Effect of intestinal ischemia/reperfusion injury on leptin and orexin-A levels

Abstract

The aim of this paper is to explore the effect of intestinal ischemia/reperfusion (I/R) injury on leptin and orexin-A levels in peripheral blood and central secretory tissues, and to examine the roles of leptin and orexin-A in acute inflammatory responses. An intestinal I/R injury model of rats was made; the rats were grouped according to the time of after 60 min ischemia. Radioimmunoassay was employed to detect the levels of leptin in serum and adipose tissue and orexin-A levels in plasma and hypothalamus. Reverse transcriptase-polymerase chain reaction was used to detect mRNA expressions of adipose leptin and hypothalamus orexin-A. Compared with the levels before the injury, serum leptin in 60 min ischemia/30 min reperfusion (I60´R30´) group decreased and that of I60´R360´ group increased. Compared with sham-operation group (sham group) after injury, serum leptin level of I60´R360´ group increased, adipose leptin levels of I60´R30´ and I60´R90´ decreased, and adipose leptin in I60´R360´ group increased. After the injury, adipose leptin mRNA expressions of I60´R30´, I60´R240´ and I60´R360´ increased, whereas that of I60´R150´ group decreased as compared with the sham group. There was no significant difference in the protein levels of orexin-A, either between plasma and hypothalamus or between pre- and post-I/R injury. Compared with sham group, hypothalamus orexin-A mRNA expressions of I60´R30´ and I60´R90´ decreased gradually after the injury, with that of I60´R150´ group reaching the lowest, and those of I60´R240´ and I60´R360´ recovering gradually, although they were still significantly lower than that of sham group. Leptin and orexin-A respond to intestinal I/R injury in a time-dependent manner, with leptin responding more quickly than orexin-A does, and both of them may contribute to the metabolic disorders in acute inflammation.