Therapeutic Potential of Pterostilbene and Resveratrol on Biomechanic, Biochemical, and Histological Parameters in Streptozotocin-Induced Diabetic Rats

Abstract

Aims: The aim of this study was to investigate the effects of pterostilbene (PTS) (trans-3,5-dimethoxy-4'-hydroxystilbene) and resveratrol (RSV) (trans-3,5,4' trihydroxystilbene) applied at different doses for the treatment of streptozotocin- (STZ-) induced diabetic rats.

Materials and methods: At the end of the 5-week experimental period, the right gastrocnemius muscles of the rats were examined biomechanically, while the left ones were examined histologically. In addition, blood glucose, serum insulin, and malondialdehyde (MDA) levels were analyzed in blood samples taken from the rats.

Results: The skeletal muscle isometric contraction forces, which showed a decrease with diabetes, were observed to increase with antioxidant applications. Blood glucose, serum insulin, and MDA levels in diabetic rats approached normal levels after applying PTS. When the electron microscopic images of the rat skeletal muscle were examined, those in the combination treatment group were observed to show a better enhancement in the skeletal muscle morphological structure compared to the other diabetic and treatment groups.

Conclusion: According to the findings, we suggest that these antioxidant treatments might have good therapeutic nutraceutical potential for some muscle diseases that coexist with diabetes. These treatments should be comprehensively investigated in the future.

Figure 1

Schematic presentation of the experimental groups.

Figure 2

Percent of weight change from day 3 after STZ application to the end of 5th week, groups were compared within themselves. The results are given as percentage mean weight ± SEM. ^∗Significantly different from DM (p < 0.05), ^#significantly different from all other groups (p < 0.05).

Figure 3

Percent change in blood glucose from day 3 after STZ application to the end of 5th week, groups were compared within themselves. The results are given as percentage mean blood glucose ± SEM. ^∗Significantly different from DM (p < 0.05).

Figure 4

The responses of isometric contraction forces at the frequencies of 1, 10, 20, 50, and 100 Hz. The change in different antioxidants (a-b) administered at the same dose compared to C and DM, the changes among groups receiving 10, 20, and 40 mg/kg PTS (c) and 10, 20 mg/kg RSV and Mix (d) compared to DM. The results are given as the mean ± SEM.

Figure 5

(a) Serum insulin (mIU/L) and (b) serum MDA values (nmol/mL). The results are given as the mean ± SEM. ^∗Significantly different from group DM (p < 0.05), ^#significantly different from PTS40 (p < 0.05).

Figure 6

Electron microscopic images of the skeletal muscle tissue samples obtained from the groups. The groups C, DM, PTS10, PTS20, PTS40, RSV10, RSV20, and Mix have been enumerated from (a) to (h), respectively. M: mitochondria, N: nucleus, V: vacuolization, L: lipid droplets, Cap: capillary vessel, F: fibroblast, E: endomysium, Arrows in (b) and (d): sarcoplasmic reticulum cisternae, Arrows in (e) and (f): glycogen particles, Z: Z line, A and I: A and I bands, Bars in (a)–(d), (f), and (h): 0.5 μm, and Bars in (e) and (g): 1 μm.