Stress alleviating plant-derived ‘green odors’: behavioral, neurochemical and neuroendocrine perspectives in laboratory animals

Exposure to physical or psychological stimuli perceived to be threatening activates the hypothalamic–pituitary–adrenal (HPA) axis and the sympathetic nervous system (SNS) resulting in a classical stress response. Prolonged activation of the HPA and SNS is associated with many adverse physiological changes, most notable the development of anxiety and depression. Recently, a number of plant-derived aliphatic alcohols and aldehydes, termed ‘green odors,’ have demonstrated stress-alleviating properties. This novel method of stress-alleviation has been shown using a number of different animal and stress models utilizing numerous experimental techniques. The object of this review is to present a balanced and critical overview of the present literature on the mammalian effects of exposure to these odors. These findings will be discussed in terms of ongoing trends in the field and possible experimental outcomes will be suggested.