Oxytocin attenuates cocaine-associated place preference via the dorsal hippocampus in male and female rats.

Cocaine addiction is the third largest cause of overdose-related deaths in the United States. Research investigating therapeutic targets for cocaine reward processes is key to combating this issue. The neuropeptide oxytocin (OXT) has been shown to reduce cocaine reward processes, though specific mechanisms are not understood. This study examines the effect of intra-dorsal hippocampal (DH) OXT on the expression of cocaine context associations using a conditioned place preference (CPP) paradigm. In this paradigm, one of two visually distinct chambers is paired with a drug. With repeated pairings, control animals display preference for the drug-associated context by spending more time in that context at test. In the present study, four conditioning days took place where male and female rats were injected with either cocaine or saline and placed into the corresponding chamber. On test day, rats received infusions of OXT or saline (VEH) into the DH and were allowed access to both chambers. The results show that while VEH-infused rats displayed cocaine CPP, OXT-infused rats did not prefer the cocaine-paired chamber. These findings implicate the DH as necessary in the mechanism by which OXT acts to block the expression of cocaine-context associations, providing insight into how OXT may exert its therapeutic effect in cocaine reward processes.

Paired Housing or a Socially-Paired Context Decreases Ethanol Conditioned Place Preference in Male Rats.

Alcohol abuse dramatically affects individuals' lives nationwide. The 2020 National Survey on Drug Use and Health (NSDUH) estimated that 10.2% of Americans suffer from alcohol use disorder. Although social support has been shown to aid in general addiction prevention and rehabilitation, the benefits of social support are not entirely understood. The present study sought to compare the benefits of social interaction on the conditioned ethanol approach behavior in rats through a conditioned place preference (CPP) paradigm in which a drug is paired with one of two distinct contexts. In experiment 1A, rats were single-housed and received conditioning trials in which ethanol was paired with the less preferred context. In experiment 1B, rats underwent procedures identical to experiment 1A, but were pair-housed throughout the paradigm. In experiment 1C, rats were single-housed, but concurrently conditioned to a socially-paired context and an ethanol-paired context. By comparing the time spent between the ethanol-paired environment and the saline-paired or socially-paired environment, we extrapolated the extent of ethanol approach behavior in the pair-housed, single-housed, and concurrently conditioned rats. Our results revealed that social interaction, both in pair-housed animals or concurrently socially-conditioned animals, diminished the ethanol approach behavior, which highlights the importance of social support in addiction prevention, treatment, and recovery programs.