Experimental animal modeling of depression and anxiety

Experimental animal models have been introduced to study aspects of psychiatric symptoms of depression and anxiety; however, there is no comprehensive animal model for these conditions. The models introduced may simulate certain symptoms (despair), be used to evaluate behavioral theories (cognitive theory of learned helplessness), allow study of underlying neurochemical mechanisms (CSF metabolites, genetic, neurotransmitter model), be used to evaluate developmental issues, and lead to finding new treatments through preclinical pharmacologic trials. A variety of models are needed, as each one attempts to deal with a particular aspect of a syndrome. Pharmacologic models, the model of uncontrollability, separation models, and genetic approaches have been summarized. Depression is viewed as a complex, multifactorial illness. Anxiety models have focused on pharmacologic treatment of motivational conflict and the elicitation of fear and panic through environmental and drug manipulations. The most recent investigations in this area address separation calls and alarm calls in primates as potential models for separation distress and panic symptomatology, arguing that the behavioral context as well as the specific behavior be considered. Animal models have emphasized adult psychopathology in the past. However, with increased recognition of psychiatric disorders in children and adolescents, animal modeling of disorders that begin in the development period assumes importance. Studies in the animal modeling of depression and anxiety involving genetic models, psychosocial models, and stress-induction models are the focus of continuing investigations and may be pertinent to child and adolescent psychopathology. They offer hope for learning more about the neurobiologic mechanisms involved in these conditions and for testing new treatment approaches.