The role of vitamin C in stress-related disorders.

Stress-related disorders, such as depression and anxiety, present marked deficits in behavioral and cognitive functions related to reward. These are highly prevalent disabling conditions with high social and economic costs. Furthermore, a significant percentage of affected individuals cannot benefit from clinical intervention, opening space for new treatments. Although the literature data have reported limited and variable results regarding oxidative stress-related endpoints in stress-related disorders, the possible neuroprotective effect of antioxidant compounds, such as ascorbic acid (vitamin C), emerges as a possible therapy strategy for psychiatric diseases. Here, we briefly present background information on biological activity of ascorbic acid, particularly functions related to the CNS homeostasis. Additionaly, we reviewed the available information on the role of ascorbic acid in stress-related diseases, focusing on supplementation and depletion studies. The vitamin C deficiency is widely associated to stress-related diseases. Although the efficacy of this vitamin in anxiety spectrum disorders is less stablished, several studies showed that ascorbic acid supplementation produces antidepressant effect and improves mood. Interestingly, the modulation of monoaminergic and glutamatergic neurotransmitter systems is postulated as pivotal target for the antidepressant and anxiolytic effects of this vitamin. Given that ascorbic acid supplementation produces fast therapeutic response with low toxicity and high tolerance, it can be considered as a putative candidate for the treatment of mood and anxiety disorders, especially those that are refractory to current treatments. Herein, the literature was reviewed considering the potential use of ascorbic acid as an adjuvant in the treatment of anxiety and depression.

Effects of ascorbic acid on anxiety state and affect in a non-clinical sample.

Objective Given that the literature data indicates that ascorbic acid may have an anxiolytic effect, we hypothesized that a single oral administration of ascorbic acid could acutely affect emotional states. Methods The effects of acid ascorbic supplementation on anxiety and other emotional states were evaluated by the State­Trait Anxiety Inventory (STAI), and Visual Analogue Mood Scale (VAMS). Immediately before, and 2 hours after receiving a single ascorbic acid dose (1000 mg) or placebo, 142 graduate students were evaluated by the STAI and VAMS in a randomized, double­blind, placebo­controlled trial. Results No changes from basal levels were observed in the STAI state­anxiety or VAMS scores. However, the ingestion of ascorbic acid by the 25% more anxious healthy subjects (women; 14 control and 23 ascorbic acid), as defined by the STAI trait­anxiety scale, produced a significant reduction from baseline anxiety scores in the STAI state­anxiety scale and VAMS anxiety subscale. The study evaluated a small sample with narrow sociodemographic characteristics, composed mainly of healthy young females (> 94%) enrolled in post­graduation courses, without controlling diet, physical activity, and formal psychiatric diagnosis. CONCLUSIONS: Despite the sample size limitation, this study provides the first evidence of an acute anxiolytic effect of ascorbic acid. Broader population studies are required to evaluate the clinical relevance of presented data.

Protective effects of diphenyl diselenide in a mouse model of brain toxicity.

Interest in organoselenide chemistry and biochemistry has increased in the past three decades, mainly due to their chemical and biological activities. Here, we investigated the protective effect of the organic selenium compound diphenyl diselenide (PhSe)2 (5 µmol/kg), in a mouse model of methylmercury (MeHg)-induced brain toxicity. Our group has previously demonstrated that the oral and repeated administration (21 days) of MeHg (40 mg/L) induced MeHg brain accumulation at toxic concentrations, and a pattern of severe cortical and cerebellar biochemical and behavioral. In order to assess neurotoxicity, the neurochemical parameters, namely, mitochondrial complexes I, II, II-III and IV, glutathione peroxidase (GPx) and glutathione reductase (GR) activities, the content of thiobarbituric acid-reactive substances (TBA-RS), 8-hydroxy-2'-deoxyguanosine (8-OHdG), and brain-derived neurotrophic factor (BDNF), as well as, metal deposition were investigated in mouse cerebral cortex. Cortical neurotoxicity induced by brain MeHg deposition was characterized by the reduction of complexes I, II, and IV activities, reduction of GPx and increased GR activities, increased TBA-RS and 8-OHdG content, and reduced BDNF levels. The daily treatment with (PhSe)2 was able to counteract the inhibitory effect of MeHg on mitochondrial activities, the increased oxidative stress parameters, TBA-RS and 8-OHdG levels, and the reduction of BDNF content. The observed protective (PhSe)2 effect could be linked to its antioxidant properties and/or its ability to reduce MeHg deposition in brain, which was here histochemically corroborated. Altogether, these data indicate that (PhSe)2 could be consider as a neuroprotectant compound to be tested under neurotoxicity.

