Chemerin influences blood lipid of aged male mice under high fat diet and exercise states through regulating the distribution and browning of white adipose tissue.

• Chemerin knockdown exacerbated HFD-induced weight gain, fat accumulation (especially in sWAT) and inhibited WAT browning, but improved blood lipid in aged mice. • Exercise-regulated improvements of blood lipid, as well as the distribution and browning of WAT were abrogated by chemerin knockdown. • Chemerin's role in regulating the distribution and browning of WAT associated with the changes of adiponectin, leptin and adiponectin/leptin ratio in serum and WAT. • Exercise-induced beneficial changes in adiponectin, leptin and adiponectin/leptin ratio were blocked by chemerin knockdown. With aging, white adipose tissue (WAT) undergoes distribution change and browning inhibition, which could be attenuated by exercise. Adipokine chemerin exerts roles in the above changes of WAT, and our previous studies demonstrated the effect of decreased chemerin on exercise-induced improvement of glucose and lipid metabolism in high fat diet (HFD) feeding male mice, so this study is to clarify whether chemerin's effects on glucose and lipid metabolism are associated with the distribution and browning of WAT. After diet and exercise interventions, body weight and adipose tissue contents in different depots of male mice were weighed, body composition and energy metabolism parameters were determined by Echo MRI Body Composition Analyzer and metabolic cage, respectively. The levels of serum adiponectin and leptin were detected by ELISA, and the protein levels of PGC-1α, UCP1, adiponectin and leptin in WAT were measured by Western blot. Chemerin knockout exacerbated HFD-induced weight gain, upregulated the increases of visceral and subcutaneous WAT (vWAT and sWAT, especial in sWAT), and inhibited WAT browning, but improved blood lipid. Exercise reduced the body weight and WAT distribution, increased sWAT browning and further improved blood lipid in aged HFD male mice, which were abrogated by chemerin knockout. Detrimental alterations of leptin, adiponectin and adiponectin/leptin ratio were discovered in the serum and WAT of aged HFD chemerin(-/-) mice; and exercise-induced beneficial changes in these adipokines were blocked by chemerin knockout. Chemerin influences blood lipid of aged male mice under HFD and exercise states through regulating the distribution and browning of WAT, which might be related to the changes of adiponectin, leptin and adiponectin/leptin ratio. [ABSTRACT FROM AUTHOR]