Tolerance to the effects of buprenorphine on schedule-controlled behavior and analgesia in rats

Responding in rats was maintained under a fixed-ratio 30 schedule of food presentation. When administered acutely buprenorphine (0.018-0.56 mg/kg) produced dose-related decreases in overall rate of responding. In addition to schedule-controlled behavior, the analgesic effects of buprenorphine were evaluated during chronic administration using the tail-flick method. Tolerance developed to the effects of buprenorphine on both measures. In general dose-effect curves for the rate-decreasing effects of buprenorphine were shifted to the right by approximately 2 log units. In one subject, however, tolerance did not develop to the rate-decreasing effects of 10 mg/kg, suggesting that behavioral tolerance to buprenorphine is dose limited. Finally, the data also suggested that tolerance may develop more slowly, yet more completely, to the analgesic than to the rate-decreasing effects of buprenorphine.