The Role Of Botul Inum Toxin-A In Lower Esophageal Sphincter Of Dog

Aim:Investigate the effect of BTA on LES after BTA injection into the LES of dogs,and then LES pressure,contents of Ach and AchE activity were determined to provide scientific proof to treat achalasia with BTA. Methods:LES pressure was determined in 20 dogs.BTA was endoscopically injected circumferentially into the LES in 10 dogs,and saline injection as control group(10 dogs).one week later,LESP was determined again.Then In vitro, LES samples were gathered.Contents of acetylcholine and cholinesterase activity were determined,and after LES cut into ultraslices,By means of Karnovsky－Roots technique,ultrastructure of nerve terminal and vesicles containing Ach were studied under light and electronic microscopy of transmission. Results:(1)The LES pressure(LESP) in BTA-treated dogs obviously weakened(28.17±3.55mmHg vs. 9.93±1.06mmHg,p<0.01) and LESP in control group didn't change(28.60±2.79mmHg vs. 26.93±2.05mmHg,p＞0.01).(2)Contents of LES acetylcholine in BTA-treated dogs remarkably decreased when compared with control group(75.48±4.67μg/mg vs.93.03±4.65μg/mg,p＜0.01＝.Consequently, LES acetylcholinesterase activity in BTA-treated dogs apparently decreased too,compared with control group(69.88±6.73 U/mg vs. 38.20±2.17 U/mg,p＜0.01). (3)The colours of motor end plate faint away and the number ofwhich became less under light microscopy. the vesicles containing Ach and AchE－positive reactant in the nerve terminal reduceded distinctly under the electronic microscopy. Conclusion:When BTA was injected into LES, LESP decreased significantly. The reason may be that BTA distroyed or inhibited the vesicles of the cholinergic nerve terminal,and as the result,the contents of Ach and AchE activity were evidently reduced.