Royal jelly supplementation reduces skeletal muscle lipotoxicity and insulin resistance in aged obese rats.

BACKGROUND

Consumption of a high-fat diet (HFD) in aged rats is associated with several metabolic disorders. The mechanism of skeletal muscle lipotoxicity and insulin resistance (IR) is multi-factorial, but the exact mechanism of how aging affects these processes unknown. Royal jelly (RJ) is a dietary supplement with many physiological and pharmacological properties. No previous studies have demonstrated the protective effects and mechanism of RJ in aged obese rats.

OBJECTIVES

The study was carried to investigate the effects of aging and HFD on skeletal muscles, and adipose tissue metabolism and inflammation, in aged rats, and whether RJ could combat such adverse effects.

METHODOLOGY

A total of 40 male rats were divided into5 groups; young rats fed a standard diet, aged rats fed a standard diet, aged rats fed RJ, aged rats fed a HFD, and aged rats fed both a HFD and RJ for 8 weeks. We investigated changes in body weights (BW), abdominal fat weights, total cholesterol, triglycerides (TG), low density lipoprotein-cholesterol (LDL-c), high density lipoprotein-cholesterol (HDL-c), muscle TG, and IR levels. Also, concentrations of TNF-α receptor 1(TNFR1) were estimated in the serum and adipose tissues.

RESULTS

Aged, obese rats showed increased BW, adipose weights, IR, and disturbed serum and muscle lipids. Also, TNFR1 was increased. Rats fed RJ showed decreased adiposity, improved lipids' profiles, improved IR, and decreased TNFR1.

CONCLUSION

Aging and HFD were associated with disturbed metabolism, and muscle lipotoxicity and inflammation, while RJ could counteract muscle lipotoxicity in rats and reduce IR, most likely due to an anti-inflammatory effect.