Effects of Chlorogenic Acid on Glucose Tolerance and Its Curve Characteristics in High-Fat Diet-Induced Obese Rats

OBJECTIVES: To observe the improvement effect and its mechanism of chlorogenic acid (CGA) on the glucose tolerance and its curve characteristics in high fat diet-induced obesity (DIO) rats. METHODS: Eight of 56 male SD rats were randomly selected as the normal diet group (CON), and the rest were fed with high-fat diet. After 4 weeks, 24 DIO rats were screened and then randomly divided into high fat diet group (HFD group), 50% CGA group and 98% CGA group. The CGA groups received intragastric administrations of 50% CGA and 98% CGA (80 mg/kg/d) once a day for 8 weeks, respectively, while the CON and HFD groups received a carrier solution PBS. Body weight was measured weekly and OGTT was performed every 4 weeks. Fasting insulin and insulin release were measured, HOMA-IR was calculated. Histopathological examination by hematoxylin and eosin staining method were evaluated in the pancreatic tissues. Non-targeted metabolomics analysis of rat serum was performed using UHPLC-Q-Orbitrap MS. RESULTS: Before the intervention of CGA, blood glucose levels at 120 min after glucose loading (P