Effects of predator scent stress on acquisition of methamphetamine conditioned place preference in adult male rats.

Although methamphetamine addiction and fatality rates are on the rise in the United States, there are currently no FDA approved drugs to treat methamphetamine use disorder (MUD). To better understand factors contributing to addiction, researchers have used various rodent models of stress including footshock, social defeat and maternal separation, however, these models involve physical or early life stress exposure and thus are less translatable to model human psychological stress. The present study implemented predatory odors as a model of psychological stress and examined whether ten days of chronic exposure to coyote urine or 2-phenylethylamine (PEA) enhanced subsequent reward to a subthreshold dose of methamphetamine. Results from the current study suggest that coyote urine, but not PEA, can enhance vulnerability to drug reward/motivation in the conditioned place preference model, as shown by increased drug-seeking behavior in animals conditioned with a subthreshold dose of methamphetamine. Specifically, methamphetamine conditioned animals previously exposed to coyote urine acquired methamphetamine CPP and displayed persistent drug-seeking behavior during the extinction trials, effects not seen in stress controls or PEA exposed rats. In conclusion, coyote urine may serve as a mild psychological stressor to alter motivation for subthreshold doses of methamphetamine and potentially other drugs associated with addiction.