Lipoic acid effects on glutamate and taurine concentrations in rat hippocampus after pilocarpine-induced seizures / Efeitos do ácido lipóico nas concentrações de glutamato e taurina no hipocampo de ratos após convulsões induzidas por pilocarpina

Pilocarpine-induced seizures can be mediated by increases in oxidative stress and by cerebral amino acid changes. The present research suggests that antioxidant compounds may afford some level of neuroprotection against the neurotoxicity of seizures in cellular level. The objective of the present study was to evaluate the lipoic acid (LA) effects in glutamate and taurine contents in rat hippocampus after pilocarpine-induced seizures. Wistar rats were treated intraperitoneally (i.p.) with 0.9 percent saline (Control), pilocarpine (400 mg/kg, Pilocarpine), LA (10 mg/kg, LA), and the association of LA (10 mg/kg) plus pilocarpine (400 mg/kg), that was injected 30 min before of administration of LA (LA plus pilocarpine). Animals were observed during 24 h. The amino acid concentrations were measured using high-performance liquid chromatograph (HPLC). In pilocarpine group, it was observed a significant increase in glutamate content (37 percent) and a decrease in taurine level (18 percent) in rat hippocampus, when compared to control group. Antioxidant pretreatment significantly reduced the glutamate level (28 percent) and augmented taurine content (32 percent) in rat hippocampus, when compared to pilocarpine group. Our findings strongly support amino acid changes in hippocampus during seizures induced by pilocarpine, and suggest that glutamate-induced brain damage plays a crucial role in pathogenic consequences of seizures, and imply that strong protective effect could be achieved using lipoic acid through the release or decrease in metabolization rate of taurine amino acid during seizures.

As convulsões induzidas pela pilocarpina podem ser mediadas através do aumento do estresse oxidativo cerebral e das alterações na concentração dos aminoácidos. O presente estudo sugere que compostos antioxidantes podem produzir neuroproteção contra a neurotoxicidade em nível celular causada pelas convulsões. O objetivo deste estudo foi avaliar os efeitos do ácido lipóico (AL) no conteúdo de glutamato e taurina no hipocampo de ratos durante convulsões induzidas por pilocarpina. Ratos Wistar foram tratados por via intraperitoneal com solução salina 0,9 por cento (controle), pilocarpina (400 mg/kg, pilocarpina), AL (10 mg/kg) e com a associação de AL (10 mg/kg); 30 min após com pilocarpina (400 mg/kg), que foi injetada 30 min após a administração de AL (AL + pilocarpina). Os animais foram observados durante 24 horas. As concentrações de aminoácidos foram determinadas por HPLC. No hipocampo dos ratos do grupo pilocarpina foi observado um aumento significativo de 37 por cento na concentração de glutamato e uma diminuição de 18 por cento no nível de taurina, quando comparado ao grupo controle. O pré-tratamento com o antioxidante reduziu significativamente o nível de glutamato em 28 por cento e aumentou em 32 por cento os níveis de taurina no hipocampo dos ratos, quando comparado ao grupo pilocarpina. Nossos resultados sugerem que ocorrem alterações na concentração dos aminoácidos no hipocampo de ratos durante as convulsões induzidas por pilocarpina, e que o glutamato pode desempenhar um papel crucial na fisiopatologia das convulsões, e que o efeito protetor poderia ser alcançado com pré-tratamento com ácido lipóico, provavelmente pelo aumento da liberação ou redução da taxa de metabolização dos aminoácidos durante as convulsões.

Efeitos fisiológicos agudos da taurina contida em uma bebida energética em indivíduos fisicamente ativos / Acute physiological effects of taurine content of an energy drink in physically active subjects

