Abstract:Objective To construct a liver-specific Rbp4 knockout mouse model and to explore the effect of liver RBP4 on glucose metabolism. Methods Homozygous liver-specific Rbp4 knockout (Rbp4flox/flox:Cre+) mouse model was obtained by multiple breeding hybridization between LoxP-labeled Rbp4flox/+ mice and Alb-Cre tool mice. The genotype of mice was identified by agarose gel electrophoresis. Eighteen-week-old male mice were selected and divided into liver-specific Rbp4 knockout mice group (Rbp4flox/flox:Cre+, n=10), littermate control mice group ( Rbp4flox/flox, n=10) and wild-type mice group (WT, n=10). Western blot and qRT-PCR were used to detect the expression levels of Rbp4 protein and mRNA in liver and the expression levels of Rbp4 mRNA in other tissues to verify the specific knockout results. HE staining was used to observe the morphological changes of liver tissue in mice. Glucose tolerance and insulin tolerance were measured at the end of the 18 th week. The expression of liver glucose metabolism genes phosphoenolpyruvate carboxylase ( Pepck ) and glucose-6-phosphatase ( G6pase ) was detected by qRT-PCR. Results Western blot and qRT-PCR results showed that the expression of Rbp4 in the liver of Rbp4flox/flox:Cre+ group was decreased (P< 0.05 ). HE staining, glucose tolerance and insulin tolerance results showed that liver-specific Rbp4 knockout had no significant effect on liver morphology, glucose tolerance and insulin tolerance. Compared with WT group, the relative expression of Pepck mRNA in Rbp4flox/flox group was increased, and the difference was statistically significant (P<0.05). Compared with WT group, there was no significant difference in the relative expression of Pepck mRNA in the liver of Rbp4flox/flox:Cre+ group (P> 0.05 ).Compared with the Rbp4flox/flox group, the relative expression of Pepck mRNA in the liver of the Rbp4flox/flox:Cre+ group was decreased, and the difference was statistically significant (P<0.05). There was no significant difference in the expression of G6pase mRNA in the liver of the three groups (P> 0.05 ). Conclusion A liver-specific Rbp4 knockout mouse model was successfully constructed. Under physiological conditions, liver-specific Rbp4 knockout had no significant effect on liver tissue morphology, glucose tolerance and insulin tolerance in mice, and reduced the expression of liver glucose metabolism gene Pepck, suggesting that RBP4 plays a role in liver glucose metabolism.