TL neuro

November 8, 2013

Taffe Lab SFN2013 Poster on MDPV

Filed under: Cathinones, MDPV, SfN Annual Meeting 2013 — mtaffe @ 10:14 am

Saturday 11/9, 1-5pm

Board: 62.15/EE3

Rapid devaluation of running wheel activity coincident with the rapid, binge-like acquisition of 3,4-methylenedioxypyrovalerone self-administration

CNAD and Dept. of Chem., The Scripps Res. Inst., La Jolla, CA

One proposed risk factor for drug abuse/addiction is impoverishment of access to non-drug rewards/reinforcers. It is also hypothesized that engagement with non-drug reinforcers will prevent or treat drug abuse/addiction but for some individuals the drug maintains a relative advantage over natural rewards. In preclinical models, it has been shown that access to a running wheel can reduce drug intravenous self-administration (IVSA) in rats under some conditions but also that drug access decreases wheel activity. This study examined the effects of access to a running wheel and to the high efficacy stimulant reinforcer 3,4-methylenedioxypyrovalerone (MDPV; “bath salts”) on IVSA and wheel activity. Male Wistar rats were given concurrent access to MDPV (0.05 mg/kg/inf, i.v.) and a running wheel that was either locked (LW) or unlocked (UW) in 60-min operant sessions. Mean MDPV intake increased across 20 sessions, but was equivalent for LW and UW groups. Mean wheel activity decreased across 20 sessions in the UW group. Inspection of individuals’ data showed that ~2/3 of the UW rats exhibited apparent “crossovers” wherein wheel activity plummeted within the same session that MDPV IVSA increased. Follow-up analyses confirmed a negative relationship between wheel activity and drug intake and confirmed that rats with crossovers earned more infusions than those without such crossovers. Also, regardless of wheel condition, the rapid acquisition of MDPV IVSA often began with a binge-like pattern of drug intake wherein post-reinforcement pauses decreased to the limit imposed by a 20 second post-infusion timeout. Analysis of post-acquisition MDPV intake confirmed that rats exhibiting binging had higher drug intakes than those that didn’t show the pattern (even after excluding the initial binge from the analysis). These results indicate that the coincident introduction of running-wheel access during access to MDPV IVSA is without effect on that IVSA, unlike a prior finding for methamphetamine (MA) IVSA. And, these results indicate that acquisition of MDPV IVSA rapidly decreases wheel activity in a devaluation similar to prior effects of MA IVSA. Lastly, acquisition of MDPV IVSA was often associated with an initial binge that predicted greater subsequent drug intake. Thus, it appears that MDPV rapidly diminishes the value of non-drug reinforcers, that initial drug intake levels are capped only by physically imposed limits and that a binge-like acquisition pattern has consequences for subsequent drug consumption. Together, these results strengthen the prediction that MDPV has an abuse/addiction liability much greater than that of MA.


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