Self-Administration of Drugs in Mouse Models of Feeding and Obesity

Preclinical studies in mice often rely on invasive protocols, such as injections or oral gavage, to deliver drugs. These stressful routes of administration have significant effects on important metabolic parameters including food intake and body weight. Although an attractive option to circumvent this is to compound the drug in rodent food or dissolve it in water, these approaches also have limitations as they are affected by drug stability at room temperature for extended periods of time, the drug's solubility in water, and that the dosing is highly dependent on timing of food or water intake. The constant availability of the drug also limits translational relevance on how drugs are administered to patients. To overcome these limitations, drugs can be mixed with highly palatable food, such as peanut butter, allowing mice to self-administer compounds. Mice reliably and reproducibly consume the drug/peanut butter pellet in a short time frame. This approach facilitates a delivery approach with minimal stress compared with an injection or gavage. This protocol demonstrates the approach of drug preparation, animal acclimatization to placebo delivery, and drug delivery. The implications of this approach are discussed in studies related to timing of drug administration and the circadian rhythm.