Effect Of Chronic Intermittent Hypoxia On Genioglossal Muscle And Its Intervention By Oxygen Therapy

Objectives To study the effect of chronic intermittent hypoxia on genioglossal muscle in rats and the intervention of oxygen therapy.Methods 1 20 adult male Sprague-Dawley rats,SPF grade,8 weeks old,were randomly divided into normal control group and CIH group(n=10)according to random number table method.Rats in the normal control group were placed in the cage of air circulation with conventional feed and drinking water;rats in the CIH group were placed in the intermittent hypoxic chamber(provided by the Institute of Frontier Interdisciplinary Studies of Peking University,model:MS-01)for 8 hours a day for 4 weeks;rats in the experimental group were anaesthetized and dissected and the genioglossal muscle tissue was taken out.Three rats in each group were randomly selected to cut off two small pieces of genioglossal muscle tissue.(about 1 mm~3)was fixed in 2.5%glutaraldehyde phosphate buffer and 10%formalin respectively.The samples were stored in refrigerator at 4℃for electron microscopy and HE staining.The residual genioglossal muscle tissue was used to detect reactive oxygen species(ROS)level by immunofluorescence staining on frozen sections.2 20 adult male Sprague-Dawley rats of SPF grade were randomly divided into normoxia group(returning to normal air feeding after intermittent hypoxia)and oxygen therapy group(receiving 37%oxygen concentration intervention after intermittent hypoxia),with 10 rats in each group(n=10).Oxygen group and oxygen therapy group were given intermittent hypoxia for 4 weeks.Oxygen group was fed in normal oxygen concentration environment for 2 weeks(4hours/day),oxygen therapy group was fed in 37%oxygen concentration environment for 2weeks(4 hours/day).At the end of 6 weeks,rats were anaesthetized and dissected,and the genioglossal muscle tissue was taken out to detect the ROS level of rat genioglossal muscle by immunofluorescence method.Results 1 There was no significant difference in body weight between the two groups before and after hypoxia(P>0.05),and there was no significant difference in body weight between the normal control group and CIH group(P>0.05);HE staining showed that the myofibrils in the control group were arranged regularly and the nuclei were arranged neatly;the myofibrils in the CIH group were disordered and the nuclei were arranged disorderly.Compared with the control group,the structure of myofibrils in CIH group was disordered,some myofibrils dissolved,and mitochondrial concentration,size,edema,ridge breakage and vacuolation were observed between myofibrils.Immunofluorescence staining of frozen sections showed that the number of ROS in genioglossal muscle in CIH group was significantly higher than that in control group(P<0.05).There was no significant difference in body weight between the two groups before and after the experiment(P>0.05),and there was no significant difference in body weight between the normoxia group and the oxygen group after the experiment(P>0.05).Immunofluorescence staining of frozen sections showed that the ROS number of genioglossal muscle in the oxygen group was significantly lower than that in the normoxia group.3 Compared with CIH group,ROS in normoxia group and oxygen therapy group decreased significantly,especially in oxygen therapy group.Conclusion 1 Chronic intermittent hypoxia can destroy the mitochondrial structure of genioglossal muscle cells.Chronic intermittent hypoxia can cause significant oxidative stress in genioglossal muscle,which may aggravate the mitochondrial damage of genioglossal muscle.2 Removal of intermittent hypoxic environment reduced ROS levels in genioglossal muscle of CIH rats,especially in genioglossal muscle of CIH rats under 37%oxygen therapy,suggesting that 37%oxygen therapy can alleviate oxidative stress in genioglossal muscle caused by chronic intermittent hypoxia.Figure 13;Table 4;Reference 138.