Effect of intermittent access to alcohol mixed in energy drink during adolescence on alcohol self-administration, anxiety, and memory during adulthood in rats

Background Mixing alcohol with caffeinated energy drinks is a common practice among young people. Consumption of alcohol mixed in energy drink is associated with increased risk of binge drinking and alcohol dependence. The purpose of this study was to determine whether voluntary intermittent access to alcohol mixed in energy drink in adolescent rats alters adult self-administration of alcohol, anxiety, and memory. Methods For 10 weeks in the home-cage, two groups of adolescent female Sprague-Dawley rats had intermittent access to energy drink (ED) or 10% alcohol mixed in energy drink (AmED) with water concurrently available. Other rat groups had daily continuous access to ED or AmED. Anxiety was measured with an open field test and memory was assessed with a novel place recognition test. For self-administration, rats pressed levers for 10% alcohol alone on a fixed ratio (FR1) and on a progressive ratio (PR). Results Intermittent access to AmED generated greater intake during the initial 30 min of access (AmED 1.70 +/- 0.04 g/kg vs. ED 1.01 +/- 0.06 g/kg) and during the subsequent 24 h (AmED 7.04 +/- 0.25 g/kg vs. ED 5.60 +/- 0.29 g/kg). Intermittent AmED caused a significant but small decrease in anxiety while neither ED nor AmED altered memory. During alcohol self-administration, group differences emerged only during PR testing during which intermittent AmED rats responded more than all other groups. Conclusions These findings suggest that intermittent access to AmED generates binge-like consumption that supports human findings that AmED generates greater alcohol consumption. Furthermore, experience with AmED may alter the motivational properties of alcohol into adulthood without necessarily causing a major impact on anxiety or memory.