Confinement to the open arm of the elevated-plus maze as anxiety paradigm: behavioral validation.

Exposure to the open arm of the elevated-plus maze was used to assess the neurobiological correlates of anxiety in the high-anxiety-related behavior (HAB) and low-anxiety-related behavior (LAB) rat lines. The authors sought to determine whether this mild stressor could be considered a valuable anxiety test revealing specific behavioral differences. Behavioral parameters scored were submitted to a discriminant and factor analysis to investigate emotional parameters discriminating HAB and LAB rats. Principal component analysis showed that the HAB rats' behavior was driven by anxiety, whereas the LAB rats' behavior was mainly explained by locomotor activity. Moreover, the rats displayed behaviors that reflected distinct coping strategies confirming anxiogenic open arm effects and differential appraisals of the stressor dependent on the genetic predisposition to either hyper- or hypo-anxiety.