Fear-potentiation in the elevated plus-maze test depends on stressor controllability and fear conditioning

The purpose of the study was to determine which stressor qualities (escapable vs. inescapable stress and unconditioned vs. conditioned stress) can potentiate fear in the elevated plus-maze. While inescapable stress potentiated fear, escapable stress did not, but escapable stress increased the locomotor activity (closed arm entries). Inescapable stress only potentiated fear when re-exposure to the former shock compartment, 24 h after footshock and without further footshock, took place just before to 90 min before testing in the elevated plus-maze. We conclude that fear-potentiation in the plus-maze depends on stressor controllability and contextual conditioning. Fear-potentiation was reduced by the anxiolytic diazepam (0.5, 1.0 and 2.0 mg/kg, s.c.) and was further enhanced by the anxiogenic DMCM (1.0 mg/kg, s.c). The fear-potentiated plus-maze test may be a valuable tool in the search for novel anxiolytics and in the study of the neurobiology of fear-potentiation, fear conditioning and generalization of fear.