Phloridzin, an Apple Polyphenol, Exerted Unfavorable Effects on Bone and Muscle in an Experimental Model of Type 2 Diabetes in Rats

Abstract

It is believed that apple fruits contain components with health-promoting effects, including some antidiabetic activity. One of the most known apple compounds is phloridzin, a glucoside of phloretin. Phloridzin and phloretin were reported to exert some favorable skeletal effects in estrogen-deficient rats and mice. The aim of the study was to investigate the effects of phloridzin on musculoskeletal system in rats with type 2 diabetes induced by a high-fat diet (HFD) and streptozotocin (STZ). The experiments were performed on mature female Wistar rats, divided into control rats (fed a standard laboratory diet), HFD/STZ control rats, and HFD/STZ rats receiving phloridzin (20 or 50 mg/kg/day per os) for four weeks. Serum biochemical parameters, muscle mass and strength, bone mass, density, histomorphometric parameters and mechanical properties were determined. The HFD/STZ rats developed hyperglycemia, with decreases in the muscle mass and strength and profound osteoporotic changes. Phloridzin at 20 mg/kg markedly augmented the unfavorable effects of diabetes on the muscle mass and strength and decreased growth of bones, whereas, at 50 mg/kg, it did not affect most of the investigated musculoskeletal parameters. Results of the study indicate the possibility of unfavorable effects of phloridzin on the musculoskeletal system in conditions of hyperglycemia.

Keywords: diabetes; osteoporosis; phloridzin; rats; skeletal muscle; skeletal system.

Figure 1

Effect of phloridzin administered orally (20 and 50 mg/kg daily for four weeks) on the body mass (Panel A) and non-fasting blood glucose concentration (Panel B) in rats with diabetes induced by high-fat diet (HFD) and streptozotocin (STZ). Results are presented as means ± standard error of the mean (SEM) (n = 8–11). HFD/STZ—control diabetic rats, HFD/STZ Phlo 20—diabetic rats treated with phloridzin at a dose of 20 mg/kg p.o. daily, HFD/STZ Phlo 50—diabetic rats treated with phloridzin at a dose of 50 mg/kg p.o. daily. The final measurements of the body mass and blood glucose concentration were made before the last phloridzin or vehicle administration. One-way analysis of variance (ANOVA) followed by Fisher’s LSD test was used for evaluation of the significance of the results. * p < 0.05, ** p < 0.01, *** p < 0.001—in comparison with the healthy control rats.