Subsequent behavioural effects of simultaneous adolescent exposure to caffeine and nicotine

Abstract

Both caffeine and nicotine are popular and widely used psychostimulants, with many people increasing their consumption of these substances in adolescence. Anxiety is a common side effect of these drugs, as well as a prevalent emotional state during the adolescent developmental period. Previous literature has examined how the separate use of caffeine and nicotine during adolescence can affect anxiety related behaviours in rats during their early adulthood. However, it is not well understood as to how the simultaneous use of both substances in adolescence can affect anxiety in early adulthood.

To investigate this, 64 rats (32 males and 32 females) were divided evenly across four separate treatment groups during their adolescent period (40-49 postnatal days old) and subjected to either saline, caffeine, nicotine or the caffeine-nicotine drug combination. At both 60 and 90 postnatal days old, the rats were subjected to three separate behavioural tests: the open field test, the novel object recognition task and the light-dark box.

Overall, the combined caffeine-nicotine treatment to have an overall anxiolytic effect on behaviour during early adulthood, whilst the nicotine-alone treatment primarily demonstrated an anxiogenic effect on rat behaviours. The caffeine-alone treatment and saline control demonstrated few treatment effects on behaviour. Sex was also found to moderate treatment effects on behaviour.

Further studies are needed to understand how the simultaneous use of caffeine and nicotine during adolescence affects behaviour in early adulthood.