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Methionine is an essential amino acid involved in critical metabolic process, and regulation of methionine flux through metabolism is important to supply this amino acid for cell needs. Elevation in plasma methionine commonly occurs due to mutations in methionine-metabolizing enzymes, such as methionine adenosyltransferase. Hypermethioninemic patients exhibit clinical manifestations, including neuronal and liver disorders involving inflammation and tissue injury, which pathophysiology is not completely established. Here, we hypothesize that alterations in macrophage inflammatory response may contribute to deleterious effects of hypermethioninemia. To this end, macrophage primary cultures were exposed to methionine (1 mM) and/or its metabolite methionine sulfoxide (0.5 mM), and M1/proinflammatory or M2/anti-inflammatory macrophage polarization was evaluated. In addition, inflammation-related pathways including oxidative stress parameters, as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) activities; reactive oxygen species (ROS) production, and purinergic signaling, as ATP/ADP/AMPase activities, were investigated. Methionine and/or methionine sulfoxide induced M1/classical macrophage activation, which is related to proinflammatory responses characterized by increased iNOS activity and TNF-α release. Further experiments showed that treatments promoted alterations on redox state of macrophages by differentially modulated SOD and CAT activities and ROS levels. Finally, methionine and/or methionine sulfoxide treatment also altered the extracellular nucleotide metabolism, promoting an increase of ATPase/ADPase activities in macrophages. In conclusion, these findings contribute to better understand the participation of proinflammatory responses in cell injury observed in hypermethioninemic patients.

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Autism is a neuropathology characterized by behavioral disorders. Considering that oxidative stress is involved in the pathophysiology of this disease, we evaluated the effects of quercetin, a flavonoid with antioxidant and neuroprotective properties, in an experimental model of autism induced by valproic acid (VPA). Twelve pregnant female rats were divided into four groups (control, quercetin, VPA, and VPA+quercetin). Quercetin (50 mg/kg) was administered orally to the animals from gestational days 6.5 to 18.5, and VPA (800 mg/kg) was administered orally in a single dosage on gestational day 12.5. Behavioral tests such as open field, social interaction, and tail flick nociceptive assays were performed on pups between 30 and 40 days old, after which the animals were euthanized. Cerebral cortex, hippocampus, striatum, and cerebellum were collected for evaluation of oxidative stress parameters. The pups exposed to VPA during the gestational period showed reduced weight gain, increased latency in the open field and tail flick tests, reduced time of social interaction, accompanied by changes in oxidative stress parameters mainly in the hippocampus and striatum. Prenatal treatment with quercetin prevented the behavioral changes and damage caused by oxidative stress, possibly due to its antioxidant action. Our findings demonstrated that quercetin has neuroprotective effects in an animal model of autism, suggesting that this natural molecule could be an important therapeutic agent for treatment of autism spectrum disorders (ASDs).

No abstract