Lack of evidence for opioid tolerance or dependence in rhesus monkeys following high-dose anabolic-androgenic steroid administration

Prolonged use of high-dose anabolic-androgenic steroids (AAS) may induce a dependence syndrome, and emerging evidence suggests that AAS effects on end ogenous opioid systems may contribute to AAS abuse. The present study teste d the hypothesis that high dose AAS treatment enhances endogenous opioid ac tivity in rhesus monkeys as revealed by 1) tolerance to the antinociceptive effects of the mu. opioid agonist morphine and 2) physical dependence as i ndicated by evidence of opioid withdrawal following administration of the o pioid antagonist naloxone. Three rhesus monkeys were treated for 14 days wi th 3.2 mg/kg/day testosterone propionate, and the effects of morphine (0.32 -10 mg/kg) and naloxone (0.01-0.32 mg/kg) were examined both before and dur ing treatment. Morphine antinociception was evaluated using a warm-water ta il-withdrawal procedure, and naloxone-precipitated withdrawal was evaluated using checked behavioral signs and measures of ventilatory rate. Chronic. testosterone administration for 14 days produced a 100-fold increase in mea n plasma testosterone levels. However, testosterone treatment did not signi ficantly alter the antinociceptive effects of morphine, and naloxone did no t precipitate signs of opioid withdrawal either before or during testostero ne treatment. These data do not support the hypothesis that high-dose AAS t reatment enhances endogenous opioid activity in rhesus monkeys in a way tha t produces opioid tolerance or dependence. (C) 2001 Elsevier Science Ltd. A ll rights reserved.