Pituitary-adrenal activity and leverpress shock escape behavior

Abstract

Three experiments were performed to explore the relationship between leverpress escape behavior and pituitary-adrenal activity. In Experiment 1, concentrations of plasma corticosterone increased from basal levels during exposure to the shock escape procedure, but were substantially decreased following the 15th escape conditioning session. In Experiment 2, steroid levels of subjects which received inescapable shock remained elevated during exposure to all 15 shock sessions. Experiment 3 examined whether normal pituitary-adrenal arousal was necessary for learning and maintenance of successfulleverpress escape behavior. Subjects for which hypothalamic cortisol implants blocked pituitary-adrenal activity learned the escape response and performed efficiently, although their escape latencies showed a small, but significant, increase over latencies of cholesterol-implanted control subjects. Collectively, these results suggest that pituitary-adrenal activity may reflect rather than mediate the acquisition of coping behavior.

Acute Stressors and Cortisol Responses: A Theoretical Integration and Synthesis of Laboratory Research.

“…Uncontrollable contexts contained elements that informed participants they were failing or could not avoid negative consequences, including manipulated task difficulty (impossible tasks, time constraints), false feedback of poor performance, harassment, or the presence of auditory distraction or other emotionally distressing stimuli when no behavioral methods for avoiding the stimuli were possible. Animal studies have documented differential HPA activation in uncontrollable versus controllable conditions (Davis et al, 1977;Dess et al, 1983;Hanson et al, 1976;Swenson & Vogel, 1983), and these meta-analytic results extend this literature to humans. Furthermore, the finding that uncontrollability leads to increased cortisol activation adds to the evidence that loss of control can have negative effects on psychological, physiological, and health outcomes (e.g., Chorpita & Barlow, 1998;Peterson, Maier, & Seligman, 1993).…”

The relationship between plasma corticosterone levels and leverpress avoidance vs. escape behaviors in rats

“…The above findings do not appear to agree with those of Davis et al (1977), who found a decrease in the plasma corticosterone concentrations of rats after 15 days of unsignaled lever press escape training, similar to that reported by Coover et al (1973) with rats in the shuttle-box avoidance task. However, there are a number of important methodological differ-ences between the present and the Davis et al (1977) studies that complicate attempts to compare them. The decrease in corticosterone level reported by the latter authors was based upon within-subjects comparisons with previous elevations earlier in the training, rather than in comparison with yoked-control animals, as in the present study.…”

“…However, several issues remain unresolved. For example, the absence of a correlation between the number of shocks and corticosterone levels could be due to the reported high variability of the latter (Davis, Porter, Livingstone, Herrmann, MacFadden, & Levine, 1977;Weiss, 1971). Also, Coover et a1.…”

The Effects of Environmental Control on Cognition in Rats (Rattus norvegicus)

“…Enrichment brought about by the animal's own environmental control may play an important role in the expression of corticosterone. The hypothalamic-pituitary-adrenal axis responds to control in that corticosterone levels were significantly lowered when rhesus monkeys were allowed to control the termination of a shock (Davis et al, 1977;Hanson, Larson, & Snowdon, 1976).…”