Analysis of licking microstructure provides no evidence for a reduction in reward value following acute or sub-chronic phencyclidine administration.
BACKGROUND
The N-methyl D-aspartate antagonist phencyclidine (PCP) is purported to mimic the negative, cognitive and positive symptoms of schizophrenia. Thus, acute and sub-chronic PCP treatment in rodents might produce anhedonia, a decrease in the pleasure produced by rewards.


OBJECTIVE
Experiment 1 investigated whether acute PCP treatment changes the value of sucrose. A comparison was made to (+)MK-801, a drug often used interchangeably with PCP in preclinical studies. Experiment 2 assessed the effects of withdrawal from sub-chronic PCP treatment on the value of sucrose.


METHODS
Experiment 1 examined the dose-response effects of PCP and (+)MK-801 on licking microstructure during sucrose consumption. Experiment 2 assessed the effects of withdrawal from sub-chronic PCP treatment (5 mg/kg twice daily for 7 days), on licking microstructure during sucrose consumption. Locomotor activity testing was carried out in experiment 2 to confirm the sensitisation effect of the PCP regimen on amphetamine-induced hyperlocomotion.


RESULTS
Low to moderate acute doses of PCP and (+)MK-801 increased the amount of sucrose consumed. Higher doses decreased consumption and the number of licks per cluster (cluster size) but also increased the average inter-lick interval, which may indicate motor impairment. There was no evidence that withdrawal from sub-chronic PCP treatment produced decreases in consumption or lick cluster size.


CONCLUSIONS
Following acute PCP treatment, we found no evidence of reduced reward value without the presence of confounding motor deficits. Sub-chronic PCP withdrawal also produced no decrease in reward value. Therefore, the current results indicate that neither acute PCP treatment nor sub-chronic PCP withdrawal produce consummatory anhedonia.
School of Psychology, Cardiff University, Tower Building, Park Place, Cardiff, CF10 3AT, UK. LydallES@Cardiff.ac.uk
Emma S
ES
Lydall
Gary
G
Gilmour
Dominic M
DM
Dwyer
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D004195:Disease Models, Animal; D016291:Dizocilpine Maleate / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage*; D005247:Feeding Behavior / Q000187:drug effects*; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D010622:Phencyclidine / Q000008:administration & dosage* / Q000633:toxicity; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors*; D012201:Reward; D012559:Schizophrenia / Q000139:chemically induced; D012565:Schizophrenic Psychology; D013395:Sucrose; D013649:Taste / Q000187:drug effects*; D013997:Time Factors
D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D013395:Sucrose; D016291:Dizocilpine Maleate; D010622:Phencyclidine