Segundo a Secretaria de Vigilância Sanitária do Ministério da Saúde, bebidas energéticas são identificadas como compostos líquidos prontos para o consumo, sendo estas constituídas de carboidratos, taurina, cafeína, glucoronolactona, inositol e vitaminas do complexo B. Existem poucas pesquisas sobre o uso de taurina contida em bebidas energéticas relacionado com a melhora de desempenho. Este trabalho teve como objetivo analisar as respostas metabólicas e hemodinâmicas decorrentes da administração da associação de taurina e cafeína durante teste ergoespirométrico em indivíduos fisicamente ativos. Para esse fim, 20 indivíduos do sexo masculino, 26 ± 4,32 anos e índice de massa corporal 23,79 ± 2,95, praticantes de atividades aeróbicas, foram submetidos a duas sessões de testes em cicloergômetro ligado a analisador metabólico de gases. O esquema das sessões foi duplo- cego e 60 minutos antes do início dos testes foi oferecida bebida experimental ou bebida placebo. Durante os testes, foram mensuradas: frequência cardíaca (FC), pressão arterial sistólica (PAS) e diastólica (PAD), lactato sanguíneo (Lac), percepção subjetiva de esforço por escala de Borg (PSE), consumo máximo de oxigênio (VO2máx), consumo de oxigênio no ponto de compensação respiratório (RCP), tempo de exercício (TE) e carga de trabalho (CAR). Para a análise dos dados, foi realizado um teste t pareado (p ≤ 0,05). Na carga de trabalho, os resultados indicaram que houve aumento de 10 watts com a administração da bebida experimental, contudo, sem significância estatística (BE: 342 ± 40,60; P: 332,50 ± 56,83). Os principais resultados deste estudo indicam que a administração de taurina contida em bebida energética não influenciou os resultados das variáveis investigadas. Assim, podemos concluir que a dose de 2g utilizada não foi capaz de aumentar o desempenho.

According to the Sanitary Surveillance Agency of the Ministry of Health, energy drinks are identified as liquid compounds ready for consumption, being made of carbohydrates, taurine, caffeine, glucoronolactone, inositol, and B-complex vitamins. Given the small number of studies on the use of taurine in energy drinks related to improved performance, this paper aimed to analyze the metabolic and haemodynamic responses resulted from the administration of the association of taurine and caffeine during an ergospyrometric test in physically active subjects. Therefore, twenty male individuals, 26 ±4.32 years and body mass 23.79 ±2.95, frequent practitioners of aerobic activities, were submitted to two test sessions in cycle ergometer hooked to a gas metabolic analyzer. The sessions schedule was double-blind, and 60 minutes before them the individuals were offered experimental drinks or placebo drinks. During the tests, the subjects were evaluated on the following variables: heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), blood lactate (Lac), subjective perceived exertion by Borg scale (SPE), maximum oxygen uptake (VO2max), oxygen uptake at the compensation respiratory point (CRP), exercise time (ET) and work load (WL). A paired t test was carried out for data analysis, where (p≤0.05). On the work load, the results indicated an increase of 10 watts with the administration of the experimental drink, with no statistical significance, though. (ED: 342 ±40.60; P: 332.50±56.83). The main results of this study point out that taurine administration contained in the energy drink did not influence in the levels of the investigated variables. Thus, we can conclude that the 2g dose used did not improve performance.

Cell volume regulation in the perfused liver of a freshwater air-breathing cat fish Clarias batrachus under aniso-osmotic conditions: roles of inorganic ions and taurine.

The roles of various inorganic ions and taurine, an organic osmolyte, in cell volume regulation were investigated in the perfused liver of a freshwater air-breathing catfish Clarias batrachus under aniso-osmotic conditions. There was a transient increase and decrease of liver cell volume following hypotonic (-80 mOsmol/l) and hypertonic (+80 mOsmol/l) exposures,respectively, which gradually decreased/increased near to the control level due to release/uptake of water within a period of 25-30 min. Liver volume decrease was accompanied by enhanced efflux of K+ (9.45 +/- 0.54 micromol/g liver) due to activation of Ba(2+)- and quinidine-sensitive K(+) channel, and to a lesser extent due to enhanced efflux of Cl(-) (4.35+/- 0.25 micromol/g liver) and Na+ (3.68+/- 0.37 micromol/g liver). Conversely, upon hypertonic exposure, there was amiloride-and ouabain-sensitive uptake of K+ (9.78+/- 0.65 micromol/g liver), and also Cl(-) (3.72 +/- 0.25 micromol/g liver).The alkalization/acidification of the liver effluents under hypo-/hypertonicity was mainly due to movement of various ions during volume regulatory processes. Taurine,an important organic osmolyte, appears also to play a very important role in hepatocyte cell volume regulation in the walking catfish as evidenced by the fact that hypo- and hyper-osmolarity caused transient efflux (5.68 +/- 0.38 micromol/g liver) and uptake (6.38 +/- 0.45 micromol/g liver) of taurine, respectively. The taurine efflux was sensitive to 4,4' -di-isothiocyanatostilbene-2,2'-disulphonic acid (DIDS, an anion channel blocker), but the uptake was insensitive to DIDS, thus indicating that the release and uptake of taurine during volume regulatory processes are unidirectional. Although the liver of walking catfish possesses the RVD and RVI mechanisms, it is to be noted that liver cells remain partly swollen and shrunken during anisotonic exposures,thereby possibly causing various volume-sensitive metabolic changes in the liver as reported earlier.

