Short-Term Oral UMP/UR Administration Regulates Lipid Metabolism in Early-Weaned Piglets

As a main ingredient of milk, the nucleotides content is about 12&#8722;58 mg/g, which plays a critical role in maintaining cellular function and lipid metabolism. This study was conducted to evaluate the effects of short-term uridine monophosphate (UMP) and uridine (UR) administration on lipid metabolism in early-weaned piglets. Twenty-one weaned piglets (7 d of age; 3.32 &#177; 0.20 kg average body weight) were randomly assigned into three groups: The control (CON), UMP, and UR group, and oral administered UMP or UR for 10 days, respectively. The results showed that supplementation with UMP significantly increased (<i>p &lt;</i> 0.05) serum low density lipoprotein (LDL) and tended to increase (<i>p =</i> 0.062) serum total cholesterol (TC) content of piglets when compared with the other two groups. Oral administration with UMP and UR significantly decreased (<i>p</i> &lt; 0.05) the serum total bile acid (TBA) and plasma free fatty acids (FFA) of piglets, and significantly reduced the fatty acid content of C12:0 (<i>p</i> &lt; 0.01) and C14:0 (<i>p</i> &lt; 0.05) in liver. Experiments about key enzymes that are involved in <i>de novo</i> synthesis of fatty acid showed that the gene expression of liver X receptors (<i>LXR&#945;</i>), sterol regulatory element-binding transcription factor 1 (<i>SREBP1c</i>), fatty acid desaturase 2 (<i>FADS2</i>), and fatty acid elongase 5 (<i>ELOVL5</i>) were remarkably down-regulated (<i>p</i> &lt; 0.05) with UMP and UR treatment, and key factors of adipose triglyceride lipase (<i>ATGL</i>), hormone-sensitive lipase (<i>HSL</i>), and carnitine palmitoyl transferase 1 (<i>CPT-1&#945;</i>) involved in fatty acid catabolism were also decreased (<i>p</i> &lt; 0.05). Additionally, the protein expression of phosphorylated-mTOR was not affected while phosphorylation of AKT was repressed (<i>p</i> &lt; 0.05). In conclusion, short-term oral UMP or UR administration could regulate fatty acid composition and lipid metabolism, thus providing energy for early-weaned piglets.