ABSTRACT
A series of six experiments were conducted to determine the effects of haloperidol, clozapine, olanzapine, and phencyclidine (PCP) on rotorod performance. Rodents were trained to walk on a rotorod to avoid a mild shock to a criterion of 20 rpm for 3 min. None of the vehicles of any of these drugs disrupted rotorod performance. Haloperidol disrupted rotorod performance at doses of 0.03, 0.1, and 0.3 mg/kg, and olanzapine disrupted rotorod performance at doses of 3.0 and 10.0 mg/kg. Clozapine produced a much milder disruption across all three doses (3.0, 10.0, and 30.0 mg/kg). PCP produced a consistent and severe disruption of rotorod performance at doses of 4.0 and 6.0 mg/kg, but not at a dose of 2.0 mg/kg. Twenty-four hours postinjection there were no residual PCP effects on rotorod performance. Coadministration of either haloperidol or olanzapine with PCP did not reverse PCP-induced disruption in rotorod performance, while clozapine produced a partial reversal at only one dose. These findings indicate that olanzapine functions similarly to classic antipsychotics with respect to their effects on locomotion and balance.
Subject(s)
Antipsychotic Agents/pharmacology , Excitatory Amino Acid Antagonists/pharmacology , Phencyclidine/pharmacology , Postural Balance/drug effects , Animals , Benzodiazepines , Clozapine/pharmacology , Dose-Response Relationship, Drug , Drug Interactions , Male , Motor Activity/drug effects , Olanzapine , Pirenzepine/analogs & derivatives , Pirenzepine/pharmacology , Rats , Rats, Sprague-DawleyABSTRACT
Two experiments were conducted to determine the behavioral properties of the naltrexone implant on: 1) rodent social interactions; and 2) the appetitive properties of cocaine. Rats were surgically implanted with a naltrexone implant (placebo, 10 or 30 mg) and placed into an open field for the recording of social interactions. The naltrexone implants increased latency to initiate contact and decreased pinning, bouts of grooming, and crawl unders on all 7 days. Other rats were surgically implanted with naltrexone (60, 120, or 240 mg) and habituated to a two-chambered conditioned place preference apparatus. After 6 days of conditioning, place preference was computer recorded. Cocaine produced a dose-dependent conditioned place preference in the rats implanted with placebo or 60 mg of naltrexone. The 120 and 240 mg naltrexone implants blocked the emergence of cocaine-induced place preference. The results indicate that naltrexone implants produce significant social behavioral effects within 1 day, and are effective at attenuating the conditioned place preference produced by cocaine.