Resumo A encefalopatia hepática (EH) é uma síndrome neuropsiquiátrica potencialmente reversível. Muitas vezes a EH causa disfunções cognitivas e motoras devido à insuficiência do fígado ou por um desvio entre a veia porta hepática e a vasculatura sistêmica. O dano no fígado provoca alterações periféricas, como no metabolismo e nas respostas inflamatórias periféricas, que desencadeiam uma neuroinflamação exacerbada. Em modelos experimentais, estratégias anti-inflamatórias têm demonstrado efeitos neuroprotetores, levando a uma redução dos prejuízos cognitivos e motores relacionados à EH. Neste cenário, evidências crescentes têm mostrado a inflamação periférica e no sistema nervoso central como um promissor alvo pré-clínico. Nesta revisão, abordamos uma visão geral de drogas e compostos naturais aprovados pelo FDA para o uso no tratamento de outras doenças neurológicas e não neurológicas, que tiveram papel neuroprotetor na EH experimental, pelo menos em parte, através de mecanismos anti-inflamatórios. Apesar dos resultados empolgantes em modelos animais, os dados avaliados devem ser criticamente interpretados, destacando a importância da tradução dos achados para ensaios clínicos. (EH reversível sistêmica periféricas exacerbada experimentais antiinflamatórias anti neuroprotetores cenário préclínico. préclínico pré clínico. clínico pré-clínico revisão experimental parte antiinflamatórios. antiinflamatórios inflamatórios. inflamatórios anti-inflamatórios animais interpretados clínicos

Abstract Hepatic encephalopathy (HE) is a potentially reversible neuropsychiatric syndrome. Often, HE causes cognitive and motor dysfunctions due to an acute or chronic insufficiency of the liver or a shunting between the hepatic portal vein and systemic vasculature. Liver damage induces peripheral changes, such as in the metabolism and peripheral inflammatory responses that trigger exacerbated neuroinflammation. In experimental models, anti-inflammatory strategies have demonstrated neuroprotective effects, leading to a reduction in HE-related cognitive and motor impairments. In this scenario, a growing body of evidence has shown that peripheral and central nervous system inflammation are promising preclinical targets. In this review, we performed an overview of FDA-approved drugs and natural compounds which are used in the treatment of other neurological and nonneurological diseases that have played a neuroprotective role in experimental HE, at least in part, through anti-inflammatory mechanisms. Despite the exciting results from animal models, the available data should be critically interpreted, highlighting the importance of translating the findings for clinical essays. (HE syndrome Often vasculature changes neuroinflammation models antiinflammatory anti effects HErelated related impairments scenario targets review FDAapproved FDA approved part mechanisms interpreted essays

RESUMO. A co-ocorrência de distúrbios comportamentais e comprometimento cognitivo pós-acidente vascular cerebral (AVC) é amplamente descrita na literatura. No entanto, os estudos geralmente não incluem a cognição social entre os domínios cognitivos avaliados. Objetivo: Investigar a potencial associação entre o reconhecimento da emoção facial, uma medida da cognição social, e os sintomas comportamentais e cognitivos na fase subaguda do AVC isquêmico. Métodos: Pacientes internados em uma Unidade de AVC com AVC isquêmico foram acompanhados até 60 dias, quando foram avaliados com os seguintes instrumentos: Mini-Exame do Estado Mental (MEEM); Bateria de Avaliação Frontal (FAB); Teste de Memória Visual da Bateria Cognitiva Breve (VMT); Fluência Verbal Fonêmica (Teste F-A-S); Span de dígitos; Teste de Reconhecimento de Emoção Facial (FERT) e Escala Hospitalar de Ansiedade e Depressão (HADS). Um grupo controle constituído por 21 indivíduos saudáveis também foi submetido à mesma avaliação. Resultados: Dezoito pacientes com AVC isquêmico foram incluídos no presente estudo, apresentando idade, sexo e anos de escolaridade semelhantes aos do grupo controle. Os sintomas de depressão e déficits de memória episódica foram significativamente mais frequentes em pacientes com AVC. O reconhecimento da expressão de tristeza correlacionou-se positivamente com os níveis de ansiedade e depressão, ao passo que o reconhecimento da expressão de medo correlacionou-se negativamente com depressão no grupo de AVC. Conclusões: Após um AVC isquêmico, pacientes podem apresentar alterações de cognição social, especificamente de reconhecimento da emoção facial, em associação com sintomas comportamentais.

