The Study Of Protective Effect And Mechanism Of Positive Acceleration Adaptive Training On Gastric Mucosa In Rats

Objective By establishing the rat model of positive acceleration adaptive training and observing the effects of adaptive training on gastric mucosal injury after positive acceleration in rats.The TXB₂、6-Keto-PGF1a、PGE₂、COX-1 mRNA and COX-2mRNA content in gastric mucosa were detected,and the TXB₂/6-K-PGF1 a ratio were calculated.To assess the protective mechanism of positive acceleration adaptive training on gastric mucosa in rats and to provide theoretical basis for the prevention of gastric mucosal injury-related diseases for pilots and astronauts.Methods Forty male SD rats were randomly divided into five groups:A、B、C、D and E.Group A was the control group,and did not undergo any treatment.Group B was exposed to +5 Gz for 5 minutes per day over 5 consecutive days.Group C was exposed to +10 Gz for 5 minutes per day over 5 consecutive days.Group D was exposed to +4Gz for 3 minutes per day over 5 consecutive days and +5 Gz for 5minutes per day over another 5 consecutive days.Group E was exposed to +4 Gz for3 minutes per day over 5 consecutive days and +10 Gz for 5 minutes per day over another 5 consecutive days.The damage to the gastric mucosa was then observed grossly and under a microscope to calculate the damage index.The TXB₂ 、6-Keto-PGF1 a and PGE₂ content in gastric mucosa was detected by ELISA,the TXB₂/6-K-PGF1 a ratio were calculate,the COX-1 mRNA and COX-2 mRNA content were detected by PT-PCR.Results（1）On unaided visual and microscopic observations,all groups developed mucosa damage,with the exception of group A.The lesion index was significantly higher in group C than in group B（5.625±1.767 vs 1.750±0.707,P < 0.05）.After adaptive training,the lesion index was significantly lower in group D than in group B（0.875±0.641 vs 1.750±0.707,P<0.05）and in group E than in group C（2.250±1.035 vs 5.625±1.767,P<0.05）.（2）The content of TXB₂ was significantly higher in group B than in group A（251.018pg/ml±50.845 pg/ml vs 121.400 pg/ml±41.629 pg/ml,P<0.05）,and in group C than in group B（331.538 pg/ml±79.102 pg/ml vs 251.018 pg/ml±50.845 pg/ml,P<0.05）.After adaptive training,the content of TXB₂ was significantly lower in group D than in group B（159.588 pg/m L ± 36.216 pg/m L vs 251.018 pg/m L ± 50.845 pg/m L,P <0.01）,and in group E than in group C（150.476 pg/m L ± 48.589 pg/m L vs 331.538pg/m L ± 79.102 pg/m L,P < 0.01）.The content of 6-K-PGF1α was significantly lower in group B than in group A（52.015pg/ml±11.827 pg/ml vs 106.322 pg/ml±16.909 pg/ml,P<0.05）,and in group C than in group A（44.726 pg/ml±18.867 pg/ml vs 106.322 pg/ml±16.909 pg/ml,P<0.05）.After adaptive training,the content of 6-K-PGF1α was significantly higher in group D than in group B（72.242 pg/m L ±12.413 pg/m L vs 52.015 pg/m L ± 11.827 pg/m L,P <0.05）,and in group E than in group C（87.426 pg/m L ± 15.833 pg/m L vs 44.726pg/m L ± 18.867 pg/m L,P < 0.05）.The ratio of TXB₂/6-K-PGF1α was significantly higher in group B than in group A（5.128±1.788 vs 1.199±0.545,P < 0.05）,and in group C than in group B（8.599±4.157 vs 5.128±1.788,P < 0.05）.After adaptive training,the ratio of TXB₂/6-K-PGF1α was significantly lower in group D than in group B（2.283 ± 0.705 vs 5.128 ± 1.788,P < 0.01）,and in group E than in group C（2.250 ± 1.035 vs 8.599 ±4.157,P < 0.01）.（3）The content of PGE₂ was significantly lower in group B than in group A（60.468pg/ml±9.697 pg/ml vs 81.462 pg/ml±20.340 pg/ml,P<0.05）,and in group C than in group B（24.598 pg/ml±6.017 pg/ml vs 60.468 pg/ml±9.697 pg/ml,P<0.05）.After adaptive training,the content of PGE₂ was significantly higher in group E than in group C（46.165 pg/ml±13.996 pg/ml vs 24.598 pg/ml±6.017 pg/ml,P<0.05）.（4）There was no significant differences on the expression of COX-1 mRNA in all groups（P>0.05）.The expression of COX-2 mRNA was significantly higher in group B than in group A（1.492±0.281 vs 0.978±0.109,P<0.05）,and in group C than group B and group A（2.642±0.320 vs 0.978±0.109,P<0.05;2.642±0.320 vs 1.492±0.281,P<0.05）.After adaptive training,the expression of COX-2 mRNA was significantly higher in group D than in group B and in group E than group C（1.782±0.099 vs1.492±0.281,P<0.05;3.268±0.083 vs 2.642±0.320,P<0.05）.（5）The content of 6-Keto-PGF1α and the expression of COX-1 mRNA,and the expression of COX-2 mRNA,had no significant correlation（P<0.05）.The content of PGE₂ and the expression of COX-1 mRNA,and the expression of COX-2 mRNA,had no significant correlation（P<0.05）.Conclusion Adaptive training can significantly reduce the gastric mucosal damage caused by high +Gz value,and its mechanism is related to the increase in PGI₂、PGE₂content,and the reduce in TXA2 content、 TXA2/PGI₂ ratio,and expression increase of COX-2 mRNA.