Effects of resveratrol on skeletal muscle strength and myofibril structure in aged rats

Study Purpose
Observe the effects of resveratrol on skeletal muscle mass, holding power, myofibril ultrastructure and AMPK/sirt1 pathway in aged rats.

Method
Twenty 25-month-old SD rats were randomly divided into an elderly control group (OC group, 10 rats) and an elderly resveratrol group (OR group, 10 rats), and another 10 6-month-old SD rats served as a young control group ( YC group). The OR group was treated with resveratrol for 6 consecutive weeks. The electronic grip instrument measures the grasping power of the rat’s forelimbs, and the gastrocnemius muscle mass of the rat is weighed with an analytical balance. The gastrocnemius muscle mass (mg)/body mass (g) is used to obtain the sarcopenia index (SI), and the rat myogenic muscles are observed under a transmission electron microscope. Changes in the length of fibromuscular segments, bright bands, dark bands, and H-bands. Western blot method was used to detect the protein expression of AMPK, P-AMPK and sirt1.

Effect of resveratrol on SI value in rats. SI: Sarcopenia Inedx; YC: Young control group; OC: Old control group; OR: Old-resveratrol-treated group. ^*P < 0.05 vs YC.

Effect of resveratrol on forelimb grip strength in rats. ^*P < 0.05 vs OC.

Effect of resveratrol on myofibril in skeletal muscle in rats. Representative TEM pictures of microstructure of gastrocnemius myofibersfromYC (Original magnification: × 15 000) (A), OC (B) and OR (C). Z, Z-line; S, sarcomeres; A, A-band; I, I-band; H, H-zone. ^*P < 0.05 vs YC, ^#P < 0.05 vs OC.

Effect of resveratrol treatment on AMPK、P-AMPK and sirt1protein expression in rats. ^*P < 0.05 vs YC, ^#P < 0.05 vs OC.

Result

The SI value of gastrocnemius in the OC group was lower than that of the YC group (P <0.05), the holding power was lower than that of the YC group (P <0.05), and the length of sarcomere, dark belt, bright belt and H belt were all higher than those in YC group (P <0.05). 0.05), the protein expression levels of AMPK, P-AMPK, and sirt1 were all lower than those of the YC group (P <0.05); compared with the OC group, there was no significant difference in the SI value of the OR group (P>0.05), and the holding power was increased (P <0.05), the length of the sarcomere, the length of the bright band and the length of the H band were all reduced (P <0.05), and there was no statistical difference in the length of the dark band (P>0.05). The protein expression levels of P-AMPK and sirt1 were both significant Increased (P <0.05).

Conclusion
Resveratrol cannot slow down the loss of muscle mass, but it can increase the grip of old rats. This effect may be related to resveratrol activating AMPK/sirt1 pathway and improving the aging of myofibril structure.

12 kinds of effects and side effects of resveratrol

Keywords: resveratrol, sarcopenia, grip, electron microscope
Sarcocytopenia was first proposed by Rosenberg in 1988. It is a type of aging hypofunction characterized by decreased skeletal muscle mass, muscle strength and endurance [1-2]. Epidemiological data shows that the incidence of sarcopenia is as high as 15% in the elderly over 65 years old, and the incidence of sarcopenia is as high as 50% in the elderly over 80 years old [3]. Sarcopenia severely affects the body function and daily life of the elderly, increases the risk of falls, fractures, disability and hospitalization in the elderly [4], increases the socioeconomic burden, and increases the mortality of the elderly. However, sarcopenia is preventable and curable, and the main method is through exercise and nutritional intervention. In recent years, sarcopenia has gradually become one of the research hotspots in the field of geriatrics. The occurrence of sarcopenia involves many factors such as apoptosis [5], decreased protein synthesis [6], insufficient hormone secretion [7], and motor neuron disability [8]. The specific mechanism of its occurrence is currently unclear.

Resveratrol is a non-flavonoid polyphenol compound with strong biological properties, mainly derived from peanuts, grapes, knotweed, mulberry and other plants. Resveratrol has a variety of pharmacological effects. Past studies have shown that resveratrol is a pure natural antioxidant that can up-regulate endogenous antioxidant factors and reduce the oxidant load in skeletal muscle cells, thereby reducing the load on muscles. Oxidative damage associated with aging [9-10]. Studies have found that resveratrol can inhibit the degradation of skeletal muscle fiber protein and improve skeletal muscle atrophy [11-14]. Resveratrol has a certain protective effect on improving muscle disuse atrophy [15]. However, the effect of resveratrol on the skeletal muscle of aged rats has not been reported. This experiment aims to explore the effect of resveratrol on the muscle strength and structure of aged rats and its possible molecular mechanism.