ABSTRACT. The co-occurrence of post-stroke behavioral disorders and cognitive impairment has been extensively investigated. However, studies usually do not include social cognition among the assessed cognitive domains. Objective: To investigate the potential association between facial emotion recognition, a measure of social cognition, and behavioral and cognitive symptoms in the subacute phase of ischemic stroke. Methods: Patients admitted to a Stroke Unit with ischemic stroke were followed up to 60 days. At this time point, they were evaluated with the following tools: Mini-Mental State Examination (MMSE); Frontal Assessment Battery (FAB); Visual Memory Test of the Brief Cognitive Battery (VMT); Phonemic Verbal Fluency (F-A-S Test); Digit Span; Facial Emotion Recognition Test (FERT) and Hospital Anxiety and Depression Scale (HADS). A control group composed of 21 healthy individuals also underwent the same evaluation. Results: Eighteen patients with ischemic stroke were enrolled in this study. They had similar age, sex and schooling years compared to controls. Depression symptoms and episodic memory deficits were significantly more frequent in patients compared to controls. The recognition of sadness expression positively correlated with the levels of anxiety and depression, while and the recognition of fear expression negatively correlated with depression in the stroke group. Conclusions: After an ischemic stroke, patients exhibit impairment in social cognition skills, specifically facial emotion recognition, in association with behavioral symptoms.

RESUMO Introdução: A Alberta Stroke Early Score (ASPECTS) foi desenvolvida para monitorização de alterações isquêmicas precoces na tomografia computadorizada de crânio, estando associada a desfechos clínicos. A ASPECTS também pode se associar aos biomarcadores periféricos que refletem a resposta fisiopatológica do cérebro ao AVC isquêmico. Objetivo: Investigar à associação entre os parâmetros periféricos com a Alberta Stroke Early Score (ASPECTS) em indivíduos após acidente vascular cerebral isquêmico. Métodos: Pacientes acima de 18 anos com AVC isquêmico agudo foram incluídos neste estudo. Nenhum paciente foi elegível para trombólise. Os pacientes foram submetidos à tomografia computadorizada sem contraste nas primeiras 24 horas da admissão, a ASPECTS e as avaliações clínicas e moleculares aplicadas no mesmo dia. O National Institutes of Health Stroke Scale (NIHSS), a escala de Rankin modificada e o Mini Exame do Estado Mental para avaliação clínica também foram aplicados a todos os indivíduos. Os níveis plasmáticos de BDNF, VCAM-1, VEGF, IL-1β, sTNFRs e adiponectina foram determinados por ELISA. Resultados: Pior desempenho neurológico (NIHSS), cognitivo (MEEM) e funcional (Rankin) foram observados no grupo com alterações na ASPECTS. Pacientes com alterações na ASPECTS também exibiram níveis mais altos de IL-1β e adiponectina. Na regressão multivariada linear, foi encontrado um coeficiente R ajustado de 0,515, indicando adiponectina e NIHSS como preditores independentes para a ASPECTS. Conclusão: Os níveis plasmáticos de adiponectina estão associados aos escores da ASPECTS.

ABSTRACT Background: The Alberta Stroke Program Early CT Score (ASPECTS) scale was developed for monitoring early ischemic changes on CT, being associated with clinical outcomes. The ASPECTS can also associate with peripheral biomarkers that reflect the pathophysiological response of the brain to the ischemic stroke. Objective: To investigate the association between peripheral biomarkers with the Alberta Stroke Program Early CT Score (ASPECTS) in individuals after ischemic stroke. Methods: Patients over 18 years old with acute ischemic stroke were enrolled in this study. No patient was eligible for thrombolysis. The patients were submitted to non-contrast CT in the first 24 hours of admission, being the Alberta Stroke Program Early CT Score and clinical and molecular evaluations applied on the same day. The National Institutes of Health Stroke Scale (NIHSS), modified Rankin scale and the Mini-Mental State Examination for clinical evaluation were also applied to all subjects. Plasma levels of BDNF, VCAM-1, VEGF, IL-1β, sTNFRs and adiponectin were determined by ELISA. Results: Worse neurological impairment (NIHSS), cognitive (MEEM) and functional (Rankin) performance was observed in the group with changes in the NCTT. Patients with NCTT changes also exhibited higher levels of IL-1β and adiponectin. In the linear multivariate regression, an adjusted R coefficient of 0.515 was found, indicating adiponectin and NIHSS as independent predictors of ASPECTS. Conclusion: Plasma levels of adiponectin are associated with the ASPECTS scores.

