Abstract
Recent investigations in neurogenomics have opened up new lines of research into a crucial genetic problemβthe pathway from genes to behavior. This paper concentrates on the involvement of protein elements in the brain neurotransmitter serotonin (5βHT) system in the genetic control of aggressive behavior. Specifically, it describes: (1) the effect of the knockout of MAO A, the principal enzyme in 5βHT degradation, (2) the association of intermale aggression with the polymorphism in the Tph2 gene encoding the key enzyme in 5βHT synthesis in the brain, tryptophan hydroxylase (TPH), and (3) the effect of selective breeding for nonaggressive behavior on 5βHT metabolism, TPH activity and 5βHT~1A~ receptors in the brain. The review provides converging lines of evidence that: (1) brain 5βHT contributes to a critical mechanism underlying genetically defined individual differences in aggressiveness, and (2) genes encoding pivotal enzymes in 5βHT metabolism (TPH and MAO A), 5βHTβtransporter, 5βHT~1A~ and 5βHT~1B~ receptors belong to a group of genes that modulate aggressive behavior. BioEssays 28: 495β503, 2006. Β© 2006 Wiley Periodicals, Inc.