Ethanol Consumption and Place‐Preference Conditioning in the Alcohol‐Preferring C57BL/6 Mouse: Relationship with Motor Activity Patterns

Abstract

Ethanol place-preference conditioning (PC) was conducted in drug-naive and ethanol pre-exposed female and male C57BL/6J (C57) mice to assess whether environmental cues can develop positive incentive value for ethanol-preferring animals when associated with administration of ethanol. After 12 days episodic access to free-choice ethanol and/or water self-administration, mice received eight ethanol injections (1.75 g/kg/i.p.) 5 min before placement in their nonpreferred PC chamber and eight saline injections paired with their preferred chamber. Control mice received eight saline injections (20 ml/kg) in both their preferred and nonpreferred chambers. Mice of both sexes developed strong ethanol PC. Correlational analysis indicated that the strength of ethanol PC for mice with a prior ethanol drinking experience was inversely related to the amount of ethanol consumed regardless of gender. Furthermore, depending on gender and previous ethanol drinking experience, ethanol PC was differentially related to initial baseline motor activity, the initial motor response to ethanol, or rapid change in the motor response to ethanol. Thus, a complicated relationship between neural systems that mediate ethanol reward and motor activity may exist as suggested by current addiction theory.

Endogenous kappa-opioid mediation of stress-induced potentiation of ethanol-conditioned place preference and self-administration

“…However, the present data is consistent with demonstrations of the successful use of the biased placeconditioning design (i.e., place-conditioning subjects with ethanol in the initially non-preferred chamber) to produce ethanol-CPP with C57Bl/6 mice (Kelley et al 1997;Nocjar et al 1999;Middaugh and Bandy 2000). In fact, the ethanol-CPP demonstrated by C57Bl/6J mice after place conditioning in a biased apparatus and subject assignment procedure was thought to possibly suggest "a greater ability to detect a smaller rewarding effect in the biased apparatus" in a recent study (Gremel et al 2006).…”

“…Note that order of place conditioning was not found to significantly affect the final place preference response at any dose of ethanol utilized (comparing grouped post-conditioning preferences of the 0.4, 0.8, and 1.6 g/kg mice conditioned with saline first vs those mice conditioned with ethanol first, F (1,42) =1.50, p = 0.23; one-way ANOVA). A biased ethanol placeconditioning design was then utilized, as it produces ethanol-CPP in C57Bl/6 mice (Nocjar et al 1999;Middaugh and Bandy 2000;Gremel et al 2006). As adapted for use here, on days 2-5 mice were administered 10 ml/kg, i.p., of an ethanol solution (5%, 10%, or 20% (v/v), corresponding to 0.4, 0.8, and 1.6 g/kg ethanol; Kuzman et al 2003;Thanos et al 2005) once daily and immediately confined in their initially non-preferred side for 25 min.…”

Distal and proximal pre-exposure to ethanol in the place conditioning task: tolerance to aversive effect, sensitization to activating effect, but no change in rewarding effect

“…This null outcome is consistent with a previous study in which C57BL/6 mice self-administered ethanol orally during pre-exposure (Nocjar et al 1999). However, that study did not show that the pre-exposure regimen produced tolerance or sensitization to any ethanol effect.…”

Homer2 Is Necessary for EtOH-Induced Neuroplasticity

“…To assess EtOH conditioned reward and locomotor activity, a biased place conditioning apparatus was used in a manner identical to previous reports for Homer1 and Homer2 KO mice (Szumlinski et al, 2004). The procedures to induce EtOH place conditioning were similar to that described for C57BL/6J mice (Nocjar et al, 1999). In brief, place conditioning to EtOH was produced by eight repeated pairings, on alternating days, of intraperitoneal injections of 0, 1, 2, or 3 g/kg EtOH with the nonpreferred compartment and water vehicle (volume of 0.02 ml/g body weight) with the preferred compartment of the place conditioning apparatus.…”

“…EtOH consumption and preference was assessed using a two-bottle choice procedure similar to that described previously for C57BL/6J (B6) mice (Nocjar et al, 1999). Briefly, mice were presented with two identical 50 ml sipper tubes in the home cage for a period of 24 h. One tube contained tap water and the other tube contained increasing concentrations of EtOH (0,3,6,and 12% v/v).…”