Experimental Study On Skeletal Muscle Apoptosis And The Expression Of Bcl-2 And Bax In COPD Rats

Objective: To observe the impact of the apoptosis on the skeletal muscle atrophy and the expression of related genes Bcl-2 and Bax in rats with Chronic obstructive pulmonary disease(COPD).Methods: 100 healthy male adult Wistar rats were randomly divided into two groups: normal control group (n=20) and model group (n=80). The COPD rat model was performed with intratracheal instillation of PEE (20u/100g.Bw) on the 30 day of the modeling and exposed to cigarette smoke for 60 days, 30 minutes per day. The control group was not exposed to smoke but was intratracheally instilled of the same amount of Physiologic Saline on the 30^th day. The model rats were continually raised for another 30 days. Malnutrition was defined when the weight of the rats in the model group was lower than 90% of the mean body weight of the control group. All model rats were re-divided into 3 groups: the control group, the non-malnutrition COPD group, the malnutrition COPD group. Diaphragmatic muscle and long extensor muscle digits from rats were taken to make paraffin section. The rates of muscle apoptosis were measured by TUNEL method, expression of related genes Bcl-2 and Bax by immunohistochemical method, and the intensity of the expression of Bcl-2 and Bax by Image-Pro Plus version 6.0 systerm to deal with the pictures. All the data was handled by SPSS 13.0 software through one-factor analysis of variance, t-test and related analysis.Results: 1.The rates of muscle apoptosis in both diaphragmatic muscle and long extensor muscle digits of the malnutrition group were significantly higher than those of non-malnutrition group (P<0.01, P<0.01) and the control group (P<0.01, P<0.01). There were no significant differences between diaphragmatic muscle and long extensor muscle digits in the rates of muscle apoptosis of all three groups (P>0.05). 2. The expression of Bcl-2 in malnutrition group were significantly lower than those of non-malnutrition group (P<0.01, P<0.01) and the control group (P<0.01,P<0.01). The expression of Bax in malnutrition group were significantly higher than those of non-malnutrition group (P<0.01, P<0.01) and the control group (P<0.01, P<0.01). There were no significant differences between diaphragmatic muscle and long extensor muscle digits in the expression of Bcl-2 and Bax of all three groups (P>0.05).Conclusion:1. An significantly increase of rates of muscle apoptosis was found in COPD model rats. Apoptosis maybe the important mechanism in skeletal muscle atrophy of COPD model rats.2. The genes Bcl-2 and Bax are the factors to adjust the muscle apoptosis of COPD model rats.