Chronic-stress induced modulation of different states of anxiety-like behavior in female rats

Stress facilitates emotionality and consolidation of aversive memories in male rodents. In addition, considerable sexual dimorphism has been observed in animal and clinical literature, both in response to stress and predisposition to anxiety disorders thought to be exacerbated by stress. In view of this, we investigated effects of chronic immobilization stress and chronic unpredictable stress on anxiety-like behavior exhibited by female Wistar rats, using the elevated plus-maze. Neither of the stress paradigms employed in this study significantly influenced anxiety, as manifested by similar open-arm exploration in control and treated animals. Previous studies have reported that in males, exposure to elevated plus-maze during an initial trial significantly reduces open-arm exploration in subsequent retesting, an effect attributed to consolidation of aversive experience of the initial exposure. Control female animals, during a second exposure to the maze 72 It after the first trial, displayed a similar shift to a state of enhanced anxiety. Furthermore, exposure to stress did not affect such consolidation of anxiety, as evidenced by similar reduction in open-arm exploration between control and stressed animals during retesting. We conclude that female rats are insensitive to chronic stress in terms of facilitation and consolidation of anxiety. (c) 2005 Elsevier Ireland Ltd. All rights reserved.