Under the influence: Effects of adolescent ethanol exposure and anxiety on motivation for uncertain gambling-like cues in male and female rats
Gambling disorder (GD) frequently co-occurs with alcohol use and anxiety disorders, suggesting possible shared mechanisms. Recent research suggests reward uncertainty may powerfully enhance attraction towards reward cues. Here, we examined the effects of adolescent ethanol exposure, anxiety, and reward uncertainty on cue-triggered motivation. Male and female adolescent rats were given free access to ethanol or control jello for 20 days. Following withdrawal, rats underwent autoshaping on a certain (100%-1) or uncertain (50%-1-2-3) reward contingency, followed by single-session conditioned reinforcement and progressive ratio tasks, and 7 days of omission training, during which lever pressing resulted in omission of reward. Finally, anxiety levels were quantified on the elevated plus maze. Here, we found that uncertainty narrowed cue attraction by significantly increasing the ratio of sign-tracking to goal-tracking, particularly amongst control jello and high anxiety animals, but not in animals exposed to ethanol during adolescence. In addition, attentional bias towards the lever cue was more persistent under uncertain conditions following omission training. We also found that females consumed more ethanol, and that uncertainty mitigated the anxiolytic effects of ethanol exposure observed in high ethanol intake animals under certainty conditions. Our results further support that reward uncertainty biases attraction towards reward cues, suggesting also that heightened anxiety may enhance vulnerability to the effects of reward uncertainty. Chronic, elevated alcohol consumption may contribute to heightened anxiety levels, while high anxiety may promote the over-attribution of incentive value to reward cues, highlighting possible mechanisms that may drive concurrent anxiety, heavy drinking, and problematic gambling.