[Serotonin in genetically determined types of defensive behavior].

A review of the data concerning the role of 5-hydroxytriptamine (5HT) in genetically defined defensive behavior. 5HT-ergic system of the brain is involved in the expression of the genetic predisposition of rodents to defensive behavior--both aggression and freezing. The results suggest that the density of 5HT1A receptors in the frontal cortex is related to the expression of aggressive behavior of both types, while functional state of the brain 5HT system is involved in mechanisms determining the strategy of choice of type of defensive behavior--freezing or aggression.