Psychobiogenetics: adapted tools for the study of the coupling between behavioral and neuroendocrine traits of emotional reactivity.

The adaptive response to environmental challenges involves both behavioral and neuroendocrine adjustments. Several examples show that the behavioral and neuroendocrine responses to environmental stimulations, far from being independent, are frequently interrelated and/or coselected. The existence of such a coselection in genetically selected models provides an advantageous tool for the study of genetic influence on emotional reactivity and the mechanism of linkage between behavioral and neuroendocrine traits. In particular, the study of the Roman rat lines which have been selected for their performance in active avoidance behavior has allowed us to establish the respective role of genetic and maturation factors in the reactivity of these animals to stress. Indeed, the role of maturation in determining interindividual differences appears to be more marked in RLA than in RHA rats. The study of genetic factors, which play a major role in shaping individual characteristics of reactivity, may help, therefore, to elucidate the biological mechanisms coupling behavioral and neuroendocrine aspects of personality structure to emotional reactivity.