Unconditioned and conditioned factors contribute to the 'reinstatement' of @entity2072 place conditioning following extinction in C57BL/6 XXXX .

@entity19 @entity2072 @entity2697 @entity11718
Relapse to drug use following prolonged periods of abstinence results, in part, from the ability of contextual cues paired previously with self-administered drug to elicit drug craving and -seeking behavior. Given the popularity of the @entity19 for the genetic analysis of drug-induced behaviors, a place conditioning model of drug-seeking behavior was used to examine the ability of @entity2072 ( @entity11718 ) to reinstate extinguished conditioned reward in @entity19 . In a series of experiments, @entity11718 place conditioning was produced in male C57BL/6 (B6) @entity19 by four pairings of @entity11718 (15 or 25 mg/kg, IP) with the non-preferred compartment of a two-compartment place conditioning apparatus. Following a post-conditioning test (Post-Test), place conditioning was extinguished by repeated testing. The @entity19 were then challenged with one of five @entity11718 doses (0, 5, 10, 15 or 25 mg/kg, IP) and allowed free access to both environments. Following extinction, @entity11718 injections reinstated place conditioning to 100% or greater, relative to the Post-Test. In a control experiment, @entity19 received either @entity11718 or @entity2697 paired with non-preferred compartment and were then challenged with either @entity11718 (15 mg/kg, IP) or @entity2697 on the Post-Test. @entity11718 -conditioned, but not @entity2697 -conditioned, @entity19 exhibited place conditioning when tested in a @entity11718 -free state. Interestingly, @entity11718 injection on the Post-Test elicited an increase in approach behavior in both @entity2697 - and @entity11718 -conditioned @entity19 and this increase was equivalent to that produced by @entity11718 conditioning alone. No direct relationships were observed between the magnitude of place conditioning and either @entity11718 -induced or -conditioned locomotor hyperactivity in the non-preferred compartment. Thus, at least two independent processes appear to underlie the ability of a @entity11718 injection to elicit approach behavior towards the non-preferred compartment of a biased place conditioning apparatus in @entity19 -reactivation of the conditioned incentive motivational properties of @entity11718 -paired cues and elicitation of unconditioned behavioral disinhibition. One or both of these processes sensitizes with the passage of time, increasing the propensity of B6 @entity19 to approach non-preferred environments upon @entity11718 re-administration.
