Objective: To explore the effects of zinc-alpha2-glycoprotein (ZAG) on body weight and body fat in high-fat-diet (HFD)-induced obesity in mice and the possible mechanism.
Methods: Thirty-six male mice were fed with standard food (SF) (n = 9) and HFD (n = 27), respectively. Five weeks later, 9 mice fed with HFD were subjected to ZAG expression plasmid DNA transfection by liposome transfection method, and another 9 mice to negative control plasmid transfection. Two weeks later, serum ZAG level in the mice was assayed by Western blot, and the effects of ZAG over-expression on body weight, body fat, serum biochemical indexes, and adipose tissue of obese mice were evaluated. The mRNA expressions of fatty acid synthase (FAS) and hormone-sensitive lipase (HSL) in liver tissue were determined by reverse transcription-polymerase chain reaction.
Results: Serum ZAG level significantly lowered in simple HFD-fed mice in comparison to SF-fed mice (0.51 +/- 0.10 AU vs. 0.75 +/- 0.07 AU, P < 0.01). Further statistical analysis demonstrated that ZAG level was negatively correlated with body weight (r = -0.56, P < 0.001), epididymal fat mass (r = -0.67, P < 0.001), percentage of epididymal fat (r = -0.65, P < 0.001), and increased weight (r = -0.57, P < 0.001) in simple SF- and HFD-fed mice. ZAG over-expression in obese mice reduced body weight and the percentage of epididymal fat. Furthermore, FAS mRNA expression decreased (P < 0.01) and HSL mRNA expression increased (P < 0.001) in the liver in ZAG over-expressing mice.
Conclusions: ZAG is closely related to obesity. Serum ZAG level is inversely correlated with body weight and percentage of body fat. The action of ZAG is associated with reduced FAS expression and increased HSL expression in the liver of obese mice.