Reinstatement of Drug-seeking in Mice Using the Conditioned Place Preference Paradigm

Summary

This protocol describes the Conditioned Place Preference (CPP) as a model of relapse. This procedure permits the measurement of relapse in laboratory animals, considering the impact of drug-associated environmental cues as craving and relapse in abstaining addicts is currently the focus of drug-abuse treatment programs.

Abstract

The present protocol describes the Conditioned Place Preference (CPP) as a model of relapse in drug addiction. In this model, animals are first trained to acquire a conditioned place preference in a drug-paired compartment, and after the post-conditioning test, they perform several sessions to extinguish the established preference. The CPP permits the evaluation of the conditioned rewarding effects of drugs related to environmental cues. Then, the extinguished CPP can be robustly reinstated by the non-contingent administration of a priming dose of the drug, and by exposure to stressful stimuli. Both methods will be explained here. When the animal reinitiates the behavioral response, a reinstatement of the conditioned reward is considered to have taken place.

The main advantages of this protocol are that it is non-invasive, inexpensive, and simple with good validity criteria. In addition, it allows the study of different environmental manipulations, such as stress or diet, which can modulate relapse into drug seeking behaviors. However, one limitation is that if the researcher aims to explore the motivation and primary reinforcing effects of the drug, it should be complemented with self-administration procedures, as they involve operant responses of animals.

Introduction

The Conditioned Place Preference (CPP) paradigm offers a simple way of assessing the conditioned reward induced by diverse stimuli^1,2, and has been used broadly to study the conditioned rewarding effects of addictive drugs³. It is based on Pavlovian conditioning, evaluating the motivational value of drug-associated environmental cues for maintaining addictive behavior⁴. In this model, environmental cues acquire secondary appetitive properties (conditioned rewarding effects) when paired with a primary reinforcer³. For example, an initially ....

Protocol

All procedures involving mice and their care complied with national, regional, and local laws and regulations, which are in accordance with Directive 2010/63/EU of the European Parliament and the council of September 22, 2010 on the protection of animals used for scientific purposes. The Animal Use and Care Committee of the University of Valencia approved the present protocol.

1. Materials and Set-up for Conditioned Place Preference:

1. Handle mice 3 days prior to testing for 1 - 2 min each. The base of the tail should be grasped. The body should be supported if possible. This is done to minimize pain and distress when ha....

Results

Firstly, representative results from the priming- and stress-induced reinstatement are shown in Figure 7 using adult OF1 male mice.

The data in Figure 7a-b representing time spent in the drug-paired compartment(s) in the Pre- and Post-C test were analyzed with a repeated measures ANOVA with a within-subjects variable Days (comparing Pre-C and Post-C). T.......

Discussion

The key point of drug addiction research is the development of treatments that diminish craving and, consequently, reduce the vulnerability to relapse. Thanks to the reinstatement model of the CPP paradigm, it is possible to study the influence of different procedural and environmental factors that modulate relapse, which is a priority of future research. There are some important points to consider, as the CPP paradigm is a test that is highly sensitive to environmental factors.

Modifi.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
MONPRE 2Z software	CIBERTEC S.A., Spain	N/A
Identical Plexiglas boxes with two equal sized compartments separated by a grey central area.	CIBERTEC S.A., Spain	N/A	The compartments have different colored walls (black vs white) and distinct floor textures (fine grid in the black compartment and wide grid in the white one). All boxes are equipped with four infrared light beams in each compartment of the box and six in the central area which allow the recording of the position of the animal and its crossings from one compartment to the other.
Cocaine hydrochloride	Laboratorios Alcaliber S.A., Madrid, Spain	N/A
Animals: mice of the OF1 outbred strain	Charles River, Barcelona Spain	N/A	Male mice who arrive to the laboratory on PND 42 and on PND 60 perform the CPP test. These animals are specially indicated for social defeat and aggression models.
Standard Diet- Teklad Global Diet 2014	Supplied by Harlan Laboratories Models, S. L. (Barcelona, Spain)		13 kcal % fat, 67 kcal % carbohydrates and 20% kcal protein; 2.9 kcal/g
High fat diet TD.06415			45 kcal % fat, 36 kcal % carbohydrates and 19% kcal protein; 4.6 kcal/g