The delayed effects of phencyclidine (PCP) disrupt latent inhibition in a conditioned taste aversion paradigm.
The acute effects of a low dose of phencyclidine (PCP) and the delayed effects of a high dose of PCP on latent inhibition (LI) were assessed in a series of experiments using conditioned taste aversion paradigms. Each paradigm involved a preexposure phase in which water-deprived male rats were allowed access to either water (nonpreexposed; NPE) or 5% sucrose (preexposed; PE), followed by a conditioning phase in which animals were allowed access to sucrose and subsequently injected with the negative reinforcer lithium chloride, and a test phase in which animals were allowed access to both sucrose and water. LI was assessed by comparing the %-sucrose consumed in PE and NPE groups on the test day. The effects of low-dose PCP (2.5 mg/kg) were assessed by comparing LI in animals treated with vehicle or PCP 15 min prior to the onset of the preexposure and conditioning phases. A 4-day paradigm involved 2 days of preexposure followed by a day of conditioning and a test day. This paradigm produced comparable levels of LI in vehicle and PCP-treated animals. A 5-day extinction paradigm involved 2 days of preexposure followed by 2 days of conditioning and a test day. This paradigm abolished LI in vehicle and PCP-treated animals. A 3-day paradigm involved 1 day of preexposure followed by a day of conditioning and a test day. One day of preexposure induced a modified LI effect in both in vehicle and PCP-treated animals. The delayed effects of high dose PCP (8.6 mg/kg) were assessed by comparing LI in animals treated with vehicle or PCP 20 h prior to the onset of the preexposure and conditioning phases in the 4-day paradigm. PCP disrupted latent inhibition in this paradigm. The results are discussed in the context of their relevance to the ability for PCP to model schizophrenic symptomatology.
Turgeon
S M
SM
Department of Psychology, Amherst College, MA 01002, USA.
Auerbach
E A
EA
Heller
M A
MA
D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D010622:Phencyclidine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013649:Taste / Q000187:drug effects*
D018691:Excitatory Amino Acid Antagonists; D010622:Phencyclidine