Lateralized effects of ethanol on aggression and serotonergic systems in Anolis carolinensis

The lateralized effects of ethanol (ETOH) upon behavior and monoamine biochemistry in the lizard, Anolis carolinensis, were examined. Eight adult male anoles consumed solutions of 19% ethanol (ETOH) twice daily over the course of 18 days, while controls consumed water. ETOH decreased the use of the left eye/right hemisphere, but not the right eye/left hemisphere, during territorial aggression (p<0.05). During crossover (i.e., ETOH to water and vice versa) this effect was reversible and replicable. Biochemically, an asymmetry was observed in 5-HT levels in the raphe both in ETOH and controls. ETOH increased levels of serotonin (5-HT; p<0.05), and 5-HIAA/5-HT ratios (p<0.05) in the raphe; serotonin levels in several brain regions correlated with aggressive responses. These results suggest that ETOH boosts 5-HT levels in animals subchronically exposed to ETOH. They further suggest that asymmetry in endogenous 5-HT systems may account for the asymmetrical regulation of aggression generally, and may explain the behavioral effects of ETOH upon lateralized aggression.