Genes for sex hormone receptors controlling mouse aggression

The stereotypies of mouse social behaviours have encouraged their systematic analysis in this genetically tractable animal. Following experiments with genes for nuclear receptors and other neuroendocrine genes, we can state seven 'lessons' of gene/behaviour causal relations bearing on sociosexual and aggressive behaviours. The effect of a given gene on a given behaviour depends upon: (1) exactly when and where that gene is expressed in the brain; (2) the gender of the animal in which it is expressed; (3) the age of the animal; (4) the nature of the opponent; and (5) the form of aggression (e.g. testosterone-facilitated aggression vs. maternal aggression). (6) Better social recognition is correlated with lower levels of aggression. We have gathered evidence for a four-gene micronet involving oestrogen receptors alpha and beta, oxytocin, and the oxytocin receptor as expressed in the hypothalamus and amygdala. (7) Some genetic influences on aggression derive from their effects on fundamental, generalized arousal of the mammalian brain, which underlies the expression of any emotional behaviour.