Molecular aspects of hepatic encephalopathy

Introduction: Liver fibrosis and its end stage, cirrhosis, is an enormous worldwide health problem. Hepatic encephalopathy (HE) or portal-systemic encephalopathy continues to be a major clinical problem of long-term cirrhosis. In this review we emphasise the molecular basis of HE and the involvement of oxidative stress in the development of this disease. Background: Several studies suggest that the pathogenesis of HE could be multifactorial and have different factors implicated, such as alterations in blood brain barrier, substances such as ammonia and manganese, and disorders in the neurotransmission of dopamine, glutamate and GABA. Development: HE is a severe complication of both acute and chronic liver failure. Neuropathologically, it is characterized by astrocyte changes known as Alzheimer type II astrocytosis. In addition, astrocytes manifest altered expression of astrocyte-specific proteins, such as, glial fibrillary acidic protein, glutamine synthetase, monoamine oxidase and peripheral type benzodiazepine receptors. Conclusions: HE is a complex neuropsychiatric syndrome associated with liver failure. These alterations are products of increases in oxidative stress in brain due to neurotoxin activity. The main strategy for HE treatment is directed at ammonia reduction, which can be achieved either by decreasing its absorption/production or increasing its removal. Resumen: Introducción: La fibrosis hepática y su etapa final, la cirrosis, representan un enorme problema de salud mundial. La encefalopatía hepática (EH) o encefalopatía portosistémica es una afección clínica de la cirrosis a largo plazo. En esta revisión se destacan las bases moleculares de la EH, así como el papel del estrés oxidativo en el desarrollo de esta enfermedad. Fuentes: Diversos estudios señalan que la EH es de origen multifactorial, las alteraciones en la barrera hematoencefálica, sustancias como el amonio y el manganeso, así como alteraciones en la neurotransmisión de dopamina, glutamato y GABA, se han implicado en la patogenia de esta enfermedad. Desarrollo: La EH es una complicación severa de la insuficiencia hepática tanto aguda como crónica. Neuropatológicamente, se caracteriza por cambios astrocitarios conocidos como astrocitosis Alzheimer tipo II y por la expresión alterada de proteínas específicas de astrocito, como la proteína acídica fibrilar glial, la glutamina sintetasa, los inhibidores de la monoaminooxidasa y los receptores periféricos tipo benzodiacepina. Conclusiones: La EH es un síndrome neuropsiquiátrico complejo asociado a una falla hepática. Estas alteraciones son producto de un incremento de estrés oxidativo en el cerebro como consecuencia de la acción de neurotoxinas. La principal estrategia para el tratamiento de la EH se dirige a la reducción del amonio, ya sea por la disminución de su absorción/producción o promoviendo su eliminación. Keywords: Hepatic encephalopathy, Ammonia, Manganese, Neurotoxins, Oxidative stress, Palabras clave: Encefalopatía hepática, Amonio, Manganeso, Neurotoxinas, Estrés oxidativ

Aspectos moleculares de la encefalopatía hepática

Resumen: Introducción: La fibrosis hepática y su etapa final, la cirrosis, representan un enorme problema de salud mundial. La encefalopatía hepática (EH) o encefalopatía portosistémica es una afección clínica de la cirrosis a largo plazo. En esta revisión se destacan las bases moleculares de la EH, así como el papel del estrés oxidativo en el desarrollo de esta enfermedad. Fuentes: Diversos estudios señalan que la EH es de origen multifactorial, las alteraciones en la barrera hematoencefálica, sustancias como el amonio y el manganeso, así como alteraciones en la neurotransmisión de dopamina, glutamato y GABA, se han implicado en la patogenia de esta enfermedad. Desarrollo: La EH es una complicación severa de la insuficiencia hepática tanto aguda como crónica. Neuropatológicamente, se caracteriza por cambios astrocitarios conocidos como astrocitosis Alzheimer tipo II y por la expresión alterada de proteínas específicas de astrocito, como la proteína acídica fibrilar glial, la glutamina sintetasa, los inhibidores de la monoaminooxidasa y los receptores periféricos tipo benzodiacepina. Conclusiones: La EH es un síndrome neuropsiquiátrico complejo asociado a una falla hepática. Estas alteraciones son producto de un incremento de estrés oxidativo en el cerebro como consecuencia de la acción de neurotoxinas. La principal estrategia para el tratamiento de la EH se dirige a la reducción del amonio, ya sea por la disminución de su absorción/producción o promoviendo su eliminación. Abstract: Introduction: Liver fibrosis and its end stage, cirrhosis, is an enormous worldwide health problem. Hepatic encephalopathy (HE) or portal-systemic encephalopathy continues to be a major clinical problem of long-term cirrhosis. In this review we emphasise the molecular basis of HE and the involvement of oxidative stress in the development of this disease. Background: Several studies suggest that the pathogenesis of HE could be multifactorial and have implicated different factors, such as alterations in blood brain barrier, substances; such as ammonia and manganese, neurotransmission disorders such as dopamine, glutamate and GABA. Development: HE is a severe complication of both acute and chronic liver failure. Neuropathologically, it is characterized by astrocyte changes known as Alzheimer type II astrocytosis. In addition, astrocytes manifest altered expression of astrocyte-specific proteins, such as, glial fibrillary acidic protein, glutamine synthetase, monoamine oxidase and peripheral type benzodiazepine receptors. Conclusions: HE is a complex neuropsychiatric syndrome associated with liver failure. These alterations are products of increases in oxidative stress in brain due to neurotoxin activity. The main strategy for HE treatment is directed at ammonia reduction, which can be achieved either by decreasing its absorption/production or increasing its removal. Palabras clave: Encefalopatía hepática, Amonio, Manganeso, Neurotoxinas, Estrés oxidativo, Keywords: Hepatic encephalopathy, Ammonia, Manganese, Neurotoxins, Oxidative stres

