Taste conditioning effects of buprenorphine in morphine-naive and morphine-experienced rats.

Male Sprague-Dawley rats were injected daily with saline (morphine-naive rats) or 20 mg kg-1 morphine (morphine-experienced rats), starting 15 days before the experiment. Subsequent taste conditioning indicated that 0.1 mg kg-1 buprenorphine significantly decreased 0.025% saccharin consumption in morphine-naive, but not in morphine-experienced rats. A 10 mg kg-1 dose of morphine gave similar results, while d-amphetamine (0.75 mg kg-1) was consistently aversive. It was concluded that morphine experience selectively blocks the aversive effects of buprenorphine in rats; thus it possibly increases the potential for buprenorphine abuse.