BACKGROUND: Abnormal placental angiogenesis is an important cause of fetal intrauterine growth restriction (IUGR), but its underlying mechanisms and therapies remain unclear. Adenosine and its mediated signaling has been reported to be associated with the development of angiogenesis. However, whether the adenosine-related signaling plays a role in modulating angiogenesis in placenta and the IUGR pregnancy outcomes remains unclear. METHODS: The angiogenesis and adenosine signaling expressions in normal and IUGR placentas were detected in different species. And the role of adenosine in regulating IUGR pregnancy outcomes was evaluated using diet-induced IUGR mouse model. Molecular mechanisms underlying adenosine-induced angiogenesis were investigated by in vitro angiogenesis assays and in vivo Matrigel plug assays. RESULTS: Here, we demonstrated poor angiogenesis and low adenosine concentration and downregulated expression of its receptor A2a (ADORA2A [adenosine A2a receptor]) in IUGR placenta. Additionally, the beneficial effects of adenosine in improving IUGR pregnancy outcomes were revealed in a diet-induced IUGR mouse model. Moreover, adenosine was found to effectively improve adenosine signaling and angiogenesis in IUGR mice placenta. Mechanistically, by using angiogenesis assays in vitro and in vivo, adenosine was shown to activate ADORA2A to promote the phosphorylation of Stat3 (signal transducer and activator of transcription 3) and Akt (protein kinase B), resulting in increased Ang (angiogenin)-dependent angiogenesis. CONCLUSIONS: Collectively, this study uncovers an unexpected mechanism of promoting placental angiogenesis by adenosine-ADORA2A signaling and advances the translation of this signaling as a prognostic indicator and therapeutic target in IUGR treatment.

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Background: Dietary nucleotides [inclusion adenosine 5’-monophosphate (AMP)] supplementation was shown to promote the feed intake of sows and increase the AMP content in their milk in our previous work, but whether AMP shapes the energy expenditure and lipid metabolism in mammals remains unknown. Here, we aimed to explore the effects and the related mechanism of dietary AMP supplementation on food intake, body composition, energy expenditure, and lipid metabolism in male mice. Methods: 4-week-old C57BL/6 mice (After a 1-wk adaptation) were fed with basal diet and basal diet supplemented with 0.1% AMP, respectively. Animal food intake and body weight were monitored and after 4 weeks all animals were sacrificed to measure the body composition, energy expenditure and lipid metabolism changes. Results: Compared with the control, the 0.1% AMP fed mice showed higher food intake while lower adipose weight. Intriguingly, dietary AMP supplementation was found to stimulate brown adipose tissue thermogenesis as evidenced by the increase in the uncoupling protein-1 level and the core temperature. Moreover, AMP supplementation was shown to promote white adipose tissue lipolysis as indicated by smaller lipid droplet size in mice. These results demonstrate that dietary AMP supplementation could enhance oxygen consumption and energy expenditure. Conclusions: This study highlights the physiological importance of AMP supplementation in mediating food intake and energy expenditure and suggests its potential as an adjuvant therapy in preventing energy metabolic disorders (mainly obesity and diabetes).