Blackcurrant Extracts increase Myocyte Proliferation and reduce Apoptosis in L6 myocytes and improve Muscle Strength and Memory in Senescence Accelerated Mice

Abstract

Musculoskeletal disorders (MSD) impact approximately 50% of adults over the age of 18, and nearly 75% of patients over the age of 65. Sarcopenia is an MSD that is age‐related and is associated with reduced muscle mass and function, as well as and significant morbidity and mortality. Advanced age is associated with significant increase in skeletal muscle cell apoptosis that parallels the loss of both muscle mass and strength. Suppression of myocyte apoptosis can be induced by caloric restriction, exercise training, hormone supplements, drugs and nutritional supplements. Blackcurrants (Ribes nigrum L., Grossulariaceae) are native to Central and Eastern Europe and Northern Asia, and the fruit are used traditionally for the treatment of viral infections. However, the fruit also has potent antioxidant and anti‐inflammatory effects. Blackcurrants contain four major anthocyanins: delphinidin‐3‐O‐glucoside, delphinidin‐3‐O‐rutinoside, cyanidin‐3‐O‐glucoside, cyanidin‐3‐O‐rutinoside. Recent clinical studies reported that blackcurrant extracts improve muscle strength muscle and improve muscle recovery after exercise. In this work, we investigate the effects of blackcurrant extracts and purified anthocyanin compounds on cell proliferation and apoptosis in L6‐rat myoblasts, and in muscle strength and memory in SAMP8 mice. L6 rat myoblasts were obtained from ATCC and cultured in Dulbecco’s Modified Eagle’s medium, with 2.5 mM L‐glutamine. Blackcurrant extracts (BCE) were prepared in ethanol and compounds were isolated and purified. Senescence accelerated (SAMP8) mice, a model of senescence acceleration and aging disorders, were from Jackson Laboratories. SAMP mice are susceptible to oxidative stress induced by age‐associated mitochondrial dysfunction and reduced ATP production. SAMP8 mice were maintained under protocol ACC14309 and treated with 100 mg/kg of the BCE for 8 weeks. The results showed that treatment of L6 myocytes with ethanol extracts of R. nigrum fruit increased the proliferation of rat L‐6 myoblasts by 300%, and prevented cellular apoptosis induced by serum and glucose starvation. Of the anthocyanins present in the extract, cyanidin‐3‐glucoside (C3G) was the most active and enhanced L6 growth by 200%, and reduced apoptosis as well. Gene expression analysis showed a concentration‐dependent increase in the anti‐apoptotic Bcl‐2 mRNA expression by ~ 284 fold, as well as enhanced expression of PPARγ by 4 fold. Both BCE and C3G reduced apoptosis by altering the Bax/Bcl‐2 ratio and increased ATP production in favor of cell proliferation. In SAMP8 mice treatment with BCE increased muscle function and improved memory and learning. Overall the data suggest that BCE and C3G have potential for reducing age associated sarcopenia and possibly musculoskeletal disorders such as muscular dystrophy by reducing myocyte apoptosis, increasing ATP production and mitochondrial biogenesis.Support or Funding InformationThis work was supported in part by the Regenstein Foundation (GBM); the Schlumberger Foundation (TOL/GBM); and a Raman Post‐Doctoral Fellowship by the University Grants Commission, Govt. of India to NAR.