Neugebauer NM, Harrod SB, Stairs DJ, Crooks PA, Dwoskin LP, Bardo MT. Lobelane decreases methamphetamine self-administration in rats.
Eur J Pharmacol 2007;
571:33-8. [PMID:
17612524 PMCID:
PMC2104779 DOI:
10.1016/j.ejphar.2007.06.003]
[Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Revised: 05/29/2007] [Accepted: 06/04/2007] [Indexed: 10/23/2022]
Abstract
Lobelane, a minor alkaloid of Lobelia inflata and a synthetic, des-oxy analog of lobeline, has good affinity for the vesicular monoamine transporter and the dopamine transporter. The current study examined the ability of lobelane to specifically decrease methamphetamine self-administration. Rats were trained on a fixed ratio 5 schedule of reinforcement to self-administer methamphetamine (0.05 mg/kg/infusion, i.v.) or to respond for sucrose pellets. Upon reaching stable responding, rats were pretreated with lobelane (0.1, 1, 3, 5.6, or 10 mg/kg, s.c.) or saline, 15 min prior to the operant session. To assess the effect of repeated lobelane on methamphetamine self-administration, rats were pretreated with lobelane (5.6 or 10 mg/kg, s.c.) for 7 sessions. Behavioral specificity was further investigated by assessing the effects of lobelane (0.1, 1, 3, 5, or 10 mg/kg, s.c.) or saline on locomotor activity. Within the dose range tested, lobelane dose-dependently decreased methamphetamine self-administration, while having no effect on sucrose-maintained responding. Locomotor activity was decreased following only the highest dose of lobelane (10 mg/kg). Across repeated pretreatments, tolerance developed to the effect of lobelane on methamphetamine self-administration, demonstrating that the ability of lobelane to specifically decrease methamphetamine self-administration is a transient effect. Thus, taken together, the results show that although lobelane interacts with the pharmacological targets believed to be responsible for its ability to decrease methamphetamine self-administration, removal of the oxygen functionalities from the lobeline molecule may have afforded a compound with an altered pharmacokinetic and/or pharmacodynamic profile.
Collapse