Effects of d-amphetamine, morphine, naloxone, and drug combinations on visual discrimination in rats.
The effects of d-amphetamine, morphine, and naloxone on visual discrimination were investigated using a two-choice discrete-trial procedure in which rats were trained to discriminate the position of a lightflash. Morphine (0.3-5.6 mg/kg) but not amphetamine (0.1-1.0 mg/kg) caused a significant dose-dependent disruption in discriminative performance. Both amphetamine and morphine increased response latencies. Naloxone (1.0 mg/kg) prevented the disruption of any aspect of performance by up to 100 mg/kg morphine. Performance after naloxone/amphetamine co-administration was not significantly different from that observed after amphetamine alone. Naloxone alone (0.3-10 mg/kg) had no effect on discrimination, spatial bias or response latencies. These results suggest that morphine and amphetamine affect different components of discrimination performance.
D000818:Animals; D003913:Dextroamphetamine / Q000494:pharmacology*; D004193:Discrimination Learning / Q000187:drug effects; D004192:Discrimination, Psychological / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology*; D051381:Rats; D014785:Vision, Ocular / Q000187:drug effects*
D009270:Naloxone; D009020:Morphine; D003913:Dextroamphetamine