Editorial: Using Stress-Based Animal Models to Understand the Mechanisms Underlying Psychiatric and Somatic Disorders

Chronic or repeated stress, particularly psychosocial stress, is an acknowledged risk factor for numerous affective and somatic disorders in modern societies. Thus, there is substantial evidence showing that chronic stress can increase the likelihood of major depressive disorder and anxiety disorders, as well as cardiovascular diseases, irritable bowel syndrome and pain syndromes, to name but a few, in vulnerable individuals. Although a number of pharmacological agents are available to treat such stress-related disorders, many patients do not respond to them, and those who do often report a number of side effects. Consequently, a major emphasis in modern basic research is to uncover the underlying etiology of these disorders and to develop novel efficacious treatment strategies. Animal models can be utilized to unravel the biological mechanisms underlying specific disorders and test the efficacy of novel drugs. While animal models cannot mimic psychiatric and somatic disorders in their entirety, assessing the impact of certain risk factors for the disorders will facilitate the understanding of their etiology and treatment options. Consistent with this knowledge, and with clinical evidence purporting chronic stress to be a risk factor for such diseases, recent attempts have focused on the development of adequate stress paradigms. It is believed that psychosocial stress paradigms are more relevant to the human situation than non-social stress paradigms, because the vast majority of stressors reported by patients suffering from psychiatric or somatic disorders are social in nature. Therefore, there is a growing consensus that social stress paradigms are better placed to reveal the behavioral, neuroen-docrine, or immunological mechanisms underlying chronic stress-induced pathology. However, in order to maximize our understanding of the mechanisms underlying stress-related disorders, various different models are necessary, including models employing physical (i.e., footshock) or pharmacological (e.g., corticosterone) stressors. Moreover, there is accumulating evidence suggesting that stress-induced gut dysbiosis and systemic low-grade inflammation play a causal role in the development of stress-associated somatic and affective disorders. Therefore, chronic/repeated stress models that result in reduced gut microbial diversity and/or promote chronic immune activation are of special relevance and importance. In this research topic, we have collated novel research articles (four) and comprehensive review articles (five) from various leaders in the field of stress-based research. The overarching goal of the topic is to reveal how chronic/repeated stress models can help us to better understand the etiology of psychiatric and somatic disorders.