Abstract: Objective: To explore the effect of the essential oil from the ripe fruit percicarp of Zanthoxylum bungeanum Maxim. on glucose metabolism in type I diabetic mice and its possible mechanism. Methods: Totally 50 healthy male Kunming mice were randomly divided into five groups of 10 animals each, including blank control, diabetic model, high-dose (15 mg/(kg mb·d)), middle-dose (9 mg/(kg mb·d)) and low-dose (3 mg/(kg mb·d)) essential oil. Type I diabetes was induced by streptozotocin (STZ). The animals in the blank control and diabetic model groups were orallytreated with the same dose of soybean oil. After 28 days of administration, the levels of insulin, glycosylated serum protein (GSP), glycosylated hemoglobin (GHb), muscle glycogen and liver glycogen were determined. The relative mRNA expression of the phosphoinositide 3-kinase (PI3K), protein kinase B (PKB) and glucose transporter 2 (GLUT2) genes in liver and of the GLUT4 gene in skeletal muscle were determined by quantitative real-time polymerase chain reaction (qRT-PCR ). The protein expression of PI3K (p110), PKB and p-PKB (Ser473) in liver was evaluated by Western blot. Fasting blood glucose and body mass were measured weekly during the experiment, and glucose tolerance was measured on the 28th day of administration. Results: Compared with the model group, food intake, water intake, fasting blood glucose, GHb concentration and GSP concentration in the essential oil treatment groupswere decreased at most by 38.91%, 35.93%, 28.60%, 30.76% and 37.29%, respectively. The levels of insulin, liver glycogen and muscle glycogen were increased at most by 22.56%, 23.61% and 149.75%, respectively. The relative mRNA expression of PI3K, PKB, GLUT2 and GLUT4 was up-regulated (P < 0.05) at most by 87.5%, 53.4%, 77.05% and 133.3%, respectively. Furthermore, the protein expression of PI3K (p110) was up-regulated by 3.20, 2.51 and 1.67 times, and the protein expression of p-PKB (Ser473) was up-regulated by 7.64, 6.12 and 2.73 times in the high-, medium- and low-dose groups, respectively. Conclusion: The essential oil has a hypoglycemic effect in type 1 diabetic mice possibly by activating the PI3K/PKB pathway to translocate GLUT2/4, and promote glucose absorption and utilization by cells.

Key words: essential oil from the ripe fruit percicarp of Zanthoxylum bungeanum Maxim.; type 1 diabetes mellitus; glucose metabolism; mechanism