Development of the endocrine pancreas and novel strategies for β-cell mass restoration and diabetes therapy

Diabetes mellitus represents a serious public health problem owing to its global prevalence in the last decade. The causes of this metabolic disease include dysfunction and/or insufficient number of β cells. Existing diabetes mellitus treatments do not reverse or control the disease. Therefore, β-cell mass restoration might be a promising treatment. Several restoration approaches have been developed: inducing the proliferation of remaining insulin-producing cells, de novo islet formation from pancreatic progenitor cells (neogenesis), and converting non-β cells within the pancreas to β cells (transdifferentiation) are the most direct, simple, and least invasive ways to increase β-cell mass. However, their clinical significance is yet to be determined. Hypothetically, β cells or islet transplantation methods might be curative strategies for diabetes mellitus; however, the scarcity of donors limits the clinical application of these approaches. Thus, alternative cell sources for β-cell replacement could include embryonic stem cells, induced pluripotent stem cells, and mesenchymal stem cells. However, most differentiated cells obtained using these techniques are functionally immature and show poor glucose-stimulated insulin secretion compared with native β cells. Currently, their clinical use is still hampered by ethical issues and the risk of tumor development post transplantation. In this review, we briefly summarize the current knowledge of mouse pancreas organogenesis, morphogenesis, and maturation, including the molecular mechanisms involved. We then discuss two possible approaches of β-cell mass restoration for diabetes mellitus therapy: β-cell regeneration and β-cell replacement. We critically analyze each strategy with respect to the accessibility of the cells, potential risk to patients, and possible clinical outcomes

Curcumin protects against the oxidative damage induced by the pesticide parathion in the hippocampus of the rat brain

One of the main concerns regarding organophosphate pesticides (OP) is their possible toxic effects. Doses that do not produce acute toxicity are capable of altering the structure and biochemistry of different tissues and organs by production of reactive oxygen species (ROS). Curcumin (CUR) is the main substance in Curcuma longa (Zingiberacea) rhizome that has strong antioxidant activity. However, the neuroprotective properties of curcumin against oxidative stress induced by prolonged exposure to parathion (PAR) is not clear. Objective: The present work evaluated the protective effect of curcumin against the oxidative damage induced in the rat hippocampus by the OP PAR. Methods: Forty female Wistar rats were distributed in four groups as follows: exposed to PAR by inhalation (PAR group); pre-treated with CUR and then exposed to PAR by inhalation, (CUR + PAR group); exposed to environmental air and treated with CUR in the food (CUR group); and exposed to environmental air (the control group). At the end of the handling process, the concentration of erythrocyte cholinesterase was monitored, as indicator of PAR intoxication and lipoperoxidation, immunohistochemistry for astrocytes, and activated microglia and apoptosis was determined in the hippocampus. Results: In the present study, we show that the administration of CUR (200 mg/kg body weight) significantly diminished the oxidative damage in the hippocampus of rats exposed to the OP PAR. Discussion: These data suggest that CUR may be an alternative to prevent neurodegenerative damage after pesticide exposure. W.S. Maney & Son Ltd 2012

