Effect of Different Restraint Schedules on the Immobility in the Forced Swim Test: Modulation by an Opiate Mechanism

L. M. CANCELA, S. ROSS1 AND V. A. MOLINA’

BRAIN RESEARCH BULLETIN

PERGAMON-ELSEVIER SCIENCE LTD

Año: 1991 vol. 26 p. 671 - 675

0361-9230

CANCELA, L. M., S. ROSS1 AND V. A. MOLINA. Effect of different restraint schedules on the immobility in the forced swim test: Modulation by an opiate mechanism. BRAIN RES BULL 26(5) 671-675, 1991 .-The present research was conducted to evaluate the influence of different stress schedules on behaviors displayed during both phases of the forced swim test (FST). In addition, the involvement of an opiate mechanism in the behavioral consequences of chronic restraint was investigated. Exposure to a single, but not to chronic, restraint event induced an increase in the immobility score obtained during the lO-min initial swimming exposure (initial test) of the FST. Animals submitted to a previous regime of repeated restraint showed a significant increase in immobility during the 5-rnin second swimming exposure (retest period) of this behavioral task. However, naloxone (NAL) administered before each of the seven restraint events, blocked the higher immobility observed in chronically stressed rats during the retest period suggesting the involvement of an opiate mechanism. Results concerning the effect of chronic stress on the behavior displayed during the FST were discussed with reference to previous reports which have proposed that immobility performed during the retest period of the FST represents an efficient adaptive response in this inescapable aversive experience.Effect of different restraint schedules on the immobility in the forced swim test: Modulation by an opiate mechanism. BRAIN RES BULL 26(5) 671-675, 1991 .-The present research was conducted to evaluate the influence of different stress schedules on behaviors displayed during both phases of the forced swim test (FST). In addition, the involvement of an opiate mechanism in the behavioral consequences of chronic restraint was investigated. Exposure to a single, but not to chronic, restraint event induced an increase in the immobility score obtained during the lO-min initial swimming exposure (initial test) of the FST. Animals submitted to a previous regime of repeated restraint showed a significant increase in immobility during the 5-rnin second swimming exposure (retest period) of this behavioral task. However, naloxone (NAL) administered before each of the seven restraint events, blocked the higher immobility observed in chronically stressed rats during the retest period suggesting the involvement of an opiate mechanism. Results concerning the effect of chronic stress on the behavior displayed during the FST were discussed with reference to previous reports which have proposed that immobility performed during the retest period of the FST represents an efficient adaptive response in this inescapable aversive experience.BRAIN RES BULL 26(5) 671-675, 1991 .-The present research was conducted to evaluate the influence of different stress schedules on behaviors displayed during both phases of the forced swim test (FST). In addition, the involvement of an opiate mechanism in the behavioral consequences of chronic restraint was investigated. Exposure to a single, but not to chronic, restraint event induced an increase in the immobility score obtained during the lO-min initial swimming exposure (initial test) of the FST. Animals submitted to a previous regime of repeated restraint showed a significant increase in immobility during the 5-rnin second swimming exposure (retest period) of this behavioral task. However, naloxone (NAL) administered before each of the seven restraint events, blocked the higher immobility observed in chronically stressed rats during the retest period suggesting the involvement of an opiate mechanism. Results concerning the effect of chronic stress on the behavior displayed during the FST were discussed with reference to previous reports which have proposed that immobility performed during the retest period of the FST represents an efficient adaptive response in this inescapable aversive experience.5-rnin second swimming exposure (retest period) of this behavioral task. However, naloxone (NAL) administered before each of the seven restraint events, blocked the higher immobility observed in chronically stressed rats during the retest period suggesting the involvement of an opiate mechanism. Results concerning the effect of chronic stress on the behavior displayed during the FST were discussed with reference to previous reports which have proposed that immobility performed during the retest period of the FST represents an efficient adaptive response in this inescapable aversive experience.of the FST represents an efficient adaptive response in this inescapable aversive experience.