Effect of Sleeve Gastrectomy on Osteopontin Circulating Levels and Expression in Adipose Tissue and Liver in Rats

Sleeve gastrectomy (SG) constitutes an effective procedure for the treatment of morbid obesity. The aim of the present study was to establish in rats the effects of surgically induced weight loss on circulating concentrations and mRNA expression in adipose tissue and liver of osteopontin (OPN), a proinflammatory protein involved in the development of obesity. Eighty male diet-induced obese Wistar rats were subjected to surgical interventions [sham operation (SH), SG, or pair-fed to the amount of food eaten by SG animals] and dietary interventions [fed ad libitum with a normal chow diet (ND) or a high-fat diet (HFD)]. Body, epididymal adipose tissue (EWAT), and liver weights were determined. Circulating OPN concentrations and the transcript levels of Spp1 (OPN) in EWAT and liver were analyzed. Rats undergoing SG showed decreased body weight (P < 0.001) and fat mass (P < 0.001) and greater excess weight loss (P < 0.001). The HFD significantly decreased serum OPN levels (P < 0.001). However, SG did not change serum OPN concentrations. OPN expression was dramatically increased in animals fed HFD (P < 0.001) in EWAT, but was unaffected by SG. The expression of OPN in the liver was not affected by HFD or SG. Circulating OPN levels decreased with HFD feeding remaining unaltered after SG. The expression of Spp1 in EWAT and liver was not modified by SG. The global improvement of metabolism after SG appears not to involve changes in serum OPN concentrations as well as in EWAT and liver expression in rats.