Prolonged treatment with L-lysine and L-arginine reduces stress-induced anxiety in an elevated plus maze.

The aim of this study was to investigate whether a chronic pretreatment with a combination of L-lysine (Lys) and L-arginine (Arg) reduces anxiogenic effects of acute stress in rats. Male rats were orally infused with a distilled water solution of L-glutamine (200 mg/kg), Lys (200 mg/kg), or a combination of Lys (200 mg/kg) plus Arg (200 mg/kg) for four consecutive days (twice daily) and subjected to restraint stress on the fifth day. Immediately thereafter, rats were placed on an elevated plus maze (EPM) and their behavior was evaluated for 10 min. Lys and Arg significantly increased exploration time rats spent on open arms of the EPM, as compared to L-glutamine controls. In addition, the combination of Lys and Arg partly, but significantly, decreased stress-enhanced plasma corticosterone measured at the end of behavioral testing. Data suggest that a treatment with a solution of Lys and Arg reduces anxiety in stressed rats.