RESUMO
AIMS: To investigate the effect of N(omega)-Nitro-L-arginine methyl ester (l-NAME) treatment, known to induce a sustained elevation of blood pressure, on ectonucleotidase activities in kidney membranes of rats. MAIN METHODS: L-NAME (30 mg/kg/day) was administered to Wistar rats for 14 days in the drinking water. Enzyme activities were determined colorimetrically and their gene expression patterns were analyzed by semi-quantitative RT-PCR. The metabolism of ATP and the accumulation of adenosine were evaluated by HPLC in kidney membranes from control and hypertensive rats. PKC phosphorylation state was investigated by Western blot. KEY FINDINGS: We observed an increase in systolic blood pressure from 115+/-12 mmHg (control group) to 152+/-18 mmHg (l-NAME-treated group). Furthermore, the hydrolysis of ATP, ADP, AMP, and p-Nph-5'TMP was also increased (17%, 35%, 27%, 20%, respectively) as was the gene expression of NTPDase2, NTPDase3 and NPP3 in kidneys of hypertensive animals. Phospho-PKC was increased in hypertensive rats. SIGNIFICANCE: The general increase in ATP hydrolysis and in ecto-5'-nucleotidase activity suggests a rise in renal adenosine levels and in renal autoregulatory responses in order to protect the kidney against the threat presented by hypertension.
Assuntos
Adenosina Trifosfatases/metabolismo , Membrana Celular/enzimologia , Hipertensão/enzimologia , Rim/enzimologia , NG-Nitroarginina Metil Éster/farmacologia , Adenosina Trifosfatases/genética , Animais , Pressão Sanguínea/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Creatinina/sangue , Modelos Animais de Doenças , Expressão Gênica/efeitos dos fármacos , Frequência Cardíaca/efeitos dos fármacos , Hipertensão/sangue , Hipertensão/fisiopatologia , Rim/efeitos dos fármacos , Rim/fisiopatologia , Masculino , Ratos , Ratos Wistar , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Learned helplessness paradigm is a widely accepted animal model of depressive-like behavior based on stress. Glutamatergic system is closely involved with the stress-neurotoxicity in the brain and recently it is pointed to have a relevant role in the pathophysiology of depression disorder. Glutamate uptake is the main mechanism to terminate the glutamatergic physiological activity and to neuroprotection against excitotoxicity. We investigated the profile of glutamate uptake in female rats submitted to the learned helplessness paradigm and to different classes of stress related to the paradigm, in slices of brain cortex, striatum and hippocampus. Glutamate uptake in slices of hippocampus differ between learned helplessness (LH) and non-learned helplessness (NLH) animals immediately persisting up to 21 days after the paradigm. In addition, there were a decrease of glutamate uptake in the three brain structures analyzed at 21 days after the paradigm for LH animals. These results may contribute to better understand the role of the glutamatergic system on the depressive-like behavior.
Assuntos
Encéfalo/metabolismo , Depressão/metabolismo , Ácido Glutâmico/metabolismo , Desamparo Aprendido , Estresse Psicológico/metabolismo , Animais , Córtex Cerebral/metabolismo , Corpo Estriado/metabolismo , Depressão/psicologia , Feminino , Hipocampo/metabolismo , Ratos , Ratos Wistar , Estresse Psicológico/psicologiaRESUMO
There is a current interest in dietary compounds (such as trans-resveratrol) that can inhibit or reverse oxidative stress, the common pathway for a variety of brain disorders, including Alzheimer's disease and stroke. The objective of the present study was to investigate the effects of resveratrol, under conditions of oxidative stress induced by H(2)O(2), on acute hippocampal slices from Wistar rats. Here, we evaluated cell viability, extracellular lactate, glutathione content, ERK(MAPK) activity, glutamate uptake and S100B secretion. Resveratrol did not change the decrease in lactate levels and in cell viability (by MTT assay) induced by 1mM H(2)O(2), but prevented the increase in cell permeability to Trypan blue induced by H(2)O(2). Moreover, resveratrol per se increased total glutathione levels and prevented the decrease in glutathione induced by 1mM H(2)O(2). The reduction of S100B secretion induced by H(2)O(2) was not changed by resveratrol. Glutamate uptake was decreased in the presence of 1mM H(2)O(2) and this effect was not prevented by resveratrol. There was also a significant activation of ERK1/2 by 1mM H(2)O(2) and resveratrol was able to completely prevent this activation, leading to activity values lower than control levels. The impairments in astrocyte activities, induced by H(2)O(2), confirmed the importance of these cells as targets for therapeutic strategy in brain disorders involving oxidative stress. This study reinforces the protective role of resveratrol and indicates some possible molecular sites of activity of this compound on glial cells, in the acute damage of brain tissue during oxidative stress.
Assuntos
Antioxidantes/farmacologia , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Peróxido de Hidrogênio/antagonistas & inibidores , Peróxido de Hidrogênio/toxicidade , Estilbenos/farmacologia , Animais , Astrócitos/efeitos dos fármacos , Astrócitos/metabolismo , Astrócitos/patologia , Permeabilidade da Membrana Celular/efeitos dos fármacos , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Ácido Glutâmico/metabolismo , Glutationa/metabolismo , Hipocampo/lesões , Hipocampo/patologia , Técnicas In Vitro , Ácido Láctico/metabolismo , Fatores de Crescimento Neural/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Wistar , Resveratrol , Subunidade beta da Proteína Ligante de Cálcio S100 , Proteínas S100/metabolismoRESUMO
In the present report we describe an NTPDase 1 (ATP diphosphohydrolase; ecto-apyrase; EC 3.6.1.5) in rat hippocampal slices. The effect of glutamate on the ATPase and ADPase activities in rat hippocampal slices of different ages was also studied since adenosine, the final product of an enzymatic chain that includes NTPDase 1 and 5'-nucleotidase, can act upon A1 receptors in turn decreasing the release of glutamate. Hippocampal slices from 7, 14, 20-23 and 60 day-old rats were prepared and ATPase and ADPase activities were measured. The parallelism of ATPase and ADPase activities in all parameters tested indicated the presence of an ATP diphosphohydrolase. In addition, a Chevillard plot indicated that ATP and ADP are hydrolyzed at the same active site on the enzyme. ATPase activity was significantly activated by glutamate in 20-23 and 60 day-old rats, but ADPase activity was not activated. These results could indicate distinct behavior of the ATPase and ADPase activities of NTPDase 1 in relation to glutamate or the simultaneous action of the ecto-ATPase. Activation of ATPase activity by glutamate may constitute an important role in this developmental period, possibly protecting against the neurotoxicity induced by ATP, as well as producing high levels of ADP, by increasing adenosine production, a neuroprotective compound.