The effects of sex and exposure to inescapable shock on shock-elicited fighting in albino rats

Abstract

A 2 by 2 factorial design was employed to investigate the effects of exposure to inescapable shock vs. no shock on the subsequent shock-elicited fighting behavior of male and female rats. Results indicated that males fought reliably more than females in response to brief test shocks. Also, prior exposure to inescapable shock was observed to reduce markedly the degree of shockelicited fighting for both male and female rats during initial test sessions. In addition, measurements of responsivity to shock were observed to decrease for shock-treated subjects as a function of continued exposure to inescapable shock during the shock-treatment phase. Taken together, these findings indicate that although sex can be a powerful determinant of degree of shock-elicited fighting in albino rats, the debilitating effect of exposures to inescapable shock does not depend upon this factor. Furthermore, the observations of behavior during shock treatment itself tentatively suggest that the marked reduction in fighting produced by this variable may be due, in part, to a behavioral change accompanying exposure to inescapable shock. Schneiderman, 1972;Tondat, 1974). For the most part, investigators have ignored questions regarding the extent to which this finding generalizes to female rat subjects. One notable exception is the study by Powell et ai. (1972) in which a fightinginterference effect following exposure to inescapable shock was reported for a combined population of male and female rats. Unfortunately, however, this study was not designed to permit separate comparisons of the effect of shock treatments on each sex involved. This oversight followed from the authors' assumption that gender was not an important variable in determining degree of shock-elicited fighting in albino rats, a contention that was based upon the results of several prior studies showing little, if any, sex effect on degree of shock-elicited fighting in this strain

Modeling signal features of escape response: Effects of cessation conditioning in "learned helplessness" paradigm.

“…One way in which modulator contingencies might work to reduce anxiety during pretreatment is by acquiring fear-inhibitory properties. The ability of a safety signal to reduce the level of fear conditioned to the pretreatment context (Jackson & Minor, 1988; Mineka et al, 1984; Rosellini et al, 1987) and to eliminate later deficits in escape performance (Anderson et al, 1987; Jackson & Minor, 1988) or other measures of pathology (Overmier & Murison, 1989; Overmier et al, 1985) is closely linked to inhibitory conditioning and the prediction of safety during the ITI.…”

“…These added shocks were intended to mimic the effect of shortening the minimum ITI but allowed us to maintain more features of the baseline shock schedule between groups, without dramatically changing the overall severity of the pretreatment session (cf. Anderson et al, 1987). All rats were tested for shuttle-escape performance 24 hr later.…”

“…Even though this manipulation did not alter the uncontrollability of pretreatment shocks, it was highly effective in reducing the amount of fear conditioned to discrete and situational stimuli associated with the stressor. Safety signals also have been shown to eliminate deficits in escape performance (Anderson, Hantual, Crowell, & Tohman, 1987; Jackson & Minor, 1988; Volpicelli, Ulm, & Altenor, 1984), hypoalgesia (Maier & Keith, 1987), and gastric ulcerations (Overmier, Murison, Skoglund, & Ursin, 1985) resulting from earlier exposure to inescapable shock.…”

“…Escape responses acquire the ability to moderate a stressor more rapidly and retain that property over a wider range of conditions than do safety stimuli (see Warren et al, in press, for a review). For instance, the inclusion of short minimum intertrial intervals (ITIs) in a schedule of shock delivery does not alter the benefits of an escape response (Rosellini, Warren, & DeCola, 1987) but retards backward inhibitory conditioning (Moscovitch & LoLordo, 1968) and eliminates the ability of a safety signal to attenuate contextual fear (Rosellini, DeCola, & Warren, 1986) or prevent later escape deficits (Anderson et al, 1987). Safety signals also lack the proactive effects of an escape response.…”