RESUMO Objetivo Investigar potenciais associações entre funções executiva, física global e de alimentação na fase aguda do acidente vascular cerebral (AVC). Métodos Trata-se de estudo transversal envolvendo 63 pacientes admitidos em unidade de AVC de um hospital público. Os critérios de exclusão foram outros diagnósticos neurológicos e/ou psiquiátricos. Os instrumentos utilizados foram: Mini-Exame do Estado Mental e Bateria de Avaliação Frontal para avaliar funções cognitivas; Alberta Stroke Program Early CT Score para quantificação da lesão cerebral; National Institutes of Health Stroke Scale para comprometimento neurológico; Escala Modificada de Rankin para funcionalidade e Functional Oral Intake Scale para função alimentar. Resultados A amostra compreendeu 34 homens e 29 mulheres, sendo a idade média de 63,6 anos. A Bateria de Avaliação Frontal correlacionou significativamente com as demais escalas. Na análise multivariada, a variável independentemente associada com a função executiva foi a Functional Oral Intake Scale. Conclusão A maioria dos pacientes com AVC apresenta alterações das funções executivas que comprometem significativamente a alimentação oral.

ABSTRACT Purpose To investigate potential associations among executive, physical and food functions in the acute phase after stroke. Methods This is a cross-sectional study that evaluated 63 patients admitted to the stroke unit of a public hospital. The exclusion criteria were other neurological and/or psychiatric diagnoses. The tools for evaluation were: Mini-Mental State Examination and Frontal Assessment Battery for cognitive functions; Alberta Stroke Program Early CT Score for quantification of brain injury; National Institutes of Health Stroke Scale for neurological impairment; Modified Rankin Scale for functionality, and the Functional Oral Intake Scale for food function. Results The sample comprised 34 men (54%) and 29 women with a mean age of 63.6 years. The Frontal Assessment Battery was significantly associated with the other scales. In multivariate analysis, executive function was independently associated with the Functional Oral Intake Scale. Conclusion Most patients exhibited executive dysfunction that significantly compromised oral intake.

Abstract Purpose: To investigated the inflammatory, angiogenic and fibrogenic activities of the Schinus terebinthifolius Raddi leaves oil (STRO) on wound healing. Methods: The excisional wound healing model was used to evaluate the effects of STRO. The mice were divided into two groups: Control, subjected to vehicle solution (ointment lanolin/vaseline base), or STRO- treated group, administered topically once a day for 3, 7 and 14 days post-excision. We evaluated the macroscopic wound closure rate; the inflammation was evaluated by leukocytes accumulation and cytokine levels in the wounds. The accumulation of neutrophil and macrophages in the wounds were determined by assaying myeloperoxidase and N-acetyl-β-D-glucosaminidase activities. The levels of TNF-α, CXCL-1 and CCL-2 in wound were evaluated by ELISA assay. Angiogenesis and collagen fibers deposition were evaluated histologically. Results: We observed that macroscopic wound closure rate was improved in wounds from STRO-group than Control-group. The wounds treated with STRO promoted a reduction in leucocyte accumulation and in pro-inflammatory cytokine. Moreover, STRO treatment increased significantly the number of blood vessels and collagen fibers deposition, as compared to control group. Conclusion: Topical application of STRO display anti-inflammatory and angiogenic effects, as well as improvement in collagen replacement, suggesting a putative use of this herb for the development of phytomedicines to treat inflammatory diseases, including wound healing.

