Astragaloside IV prevents high-fat diet induced obesity partially through enhancing leptin signaling transduction

Aim To investigate the effects of astragaloside IV （ASI） on high-fat diet （HFD） induced obese mice. Methods The male mice aged 6 weeks were randomly divided into three groups （u- 18/group）, namely control group, model group and ASI-treated group. Control group were fed with standard diet, whereas the other two groups were given high fat diet. ASI-treated mice were daily intraperitoneally injected with ASI （25 nag · kg^-1）. Mean- while, the other group mice were treated with saline. Body weight of mice was monitored every week and lasted for 13 weeks. Serum cholesterol and triglyceride content were measured with respective kits. Serum leptin level was deter- mined by ELISA kit. Expression of leptin receptor in hypothalamus was measured by Western blot assay. Gene ex- pression of neuropeptide Y （NPY） and agouti-related protein （AGRP） in hypothalamus was detected by qPCR assay. In addition, leptin receptor-deficient db/db mice were given intraperitoneally with ASI （25 mg ~ kg-1） or saline for 13 weeks （u- 8/group）. Results ASI blocked body weight gain, suppressed appetite, improved leptin resistance, lowered serum triacylglycerol （TG） and total cholesterol （TC） contents, reduced accumulation of fat tissues and pre- vented enlargement of adipose cells in HFD fed mice. Furthermore, ASI increased the protein expression level of lep- tin receptor in hypothalamus, and inhibited the mRNA expression levels of NPY and AGRP. However, ASI could not decrease body gain in leptin receptor - deficient db/db mice as well as the mRNA expression levels of NPY and AGRP. Conclusion The study suggested that ASI could efficiently prevent HFD-induced obesity in C57BL/6 mice,which was partially mediated through enhancing leptin signaling transduction.