Sleeve gastrectomy reduces xanthine oxidase and uric acid in a rat model of morbid obesity.

Serum uric acid (sUA) plays a major role in the development of morbidities associated with obesity, especially cardiovascular diseases. Within the purine pathway, xanthine oxidase (XOD) represents the key enzyme. The aim of this study was to investigate the dynamics of sUA and XOD following sleeve gastrectomy (SG) in a rat model of high-fat-diet (HFD) induced obesity. Over a period of 11 weeks, 30 rats received a HFD, and 10 rats received a low fat diet (LFD). Thereafter, 10 randomly selected HFD rats and 10 LFD rats were sacrificed. The remaining 20 HFD rats were randomly assigned to either SG or sham operation (SH) and studied 14 days postoperatively. The white adipose tissues (WAT) from visceral (intestinal and retroperitoneal) and inguinal (subcutaneous) depots were collected. sUA and urine UA (uUA) were measured by high performance liquid chromatography-mass spectrometry (HPLC-MS/MS). Abundance and activity of XOD was investigated in the liver, colon, adipose tissue, and skeletal muscle by enzyme-linked immunosorbent assay (ELISA). HFD led to significant weight gain, elevated sUA levels, increased WAT and increase of XOD activity. Fourteen days postoperatively, SG rats showed a significant decrease of weight and adipose tissue, improved glucose metabolism, and changes of gut hormones. The sUA and uUA levels were significantly decreased following SG. Furthermore, XOD activity was significantly down-regulated in WAT. HFD induces elevated sUA levels by gain of WAT and increase of XOD activity. Following SG, the reduction of WAT as the major source of XOD and the lowering of XOD activity are the basis for the decrease of sUA.