Protective Effect Of Prototype Glutathione On The Disfunction Of Diaphragmatic Muscle In Type2Diabetic Rats

Objective: Diabetes is a chronic metabolic disease which characterized by the increase of blood glucose level. The incidence of diabetes was increased year by year and harm the human body seriously. Now more clinical researches were focus on diabetes induced cardiovascular and kidney damage, fewer reports on skeletal lesions caused by diabetes, so further studies are needed. Skeletal muscle is one of the main organ which using glucose to provide energy, damage isand also the main organ which damaged by high blood sugar. The common symptoms include muscle weakness, muscle atrophy and muscle aches. Oxidative stress can cause excessive oxygen free radicals, excessive oxygen free radicals cause cell membrane and intracellular organelles impaired, resulting in damage to the structure and function of cells, not only can lead to various complications of diabetes lesions, but also cause insulin resistance in skeletal muscle. Reduced glutathione can get rid of the oxygen ions and other radicals, protect cell membrane integrality, promote intracellular activity, and antioxidant role, it is the major metabolite regulate substance in human cells. This study is to observe the protection and likely antioxidative mechanism of reduced glutathione on diabetic induced diaphragm injury.Methods:Thirty male SD rats were randomly divided into type2diabetes (2-DM group, n=10) and reduced glutathione (GSH group, n=10) group after given high fat and high-sugar diet for8weeks. Normal control rat (CON group, n=10) as the control. Diabetic rats in2-DM and GSH groups were induced by intraperitoneal injection of streptozotocin (30mg/kg). The rats in GSH group were injected intraperitoneally with GSH at500ug/g, the rats in2-DM and CON groups were treated by intraperitoneal injection of saline as control. The rats were sacrificed after8weeks, then diaphragm contractility was assessed using Peak twitch tension (Pt), maximal rise velocity of tension (+dT/dtmax), maximal fall velocity of tension (-dT/dtmax), maximum tetanic tension (Po) in isolated diaphragm strip. Malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were detected in the diaphragm tissue. The gene expression of Titin and Nebulin proteins in diaphragm were examined by reverse transcription-polymerase chain reaction (RT-PCR).Results:(1) Compared with CON group, Pt, Po,+dT/dtmax,-dT/dtmax were significantly lower than in2-DM group (P<0.01); Pt, Po,+dT/dtmax,-dT/dtmax in GSH group were higher than in2-DM group (P<0.01); there were not statistically differences of Pt, Po,+dT/dtmax and-dT/dtmax between GSH group and CON group.(2) MDA content was increased and SOD activity was decreased, which was statistically significant in2-DM group compared with CON group (P<0.05); The difference was statistically significance in the decrease of MDA content and increase of SOD activity between GSH group and2-DM group (P<0.05).(3) The diaphragm muscle fibers were arranged in neat rows, dense, sarcomere was clear, mitochondria were arranged neatly, no swelling, and high density in CON group. The diaphragm muscle fiber cells were swellen, filaments were disordered, part of the muscle cells were broken, sarcomeres weredisappeared, mitochondria were swelled and the number was reduced, even a large number of mitochondria vesicles or vacuoles were appeared in2-DM rats, In GSH group, the arrangement of diaphragm muscle fibers were significantly improvement and sarcomere was clear compared with2-DM group.(4) RT-PCR detecting were shown: Compared with CON group, the mRNA expressions of Titin and Nubulin protein were significantly decreased in2-DM group (P<0.01); The protein expressions of Titin and Nebulin at mRNA level in GSH group were significantly increased compared with2-DM group (P<0.01). There were no statistically significant in the expression of Titin and Nebulin at mRNA level between CON group and GSH group.Conclusion:GSH can improve the mechanical properties of the diaphragm contraction damaged by diabetes and reduce oxidative stress injury, it may be by increase the mRNA expressions of cytoskeletal Titin and Nebulin protein.