Uridine's rise and fall: Food for thought

Physiology The nucleoside uridine is well known for its role in critical cellular functions such as nucleic acid synthesis. Its role in whole-animal physiology has received comparatively little attention. In mammals, plasma uridine levels are tightly regulated, but the underlying mechanisms are unclear. Studying mouse models, Deng et al. show that plasma uridine levels are controlled by feeding behavior (see the Perspective by Jastroch and Tschop). Fasting causes an adipocyte-mediated rise in plasma uridine, which triggers a lowering of body temperature. Feeding causes a bile-mediated drop in plasma uridine, which enhances insulin sensitivity in a leptin-dependent manner. Thus, uridine is part of a complex regulatory loop that affects energy balance and potentially contributes to metabolic disease. Science , this issue p. [eaaf5375][1]; see also p. [1124][2] [1]: /lookup/doi/10.1126/science.aaf5375 [2]: /lookup/doi/10.1126/science.aan0825