Date of Award

12-1985

Degree Name

Doctor of Philosophy

Department

Psychology

First Advisor

Dr. Frederick Gault

Second Advisor

Dr. David Lyon

Third Advisor

Dr. Arthur Snapper

Fourth Advisor

Dr. Robert Harmon

Abstract

Glucocorticoids are used medicinally for numerous chronic ailments. While dramatically effective, glucocorticoid treatment is replete with psychiatric complications. The behavioral toxicology of glucocorticoids, however, remains relatively unexplored. Therefore, 13 laboratory studies were performed to analyze the influence of prednisolone, a representative glucocorticoid, upon varied behavioral and physiological endpoints in rats. Experiments 1-3 showed prednisolone to produce marked hypodipsia, body weight loss, selective adrenal gland atrophy, hyperactivity, hyperalgesia, altered grasping responses, hyperglycemia, enhanced predation, and conditioned taste aversion. Most of these findings were directly dependent upon dose, and where explored, number of treatments. The remaining ten studies examined both acute and chronic exposure effects of prednisolone upon various learned operant behaviors. Experiments 4-8 employed a VI-15" schedule while Experiments 9-11 employed a FR-20 schedule for either food or water response consequences. In general, results from these studies established that acute doses (2,4,8 and 16 mg/kg) do not have an appreciable impact upon VI- or FR-maintained responding, regardless of appetitive reinforcer used; that a time-course cannot be established with acute doses upon VI-maintained responding (0.5-8.0 hr. pre-treatment); and yet, that VI- or FR-maintained behavior is dramatically impacted upon, if prednisolone treatment is chronic rather than acute. Experiment 12 employed a DRL-15" schedule for food to assess, with pre- and post-drug sessions, whether the behavioral suppression which develops under repeated prednisolone is due to an accruing debilitation, or an increasing drug sensitization. DRL results generally supported the debilitation hypothesis, however, some subjects also showed sensitization. Experiment 13 examined the influence of repeated prednisolone upon acquisition of Sidman avoidance in a shuttle box. Results showed that learning can be influenced and is dose-dependent. Future studies should analyze: the physiological mechanisms by which prednisolone exerts behavioral influence; how the environment can modify these actions; whether other drugs interact to exascerbate prednisolone's influence; and which agents therapeutically attenuate prednisolone's deleterious behavioral sequelae.

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Dissertation-Open Access

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Psychology Commons

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