How the gut influences metabolism in response to food
27th November 2018
Researchers at the Institute of Cancer Sciences, University of Glasgow have published a study looking at how the intestine coordinates a multi-organ programme which is essential to achieve a balance between the use and storing of body energy in response to food.
When nutrients such as sugars and fats are absorbed in the gut, any excess nutrients are stored away in the body as energy reserves, for example, in adipose (fat) tissue and the liver. These energy reserves can then be used as backup when food is scarce, and the body has mechanisms for mobilising these backup nutrients. However, in order for the body to use these resources efficiently, it’s important for it to be able to recognise when these reserves should be used and when they shouldn’t.
In this study in fruit flies, published in Cell Metabolism, researchers found that when there is food in the gut, the gut releases a hormone that acts on neurons in the central nervous system (CNS), which in turn tunes down signals to the energy reserve tissues to indicate such reserves are not needed. In contrast, under starvation conditions, the gut does not release this hormone, which then allows the CNS to turn up the activity of these neurons to allow mobilisation of energy reserves.
Therefore, flies lacking the nutrient-sensing hormone released by the gut showed uncontrolled use of energy reserves, and as a result these flies are not able to build up sufficient reserves to allow them to cope with periods of hunger. Interestingly, the human version of one of the proteins involved in this pathway has previously been associated with obesity, through an unknown mechanism.
These findings highlight the long-reaching impact of intestinal function to organismal health and disease. Important implications of this work include intestinal pathologies such as colorectal cancer, as it may explain the origin and mechanisms of metabolic disorders and disruption of multiple CNS-controlled body functions, including sleep and feeding, often observed in cancer patients.
Scopelliti A, Bauer C, Yu Y, Zhang T, Kruspig B, Murphy DJ, Vidal M, Maddocks ODK, Cordero JB. A Neuronal Relay Mediates a Nutrient Responsive Gut/Fat Body Axis Regulating Energy Homeostasis in Adult Drosophila. Cell Metab 2018. doi: 10.1016/j.cmet.2018.09.021