The Relationship Between Gastric Emptying In Diabetic Rats With Leptin Expression

Objective To investigate the relation between the delayed gastric emptying and leptin in different diabetic stage.Methods Forty Wistar rats were randomly divided into four groups:1-wk normal control group(NC₁ group,n=6),4-wk normal control group (NC₂ group,n=6),1-wk diabetes mellitus group(DM₁ group,n=14) and 4-wk diabetes mellitus group(DM₂ group,n=14).Diabetes was induced by intraperitoneal injection of streptozotocin(STZ).One week and four weeks after the STZ injection,gastric emptying was measured by intragastric administration of phenol red and the expression of leptin and its receptor mRNA were detected by radioimmunoassay and semi-quantitative RT-PCR separately.Results One week after the STZ injection,the body weight of the DM₁ group was no differ from the NC₁ group significantly.The serum leptin decreased compared with the NC₁ group,but gastric emptying rates and gastric leptin increased significantly compared with the NC₁ group.Leptin integral optical density and its receptor(OB-Rb) mRNA expression levels in the stomach of the DM₁ group were not changed significantly compared with the NC₁ group;four weeks after the STZ injection, the body weight,gastric emptying rates,the contents of serum leptin and gastric leptin in the DM₂ group decreased significantly compared with the NC₂ group.However,the leptin integral optical density and leptin receptor(OB-Rb) were still unchanged compared with the NC₂ group.Conclusion The decreased serum leptin levels on the short-term hyperglycemia may participate in the rapid gastric emptying and increase ingestion reaction,which can maintain energy balance of the body.Furthermore,the increased contents of gastric leptin which may be induced by body feedback mechanism could reduce excessive food intake and prevent hyperglycemia raising.The long-term hyperglycemia may inhibit the expression and release of serum and gastric leptin to stimulate food intake to maintain energy balance.