Rs 102221

Serotonin hydrochloride, MDL 72,222, RS 102221, MDL 100,907, SR95531 and CGP 54626 hydrochloride were purchased from Tocris Bioscience UK. Picrotoxin, kynurenic acid and α-Methylserotonin maleate salt were purchased from Sigma-Aldrich UK.

All drugs used in electrophysiological experiments (TTX, mCPP, RS 102221) were purchased from Tocris (Bristol, UK). TTX, and mCPP were dissolved in ddH₂O at a stock concentration of 5 mM and 50 mM, respectively, and stored at −20°C. RS 102221 was dissolved to 100 mM in DMSO and stored at −20°C. On the day of the experiment, drugs were diluted to their final concentrations in normal aCSF. For behavioral and immunohistochemical experiments, SB 242,084 was purchased from Caymen Chemical (Ann Arbor, Michigan), suspended in 0.5% carboxymethylcellulose vehicle at a working concentration of 0.3 mg/ml, then injected at 3 mg/kg. This dose was chosen primarily based on results from Breese and colleagues indicating that pretreatment with 3 mg/kg SB 242,084 reduced withdrawal-induced anxiety in rats in the social interaction test (Overstreet et al., 2003 (link)) and voluntary ethanol consumption following withdrawal (Overstreet et al., 2007 (link)). This highly selective 5HT2c-R antagonist exhibits 158-fold selectivity over 5HT2a receptors and 100-fold selectivity over 5HT1b receptors. There is some evidence that SB 242,084 has locomotor activating effects that follow an inverted U shaped curve peaking at 1 mg/kg, but are not present at 3 mg/kg (Martin et al., 2002 (link)). Our use of the 3 mg/kg dose circumvents this potential confound.