Regulation of serotonin in depression: Efficacy of ayurvedic plants

Abstract

Depression is an etiologically heterogeneous group of chronic psychiatric illnesses associated with significant morbidity, mortality, and disability. Among the several theories behind the pathophysiological basis of depression, imbalances of the monoamine neurotransmitters (monoamine hypothesis), especially serotonin, have been the most extensively investigated. Several antidepressant drugs targeting the serotonin system have been developed (e.g., selective serotonin reuptake inhibitors) with the intended physiological effect to enhance serotonin signaling at the synapse. Although these drugs represent popular and effective treatments for depression, they are also associated with side effects and limitations in their efficacy. Herbal remedies, often employed as part of traditional systems of medicine and generally associated with favorable safety profiles, have the potential to provide effective alternatives to currently employed modern synthetic antidepressants. Ayurveda is one of the oldest systems of medicine in the world and has been practiced for centuries in India. Ayurveda has described the use of several medicinal plants to prevent, treat, and manage numerous diseases. The following chapter discusses a selection of ayurveda medicinal plants with serotonergic properties that are currently used or have the potential to be developed as antidepressants. The plants discussed here include Areca catechu, Withania somnifera, Bacopa monnieri, Berberis aristata, Tinospora cordifolia, Curcuma longa, Nyctanthes arbor-tristis, Zingiber officinale, and Ocimum sanctum. To date, the major scientific evidence signifying the antidepressant properties of these plants comes from animal depression models such as the forced-swim and tail suspension tests coupled with biochemical and/or pharmacological studies, demonstrating that these plants modulate the serotonin system in the brain. Moving forward, standardization of drug products derived from these plants coupled with well-designed clinical studies and further investigations into the molecular mechanisms behind their serotonergic properties will be important to realize their potential to alleviate the global burden of depressive disorders. © 2017 by Taylor & Francis Group, LLC.