4.3. Drinking in the Dark (DID) Ethanol Self-Administration Procedure

Mice were randomly assigned to 4 treatment groups: H₂O (n = 9), ABX (n = 9), SB (n = 11) and ABX+SB (n = 11). All mice had 24 h access to their respective drinking bottles for 2 weeks before the start of ethanol experiments. The DID model is widely used to assess differences in binge-like drinking behaviors [59]. We used a modified version of this procedure in our current study where mice had daily limited intermittent access (2 h) to one bottle containing 20% ethanol beginning at 3 h into the circadian dark phase (3:00 p.m. to 5:00 p.m.) 5 days a week (Monday-Friday) for 4 weeks. This approach was shown to maintain consistent ethanol intake levels during the 5 consecutive days of ethanol exposure [3]. During DID, each drinking bottle was exchanged with a designated bottle containing 20% ethanol.