The relationship between gastric emptying and expression of Leptin in diabetic rats

Objective Aim To explore the relationship between gastric emptying and expression of leptin and its receptor in different diabetic stages. Methods Fourty Wistar rats were randomly divided into four groups: 1-week normal control group(NC 1 group; n=6), 4-week normal control group (NC2 group;n=6), 1- week diabetes mellitus group (DM 1 group; n = 14)and 4-week diabetes mellitus group (DM2 group ; n = 14). One week and four weeks after the STZ injection, gastric emptying measured by intragastric administration of phenol red;serum leptin concentrations were measured with that of radioimmunoassay; expression of OB-Rb mRNA in hypothalamus was detected with semi-quantitative RT-PCR. Results 1-week after the STZ injection, the expression of serum leptin and OB-Rb mRNA in hypothalamus of DM1 group was decreased signifieantly compared with that of the control (P ＜0.05;P ＜ 0.05) ;DM1 group showed significantly accelerated rates of gastric emptying of the fluid compared with that of the NC1 group (P ＜ 0.01). 4-week after the STZ injection, serum leptin and gastric emptying of the DM2 group decreased significantly compared with that of the NC2 group(P ＜0.05; P ＜ 0.01). Oppositely, the expression of OB-Rb mRNA in the hypothalamus of DM2 group increased significantly(P＜0.05). Conclusion The decreased serum leptin and OB-Rb in the hypothalamua on the short-term hyperglycemia may participate in the rapid gastric emptying and increase ingestion reaction, which can maintain energy balance of the body. The high expression of OB-Rb in the hypothalamus may be a protective mechanism that it could increase leptin sensitivity to inhibit gastric emptying on the long-term hyperglycemia. Key words: Diabetes mellitus;  gastric emptying;  Leptin ;  OB-Rb