Steroid hormone 20-hydroxyecdysone disturbs fat body lipid metabolism and negatively regulates gluconeogenesis in Hyphantria cunea larvae

The steroid hormone 20-hydroxyecdysone(20E)has been described to regu-late fat body lipid metabolism in insects,but its accurate regulatory mechanism,especially the crosstalk between 20E-induced lipid metabolism and gluconeogenesis remains largely unclear.Here,we specially investigated the effect of 20E on lipid metabolism and glu-coneogenesis in the fat body of Hyphantria cunea larvae,a notorious pest in forestry.Lipidomics analysis showed that a total of 1 907 lipid species were identified in the fat body of H.cunea larvae assigned to 6 groups and 48 lipid classes.The differentially abun-dant lipids analysis showed a significant difference between 20E-treated and control sam-ples,indicating that 20E caused a remarkable alteration of lipidomics profiles in the fat body of H.cunea larvae.Further studies demonstrated that 20E accelerated fatty acid β-oxidation,inhibited lipid synthesis,and promoted lipolysis.Meanwhile,the activities of pyruvate carboxylase,phosphoenolpyruvate carboxykinase,fructose-1,6-bisphosphatase,and glucose-6-phosphatase were dramatically suppressed by 20E in the fat body of H.cunea larvae.As well,the transcriptions of genes encoding these 4 rate-limiting gluco-neogenic enzymes were significantly downregulated in the fat body of H.cunea larvae after treatment with 20E.Taken together,our results revealed that 20E disturbed fat body lipid homeostasis,accelerated fatty acid β-oxidation and promoted lipolysis,but nega-tively regulated gluconeogenesis in H.cunea larvae.The findings might provide a new insight into hormonal regulation of glucose and lipid metabolism in insect fat body.