Stress, Adaptogens and Their Evaluation: An Overview

All organisms are in a state of dynamic equilibrium or homeostasis which is constantly challenged by internal/external aversive stimuli called stressors. Stress occur when such homeostasis is threatened and a set of physiological and behavioral adaptive responses come into play. These coordinated adaptive responses enhance the probability of survival. Such stress responses are mediated by the stress system and is orchestrated by the brain (CNS) in conjunction with peripheral organs. Failure to adapt to stressors results in dysregulation of the stress system and may lead to psychiatric, endocrine/metabolic and/ or autoimmune diseases or increase vulnerability to such diseases [1]. Stress and stress related disorders account for over 70% of the global illnesses. Studies on the pathophysiological aspects of stress has been a subject of research for long and Cannon in 1929 [2] first suggested that any aversive emotional stimulus is capable of causing physical damage to the body and can produce disease states like anxiety and depression, hypertension, immunosuppression, endocrine disorders, diabetes mellitus, peptic ulcer, etc. In 1936, Selye [3] introduced the concept of stress in biology and medicine and defined it as a non-specific response of the body to any environmental demand placed upon it. He described a response triad viz. adrenal hypertrophy, gastrointestinal ulceration, and thymolymphatic involution/atrophy, which should be elicited by any stressor and suggested the HPA axis as the principal regulator of the stress response. He considered the adrenal cortex to be the organ of integration during stress. Selye also introduced the term general adaptation syndrome (GAS) with its three successive phases: the alarm reaction, stage of resistance, and exhaustion stage [3]. First, an initial alarm reaction, analogous to Cannon’s ‘fight or flight’ response, second, a stage of adaptation associated with resistance to the stressor, and eventually a stage of exhaustion and organism’s death. However, his idea of non-specificity of stress response was replaced by one of specificity and accordingly the concept of stress was altered. Stress and stress research has evolved considerably over the years and it is now increasingly being recognized as a highly interactive phenomenon and terms like stress syndrome, stress system and allostasis have emerged. Allostasis is the process of adaptation of the body upon the exposure Abstract