Repeated exposure of adolescent rats to oral methylphenidate does not induce behavioral sensitization or cross-sensitization to nicotine

Several lines of evidence indicate that the use of stimulant drugs, including methylphenidate (MPD), increases tobacco smoking. This has raised concerns that MPD use during adolescence could facilitate nicotine abuse. Preclinical studies have shown that repeated treatment with an addictive drug produces sensitization to that drug and usually cross-sensitization to other drugs. Behavioral sensitization has been implicated in the development of drug addiction. We examined whether repeated oral MPD administration during adolescence could induce behavioral sensitization to MPD and long-lasting cross-sensitization to nicotine. Adolescent male Wistar rats were treated orally with 10 mg/kg MPD or saline (SAL) from postnatal day (PND) 27 to 33. To evaluate behavioral sensitization to MPD in adolescent rats (PND 39), the SAL pretreated group was subdivided into two groups that received intragastric SAL (1.0 mL/kg) or MPD (10 mg/kg); MPD pretreated rats received MPD (10 mg/kg). Cross-sensitization was evaluated on PND 39 or PND 70 (adulthood). To this end, SAL- and MPD-pretreated groups received subcutaneous injections of SAL (1.0 mL/kg) or nicotine (0.4 mg/kg). All groups had 8 animals. Immediately after injections, locomotor activity was determined. The locomotor response to MPD challenge of MPD-pretreated rats was not significantly different from that of the SAL-pretreated group. Moreover, the locomotor response of MPD-pretreated rats to nicotine challenge was not significantly different from that of the SAL-pretreated group. This lack of sensitization and cross-sensitization suggests that MPD treatment during adolescence does not induce short- or long-term neuroadaptation in rats that could increase sensitivity to MPD or nicotine

l-Leucine supplemented whey protein. Dose–response effect on heart mTOR activation of sedentary and trained rats

AbstractThe aim of the study was to investigate the effect of leucine supplementation combined with exercise and whey protein in cardiac mTOR anabolic pathway. Ninety-six weanling male Wistar rats were divided into eight groups and fed diets containing either casein or WP plus increasing levels (0, 3, 4.5 and 6% of diet) of l-leucine for 30days. A parallel set of eight groups was exercised for comparison. Serum aspartate amino transferase, alanine aminotransferase, creatine kinase, lactate dehydrogenase and branched chain amino acids were determined by standard methods, and mammalian target of rapamycin (mTOR) and p70S6K by the Western blot analysis. Chronic l-leucine supplementation was capable of increasing both mTOR and p70S6K phosphorylation in the heart in a dose-dependent fashion, independent of the type of dietary protein in both groups, sedentary and exercised, but the exercise potentialized the activation of the anabolic pathway. The content of protein in heart increase with l-leucine supplementation and the heart mass relativized by body mass did not change. In conclusion, the combination of l-leucine and milk proteins (casein or whey protein) has the potential to increase the mTOR pathway in the cardiac muscle without increasing the heart mass. The novelty of this study is to show the effectiveness of a blend of leucine and whey protein as a viable alternative to maximize the activation of the anabolic pathway of cardiac muscle and that the exercise can improve this process

Descrição e Análise Crítica do Regime de Fruta Escolar em Portugal

A alimentação saudável é um factor determinante para a promoção e protecção da saúde. Os hortofrutícolas, enquanto componentes de uma alimentação saudável, parecem exercer um efeito protector num vasto leque de doenças crónicas. Porém, vários estudos demonstram consumos, em crianças, inferiores às recomendações. O objectivo deste trabalho é descrever e analisar criticamente o percurso da estratégia portuguesa para a promoção do consumo de hortofrutícolas a nível escolar, o Regime de Fruta Escolar, e ao mesmo tempo fazer uma revisão da literatura no que diz respeito ao impacto de outros programas semelhantes implementados noutros países. Este programa é co-financiado através de ajuda comunitária para aquisição e distribuição de produtos hortofrutícolas a crianças, em idade escolar, que frequentem estabelecimentos de ensino público, englobando dois tipos de medidas: distribuição gratuita de hortofrutícolas e medidas de acompanhamento para promover o consumo. Diversos estudos sugerem que estes programas são eficazes no aumento do consumo de hortofrutícolas em crianças emidade escolar, contribuindo ainda para o desenvolvimento e melhoria dos conhecimentos acerca dos seus benefícios para a saúde. Pode também ser uma estratégia eficaz na redução das desigualdades sociais na saúde. Justifica-se o investimento neste tipo de programas como medida de saúde pública para o combate à obesidade e ao baixo consumo de hortofrutícolas.A healthy diet is a determinant factor for health promotion and protection. Fruit and vegetables, as a part of a healthy diet, seem to play an important protective role in a large number of chronic diseases. However, several studies show that, in children, the fruit and vegetable intake is below the recommended levels. The main objective of this work is to describe and critically analyze the Portuguese strategy for the promotion of fruit and vegetables consumption at school environment, the School Fruit Scheme. This program is co-financed by European Commission for fruit and vegetables acquisition and supplying for school-aged children, attending public schools, including two different types of measures: free fruit and vegetables supply and accompanying measures to promote consumption. Several studies suggest that these programs are effective at increasing fruit and vegetables intake in school-aged children, contributing also to the development and improvement of health benefits' knowledge. It can also be an efficient strategy to reduce the social inequalities in health. The investment in these kind of programs as a public health measure to fight obesity and low fruit and vegetables intake is thus justified