Dose-related anxiogenic effect of glycine in the elevated plus maze and in electrodermal activity

We investigated effect of glycine on anxiety at different doses using electrodermal activity and an elevated-plus maze. A single dose of glycine was injected intraperitoneally into three different groups of mice at 250 mg/kg, 750 mg/kg, and 1250 mg/kg. The anxiety scores with the elevated-plus maze, consisting of two open arms and two enclosed arms, were measured 30 minutes after injection. Then skin conductance level was measured. Glycine significantly decreased the times spent on the open arms in middle-dose and high-dose groups compared with the control group. The skin conductance level was statistically lower in high dose group than control groups. Conclusion; glycine at a dose of 750 mg/kg induced a nearly maximal anxiogenic effect because a higher dose was not more effective.