Acute opioid administration effects on sensory and motor function in baboons: Buprenorphine, morphine, and naloxone

The effects of acute administration of the opioid compounds buprenorphine, morphine, and naloxone were studied on auditory and visual threshold functions and reaction time performances in baboons. Baboons were trained in a reaction time procedure to hold a lever depressed, and release the lever when a signal was presented. Auditory and visual signals were employed in separate sessions. Drug was administered 30 min prior to testing. Dose-related increases in visual and auditory thresholds were observed following buprenorphine, with visual thresholds being somewhat more drug-sensitive. Buprenorphine also increased reaction times to both high-intensity and low-intensity stimuli. High doses of morphine increased reaction times to high-intensity auditory and low-intensity visual stimuli; thresholds for both modalities were unaffected by any dose of morphine. Naloxone produced no consistent effects on thresholds or reaction times. False alarm rates were not significantly changed by buprenorphine, morphine, or naloxone.