Effects of ghrelin on mice of obesity and insulin resistance / 医学研究生学报

ABSTRACT

ObjectiveThe effect of ghrelin on glucose metabolism is still controversial. This study aims to investigate the effects of long-term application of acyl ghrelin (AG) and des-acyl ghrelin (DAG) on insulin resistance and serum inflammatory factor levels by establishing a mouse model of obesity, induced by a high-fat diet.MethodsThirty two male C57BL/6 mice were randomly divided into 4 groups, 8 in each group. Except for the control group, the high fat diet group (HFD), HFD+AG group and HFD+DAG group were given a high-fat diet to induce obesity in mice. Control group standard feed and an intraperitoneal injection of 10mL isotonic saline were given every day. HFD high-fat feed and an intraperitoneal injection of 10mL isotonic saline were given every day. HFD+AG group high-fat diet was fed with 0.8mg AG; HFD+DAG group high-fat diet was fed with 0.8mg DAG. Intraperitoneal glucose tolerance test (IPGTT) was performed 16 weeks later. The blood glucose was collected from the tail veins at 0min, 30min, 60min and 120min after injection, respectively, the fluctuation curve was drawn, the area under the curve was calculated, and then the epididymal fat index was weighted. Fasting insulin, interleukin 6 (IL6) and TNFα levels were measured by enzyme-linked immunosorbent assay (ELISA). Then the insulin resistance index (HOMA IR) was compared.ResultsAfter 6 weeks of feeding, the weight of the mice in HFD was significantly higher than that of the control group (P<0.05). After 14 and 12 weeks of administration, the mice in the HFD+AG group and the HFD+DAG group had a significant weight loss (P<0.05). The fat mass of the epididymis in the HFD+DAG group [(0.92±0.32)g] was significantly lower than that of the HFD group [(1.08±0.11)g] (P<0.05); the fasting insulin level was significantly lower, too (P<0.05). The insulin resistance index (4.94±1.27, 4.08±1.35), IL6 [(34.82±6.23), (36.90±5.27)pg/mL] and TNFα levels [(73.01±7.75), (69.39±8.43)pg/mL] in the HFD+AG group and HFD+DAG group were significantly lower than those in the HFD group [(81.70±7.53), (45.85±6.41) pg/mL, (81.70±7.53)pg/mL], with statistically significant differences (P<0.05). The serum levels of IL 6 and TNFα in the HFD group were significantly lower than those in the control group (P<0.05).ConclusionLong-term application of AG and DAG could improve the insulin resistance and reduce the inflammation level of the mice induced by a high-fat diet. DAG can also decrease the visceral fat in mice.