Resumo: A liberação da placenta após o parto envolve a perda da adesão materno-fetal e ocorre somente após a maturação completa do placentoma, que está relacionada com a diminuição da celularidade dos tecidos fetal e materno. A apoptose é requerida tanto para a maturação quanto para a liberação normal da placenta após o parto. O objetivo do presente estudo foi avaliar a ocorrência de apoptose em amostras de placenta de vacas em diferentes fases de gestação. Amostras de placentomas de 15 vacas saudáveis com 4 (n=5), 6 (n=5) e 9 (n=5) meses de gestação foram colhidas e processadas rotineiramente para a histologia, imunoistoquímica e histoquímica. As lâminas obtidas foram coradas em HE, Picrosirius Red e submetidas à análise imunoistoquímica das proteínas Caspase 3, Caspase 8, Bax e Bid. O aumento no número de vasos não necessariamente se associou ao aumento do calibre destes durante a evolução da gestação. Os resultados de histomorfometria revelaram aumento da marcação para Bax e Caspases 3 e 8 em células trofoblásticas binucleadas no final da gestação, enquanto o Bid se manteve sem alteração significativa. A histomorfometria das células trofoblásticas mononucleadas revelou expressão alta para Bax no início de gestação, com diminuição aos 6 meses de gestação e aumento das imunomarcações para Caspases 3 e 8, e Bid com o avanço gestacional. Os colágenos tipo I e III não aumentaram do terço médio ao final da gestação, o que é importante para a diminuição da adesão materno-fetal. Esses resultados confirmam que as Caspases 3 e 8, e o Bax estão envolvidos nos mecanismos de ativação da apoptose pela via intrínseca mitocondrial e/ou extrínseca ao longo da gestação em células trofoblásticas binucleadas, e que nas células trofoblásticas mononucleadas o Bax deixa de ser importante, enquanto o Bid e as Caspases 3 e 8 se tornam os mais significativos.

Abstract: Placental release after birth involves loss of maternal-fetal adhesion and occurs only after complete maturation of the placentoma related to the decrease in cellularity of fetal and maternal tissues. Apoptosis is required for both the normal maturation and release of the placenta after birth. The aim of this study was to evaluate the occurrence of apoptosis in samples of the placenta of cows in different stages of gestation. Samples of 15 healthy cow placentomas at 4 (n=5), 6 (n=5) and 9 (n=5) months of gestation were harvested and processed for routine histology, immunohistochemistry and histochemistry. The slides were stained with HE, PicroSirius Red and subjected to immunohistochemical analysis of proteins Caspase 3, Caspase 8, Bax and Bid. Increase in number of vessels was not associated with increase in vascular area during progression of gestation. The results of histomorphometry revealed increased labeling for Bax and Caspases 3 and 8 in trophoblastic binucleated cells in late pregnancy, where the Bid remained without significant change. Histomorphometry analyzing the mononuclear trophoblast cells showed a high expression for Bax in early pregnancy, but decreased at 6 months of gestation. Immunolabeling revealed increased Caspases 3/8 and Bid with advancing of gestation. Further evaluation of type I and III collagen showed a decrease of both types of collagens at the end of gestation, what is very important for the reduction of maternal-fetal adhesion. These results confirm that Caspases 3 and 8 and Bax are involved in the mechanisms of activation of apoptosis through mitochondrial intrinsic and/or extrinsic pathway during pregnancy in trophoblastic binucleated cells. In mononuclear trophoblast cells Bax looses importance in the apoptosis process, awhile Bid and caspases 3 and 8 become the most significant.

O presente estudo teve como objetivo investigar alterações comportamentais e processos inflamatórios na isquemia cerebral induzida pela oclusão unilateral da carótida comum esquerda (UCCAO) em camundongos. As alterações comportamentais foram avaliadas após 15 minutos de isquemia e 24 horas de reperfusão. O teste de reconhecimento de objetos foi utilizado para avaliação da memória e do aprendizado. Em seguida, os animais foram mortos e os encéfalos foram coletados e processados para avaliação das alterações patológicas pelas técnicas de TTC e H&E, assim como da dosagem de mediadores inflamatórios por ELISA. A UCCAO promoveu alterações de memória após a reperfusão. Foram visualizadas áreas de infarto cerebral pela coloração de TTC e cavidades necróticas circundadas por neurônios isquêmicos no cérebro e neurodegeneração hipocampal. A UCCAO causou aumento dos níveis encefálicos de TNF-a, IL-1b e CXCL1. Estes achados demonstraram o envolvimento dos mediadores inflamatórios no sistema nervoso central e da neurodegeneração no déficit cognitivo após isquemia cerebral aguda.

The present study aimed to investigate behavioral changes and neuroinflammatory process following left unilateral common carotid artery occlusion (UCCAO), a model of cerebral ischemia. Post-ischemic behavioral changes following 15 min UCCAO were recorded 24 hours after reperfusion. The novel object recognition task was used to assess learning and memory. After behavioral test, brains from sham and ischemic mice were removed and processed to evaluate central nervous system pathology by TTC and H&E techniques as well as inflammatory mediators by ELISA. UCCAO promoted long-term memory impairment after reperfusion. Infarct areas were observed in the cerebrum by TTC stain. Moreover, the histopathological analysis revealed cerebral necrotic cavities surrounded by ischemic neurons and hippocampal neurodegeneration. In parallel with memory dysfunction, brain levels of TNF-a, IL-1b and CXCL1 were increased post ischemia compared with sham-operated group. These findings suggest an involvement of central nervous system inflammatory mediators and brain damage in cognitive impairment following unilateral acute ischemia.

