Quinpirole dihydrochloride

Three weeks after 6-OHDA lesions, all rats in experiment 2 (n=9) received injections of the D₁ receptor agonist (+)-SKF-81297 hydrobromide (SKF81297; 0.8 mg/kg, sc; Sigma) on three separate occasions 2-3 d apart to sensitize both D1 and D2 receptors (Dupre et al., 2007 (link); Pollack and Yates, 1999 (link)). Contralateral rotations and AIMs were measured immediately after injections. Rats displaying ALO AIMs scores of ≥ 45 by the 3rd day of D1 receptor agonist priming were retained for further study (n = 9 of 9, 100%). Thereafter, rats were tested for AIMs every 3-4 d in a within-subjects design, receiving a pre-treatment of VEH (dH2O) or various doses of Propranolol (5 or 20 mg/kg, ip) 5 min prior to injection of vehicle (10% DMSO and 90% sterile saline), a low dose of the D1 receptor agonist SKF81297 (0.08 mg/kg, sc), or a low dose of the D2 receptor agonist (±)- Quinpirole dihydrochloride (Quinpirole; 0.05 mg/kg, sc; Sigma; Bhide et al., 2013 (link); Dupre et al., 2007 (link)). Rats were monitored for AIMs and rotations for 1 min every 10 min over 3 h following the DA agonist injections. At least 48 h after final treatment, rats were rapidly decapitated and dorsal striata were dissected for subsequent analysis of monoamine content in order to quantify degree of DA depletion.

Quinpirole dihydrochloride (Sigma-Aldrich, St. Louis, Missouri, USA) was dissolved in sterile 0.9% saline and administered i.p. in a volume of 1 ml/kg body weight. L-741,626 (Tocris, Ellisville, Missouri, USA) was dissolved in 5% ethanol with 1 M HCl, added by drops until the solution was clear, and injected s.c., typically in a volume of 1 ml/kg body weight (see Baladi et al., 2011a (link); Collins et al., 2005 (link), 2007 (link)). PG 01037 hydrochloride, generously provided by Dr. Amy Newman, was synthesized by J Cao in the Medicinal Chemistry Section, Intramural Research Program, National Institute on Drug Abuse (Baltimore, Maryland, USA) using previously published methods (Grundt et al., 2005 (link)); PG 01037 was dissolved in 0.9% saline and administered s.c., typically in a volume of 1 ml/kg body weight.

Quinpirole dihydrochloride (Sigma-Aldrich, St. Louis, MO, USA) and (±) DOM hydrochloride (NIDA Research Technology Branch, Rockville, MD, USA) were dissolved in sterile 0.9% saline and administered i.p. Insulin (protamine zinc recombinant human insulin; Boehringer Ingelheim Vetmedica, Inc., St. Joseph, MO) was dissolved in sterile 0.9% saline and injected i.p. All injection volumes were 1 ml/kg body weight.