There is a seemingly endless list of compounds used by humans that may have psychoactive reinforcing properties underlying their repeated use; many have never been adequately studied. In a 2019 paper, the potential reinforcing properties of cotinine, a major nicotine metabolite, were investigated for the first time. To pursue this line of inquiry, cotinine was assessed using the planarian as an animal model in environmental place conditioning (EPC) also known as conditioned place preference (CPP). In this 2019 study, planarians demonstrated that the compound cotinine, which is present in tobacco smoke, and is also the principal nicotine metabolite, establishes a conditioned place preference. These data represent the first ever demonstration that cotinine will establish a conditioned place preference in planarians and possibly contribute to the addictive properties of nicotine. In the present paper, arguments will be made for the merits of the use of the planarian as a useful experimental animal and in addition, a review of the utility of the conditioned place preference to assess psychoactive effects of drugs of abuse.

Conditioned place preference, Environmental place conditioning, Planarians, Cotinine, Psychoactive effects, Incentive salience