interleucina-1beta/sangue , Interleucina-1beta/efeitos dos fármacos , Mioclonia , Neuropeptídeos/efeitos dos fármacos , Pentilenotetrazol/efeitos adversos , Hormônios Peptídicos/farmacologia , Distribuição Aleatória , Ratos Wistar , Convulsões/induzido quimicamente , Convulsões/metabolismo , Substância P/sangue , Substância P/efeitos dos fármacos , Fatores de Tempo , Peptídeo Intestinal Vasoativo/farmacologiaRESUMO
SUMMARY OBJECTIVE We aimed to explore the effects of neuropeptides ghrelin, obestatin, and vasoactive intestinal peptide (VIP) on seizures and plasma concentrations of neuroinflammation biomarkers including calcitonin gene-related peptide (CGRP), substance-P (SP), and interleukin-1 beta (IL-1β) in pentylenetetrazol-induced seizures in rats. METHODS Ghrelin (80 µg/kg), obestatin (1 µg/kg), VIP (25 ng/kg) or saline were administered to rats intraperitoneally 30 min before pentylenetetrazole (PTZ, 50 mg/kg) injections. Stages of epileptic seizures were evaluated by Racine's scale, and plasma CGRP, SP, and IL-1β concentrations were measured using ELISA. RESULTS Both obestatin and VIP shortened onset-time of generalized tonic-clonic seizure, respectively, moreover VIP also shortened the onset-time of first myoclonic-jerk induced by PTZ. While PTZ increased plasma CGRP, SP and IL-1β concentrations, ghrelin reduced the increases evoked by PTZ. While VIP further increased PTZ-evoked CGRP levels, it diminished IL-1β concentrations. However, obestatin did not change CGRP, SP, and IL-1β concentrations. CONCLUSION Our results suggest that ghrelin acts as an anticonvulsant, obestatin acts as a proconvulsant, and VIP has dual action on epilepsy. Receptors of those neuropeptides may be promising targets for epilepsy treatment.
RESUMO OBJETIVO Nosso objetivo foi explorar os efeitos dos neuropeptídeos grelina, obestatina e peptídeo intestinal vasoativo (VIP) nas convulsões e concentrações plasmáticas de biomarcadores neuroinflamatórios, incluindo peptídeo relacionado ao gene da calcitonina (CGRP), substância-P (SP) e interleucina-1 beta (IL-1β) em convulsões induzidas por pentilenotetrazol em ratos. MÉTODOS Grelina (80 µg/kg), obestatina (1 µg/kg), VIP (25 ng/kg) ou solução salina foram administrados a ratos intraperitonealmente 30 minutos antes de injeções de pentilenotetrazol (PTZ, 50 mg/kg). Os estágios das crises epilépticas foram avaliados pela escala de Racine e as concentrações plasmáticas de CGRP, SP e IL-1β foram medidas usando Elisa. RESULTADOS Tanto a obestatina quanto o VIP encurtaram o tempo de início da crise tônico-clônica generalizada, respectivamente. Além disso, o VIP também encurtou o tempo de início do primeiro impulso mioclônico induzido por PTZ. Enquanto o PTZ aumentou as concentrações plasmáticas de CGRP, SP e IL-1β, a grelina reduziu os aumentos evocados por PTZ. Enquanto o VIP aumenta ainda mais os níveis de CGRP evocados por PTZ, diminui as concentrações de IL-1β. No entanto, a obestatina não alterou as concentrações de CGRP, SP e IL-1β. CONCLUSÃO Nossos resultados sugerem que a grelina tem anticonvulsivante, a obestatina tem proconvulsivante e o VIP tem ação dupla na epilepsia. Receptores desses neuropeptídeos podem ser alvos promissores para o tratamento da epilepsia.
Assuntos
Animais , Masculino , Pentilenotetrazol/efeitos adversos , Convulsões/induzido quimicamente , Neuropeptídeos/efeitos adversos , Convulsivantes/efeitos adversos , Hormônios Peptídicos/farmacologia , Convulsões/metabolismo , Fatores de Tempo , Peptídeo Intestinal Vasoativo/farmacologia , Biomarcadores/sangue , Distribuição Aleatória , Substância P/efeitos adversos , Substância P/sangue , Peptídeo Relacionado com Gene de Calcitonina/efeitos adversos , Peptídeo Relacionado com Gene de Calcitonina/sangue , Ratos Wistar , Modelos Animais de Doenças , Interleucina-1beta/efeitos adversos , Interleucina-1beta/sangue , Grelina/farmacologia , Inflamação , MiocloniaRESUMO
Epilepsy produces chronic chemical changes induced by altered cellular structures, and acute ones produced by conditions leading into individual seizures. Here, we aim to quantify 24 molecules simultaneously at baseline and during periods of lowered seizure threshold in rats. Using serial hippocampal microdialysis collections starting two weeks after the pilocarpine-induced status epilepticus, we evaluated how this chronic epilepsy model affects molecule levels and their interactions. Then, we quantified the changes occurring when the brain moves into a pro-seizure state using a novel model of physiological ictogenesis. Compared with controls, pilocarpine animals had significantly decreased baseline levels of adenosine, homovanillic acid, and serotonin, but significantly increased levels of choline, glutamate, phenylalanine, and tyrosine. Step-wise linear regression identified that choline, homovanillic acid, adenosine, and serotonin are the most important features to characterize the difference in the extracellular milieu between pilocarpine and control animals. When increasing the hippocampal seizure risk, the concentrations of normetanephrine, serine, aspartate, and 5-hydroxyindoleacetic acid were the most prominent; however, there were no specific, consistent changes prior to individual seizures.