To develop a composite nutritional preparation that can effectively improve exercise performance under calorie restriction (CR) condition.

A total of 24 male C57BL/6J mice (weighing 23~26 g, 8 weeks old) were randomly divided into control group (CON), CR, CR+basal nutrient group (CRN1), and CR+compound nutrient group (CRN2). All groups underwent moderate-intensity running training 5 d per week, for totally 3 weeks. The grip strength of the forelimbs were measured weekly, and in 3 weeks after training, exhaustion and post-exhaustion distance tests were conducted to evaluate exercise performance. Blood biochemical indicators, levels of skeletal muscle and liver redox biomarkers, and histopathological conditions were measured and observed.

After 21 d of intervention, the CR group and CRN1 group had the post-exhaustion running distance prolonged by 278% and 289%, respectively, reduced blood glucose level, and decreased muscle mass, subcutaneous fat and epididymal fat mass when compared with the CON group (P<0. 05). Compared with the CON group, the CRN1 and CRN2 groups demonstrated significantly higher gastrocnemius glycogen content. The CRN2 group obtained even longer post-exhaustion distance (increased by 52% and 36% respectively, compared with the CON group and CRN1 group, P<0. 05), enhanced grip strength of the forelimbs (raised by 9%, 17% and 15%, respectively than the CON, CR and CRN1 groups, P<0. 05), elevated brown fat mass (compared to the CON group and CRN1 group, P<0. 05), increased blood glucose level (compared to the CRN1 group, P<0. 05), decreased blood low-density lipoprotein cholesterol level (compared to the CON and CR groups, P<0. 05), and increased glutathione peroxidase content in the gastrocnemius muscle (compared to the CON group, P<0. 05).

Supplementing with compound nutritional supplements in mice under CR can promote exercise performance, including improving fatigue recovery after exhaustive exercise and enhancing forelimb grip strength.

To investigate the effect and mechanism of quercetin (QUE) in improving lipid accumulation in hepatocytes by regulating lipolysis and lipophagy pathway.

The human hepatocyte cell line 5 (HHL-5) was induced by palmitic acid (PA) to establish a steatogenic hepatocyte model. Quercetin at different concentrations (5, 10, 20 and 40 μmol/L) has been utilized to interfere with HHL-5 cells for 24 h, and the experiment was divided into six groups: control group, PA group, PA+QUE5 group, PA+QUE10 group, PA+QUE20 groupand PA+QUE40 group. In order to determine the influence of lipophagy on QUE effect, 3-methyladenine (3-MA) was used to block autophagy, and HHL-5 cells were divided into the control, PA, PA+QUE40, 3-MA, PA+3-MA and PA+3-MA+QUE40 groups. The contents of triglyceride (TG), accumulations of lipid droplets, expression of lipolysis and lipophagy related molecules, and degree of co-localization, and expression level of substrate of autophagy P62 were detected in above 2 types of experimental groups.

Compared with the control group, the TG content and the lipid accumulation were significantly increased, the protein levels, average fluorescence intensities and colocalization degree of lipolysis related molecules adipose triglycerides lipase(ATGL) and comparative gene identification-58(CGI58), and lipophagy related molecules Ras-related protein 7(RAB7) and microtubule-associated protein 1 light chain 3 beta (LC3β) were significantly decreased, while the expression of P62 was enhanced in HHL-5 cells in the PA group (all P<0.05). Compared with the PA group, the triglyceride content and the degree of lipid accumulation in the PA+QUE40 group were significantly decreased, and the protein expression level, average fluorescence intensity and co-localization degree of lipolysis and lipophagy related molecules were significantly increased, while P62 was significantly decreased (P<0.05). When 3-MA was added to the steatogenic hepatocytes to inhibit autophagy, the improvement effect of QUE on lipid accumulation and the regulation of lipolysis and liphagy related molecules in steatogenic hepatocytes were neutralized.

QUE alleviates lipid accumulation in HHL-5 cells by promoting the expression and interaction of molecules related to lipolysis and lipophagy pathways. However, these effects can be weakened by the autophagy inhibitor 3-MA.