title: Intravenous self-administration of heroin, cocaine, and the combination in Balb/c mice.
abstract: Polydrug abuse, including the abuse of cocaine + heroin combinations (or 'speedballs') is an increasingly significant problem. The use of genetically defined populations of mice has the potential to add considerably to the study of polydrug abuse. Balb/cByJ (Balb/c) mice have been shown to self-administer opiates, but not cocaine, therefore these mice were chosen for the initial characterization of intravenous self-administration of cocaine + heroin combinations. Mice were implanted with chronic indwelling jugular catheters and given the opportunity to self-administer heroin, cocaine or heroin + cocaine combinations. Heroin was self-administered, while, under the same conditions, none of the mice tested acquired cocaine self-administration. However, heroin + cocaine combinations were self-administered in naive mice as well as in mice that had failed to self-administer cocaine alone. The heroin + cocaine combination dose-effect curve resembled the heroin dose-effect curve. It is hypothesized that heroin may interact with effects of cocaine that function to limit self-administration in Balb/c mice, facilitating the acquisition and maintenance of self-administration of cocaine + heroin combinations.
authors.affiliation: Department of Neuropharmacology, The Scripps Research Institute, La Jolla, CA 92037, USA. aroberts@pluto.scripps.edu
authors.forename: A J
authors.initials: AJ
authors.lastname: Roberts
authors.forename: I Y
authors.initials: IY
authors.lastname: Polis
authors.forename: L H
authors.initials: LH
authors.lastname: Gold
mesh_terms: D000818:Animals; D002405:Catheterization, Central Venous; D003042:Cocaine / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D003932:Heroin / Q000008:administration & dosage*; D007275:Injections, Intravenous; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009294:Narcotics / Q000008:administration & dosage*; D012646:Self Administration; D015819:Substance Abuse, Intravenous
chemical_list: D004338:Drug Combinations; D009294:Narcotics; D003932:Heroin; D003042:Cocaine