Materials and Reagents

Animals

1. Floxed Stat3 mice (C57Bl6 background) [Osaka, Japan (Takeda et al., 1998)]
   Note: All experiments were carried out in accordance with the guidelines and approval of the Institutional Animal Care Committee of the CHUM Research Center. Floxed Stat3 mice (C57Bl6 background) in which loxP sites flank exon 22 of the Stat3 gene that encodes a tyrosine residue (tyr705) essential for Stat3 activation, were graciously provided by Dr. Shizuo Akira [Osaka, Japan (Takeda et al., 1998)]. Female mice homozygous for the floxed Stat3 allele were crossed with male mice heterozygous for the floxed Stat3 allele and heterozygous for the DAT-Cre transgene [B6.SJL-Slc6a3tm1.1(cre)Bkmn/J] (Backman et al., 2006) to generate DAT-Cre-Stat3^fl/fl mice and littermate controls (Stat3^fl/fl or Stat3^fl). Male mice were weaned at P28 and housed in a temperature and humidity controlled room that was maintained on a 12:12 hour reverse light/dark cycle. CPP experiment (pre-test, conditioning trials and post-test) was conducted in the dark phase of the cycle.

Equipment

1. Low-profile wireless running wheel for mouse (Med Associates Inc., catalog number: ENV-044 )
   
2. Three-compartment automated mouse CPP chambers (Med Associates Inc., catalog number: ENV-3013 )
   

Software

1. Wheel Manager software (Med Associates Inc., catalog number: SOF-860)

Procedure