The Conditioned Place Preference (CPP) test is a widely used method in behavioral neuroscience to study reward and addiction. It is based on the principles of Pavlovian conditioning, where an animal associates a particular environment with a rewarding stimulus. In the CPP test, animals are placed in a chamber divided into two distinct compartments, each with different sensory cues. One compartment is associated with a rewarding stimulus, such as drugs or food, while the other compartment is not. Over time, animals learn to prefer the compartment associated with the reward, demonstrating their ability to form an association between the environment and the rewarding experience. This test allows researchers to investigate the neural mechanisms underlying reward processing and addiction-related behaviors.

Customizable Features of Conditioned Place Preference (CPP) Chamber

Customizable features of the conditioned place preference chamber can vary depending on the research question and experimental design. Our team can adapt the chamber to your research study depending on the effects of different drugs and stimuli. Here are some common modifications:

Physical Features

• Size and shape of the chamber
• Type of flooring (e.g., grid, mesh, solid, or perforated)
• Lighting conditions
• Soundproofing

Stimulus, Control, and Test Article Administration for CPP Test

• Experimental Groups (e.g., saline or vehicle)
• Stimulus Type (Alcohol, Drugs, Food, etc.)
• Method of drug administration (e.g., injection, oral, or vapor)

Conditioning

• Type of conditioning stimulus (e.g., light, sound, or odor)
• Number of conditioning sessions
• Duration of conditioning sessions
• Time between conditioning sessions

Protocol for Conditioned Place Preference (CPP) Experiment

Conditioned Place Preference (CPP) is a classical conditioning paradigm used to measure the rewarding or aversive effects of a stimulus. This protocol outlines the steps involved in conducting a CPP experiment. By following this protocol, researchers can effectively measure the rewarding or aversive effects of a stimulus and gain insights into the underlying mechanisms of the conditioned place preference phenomenon.

Materials

Item	Purpose	Manufacturer	Catalog
Conditioned Place Preference Chamber	Experimental	Anilocus	SKU: 16752
Animals	Test subjects	Varies	N/A
Stimulus	Reward or Aversion; depends on Experimental Design	Varies	Varies
4K Webcam: Studio-Quality Webcam	Behavior Recording	Lumina	B09T749G1S
Panlab SMART video tracking system	Automated Video Behavior Tracking Software	Harvard Apparatus	V3.0
Fisherbrand™ Timer	Timekeeping	Fisher Scientific	02-261-840
Zep RTU Peroxide Disinfectant & Cleaner	Cleaning Solution	Zep	ZUPRXDC128

Experimental Design

1. Randomly assign animals to two groups: Control and Experimental.
2. Counterbalance the conditioning chamber assignments to ensure equal exposure to each chamber.
3. Pre-test the animals to determine their baseline preference for each chamber.

Habituation

1. Place each mouse individually in the neutral chamber for a specified time (e.g., 10 minutes) for habituation.
2. Repeat this process for a few consecutive days to ensure mice are accustomed to the testing environment.

Acquisition Phase

1. Assign one conditioning chamber (e.g., Chamber A) as the “paired” chamber and the other (e.g., Chamber B) as the “unpaired” chamber.
2. Divide animals into two groups: drug-paired and saline-paired.
3. On alternating days, place the mice in one of the conditioning chambers and administer the drug (e.g., methamphetamine) in the drug-paired chamber and saline in the saline-paired chamber.
4. Assign an equal number of mice to each chamber pairing.
5. Place the animal in the assigned chamber for a specified duration (e.g., 30 minutes) and administer the stimulus. Ensure equal exposure to drug and saline.
6. Repeat the conditioning session for multiple days, with a fixed number of trials each day.

Expression Phase

1. After the conditioning phase, conduct the expression (preference) tests to measure the conditioned preference.
2. Allow the animals to explore both chambers freely for a specified duration (e.g., 15 minutes) without any stimulus or intervention.
3. Monitor and record the time spent by each animal in each chamber during the expression test.
4. Repeat the expression test for multiple days, maintaining the same duration each day.

Extinction Phase

1. Starting the day after the expression phase, remove the drug and saline from the respective chambers.
2. Repeat the preference test daily, like the expression phase, but without administering any drug or saline.
3. Continue this for a specified period (e.g., 5-7 days) or until the mice no longer show a preference for either chamber.

Reinstatement Phase

1. After the extinction phase, reinstate the drug effect by re-administering methamphetamine in the drug-paired chamber.
2. Conduct another preference test to assess if the mice show a reinstatement of drug preference.
3. Record and analyze the time spent by each mouse in both chambers.

Data Analysis

1. Calculate the time spent in each chamber during the expression test.
2. Compute the difference in the time spent in the paired chamber and unpaired chamber (CPP score).
3. Analyze the data using appropriate statistical tests (e.g., t-test, ANOVA) to determine the significance of the CPP score.
4. Interpret the results and draw conclusions based on the experimental objectives.

Ethical Considerations

1. Minimize stress and discomfort to the animals during the experiment.
2. Obtain necessary approvals and permissions from relevant ethics committees.
3. Ensure that the experiment adheres to ethical guidelines and regulations for animal research. If your team needs guidance with this study for an outlined IACUC-approved protocol, please contact us for more information.

References

1. Prus AJ, James JR, Rosecrans JA. Conditioned Place Preference. In: Buccafusco JJ, editor. Methods of Behavior Analysis in Neuroscience. 2nd edition. Boca Raton (FL): CRC Press/Taylor & Francis; 2009. Chapter 4.
2. Michael T. Bardo, David B. Horton, Justin R. Yates. Chapter 7 – Conditioned Place Preference as a Preclinical Model for Screening Pharmacotherapies for Drug Abuse. Editor(s): Carrie G. Markgraf, Thomas J. Hudzik, David R. Compton. Nonclinical Assessment of Abuse Potential for New Pharmaceuticals. Academic Press. 2015. Pages 151-196. ISBN: 9780124201729. https://doi.org/10.1016/B978-0-12-420172-9.00007-2.
3. Sun, Y., Chen, G., Zhou, K., Zhu, Y. A Conditioned Place Preference Protocol for Measuring Incubation of Craving in Rats. J. Vis. Exp. (141), e58384, doi:10.3791/58384 (2018).