PURPOSE:To evaluate wound contraction and the concentration of mast cells in skin wounds treated with 5% BPT essential oil-based ointment in rats.METHODS:Twenty rats, male, of adult age, were submitted to skin surgery on the right (RA) and left antimeres (LA) of the thoracic region. They were divided into two groups: control (RA - wounds receiving daily topical application of vaseline and lanolin) and treated (LA - wounds treated daily with the topical ointment). The skin region with wounds were collected at days 4, 7, 14 and 21 after surgery. Those were fixed in 10% formaldehyde and later processed for paraffin embedding. Sections were obtained and stained by H.E for histopathology analysis. The degree of epithelial contraction was measured and mast cell concentration were also evaluated.RESULTS:The treated group showed higher mast cell concentrations (p<0.05) associated with increased contraction at day 7 and 14 respectively.CONCLUSION: Ointment containing 5% Brazilian pepper tree oil increases mast cell concentration and promotes skin wound contraction in rats.

PURPOSE: To evaluate the effects of aroeira (Schinus terebinthifolius) ointment on skin wound healing in rats. METHODS: Adult male rats (n=20) were divided into four groups of five animals each, as follows: G4, G7, G14 and G21, which corresponds to 4th, 7th, 14th and 21th days postoperatively. Each animal were made two incisions on the skin, including the subcutaneous tissue, in the right and left sides of thoracic region, separated by a distance of two inches. The right lesion was treated with base ointment (vaseline, lanolin); the left one was treated with base ointment containing 5% of aroeira oil. At the end of each experimental period the lesions were evaluated for the contraction degree. Then held the collection of fragments that were fixed in 10% formalin and processed for paraffin embedding. In the histological sections (5μm) was evaluated the morphology and quantified the collagen and blood vessels. The data obtained were submitted to ANOVA test complemented by Tukey-Kramer test (p<0.05). RESULTS: The contraction of the lesions was higher in wounds treated with aroeira oil than in controls at 7th and 14th days (p<0.01), whereas in the 21st day all lesions were already completely healed. The morphology showed granulation tissue more developed, with fibroblasts more bulky and collagen fibers more arranged in the experimental group at 4th, 7th and 14th days. The morphometry showed a significant increase in the quantification of collagen fibers in the experimental group at 7th and 14th days (p<0.05). CONCLUSION: The aroeira oil accelerates the healing process of wounds as a macroscopic, morphological and morphometrical analysis.

OBJECTIVE: Ischemic stroke may result from transient or permanent reductions of regional cerebral blood flow. Polymorphonuclear neutrophils have been described as the earliest inflammatory cells to arrive in ischemic tissue. CXCR1/2 receptors are involved in the recruitment of these cells. However, the contribution of these chemokine receptors during transient brain ischemia in mice remains poorly understood. In this work, we investigated the effects of reparixin, an allosteric antagonist of CXCR1/2 receptors, in a model of middle cerebral artery occlusion and reperfusion in mice. METHODS: C57BL/6J male mice treated with reparixin or vehicle were subjected to a middle cerebral artery occlusion procedure 1 h after the treatment. Ninety minutes after ischemia induction, the monofilament that prevented blood flow was removed. Twenty-four hours after the reperfusion procedure, behavioral changes, including motor signs, were analyzed with the SmithKline/Harwell/lmperial College/Royal Hospital/Phenotype Assessment (SHIRPA) battery. The animals were sacrificed, and brain tissue was removed for histological and biochemical analyses. Histological sections were stained with hematoxylin and eosin, neutrophil infiltration was estimated by myeloperoxidase activity and the inflammatory cytokine IL-iβ was measured by ELISA. RESULTS: Pre-treatment with reparixin reduced the motor deficits observed in this model of ischemia and reperfusion. Myeloperoxidase activity and IL-iβ were reduced in the reparixin-treated group. Histological analysis revealed that ischemic injury was also attenuated by reparixin pre-treatment. CONCLUSIONS: Our results suggest that the blockade of the CXCR1/2 receptors by reparixin promotes neuroprotective effects by reducing the levels of polymorphonuclear infiltration in the brain and the tissue damage associated with middle cerebral artery occlusion and reperfusion.

