| In peacetime and wartime the submarine may sink owing to accidents. To save their lives in the submarine the crew must carry out underwater escape. The fast buoyant ascent escape is a new advanced single-man escaping technique, which comes from undecompression diving. Before the submarine crew carry out fast buoyant ascent escape, they must be in escape immersion suit, compressed quickly in the escape trunk whose pressure must be equal to that of the outside, then leave the submarine, emerge quickly to the water surface and waiting for rescue. This technique has many advantages, such as escaping deeperly, operating easily, low incidence of diving sickness. At present the greatest escaping depth is 183m for human body test. The former research showed the diver presented stress response after stimulated fast ascent escape from various depth: ST section drop in ECG, the concentration of dynorphin, β-endorphin, CRH and ACTH in plasma increased. However, deeper research has not yet been reported. Glucocorticoid receptor (GR) is the key molecule inducing the reaction of target cells to the hormone, the protein expression and affinity of which is concerned with many sickness and pathological-physiological reaction. So far the changes of GR in escaping stress have not been reported. The major objectives of this study are: 1. establishing the rat model of fast compression and decompression; 2. observing the changes of GR mRNA from hepatic cells after fast compression and decompression exposure; 3. with histological pathology and serum biochemistry, exploring changes of liver function after fast compression and decompression exposure. This study was to explore the mechanism of GR in regulating stress response after fast compression and decompression exposure, and provide theoretical basis for the medical care of greater-depth fast buoyant ascent escape.The main results of our study are as follows:1. Using the healthy adult SD rats, we carried out different schems of fast compression and decompression. After being compressed to 2.1 MPa abs atm at 11.8m/s speed and stayed for 2 seconds, then being decompressed at 2.5m/s speed to normal, the rats had not appeared obvious changes; the bubbling sound of precordial region were all 0 Spencer level through Doppler detectation assay. The results suggested the rat model of fast compression and decompression has been established.2. The concentration of serum LDH of 1h group after fast compression and decompression was increased (p<0.05). Histology changes showed the central vein of liver had hyperemia; the heptic cells around it appeared local denaturation and necrosis. This result suggested the liver existed slight inflammatory injury which might result from stress response after fast compression and decompression exposure.3. The transcriptional levels of GR mRNA of liver tissue after fast compression and decompression exposure were detected by RT-PCR assay. The level of GR mRNA of 1h group was markedly lower than that of normal group(p<0.01); The levels of GR mRNA of 2h group, 4h group were increased, but yet obviously lower than that of normal group(p<0.01). Till 24h after fast compression and decompression exposure, the expression of GR mRNA achieved to the normal level (p>0.05). 4. Refering to β-actin, electrophoresis showed the GR mRNA level of group 1h was only 2.8%, group 2h up to 9.3%, group 4h up to 15.8%, there were statistical significance compared to that of normal group (p<0.01). The GR mRNA level of group 24h was up to 63.5%, there was no statistical significance compared to that of normal group (p>0.05).The above results showed fast compression and decompression exposure could cause obvious stress response for rats. It resulted in the concentration of serum LDH increasing, made the expression of liver GR mRNA decreasing quickly and sharply. From this study, we can conclude that massive glucocorticoid induced by stress down-regulated its GR transcription, through which inhibited the ultra-production of many inflammatory factors and prot... |
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