Effects of Chronic Exposure to Stressors on Avoidance-Escape Behavior and on Brain Norepinephrine*

Abstract

A single exposure to a severe stressor (either cold swim or inescapable shock) impairs subsequent performance in a shuttle avoidance-escape task (1), a deficit attributed to reduction in brain noradrenergic activity produced by these stressors. In the present paper, two experiments are described which examine how repeated exposure to such stressors affects (a) shuttle avoidance-escape performance (Experiment 1), and (b) aspects of brain norepinephrine metabolism (Experiment 2). Experiment 1 showed that, whereas subjects receiving the single exposure to cold swim or shock showed a large avoidance-escape deficit, subjects that received repeated exposure to these stressors for 14 days performed similarly to the control group that received no stressor. Experiment 2 showed that, whereas subjects that received one session of the inescapable shock stressor showed a lower level of norepinephrine in hypothalamus and cortex than did subjects that received no shock, subjects that received repeated exposure to inescapable shock or cold swim showed neurochemical "habituation." Subjects that received repeated shock showed elevated tyrosine hydroxylase activity and no depletion of norepinephrine level, and both repeated shock and cold swim caused a decrease in uptake of 3H-norepinephrine by slices of cortex in vitro. Thus, it is concluded that the behavioral and neurochemical changes that were observed after the stressful conditions studied are consistent with the hypothesis that changes in avoidance-escape responding following exposure to these stressful events are due to changes in brain noradrenergic activity.

The Psychological Benefits of Vigorous Exercise: A Study of Discordant MZ Twin Pairs

“…Drawing on Lees and Dygdon's (1988) argument that exercise can initially be unpleasant but can over time become pleasant due to counterconditioning, or the suppression of an unwanted response to a stimulus by the conditioning of a competing (e.g., endorphin) response, Salmon (2001) noted that the effects of counter-conditioning routinely extend beyond the originally aversive stimulus in nonhuman animal experiments so that counter-conditioning becomes a more general form of 'toughening up' (Gray, 1982). For example, after developing tolerance to exposure to cold water through counter-conditioning, animals also display tolerance to uncontrollable electric shock, and vice versa (Weiss et al, 1975).…”

Arousal and physiological toughness: Implications for mental and physical health.

“…[The direction of causality indicated by solid lines is uniformly from left to right. Letters in Figure 1 refer to the following studies and reviews: (a) Levine, 1960;Denenberg, 1967; G. S. Solomon, Kay, & Morley, 1986;(c and d) Pfeifer, 1976;(e1 and e2) Weiss, Glazer, Pohorecky, Brick, & Miller, 1975; (f) Bhagat & Horenstein, 1976;(g) Stone, 1968; Bryar, Fregly, & Field, 1983; (i and j) Sklar & Anisman, 1981 (review); (k) Brown & Van Huss, 1973;Brown et al, 1979; Bhagat & Horenstein, 1976;Alho, Koistinaho, Kovanen, Suominen, & Hervonen, 1984; Harri, 1979; Sklar & Anisman, 1981 (review); (o) Starzec, Berger, & Hesse, 1983; (p) Ritter & Pelzer, 1978;(q) Greenberg & Wiess, 1978; Meaney et al, 1987; (t, u, and v) Sklar & Anisman, 1981;Calabrese, Kling, & Gold, 1987 (both reviews). ] Figures 1 and 2 are included merely to provide a quick visual image of the relations and gaps in this nomological net; the reader need not study the fi gures to follow this presentation.…”

Behavioral Medicine: Symbiosis between Laboratory and Clinic

“…Subsequently, he has participated in experiments show . ng that, under some circumstances, repeated exposures to a stressor can �licit biochemical changes that reduce the depletion of brain norepineph rine, increase the effectiveness of that neurotransmitter at the synapse, reduce the elevation of plasma corticosterone (which would be expected to reduce suppression of the immune system), and reduce depressive effects on subsequent behavior (Glazer et al 1975. Finally, rats handled daily from birth through weaning have been found to have subse quently a greater antibody response to inoculation of fiagellin than rats not subjected to this form of stress (Solomoltl et al 1968).…”