The question on how cells, tissues and organisms are able to detect energy/nutrient availability has been the focus of research for many years. Data gleaned recently have identified different nutrient-sensing circuits implicated in the regulation of different homeostatic process. Furthermore, there has been a steady increase in our knowledge regarding the cellular and molecular mechanisms involved in nutrient detection and integration. In particular, this has allowed for a better understanding of the neural and endocrine circuits involved in nutrient and energy sensing and their adaptation to different metabolic needs in a tissue-specific manner.
Work carry out by different groups have uncovered the mechanism by which hypothalamic neurons sense nutrient bioavailability, with a relevant contribution of AMPK and mTOR among others, as sensors of cellular energy status. Interestingly, the orexigenic/anorexigenci effects of different neuropeptides and peripheral hormones appear to be mediated by an AMPK-driven regulation of hypothalamic lipid metabolism, and may involve also the modulation of mTOR signaling. Their integrative role in terms of energy homeostasis involved different mechanisms including regulation of food intake, energy expenditure or metabolic homeostasis at relevant target tissues. Furthermore recent developments has shown the involvement of central energy sensors in orchestrating the adaptative response of different hypothalamic-pituitary axis to changes in energy availability. This development helps to understand the interplay between peripheral signals and central neurotransmitters and neuropeptides in order to elicit a biological response at the whole organism.