Modulation of GRP78‐CHOP‐JNK‐Caspase12 pathway by Chinese herb medicine in atrophied soleus muscle induced by tail suspension

Abstract

ObjectiveMicrogravity could induce a series of changes on the physiological state in humans and animals, among which skeletal muscle atrophy is striking. The countermeasure of skeletal muscle atrophy mainly relies on the physical exercise which need expensive and heavy special apparatus in space. However, complementary medicine such as Chinese herb medicine may have distinctive effects on the countermeasure of skeletal muscle atrophy induced by microgravity or simulated microgravity. This study was carried out to test the effects of Xuefuzhuyu capsules(XFZY), an Chinese medicine known to improve the blood supply of tissue, on the skeletal muscle atrophy induced by simulated microgravity.MethodsRats fed the XFZY were tail‐suspended for 30 days(XFZY group), and the muscle mass and cross‐sectional area (CSA) were then compared with those of the suspended rats(TS group) and control rats(Con group). The protein expression and phosphorylation level in soleus muscle were measured by Western blot.ResultsTreatment with the XFZY attenuated the loss of muscle mass and CSA induced by tail suspension in rats. Furthermore, western blot analysis showed that the phosphatidyl‐inositol 3‐kinase/Phospho‐AKT were both down‐regulated after 30d tail suspension, which were reversed by treatment of XFZY. Meanwhile, Tai suspension increased the expression of GRP78, CHOP, phospho‐JNK level and Caspase 12 in soleus muscle, and XFZY alleviated the increased protein expression in soleus muscle induced by tail suspension.ConclusionOur results suggested that the XFZY can partially reverse the effects of tail suspension on soleus muscle and maybe target on the endoplasmic reticulum stress (ERS) system by regulating GRP78‐CHOP‐JNK‐Caspase12 pathway.