| Abstract: | Trained 4 monkeys, 2 rhesus and 2 cynomolgus, to perform a multiple FR extinction schedule for banana pellets. Subsequently, all Ss were given hydromorphone (HYM 0.025 mg/kg]) self-administration training (up to 40 infusions), which consisted of substitution of FR 2 cocaine for FR 80 banana pellets and substitution of FR 2 HYM for FR 2 cocaine. All Ss acquired cocaine self-administration. They also acquired HYM self-administration when it was substituted for cocaine. Next, 50 HYM (1 mg/kg/day) self-maintenance sessions were given. Naloxone (0.4 mg) disrupted appetitive responding for banana pellets in the 2 rhesus. A HYM challenge dose of 1 mg/kg was given noncontingently to assess whether tolerance to the daily maintenance dose had been acquired. The bolus dose of HYM suppressed leverpressing for food in both species, a result indicating a lack of tolerance. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) |
