Racemic blebb

Methamphetamine hydrochloride (Sigma-Aldrich) was delivered IV at 0.02 mg in a 0.05 ml infusion to rats for self-administration and IP at 1.0 mg/kg to rats or 2.0 mg/kg to mice for CPP. Both enantiomers of Blebbistatin (Blebb; − = active Blebb, + = inactive Blebb [Vehicle control]; Calbiochem) were infused into the BLC at a concentration of 90ng/μl in 10% DMSO and 0.9% saline. To address poor solubility of active (−) Blebb, racemic (+/−) Blebb (Tocris) was used for IP injections. It was diluted to 1 mg/ml in a vehicle of 0.9% saline and 6.7% DMSO/25% Hydroxypropyl β-Cyclodextrin (HPβCD) and delivered to mice at 10 mg/kg.
Intra-BLC infusions were delivered at a rate of 0.25 μl/min over 2 min for rats and 0.15 μl/min over 2 min for mice. Infusers were left in place for 1 min to allow for diffusion of the drug away from the needle tip. At the completion of behavioral procedures, 40 μm sections were stained with cresyl violet to verify placement of the infusion needle tips within the BLC (Supplemental Figure S1).

Several different doses of methamphetamine hydrochloride (Sigma-Aldrich) were used, depending on age, species and behavioral task. Adult rats undergoing self-administration received METH IV at 0.02 mg in a 0.05 ml infusion. For conditioned place preference (CPP), adult female mice received 2mg/kg of METH IP and adolescent mice received one of three METH doses IP (1, 1.5 or 2 mg/kg). Racemic Blebb (Tocris) was diluted to 1 mg/ml in a vehicle of 0.9% saline and 6.7%DMSO/25% Hydroxypropyl β-Cyclodextrin (HPβCD) and delivered to mice at 10mg/kg (IP). For intracranial infusions, both enantiomers of Blebb (- = active Blebb, += inactive Blebb [Vehicle control]; Calbiochem) were infused into the BLC at a concentration of 90ng/μl in 10% DMSO and 0.9% saline. The delivery rate of intra-BLC infusions was 0.25 μl/min over 2 min for rats. Injectors were left in place for 1 min following infusion to allow for sufficient diffusion of drug away from the needle tip.