Benzodiazepine and serotonergic modulation of antipredator and conspecific defense

The mammalian defense repertory comprises an array of individual behaviors that are extraordinarily sensitive to relevant features of the threat stimulus and the situation in which it occurs. In parallel with increasing awareness of the specificity and complexity of defensive behaviors and of their potential relevance to psychopathologies (e.g. anxiety, panic, and depression) is an escalating use of natural threat stimuli such as attacking conspecifics or predators in paradigms aimed at evaluating drug effects on defense. A review of the literature on benzodiazepine (BZ) and serotonin (5-HT) effects on conspecific and antipredator defense, including defensive analgesia, indicates that both types of stimuli elicit a wide array of relevant defensive behaviors. These studies suggest specificity of drug effects on particular behaviors, rather than a general alteration of all aspects of defense. However, stimulus variability and possible confounding of effects are a considerable problem with conspecific defense paradigms, while antipredator paradigms utilizing human experimenters as the predator may be difficult to use with the domesticated laboratory animal subjects. In addition, sensitivity to the organization of defensive behaviors and to differences between species in defense patterns is necessary to adequate interpretation of results. Nonetheless, these paradigms have permitted major advancements in analysis of the behavioral defense systems and their sensitive use in drug studies will greatly facilitate an understanding of the physiology of defense.