Bile Cholesterol Content And The Contraction Function Of The Gallbladder The Relationship And The Regulating Mechanism Study

BackgroundGallstone has become one of the frequently-occurring diseases that affecting the human health. About85%of gallstones are cholesterol gallstones. But the mechanism of the gallstone formation still remains unknown. Recent researches have revealed that the changes in the gallbladder bile may be a direct factor affecting the contraction of the gallbladder, which could promote the gallstone formation. Type I cholecystokinin receptor (CCK-1R) widely locates in the smooth muscle and the mucosal cells in the gallbladder, which can cause the gallbladder contraction by binding with its ligand, cholecystokinin (CCK). Caveolin-3(Cav-3) is the main scaffolding protein in caveolae, which plays an important role in the signal transduction of G protein. The in vitro studies have found that, in gallstone patients, the cholesterol content increased in the plasma membrane in the smooth muscle, and the expression of Cav-3also increased, while the affinity of CCK and CCK-1R decreased, resulting in the decreased contraction of the smooth muscle. However, the relationship between the bile total cholesterol (TC) content and the gallbladder contraction and its effect on the expression of CCK-1R and Cav-3on histology and cell level have not been investigated.Objective(1) To investigate the difference of the serum content between gallstone group and non-gallstone group;(2) To analyze the relationship between the bile total cholesterol (TC) content and the contraction of the gallbladder;(3) To investigate the effect of the increased bile TC content on the expression of CCK-1R and Cav-3, and to explore the mechanism in inhibiting gallbladder contraction.Methods(1) The venous blood of gallstone patients and non-gallstone patients was collected, and the variation of the serum content was compared.(2) The bile in the gallbladder from gallstone patients and non-gallstone patients was collected, and the content of the bile TC and total bile acid (TBA) was detected;(3) The gallbladder contraction test in patients with gallstones was performed before the gallbladder surgery; (4) The expression of CCK-1R and Cav-3in gallbladder mucosa and the smooth muscle was detected using immunohistochemistry staining method.(5) The co-localization of CCK-1R and Cav-3in gallbladder mucosa and the smooth muscle was observed using immunofluorescence method.Results(1) No significant difference of the serum content between two groups was observed.(2) The content of bile TC and TBA in patients with gallstones was significantly higher than that in patients without gallstones.(3) The bile TC content in patients with a worse contraction of the gallbladder was significantly higher than that in patients with a better contraction of the gallbladder.(4) The EF value in gallstone patients was significantly negatively correlated with the bile TC content.(5) The immunohistochemistry staining revealed that the expression of Cav-3in the gallbladder mucosa in gallstone group was significantly higher than that in non-gallstone group. No significant difference of the expression of Cav-3in the smooth muscle between two groups was observed. And there was no significant difference of the expression of CCK-1R in both gallbladder mucosa and the smooth muscle between two groups.(6) The co-localization of CCK-1R and Cav-3in gallstone groups was obvious in both gallbladder mucosa and the smooth muscle, while no obvious co-localization was observed in non-gallstone group.ConclusionThe increase of bile TC content can inhibit the contraction of the gallbladder, and the mechanism may relate to excess Cav-3binding with CCK-1R, thus affecting the function of CCK.