Neuroprotective effects of phytochemicals on dopaminergic neuron cultures

Introduction: Parkinson's disease is a progressive neurodegenerative disorder characterised by a loss of dopaminergic neurons in the substantia nigra pars compacta, which results in a significant decrease in dopamine levels and consequent functional motor impairment. Development: Although its aetiology is not fully understood, several pathogenic mechanisms, including oxidative stress, have been proposed. Current therapeutic approaches are based on dopamine replacement drugs; these agents, however, are not able to stop or even slow disease progression. Novel therapeutic approaches aimed at acting on the pathways leading to neuronal dysfunction and death are under investigation. Conclusions: In recent years, such natural molecules as polyphenols, alkaloids, and saponins have been shown to have a neuroprotective effect due to their antioxidant and anti-inflammatory properties. The aim of our review is to analyse the most relevant studies worldwide addressing the benefits of some phytochemicals used in in vitro models of Parkinson's disease. Resumen: Introducción: La enfermedad de Parkinson es un trastorno neurodegenerativo progresivo caracterizado por la pérdida de neuronas dopaminérgicas de la sustancia nigra pars compacta, promoviendo una disminución significativa en los niveles de dopamina y en consecuencia el deterioro funcional del circuito motor. Desarrollo: Aunque su etiología no está bien esclarecida, se han propuesto varios mecanismos patogénicos, entre ellos destaca el estrés oxidativo. La terapia actual se basa en medicamentos que reemplazan la dopamina, sin embargo, no son capaces de detener o incluso ralentizar la progresión de la enfermedad. En la actualidad están siendo investigados nuevos enfoques terapéuticos con la intención de influir en las vías que conducen a la disfunción y muerte neuronal. Conclusiones: En los últimos años, se ha evidenciado el efecto neuroprotector de moléculas naturales debido a sus propiedades antioxidantes y antiinflamatorias dentro de los cuales destacan los polifenoles, los alcaloides y las saponinas. El objetivo de esta revisión es recopilar los estudios más importantes a nivel mundial que establecen las propiedades benéficas de algunos fitoquímicos utilizados en modelos in vitro de la enfermedad de Parkinson. Keywords: Phytochemicals, Neuroprotection, Dopaminergic neurons, Parkinson's disease, Oxidative stress, Neurotoxicity, Palabras clave: Fitofármacos, Neuroprotección, Neuronas dopaminérgicas, Enfermedad de Parkinson, Estrés oxidativo, Neurotoxicida

Efecto neuroprotector de fitoquímicos en cultivo de neuronas dopaminérgicas

Resumen: Introducción: La enfermedad de Parkinson es un trastorno neurodegenerativo progresivo caracterizado por la pérdida de neuronas dopaminérgicas de la sustancia nigra pars compacta, promoviendo una disminución significativa en los niveles de dopamina y en consecuencia el deterioro funcional del circuito motor. Desarrollo: Aunque su etiología no está bien esclarecida, se han propuesto varios mecanismos patogénicos, entre ellos destaca el estrés oxidativo. La terapia actual se basa en medicamentos que reemplazan la dopamina, sin embargo, no son capaces de detener o incluso ralentizar la progresión de la enfermedad. En la actualidad están siendo investigados nuevos enfoques terapéuticos con la intención de influir en las vías que conducen a la disfunción y muerte neuronal. Conclusiones: En los últimos años, se ha evidenciado el efecto neuroprotector de moléculas naturales debido a sus propiedades antioxidantes y antiinflamatorias dentro de los cuales destacan los polifenoles, los alcaloides y las saponinas. El objetivo de esta revisión es recopilar los estudios más importantes a nivel mundial que establecen las propiedades benéficas de algunos fitoquímicos utilizados en modelos in vitro de la enfermedad de Parkinson. Abstract: Introduction: Parkinson's disease is a progressive neurodegenerative disorder characterised by a loss of dopaminergic neurons in the substantia nigra pars compacta, which results in a significant decrease in dopamine levels and consequent functional motor impairment. Development: Although its aetiology is not fully understood, several pathogenic mechanisms, including oxidative stress, have been proposed. Current therapeutic approaches are based on dopamine replacement drugs; these agents, however, are not able to stop or even slow disease progression. Novel therapeutic approaches aimed at acting on the pathways leading to neuronal dysfunction and death are under investigation. Conclusions: In recent years, such natural molecules as polyphenols, alkaloids, and saponins have been shown to have a neuroprotective effect due to their antioxidant and anti-inflammatory properties. The aim of our review is to analyse the most relevant studies worldwide addressing the benefits of some phytochemicals used in in vitro models of Parkinson's disease. Palabras clave: Fitofármacos, Neuroprotección, Neuronas dopaminérgicas, Enfermedad de Parkinson, Estrés oxidativo, Neurotoxicidad, Keywords: Phytochemicals, Neuroprotection, Dopaminergic neurons, Parkinson's disease, Oxidative stress, Neurotoxicit

C-26 and C-30 apocarotenoids from seeds of Ditaxis heterantha with antioxidant activity and protection against DNA oxidative damage

The hexane extracts of seeds of Ditaxis heterantha afforded two new apocarotenoids whose structures corresponded to methyl 3-oxo-12′-apo- ε-caroten-12′-oate (1) (heteranthin) and methyl 3β,6β- epoxy-5β-hydroxy-4,5-dihydro-8′-apo-ε-caroten-8′-oate (2) (ditaxin). Both compounds were evaluated for antioxidant activity and protection against DNA oxidative damage by using DPPH. free radical scavenging and Comet assays, respectively. © 2006 American Chemical Society and American Society of Pharmacognosy