Reactive oxygen species play a role in muscle wasting during thyrotoxicosis

Abstract

The role of reactive oxygen species (ROS) in muscle protein hydrolysis and protein oxidation in thyrotoxicosis has not been explored. This study indicates that ROS play a role in skeletal muscle wasting pathways in thyrotoxicosis. Two experimental groups (rats) were treated for 5 days with either 3,3',5-triiodothyronine (HT) or HT with α-tocopherol (HT + αT). Two controls were used, vehicle (Control) and control treated with αT (Control + αT). Serum T3, peritoneal fat, serum glycerol, muscle and body weight, temperature, mitochondrial metabolism (cytochrome c oxidase activity), oxidative stress parameters and proteolytic activities were examined. High body temperature induced by HT returned to normal when animals were treated with αT, although total body and muscle weight did not. An increase in lipolysis was observed in the HT + αT group, as peritoneal fat decreased significantly together with an increase in serum glycerol. GSH, GSSG and total radical-trapping antioxidant parameter (TRAP) decreased and catalase activity increased in the HT group. The glutathione redox ratio was higher in HT + αT than in both HT and Control + αT groups. Carbonyl proteins, AOPP, mitochondrial and chymotrypsin-like proteolytic activities were higher in the HT group than in the Control. HT treatment with αT restored mitochondrial metabolism, TRAP, carbonyl protein, chymotrypsin-like activity and AOPP to the level as that of the Control + αT. Calpain activity was lower in the HT + αT group than in HT and Control + αT and superoxide dismutase (SOD) activity was higher in the HT + αT group than in the Control + αT. Although αT did not reverse muscle loss, ROS was involved in proteolysis to some degree.

Oxidative and proteolysis‐related parameters of skeletal muscle from hamsters with experimental pulmonary emphysema: a comparison between papain and elastase induction

“…; Bernardes et al . ). Perhaps the thiolation group or tripeptide may have other destinations, such as thiolation or glutathiolation.…”

Isoflavin‐β modifies muscle oxidative stress and prevents a thyrotoxicosis‐induced loss of muscle mass in rats

“…For the initial investigation of the ability of Iso‐β to prevent thyrotoxicosis‐induced loss of muscle mass, the experiments were conducted in the same manner, but a 5‐day model of thyrotoxicosis was used. This experimental time was chosen based on our previous experience showing that muscle wasting was only observed after 5 days of T3 administration. To achieve this, rats were divided into 3 experimental groups ( n = 5): control; thyrotoxicosis (5TT); and thyrotoxicosis treated with Iso‐β (5TT‐Iso‐β).…”

“…Weight loss, weakness, and fatigue are among the hallmarks of the disease. Studies have suggested that oxidative stress is associated with development of myopathy related to muscle loss and atrophy in a very specific manner through protein oxidation …”

“…Recently, our group demonstrated that oxidative stress plays a role in muscle wasting in an experimental model of thyrotoxicosis during 5 days of 3,3′,5‐triiodothyronine (T3) administration . Before that, Guarnier et al .…”

“…However, those studies have shown divergent results, and the relationship between isoflavones and thyroid hormones is unclear. Furthermore, despite the described antioxidant action of isoflavones and the evidence that certain antioxidants, such as α‐tocopherol and N ‐acetylcysteine, could improve muscle conditions in experimental models of weight loss, participation of isoflavones in the process of muscle atrophy in thyrotoxicosis has not been investigated. Thus, we performed an initial experiment and observed that Iso‐β prevented thyrotoxicosis‐induced loss of muscle mass after 5 days of T3 administration.…”