(S)-(-)-Sulpiride (Sulpiride) (Sigma Aldrich, UK) is a relative selective D2/3 dopamine receptor antagonist (Kohli and Cripe, 1979 (link); Pauwels et al., 1993 (link); Ago et al., 2005 ). It was prepared in two different concentrations, 3.75 μg/μl and 2.5 μg/μl. The drug was dissolved in 4000 μl of 0.1M HCl in saline. Solution was neutralised by slow addition of 1M NaOH until pH reached 7. Stock solution was diluted with phosphate-buffered saline (pbs) until a concentration of 10 μg/μl was achieved (a target volume of 10000 μl). Stock solution was filtered, aliquoted and stored at −20° C for a maximum of 2 weeks. Stock solution aliquot was thawed, diluted with pbs and filtered to desired concentration (3.75 or 2.5 μg/μl) before infusion. Vehicle was treated in an identical fashion but sans drug.
Sulpiride (and corresponding vehicle) was infused at a rate of 0.5 μl/min over 1 minute. A 10 minute pre-treatment period was allowed before animals were tested. All animals treated with Sulpiride were treated with both doses of drug and the vehicle.
Sulpiride (and corresponding vehicle) was infused at a rate of 0.5 μl/min over 1 minute. A 10 minute pre-treatment period was allowed before animals were tested. All animals treated with Sulpiride were treated with both doses of drug and the vehicle.