ANABOLIC-ANDROGENIC STEROID EFFECTS ON ACUTE & CHRONIC NOCICEPTION AND MORPHINE ANTINOCICEPTION By

by Kimberly T. Tsutsui, M.S. Washington State University May 2010 Chair: Rebecca. M. Craft Use of anabolic-androgenic steroids (AAS) has been anecdotally associated with pain reduction as well as opioid abuse. The purpose of the current study was to investigate the effects of AAS on nociception and morphine antinociception in acute pain models, as well as on chronic nociception in an arthritis model, in adult male Sprague-Dawley rats. Rats were injected s.c. for 28 days with either 5 mg/kg dihydrotestosterone proprionate (DHT), testosterone proprionate (T), or stanozolol proprionate (STAN), or safflower oil vehicle (N=16-20/group). Half of the rats in each group were tested on acute thermal and mechanical nociceptive assays on day 28, without and then with morphine. The other half of the rats in each group were injected with mineral oil or complete Freund’s adjuvant (CFA) into one hindpaw, and then tested for thermal hyperalgesia, mechanical allodynia, inflammation and locomotor suppression intermittently for 28 days. Body weight was recorded at least weekly, and reproductive organs were harvested on the last day of testing. While AAS affected body weight and reproductive organ weights in a mostly expected manner, AAS did not significantly alter acute nociception nor did they significantly attenuate the development of various pain parameters after administration v of CFA. Further, morphine antinociception was only modulated by DHT, only on the hotplate test, and in the opposite direction to what was predicted: rather than potentiating morphine antinociception, DHT decreased morphine potency. The findings of this study have produced results that conflict with many past findings of experiments that utilized gonadectomized subjects, implicating a need for further pain studies done in gonadally intact subjects that more accurately model human AAS users.