Regulation of taurine transporter activity in cultured rat retinal ganglion cells and rat retinal Muller cells

Diabetic retinopathy is one of the most common complications of diabetes. The amino acid taurine is believed to play an antioxidant protective role in diabetic retinopathy through the scavenging of the reactive species. It is not well established whether taurine uptake is altered in retinal cells during diabetic conditions. Thus, the present study was designed to investigate the changes in taurine transport in cultures of rat retinal Muller cells and rat retinal ganglion cells under conditions associated with diabetes. Taurine was abundantly up taken by rat retinal Muller cells and rat retinal ganglion cells under normal glycemic condition. Taurine was actively transported to rat Muller cells and rat retinal ganglion cells in a Na + and CI - dependent manner. Taurine uptake further significantly elevated in both types of cells after the incubation with high glucose concentration. This effect could be attributed to the increase in osmolarity. Because nitric oxide [NO] is a molecule implicated in the pathogenesis of diabetes, we also determined the activity of the taurine transporter in cultured rat retinal Muller cells and rat retinal ganglion cells in the presence of the NO donors, SIN-1 and SNAP. Taurine uptake was elevated above control values after 24-h incubation with low concentration of NO donors. We finally investigated the ability of neurotoxic glutamate to change taurine transporter activity in both types of cells. Uptake of taurine was significantly increased in rat retinal ganglion cells when only incubated with high concentration of glutamate. Our data provide evidence that taurine transporter is present in cultured rat retinal ganglion and Muller cells and is regulated by hyperosmolarity. The data are relevant to diseases such as diabetes and neuronal degeneration where retinal cell volume may dramatically change

Studies on protein and taurine in normal, senile and diabetic cataractous human lenses.

An attempt has been made to explore the possible role of Taurine in cataractogenesis. Normal lenses were obtained from eye bank donors and cataractous lenses from patients who had undergone surgery for cataract extraction. Lenses were weighed and homogenised. Extraction, isolation and estimation of protein and taurine were carried out. It has been found that the lens wet weight increased progressively with the stage of maturation of cataract, i.e., from mature to hypermature which was significant and also with increase in age. Diabetic cataract group also showed an increase similar to that of senile cataract. Taurine and total protein decreases with different stages of maturation of cataract but not with age. It may be suggested that in the process of development of human senile cataract, there is (a) alteration in the structural integrity and permeability of lens membrane to protein and amino acids including taurine, (b) changes in the lens function including possible inhibition of proteins and amino acids (taurine) synthesis and transport across the cell membrane.

Efecto de la activacion gabaergica sobre la maduracion sexual en ratas hembras peripuberales / Effect prologed gabaergic activation on the pubertal development of female rats

Evaluamos 1) efecto del tratamiento prolongado (días 23-29 postnatales) con ácido aminooxiacético (AAOA) sobre el desarrollo puberal en ratas hembra; este tratamiento aumentó el contenido de GABA (p< 0.002), disminuyendo el de GnRH y glutamato (p < 0.05 y < 0.02) en hipotálamo. La LH (p < 0.05) y el estradiol (p < 0.005) séricos cayeron. La apertura vaginal fue a los 30.8 + 0.6 días en los controles, y a los 36.7 + 0.98 días en las tratadas (p < 0.0001). 2) A los 30 días, el tratamiento agudo con AAOA redujo la liberación ex vivo de GnRH y de glutamato la de taurina. Este efecto fue similar al observado agregando al medio agonistas GABA-A y B. Conclusiones: la activación peripuberal del sistema GABAérgico frena el eje reprodutor, produciendo un retraso en el desarrollo. Esto podría atribuirse a la existencia, en esta etapa, de interrelaciones fisiológicas entre los aminoácidos que regulan la secreción de GnRH (GABA, glutamato, taurina).

