High-Pressured Liquid Chromatography Results. Monoamine concentrations in the striatum, nucleus accumbens, and medial prefrontal cortex tissues in rats euthanized 20 min after the last of seven daily injections of saline, 5 mg/kg cocaine, 1 mg/kg MDPV, or 1 mg/kg MDPV + 5 mg/kg cocaine. Tissue concentrations are expressed as ng/mg wet tissue weight.