Chronic stress and energy homoeostasis

major factor negatively influencing a balanced lifestyle which is crucial to maintain a healthy aging process. While acute stress can be beneficial for dealing with unexpected situations, prolonged stress has been shown to have adverse consequences on many organ systems as well as negative impacts on behavioural and physiological responses including feeding behaviour and energy homeostasis. In humans, stress affects individuals differently with regards to feeding; some decrease food intake and lose weight during or after stress, while most others increase their food intake during stress. Importantly, however, independent of hypoor hyperphagia, people often report that they prefer highly palatable food during periods of prolonged stress, rich in both sugar and fat, which significantly contributes to the development of obesity. Similarly, when rodents have a choice of highly palatable diet, stress also increases the intake of such calorie dense foods [1]. Despite these well documented observations in both humans and animals the underlying neuronal pathways that are responsible for controlling this behaviour are still unclear. Central control of energy homeostasis is known to be orchestrated by a complex neuronal network with neuropeptide Y (NPY)-ergic pathways being one of the most prominent. NPY is a 36-amino acid neuropeptide that is highly expressed in the arcuate nucleus of the hypothalamus (Arc), a brain region critical in the regulation of energy homeostasis. However, recent study also points to an important role of NPY in aging and lifespan determination, with lack of NPY in mice leading to loss of the beneficial effects under calorie restriction which would otherwise confer on lifespan extension [2]. Negative energy balance leads to an increase in Arc-NPY level, which activates energyconservation pathways, accompanied by hyperphagia and reduction in energy expenditure, allowing the reestablishment of energy balance. Apart from the Arc, NPY-expressing neurons are also found at a considerably high level in the medial nuclei of the central amygdala (CeA), a region known to be critical in controlling anxiety and stress related behaviours [3]. However, the involvement of CeA activity in the control of energy homeostasis had not been explored. In a recent study we have now demonstrated that CeANPY neurons play a pivotal role in the regulation of Editorial