Saccharin sodium salt

(+)MA hydrochloride was purchased from Sigma Aldrich (St. Louis, MO, USA) and dissolved in tap water for drinking studies or in sterile 0.9% saline (Baxter Healthcare Corp., Deerfield, IL, USA) for IP injection. Saccharin sodium salt (SACC) and quinine hemisulfate (QUIN) were obtained from Sigma Aldrich and dissolved in tap water for tastant studies. Genomic DNA was extracted from ear punch samples using QuickExtract DNA extraction solution (Qiagen, Valecia, CA, USA) and Taar1 was amplified (forward 5’-ctttctgctgggctgtctga-3’, reverse 5’-caacagcgctcaacagttctc-3’) and genotype determined utilizing a rtPCR assay, based on standard Taqman procedures^{35 (link)} and methods similar to those fully detailed in our previous publications.^{18 (link),19 (link)}

As illustrated in Fig. 1b, after mice were exposed to caffeine, alcohol self-administration and preference were examined using a two-bottle choice experiment [31 (link)]. Mice were given 24 h access to two bottles, one containing tap water and the other containing an ethanol solution. The concentration of ethanol was raised every fourth day, increasing from 3 to 6 to 10 to 15 to 20% (v/v) ethanol. One week after the ethanol self-administration experiment, the same mice were tested for saccharin sodium salt (sweet) and quinine hemisulphate salt (bitter) (Sigma, St. Louis, Missouri) solutions. The concentration of saccharin (0.03 and 0.06%) and quinine (30 and 60 μM) were raised every fourth day. The positions of the bottles were changed every 2 days to control for position preference. Average consumption per day was obtained for each ethanol concentration and taste solution. Evaporation and leakage were accounted for using 3 control cages with ethanol and water containing bottles but no mouse.