title: A two-injection protocol for nicotine sensitization.
abstract: Sensitization to the locomotor activating effect of drugs of abuse occurs following repeated exposure to a drug, and/or when limited exposure to a drug is paired with a specific environment. Conditioned, or context-dependent, sensitization has been well-characterized using limited exposure protocols in, for example, cocaine- and amphetamine-treated animals. However, little data exists regarding limited exposure protocols for other drugs of abuse, such as nicotine. The current experiment investigated whether a two-injection protocol of nicotine administration would result in locomotor sensitization. Mice administered two injections of nicotine (0.175mg/kg, s.c.) 7d apart demonstrated significant locomotor sensitization in response to the second exposure. Furthermore, the development of this sensitization was blocked by the administration of the nicotinic acetylcholine receptor antagonist mecamylamine (2mg/kg) prior to the first nicotine exposure. In a follow-up study, we found that this two-injection nicotine sensitization was independent of context, as separate groups of mice given an initial nicotine exposure (0.175mg/kg, s.c.) in either the specific environment in which locomotor activity was tested or in their home cages demonstrated equivalent levels of locomotor activity during subsequent testing 7d later. These data suggest a novel approach to nicotine sensitization using limited nicotine exposure.
authors.affiliation: Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, J5, 68159 Mannheim, Germany. Electronic address: rick.bernardi@zi-mannheim.de.
authors.forename: Rick E
authors.initials: RE
authors.lastname: Bernardi
authors.affiliation: Institute of Psychopharmacology, Central Institute of Mental Health, Medical Faculty Mannheim/Heidelberg University, J5, 68159 Mannheim, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Spanagel
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D004305:Dose-Response Relationship, Drug; D008297:Male; D008464:Mecamylamine / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D009043:Motor Activity / Q000187:drug effects*; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D018733:Nicotinic Antagonists / Q000494:pharmacology; D013997:Time Factors
chemical_list: D018722:Nicotinic Agonists; D018733:Nicotinic Antagonists; D008464:Mecamylamine; D009538:Nicotine
keywords: Context; Locomotor activity; Locomotor sensitization; Nicotine