The Effect Of Glial Cell Line-derived Neurotrophic Factor On The Dissimilation And Remodeling Of Nicotinic Acetylcholine Receptors In Skeletal Muscle Of Sepsis Rats

Objective To investigate the regulation of glial cell-derived neurotrophic factor(GDNF)on sepsis-induced dissociation of nicotinic acetylcholine receptors in skeletal muscle and to investigate its effect on skeletal muscle in sepsis rats Improvement of neuromuscular dysfunction.Methods 60 healthy adult Sprague-Dawley rats were selected and randomized into 6 groups(n=10): sham operation group(sham group)and 4-hour group(4 hours group).6-hour group(6-hour group),12-hour group(12-hour group),24-hour group(24-hour group),and GDNF+24-hour group(GDNF+24-hour group).The sham group only underwent laparotomy In the other groups,cecal ligation and puncture(CLP)was used to construct the sepsis model.In each group,abdominal aorta and tail vein blood samples were taken within 1 hour after modeling(CLP)or sham operation.Serum TNF-α and interleukin 6 were measured by ELISA.(IL-6)levels.Rat survival rates were observed after modeling or sham surgery.The horizontal movement distance and number of erections were observed in each group of rats.The rats were anesthetized and the rat sciatic nerves were dissected to measure the compound muscle action potential(CMAP)in rats.The rats were sacrificed and the specimens were collected.The anterior tibial muscle was taken and the expression and distribution of γ-nAChR,α7-nAChR,and GFR-α in the anterior tibial membrane were measured by immunofluorescence.The γ-nAChR,α7 in muscle specimens was measured by Western-blot.-nAChR,neuregulin-1,GFR-α,ERK1/2,and GDNF protein expression.Results(1)Cytokine levels: Compared with the sham group,IL-6 and TNF-α levels in the CLP group were significantly higher than those in the sham group,and they gradually increased with the prolongation of time(P<0.05).(2)Comparison of the number of erections in each group: In the comparison of the number of erections,the erection frequency of CLP group was significantly lower than that of sham group,and the number of erections of rats decreased gradually with the extension of CLP modeling time,and the difference was statistically significant.(P<0.05);In the comparison of horizontal distance of movement,the distance of horizontal movement of CLP group was also significantly lower than that of sham group,and with the extension of CLP modeling time,the distance of horizontal movement of rats gradually decreased,and the difference was statistically significant(P<0.05).(3)Comparison of CMAP in rats: Comparison of CMAP composite action potential in rats,compared with sham group,amplitude,frequency,conduction velocity of action potential in CLP group Compared with the sham group,both the latency and the incubation period increased.With the prolongation of the CLP modeling time,the corresponding indicators of the action potential of the anterior tibial muscle increased gradually,and the difference was statistically significant(P<0.05).(4)Immunofluorescence analysis of the expression and distribution of γ-nAChR,α7-nAChR and GFR-α in rat tibialis anterior muscle cell membrane: γ-nAChR,α7-nAChR and GFR-α are expressed on the cell membrane,and the sham group Compared with the CLP group,the fluorescence intensity of γ-nAChR,α7-nAChR and GFR-α were significantly increased,and the fluorescence intensity gradually increased with the prolongation of the CLP modeling time.The difference was statistically significant(P<0.05).(5)Western-blot determination of γ-nAChR,α7-nAChR,neuregulin-1,GFR-α,ERK1/2,and GDNF in muscle samples: Compared with sham group,γ-nACh R,α7-The expression of nAChR increased,and the expression of γ-nAChR,α7-n AChR,GFR-α and ERK1/2 increased with time,and the expression of neuregulin-1 and GDNF decreased gradually.The difference was statistically significant(P<0.05).Conclusions(1)Sepsis can lead to increased expression of naive acetylcholine receptors γ-nAChR and α7-n ACh R on the skeletal muscle cell membrane,which is distributed on the entire cell membrane of skeletal muscle.(2)Within 24 hours of the acute phase of sepsis,CMAP of skeletal muscles of rats showed a gradual downward trend with time,and skeletal muscle neuromuscular dysfunction gradually increased.(3)Within 24 hours of the acute phase of sepsis,the expression of γ-nAChR and α7-nAChR gradually increased with time,and the protective factors neuregulin-1 and GDNF gradually decreased.(4)Exogenous administration of GDNF can improve skeletal muscle neuromuscular dysfunction caused by sepsis by reducing the expression of γ-and α7-n AChR.(5)GDNF exerts neuromodulatory effects through extracellular signal-regulated kinase ERK1/2 and GDNF receptor GFR-α signal transduction pathways.