O vírus herpes simplex-1 (HSV-1) é um patógeno que pode causar encefalite grave em humanos. Neste estudo, buscamos investigar o papel da interleucina-4 (IL-4) no modelo de infecção intracerebral por HSV-1. Camundongos C57BL/6 selvagens (WT) e deficientes no gene IL-4 (IL-4-/-) foram inoculados com 10(4) unidades formadoras de placas de HSV-1 por via intracraniana. A análise histopatológica revelou um padrão distinto de infiltrado leucocitário. Camundongos WT infectados apresentaram infiltrado de células mononucleares, enquanto camundongos IL-4-/- desenvolveram meningoencefalite com predomínio de neutrófilos 3 dias pós-infecção (dpi). Animais IL-4-/- tiveram menor adesão de leucócitos 3 dpi quando comparados aos animais WT infectados à microscopia intravital. Em contrapartida, não foram encontradas diferenças nos níveis cerebrais de CXCL1, CXCL9, CCL3, CCL5 e TNF-α entre camundongos WT e IL-4-/- infectados. Esses resultados sugerem que IL-4 pode desempenhar um papel no recrutamento de células no sistema nervoso central neste modelo agudo de encefalite grave causada pelo HSV-1.

Herpes simplex virus-1 (HSV-1) is a pathogen that may cause severe encephalitis in humans. In this study, we aimed to investigate the role of interleukin-4 (IL-4) in a model of HSV-1 brain infection. IL-4 knockout (IL-4-/-) and wild type (WT) C57BL/6 mice were inoculated with 10(4) plaque-forming units of HSV-1 by the intracranial route. Histopathologic analysis revealed a distinct profile of infiltrating cells at 3 days post-infection (dpi). Infected WT mice presented mononuclear inflammatory cells while IL-4-/- mice developed meningoencephalitis with predominance of neutrophils. IL-4-/- mice had diminished leukocyte adhesion at 3 dpi when compared to infected WT animals in intravital microscopy study. Conversely no differences were found in cerebral levels of CXCL1, CXCL9, CCL3, CCL5 and TNF-α between WT and IL-4-/- infected mice. IL-4 may play a role in the recruitment of cells into central nervous system in this acute model of severe encephalitis caused by HSV-1.

OBJETIVO: A encefalopatia hepática (EH) é uma síndrome neuropsiquiátrica resultante da falência hepática. O objetivo do presente estudo foi estabelecer um modelo de EH induzida por tioacetamida (TAA) em camundongos C57BL/6 avaliando transtornos comportamentais, falência hepática e alterações na liberação de neurotransmissores. MÉTODO: A EH foi induzida por meio de uma única dose intraperitoneal de TAA (200 mg/kg, 600 mg/kg, 1.200 mg/kg). As alterações comportamentais foram avaliadas utilizando a bateria SHIRPA. A falência hepática foi confirmada através de análises histopatológicas e a liberação de glutamato medida, por ensaio fluorimétrico. RESULTADOS: Foram encontradas alterações significativas no estado neuropsiquiátrico, comportamento motor e função reflexa e sensorial no grupo que recebeu 600 mg/kg de TAA. Análises bioquímicas revelaram aumento na liberação de glutamato no córtex cerebral dos camundongos com EH. CONCLUSÃO: A EH induzida por 600 mg/kg de TAA em camundongos C57BL/6 parece ser um modelo apropriado para a investigação da patogênese e dos transtornos clínicos da EH.

OBJECTIVE: Hepatic encephalopathy (HE) is a neuropsychiatric syndrome resulting from liver failure. In the present study, we aimed to standardize an animal model of HE induced by thioacetamide (TAA) in C57BL/6 mice evaluating behavioral symptoms in association with liver damage and alterations in neurotransmitter release. METHOD: HE was induced by an intraperitoneal single dose of TAA (200 mg/kg, 600 mg/kg or 1,200 mg/kg). Behavioral symptoms were evaluated using the SHIRPA battery. Liver damage was confirmed by histopathological analysis. The glutamate release was measured using fluorimetric assay. RESULTS: The neuropsychiatric state, motor behavior and reflex and sensory functions were significantly altered in the group receiving 600 mg/kg of TAA. Biochemical analysis revealed an increase in the glutamate release in the cerebral cortex of HE mice. CONCLUSION: HE induced by 600mg/kg TAA injection in C57BL/6 mice seems to be a suitable model to investigate the pathogenesis and clinical disorders of HE.