Espectroscopia por ressonância magnética em epilepsia / Magnetic resonance spectroscopic imaging in epilepsy

A evoluçäo da cirurgia para epilepsia vem sendo acompanhada por novos métodos de neuroimagem, näo só morfológicos, como, também, funcionais. Dentre esses últimos, destacamos a espectroscopia por ressonância magnética (ERM), de especial interesse deste artigo. A ERM parece ser promissora na definiçäo da identificaçäo do foco epileptogênico, pela demonstraçäo das alteraçöes dos metabólicos do fósforo (31P-ERM) e avaliaçäo pelo próton de H+ (1H-ERM). Reconhece-se a variaçäo da 1H-ERM normal, segundo alteraçöes idade-relacionadas, para localizaçäo do foco epileptogênico, no período interictal, pelas taxas de NAA (N-acetilaspartato), Cr (creatina) e Co (colina), e relaçöes NAA: Co e NAA: Cr; e no ictal, pelas mesmas taxas e pela avaliaçäo do lactato. A estimativa de aminoácidos neurotransmissores também auxilia nessa topografia. A ERM, em especial, a 1H-ERM, é de grande potencialidade no estudo bioquímico do cérebro, in vivo, e poderá vir a ter crescente importância no diagnóstico topográfico da regiäo epileptogênica dos pacientes com epilepsia, na dependência da idade e do local do foco

The role of xanthine oxidase and the effects of antioxidants in ischemia reperfusion cell injury

During last years considerable interest has been devoted to understand the role of oxugen radicals in the inschemia induced cell injury associated with reperfusion. In the brain and in others tissues, free radicals play a role as modulators of vascular tone as well as a cytotoxic role as part of the ischemia associated pathology. This review discusses methods for free radical detection in brain and in other tissues, mechanisms of radical production in the course of the ischemia reperfusion process, and the efficacy of potential antioxidant agents in post ischemia therapy, especially with respect to allopurinol, an inhibitor of xanthine oxidase, and the role of taurine and its derivatives as antioxidants in different organs including the brain.

The involvement of taurine in the action mechanism of sodium valproate (VPA) in the treatment of epilepsy

Existen evidencias qye han mostrado que en el mecanismo de acción del valproato de sodio (VPA) utilizado en la terapêutica de la epilepsia, el mismo interacciona con receptores gabaérgicos y canales iónicos. Sin embargo, no hay evidencias concluyentes de que el valproato de sodio interaccione con otros receptores cerebrales. Basados en este hecho, la taurina (aminoácido neurotransmisor) que se distribuye en el cerebro y en el sistema visual, podría estar involucrada en el mecanismo de acción del valproato de sodio. Este trabajo además, trata de informar que la taurina, posiblemente asociada con la acción del valproato de sodio, sea también beneficiosa para suprimir una crisis epiléptica. También se discute su distribución cerebral, su sitio receptivo y su probable actividad modulatoria en relación al valproato de sodio en la terapia de la epilepsia

Rol biológico y nutricional de la taurina y sus derivados en la fisiologia organica y celular / Biological and nutritional role of taurine and its derivatives on cellular and organic physiology

Se describen varios aspectos relacionados con el rol biológico y nutricional de la taurina y sus derivados, en células de mamíferos, con especial referencia a lo que sucede en el humano. Se analizan, además, algunos aspectos relacionados con la estructura y función de la molécula respecto a su capacidad antioxidante y osmoreguladora. Se discuten también las alteraciones que en algunos casos se pueden presentar en la distribución de este aminoácido, las cuales se producen ya sea por cambios en su biosíntesis en algunas etapas del desarrollo, o bien, por cambios a nivel del transporte en algunos tejidos donde las concentraciones están aumentadas varias veces en relación a las concentracicones plasmáticas. Existen algunas evidencias acerca de la posibilidad que la taurina pueda ser considerada como un nutriente condicionalmente esencial, en algunos casos en los que sus concentraciones en el plasma y fluidos biológicos tienen ciertas implicaciones clínicas y nutricionales

Effect of carnitine on malondialdehyde, taurine and glutathione levels in heart of rats subjected to myocardial stress by isoproterenol.

The effect of carnitine on free fatty acid, malondialdehyde, taurine and glutathione levels in myocardium was studied in rats administered isoproterenol to induce a stress in the myocardium resulting in myocardial ischaemia. Carnitine decreased the levels of free fatty acid and malondialdehyde (an index of lipid peroxidation) when compared to control rats given isoproterenol alone. Taurine and glutathione also registered a fall in the carnitine treated animals when compared to rats treated with isoproterenol alone. The results indicate that carnitine by decreasing the levels of these parameters helps the myocardium to survive from the stress induced by isoproterenol.