Psychic trauma causes increased impulsivity in a model of gambling addiction by altering dopamine and serotonin metabolism in the prefrontal cortex

BACKGROUND: Gambling addiction (gambling) involves frequently repeated episodes of gambling that are detrimental to social, professional, material, and family values. Gambling addiction is often combined with posttraumatic stress disorder.

AIM: This study aimed to examine the effect of predator presentation stress on the manifestations of gambling addiction in an animal model in a test of probability and magnitude of reinforcement in the Iowa gambling task and monoamine metabolism in the prefrontal cortex of rats.

MATERIALS AND METHODS: Rats were trained in a test of probability and magnitude of reinforcement in the Iowa gambling task in a 3-beam maze. Each run in arm 1 of the maze was reinforced with one sunflower seed, each second run in arm 2 with two seeds, and each third run in arm 3 with three seeds. Correspondingly, half of the runs in arm 2 and 2/3 of the runs in arm 3 were left unreinforced. After training, the animals were placed in a terrarium with a tiger python, one of which was victimized for its food requirements. On day 14 after predator presentation, dopamine and serotonin metabolism in the prefrontal cortex was determined using high-performance liquid chromatography with electrochemical detection.

RESULTS: The levels of the dopamine metabolite dioxyphenylacetic acid and the ratio of dioxyphenylacetic acid to dopamine in the prefrontal cortex decreased. The levels of serotonin, its metabolite 5-hydroxyindoleacetic acid, and the ratio of 5-hydroxyindoleacetic acid to serotonin in the prefrontal cortex were also decreased in rats after exposure to a predator. Moreover, predator presentation induced significant behavioral changes in rats, increasing impulsivity in making choices in a test of probability and magnitude of reinforcement in the Iowa gambling task. The acute vital stress of predator presentation increased the number of escapes to arm 3 of the maze, suggesting that the animals exhibited more risky behavior when choosing reinforcements of different strengths and probability.

CONCLUSIONS: The animal model showed that the depletion of the dopaminergic and serotoninergic systems of the prefrontal cortex underlies pathological gambling addiction and inadequate decision-making caused by posttraumatic stress disorder.