Methylphenidate, a psychostimulant that affects both dopaminergic and noradrenergic systems, is one of the most frequently prescribed treatments for attention-deficit hyperactivity disorder. The present study investigated the effects of chronic administration of methylphenidate to juvenile rats on spatial memory, brain-derived neurotrophic factor immunocontent and acetylcholinesterase activity in hippocampus and prefrontal cortex. Rats received intraperitoneal injections of methylphenidate (2.0mg/kg) once a day, from the 15th to the 45th day of age or an equivalent volume of 0.9% saline solution (controls). Twenty-four hours after the last injection, animals were subjected to testing in the Morris water maze. After that, animals were sacrificed and hippocampus and prefrontal cortex were dissected out for determination of brain-derived neurotrophic factor immunocontent and acetylcholinesterase activity. Chronic administration of methylphenidate provoked cognitive impairments on spatial reference and working memory tasks. A reduction on brain-derived neurotrophic factor immunocontent and increased acetylcholinesterase activity in prefrontal cortex, but not in hippocampus, of rats treated with methylphenidate were also observed. These results suggest that the deficit in spatial memory may be associated to decreased brain-derived neurotrophic factor immunocontent and increased acetylcholinesterase in prefrontal cortex of juvenile rats subjected to methylphenidate administration.

The use of psychostimulant methylphenidate has increased in recent years for the treatment of attention-deficit hyperactivity disorder in children and adolescents. However, the behavioral and neurochemical changes promoted by its use are not yet fully understood, particularly when used for a prolonged period during stages of brain development. Thus, the aim of this study was to determine some parameters of oxidative stress in encephalic structures of juvenile rats subjected to chronic methylphenidate treatment. Wistar rats received intraperitoneal injections of methylphenidate (2.0 mg/kg) once a day, from the 15th to the 45th day of age or an equivalent volume of 0.9% saline solution (controls). Two hours after the last injection, animals were euthanized and the encephalic structures obtained for determination of oxidative stress parameters. Results showed that methylphenidate administration increased the activities of superoxide dismutase and catalase, but did not alter the levels of reactive species, thiobarbituric acid reactive substances levels and sulfhydryl group in cerebellum of rats. In striatum and hippocampus, the methylphenidate-treated rats presented a decrease in the levels of reactive species and thiobarbituric acid reactive substances, but did not present changes in the sulfhydryl groups levels. In prefrontal cortex, methylphenidate promoted an increase in reactive species formation, SOD/CAT ratio, and increased the lipid peroxidation and protein damage. These findings suggest that the encephalic structures respond differently to methylphenidate treatment, at least, when administered chronically to young rats. Notably, the prefrontal cortex of juvenile rats showed greater sensitivity to oxidative effects promoted by methylphenidate in relation to other encephalic structures analyzed.

Mild hyperhomocysteinemia is considered to be a risk factor for cerebral and cardiovascular disorders and can be modeled in experimental rats. Inflammation has been implicated in the toxic effects of homocysteine. Cholinergic signaling controls cytokine production and inflammation through the "cholinergic anti-inflammatory pathway," and brain acetylcholinesterase activity plays a role in this regulation. The aim of this present study is to investigate the effect of mild chronic hyperhomocysteinemia on proinflammatory cytokine levels in the brain, heart, and serum of rats. Activity, immunocontent, and gene expression of acetylcholinesterase in the brain and butyrylcholinesterase activity in serum were also evaluated. Mild hyperhomocysteinemia was induced in Wistar rats by homocysteine administration (0.03 μmol/g of body weight) twice a day, from the 30th to the 60th days of life. Controls received saline in the same volumes. Results demonstrated an increase in tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and the chemokine monocyte chemotactic protein-1 (MCP-1) in the hippocampus, as well as an increase in IL-1β and IL-6 levels in cerebral cortex. Acetylcholinesterase activity was increased in rats subjected to mild hyperhomocysteinemia in both cerebral structures tested; the immunocontent of this enzyme was also increased in the cerebral cortex and decreased in the hippocampus. Levels of acetylcholinesterase mRNA transcripts were not altered. Peripherally, homocysteine increased TNF-α, IL-6, and MCP-1 levels in the heart and IL-6 levels in serum. Taken altogether, these findings suggest that homocysteine promotes an inflammatory status that can contribute, at least in part, to neuronal and cardiovascular dysfunctions observed in mild hyperhomocysteinemia.

Studies have shown autophagy participation in the immunopathology of inflammatory diseases. However, autophagy role in asthma and in eosinophil extracellular traps (EETs) release is poorly understood. Here, we attempted to investigate the autophagy involvement in EETs release and in lung inflammation in an experimental asthma model. Mice were sensitized with ovalbumin (OVA), followed by OVA challenge.Before the challenge with OVA, mice were treated with an autophagy inhibitor, 3-methyladenine (3-MA). We showed that 3-MA treatment decreases the number of eosinophils, eosinophil peroxidase (EPO) activity, goblet cells hyperplasia, proinflammatory cytokines, and nuclear factor kappa B (NFκB) p65 immunocontent in the lung. Moreover, 3-MA was able to improve oxidative stress, mitochondrial energy metabolism, and Na + , K + -ATPase activity. We demonstrated that treatment with autophagy inhibitor 3-MA reduced EETs formation in the airway. On the basis of our results, 3-MA treatment can be an interesting alternative for reducing lung inflammation, oxidative stress, mitochondrial damage, and EETs formation in asthma. K E Y W O R D Sasthma, autophagy, eosinophil extracellular traps, eosinophils, inflammation

It has been shown that elevation of plasma methionine (Met) and its metabolites may occur in several genetic abnormalities. In this study we investigated the in vitro and in vivo effects of the Met and methionine sulfoxide (MetO) on oxidative stress parameters in the liver of rats. For in vitro studies, liver homogenates were incubated with Met, MetO, and Mix (Met + MetO). For in vivo studies, the animals were divided into groups: saline, Met 0.4 g/kg, MetO 0.1 g/kg, and Met 0.4 g/kg + MetO 0.1 g/kg. The animals were euthanized 1 and 3 h after injection. In vitro results showed that Met 1 and 2 mM and Mix increased catalase (CAT) activity. Superoxide dismutase (SOD) was enhanced by Met 1 and 2 mM, MetO 0.5 mM, and Mix. Dichlorofluorescein oxidation was increased by Met 1 mM and Mix. In vivo results showed that Met, MetO, and Mix decreased TBARS levels at 1 h. Total thiol content decreased 1 h after and increased 3 h after MetO and Met plus MetO administrations. Carbonyl content was enhanced by Met and was reduced by MetO 1 h after administration. Met, MetO and Met plus MetO decreased CAT activity 1 and 3 h after administration. Furthermore, only MetO increased SOD activity. In addition, Met, MetO, and Mix decreased dichlorofluorescein oxidation at 1 and 3 h. Our data indicate that Met/MetO in vivo and in vitro modify liver homeostasis by altering the redox cellular state. However, the hepatic changes caused by these compounds suggest a short-time adaptation of this tissue.