Naloxone attenuates incubated sucrose craving in rats.
BACKGROUND
Cue-induced craving precedes drug relapse and contributes to eating disorders. Opiate antagonists have been demonstrated to be effective at reducing cravings for drugs and food. Craving, as defined as responding for a stimulus previously associated with a reward, increases, or incubates, over forced abstinence in an animal model of relapse.


OBJECTIVE
This paper aims to determine anticraving effects of the opiate antagonist, naloxone, on the incubation of sucrose craving.


METHODS
106 male Long-Evans rats lever pressed for 10% sucrose solution 2 h/day for 10 days. On either day 1 or 30 of forced abstinence, rats responded in extinction for 6 h and then were injected (ip) with either saline or naloxone (0.001, 0.01, 0.1, 1, or 10 mg/kg). The rats then responded for 1 h for presentation of a tone + light cue previously presented with every sucrose delivery during self-administration training.


RESULTS
The rats responded more in extinction and following saline on day 30 vs day 1 (an incubation of craving). Except for a trend for a decrease in responding following 10 mg/kg on day 1, naloxone was primarily effective on day 30. On day 30, naloxone significantly reduced responding at all doses except for 0.1 mg/kg.


CONCLUSIONS
The time-dependent increase in sensitivity to an opiate antagonist is consistent with time-dependent changes in the opiate system following forced abstinence from sucrose. These changes may partly underlie the incubation of sucrose craving. In addition, these findings could be used to support the use of naloxone as an anticraving medication in protracted abstinence.
Grimm
Jeffrey W
JW
Department of Psychology, Western Washington University, Bellingham, WA 98225-9089, USA. jeff.grimm@wwu.edu
Manaois
Meghan
M
Osincup
Dan
D
Wells
Barbara
B
Buse
Carl
C
D000284:Administration, Oral; D000704:Analysis of Variance; D000818:Animals; D016739:Behavior, Addictive / Q000517:prevention & control* / Q000523:psychology; D001522:Behavior, Animal / Q000187:drug effects; D003214:Conditioning, Classical / Q000187:drug effects; D005108:Extinction, Psychological / Q000187:drug effects; D005518:Food Preferences / Q000187:drug effects* / Q000523:psychology; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009270:Naloxone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology; D051381:Rats; D020318:Rats, Long-Evans; D012646:Self Administration / Q000379:methods; D012965:Sodium Chloride / Q000008:administration & dosage; D013395:Sucrose / Q000008:administration & dosage*
D009292:Narcotic Antagonists; D009270:Naloxone; D012965:Sodium Chloride; D013395:Sucrose