Characterization of conditioned place preference to cocaine in congenic dopamine transporter knockout female mice
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- Medvedev, I.O., Gainetdinov, R.R., Sotnikova, T.D. et al. Psychopharmacology (2005) 180: 408. doi:10.1007/s00213-005-2173-y
The dopamine transporter (DAT) is thought to play a major role in the rewarding effects of cocaine. Therefore, it is surprising that cocaine reveals conditioned effects in DAT knockout (DAT-KO) mice.
To examine these findings further, we obtained complete dose–effect curves for DAT-KO and DAT wild-type (DAT-WT) mice in a cocaine conditioned place preference (CPP) procedure.
Congenic C57BL6 background female DAT-KO and DAT-WT mice were conditioned in a three-compartment place preference apparatus. Conditioning consisted of three 30-min sessions with cocaine (2.5, 5.0, 10.0, 20.0, or 40.0 mg/kg) and three 30-min sessions with saline. The distribution of time in each choice compartment was determined after each pair of conditioning sessions (one cocaine and one saline session).
DAT-WT mice revealed CPP over a wide range of cocaine doses (5.0–40 mg/kg), whereas DAT-KO mice revealed CPP over a more restricted range of doses, with consistent CPP only occurring with 10 mg/kg of cocaine.
CPP for cocaine develops in both DAT-KO and DAT-WT mice; however, the dose range at which CPP develops is much more restricted in DAT-KO mice than in DAT-WT mice. These observations corroborate the significant role of DAT inhibition in cocaine’s conditioned effects.