Interferência dos ácidos graxos ômega-3 nos lipídeos sangüíneos de ratos submetidos ao exercício de natação / Omega-3 fatty acids interference on the blood lipids of rats subjected to swimming exercise

OBJETIVO: Investigar os efeitos da suplementação com ácidos graxos ômega-3, nas doses de 0,5 e 1,0g/kg/dia, nos lipídeos sangüíneos de ratos submetidos ou não ao protocolo do nado. MÉTODOS: Ratos Wistar foram divididos em grupos: controle, controle+nado, ácidos graxos ômega-3 e ácidos graxos ômega-3+nado. Os ácidos graxos ômega-3 e ácidos graxos ômega-3+nado receberam suplementação; os demais receberam água por gavagem. Os controle+nado e ácidos graxos ômega-3+nado foram submetidos ao exercício. Foram avaliadas as concentrações plasmáticas de colesterol total, triglicérides e lipoproteína de alta densidade, antes e após os procedimentos experimentais. RESULTADOS: No protocolo de 0,5g/kg/dia, em relação às concentrações de colesterol total, foi observada redução significativa proporcionalmente maior no grupo ácidos graxos ômega-3+nado, apesar de o grupo controle+nado e o ácidos graxos ômega-3 também terem apresentado diminuição. No ensaio de 1,0g/kg/dia todos os grupos apresentaram uma diminuição que foi maior, respectivamente, no ácidos graxos ômega-3+nado e, a seguir, no ácidos graxos ômega-3. Quanto aos triglicérides, foram encontradas reduções em todos os grupos experimentais, que foi maior no grupo ácidos graxos ômega-3+nado, do protocolo de 0,5g/kg/dia, enquanto que no de 1,0g/kg/dia a diminuição foi significativa apenas nos grupos ácidos graxos ômega-3 e ácidos graxos ômega-3+nado. Quanto ao HDL, no protocolo de 0,5g/kg/dia foi encontrado aumento nos animais que não foram suplementados, enquanto que em todos os grupos de 1,0g/kg/dia houve uma diminuição do HDL. CONCLUSÃO: A suplementação com ácidos graxos ômega-3 nas doses 0,5 ou 1,0g/kg/dia, associada ao nado, reduzem as concentrações plasmáticas de colesterol total e triglcérides, mas estudos adicionais, também com outras doses, são necessários para a compreensão da relação entre a ingestão de óleo de peixe e as concentrações de lipídeos sangüíneos.

OBJECTIVE: To investigate the effects of omega-3 fatty acid supplementation at doses of 0.5 and 1.0g/kg/day on the blood lipids of rats submitted or not to swimming exercise. METHODS: Wistar rats were divided into the following groups: control, control+swimming, omega-3 fatty acids and omega-3 fatty acids+swimming. The omega-3 fatty acids and omega-3 fatty acids+swimming groups received supplements by gavage, while the remaining animals received water by the same method. The control+swimming and omega-3 fatty acids +swimming groups were submitted to exercise. Plasma concentrations of total cholesterol, triglycerides and HDL were determined before and after the experimental procedures. RESULTS: The concentrations of total cholesterol in the 0.5g/kg/day groups reduced proportionally more in the omega-3 fatty acids+swimming group, even though total cholesterol of the control+swimming and omega-3 fatty acids groups also decreased. Total cholesterol decreased in both groups receiving 1.0g/kg/day supplementation, but the decrease was higher in the omega-3 fatty acids+swimming group than in the omega-3 fatty acids group. Triglycerides also decreased in all experimental groups. The greatest decrease was seen in the omega-3 fatty acids+swimming group receiving 0.5g/kg/day supplementation. In the 1.0g/kg/day protocol, the decrease was significant in both groups: the omega-3 fatty acids and omega-3 fatty acids+swimming groups. HDL increased among the non-supplemented animals and decreased among the animals receiving a supplementation of 1.0g/kg/day. CONCLUSION: Omega-3 fatty acid supplementation at doses of 0.5 or 1.0g/kg/day associated with swimming exercise reduced plasma concentrations of total cholesterol and triglycerides, yet additional studies, including varying doses, are necessary to better understand the relationship between ingestion of fish oil and blood lipid concentrations.

Biodisponibilidade do licopeno / Bioavailability of lycopene

Esta revisão procura reunir diversos estudos que avaliam os fatores que influenciam a biodisponibilidade do licopeno, bem como os alimentos fontes e a recomendação de ingestão desse carotenóide. Para tanto, foi realizado um levantamento bibliográfico, mediante consulta às bases de dados Medline (National Library of Medicine, USA) e Lilacs (Bireme, Brasil) nas quais foram selecionadas publicações científicas em português e inglês, nos últimos quinze anos, que utilizaram os temas: licopeno, carotenóides e/ou biosponibilidade. O licopeno é um carotenóide sem atividade de pró-vitamina A, mas um potente antioxidante, sendo essa função possivelmente associada à redução do risco da ocorrência do câncer e certas doenças crônicas. Esse nutriente é encontrado em um número limitado de alimentos, e, além disso, o organismo não é capaz de sintetizá-lo; dessa forma, o licopeno é obtido exclusivamente por meio da dieta alimentar. A quantidade sugerida de ingestão de licopeno varia de 4 a 35mg/dia. Estudos mostram que existem vários fatores que podem interferir na biodisponibilidade do licopeno, tais como absorção intestinal, quantidade de licopeno no alimento fonte, formas de apresentação (isômeros e sintéticos), presença da matriz alimentar, presença de outros nutrientes na refeição (como gordura, fibra, outros carotenóides, entre outros), ingestão de drogas, processamento do alimento, além da individualidade biológica e do estado nutricional do indivíduo. Estudos da biodisponibilidade do licopeno têm sido desenvolvidos a partir do tomate e seus produtos, por esse ser a fonte mais comumente consumida. O desenvolvimento do estudo enfatizou a importância da melhor forma de absorção desse nutriente, relevante que é para a prevenção de inúmeras doenças.