Effects of cholecystokinin on gallbladder stasis and cholesterol gallstone formation

Recent studies suggest an etiologic role for gallbladder stasis in the genesis of cholesterol gallstones. The effect of periodic gallbladder emptying on stone prevention is not clear. Using the prairie dog model, we tested the hypothesis that daily cholecystokinin-octapeptide (CCK-OP) prevents gallbladder stasis and cholesterol gallstone formation. Prairie dogs were fed either a control or a 0.4% cholesterol-enriched chow for 6 weeks. Cholesterol-fed animals received a daily intramuscular injection of either saline, CCK-OP, 0.2 μg/kg or CCK-OP, 1.0 μg/kg. Gallbladder bile lithogenic index (LI), bile salt pool size (BSPS), and the degree of radioisotope equilibration between gallbladder and hepatic bile (Rsa-an index of stasis) were determined. The more physiologic dose of CCK-OP (0.2) significantly reduced BSPS and bile lithogenicity, prevented stasis and reduced the incidence of gallstones. Our data suggest that (1) periodic gallbladder emptying decreases bile lithogenicity, prevents stasis, and reduces the incidence of cholelithiasis, (2) stasis is essential to gallstone formation and (3) daily physiologic doses of CCK-OP may be useful for gallstone prophylaxis in high-risk patients.     

The Use of Simvastatin for the Prevention of Gallstones in the Lithogenic Prairie Dog Model

Background: Surgery for morbid obesity is rapidly increasing. Patients undergoing bariatric surgery are prone to gallstone development during the rapid weight loss. These patients are often given medications such as ursodeoxycholic acid to prevent gallstone formation; however, these medications are often poorly tolerated by patients, who subsequently discontinue them. We performed a study in a lithogenic animal model to assess the effectiveness of a potential alternate medication for gallstone prevention. Methods: 20 male prairie dogs were randomly separated into 2 groups and fed a lithogenic diet for 28 days. The study group animals were given 2.5 mg of the HMG-CoA reductase inhibitor simvastatin. Total cholesterol and triglycerides were measured and an open cholecystectomy was performed on each animal at the conclusion of the study period. The gallbladder was visually inspected for gallstones and microscopic biliary cholesterol crystal formation. Results: There was a decrease of 36% in the total cholesterol of the study animals compared to controls. The animals treated with simvastatin showed gallstone formation in 5/10 (50%) of animals, compared with 6/10 (60%) of control animals. The study animals demonstrated microscopic cholesterol crystal formation in 80%, identical to the number found in the control animals. Conclusion: Despite a reduction in cholesterol, simvastatin prevented neither gallstone formation nor biliary cholesterol crystals in this animal model. Given the rapid increase in the number of bariatric surgical procedures coupled with the poor tolerance of ursodeoxycholic acid, viable alternatives should continue to be sought for these patients.     

The prevention of experimental cholesterol gallstones by ileectomy in mice

After a lithogenic diet containing 0.5 per cent cholesterol and 0.25 per cent sodium cholate was fed to a group of normal Crj-ICR male mice for 10 days, cholesterol gallstones developed. No formation of gallstones occurred, however, in a group of mice from which 20 cms of terminal ileum had been removed prior to the feeding of the lithogenic diet. The biliary concentrations of cholesterol, phospholipids and bile acids were markedly lower in the ileectomized mice, with the decrease in cholesterol concentration being most significant. On the other hand, fecal excretion of sterols and bile acids increased in the ileectomized mice. The pool size of bile acids increased after the feeding of the lithogenic diet, but ileectomy decreased the pool size in mice fed the ordinary or lithogenic diets. The biliary concentration of cholic acid increased after the feeding of the lithogenic diet, but decreased with ileectomy. The biliary concentration and fecal excretion of deoxycholic acid markedly increased, while those of beta-muricholic acid and its secondary bile acids, omega-muricholic acid and hyodeoxycholic acid, decreased. The increase in plasma and liver cholesterol levels after the feeding of the lithogenic diet was prevented by ileectomy. These data suggest that ileectomy prevents the formation of cholesterol gallstones after the feeding of a lithogenic diet due to a decrease in cholic acid absorption.     

The prevention of experimental cholesterol gallstones by ileectomy in mice

After a lithogenic diet containing 0.5 per cent cholesterol and 0.25 per cent sodium cholate was fed to a group of normal Crj-ICR male mice for 10 days, cholesterol gallstones developed. No formation of gallstones occurred, however, in a group of mice from which 20 cms of terminal ileum had been removed prior to the feeding of the lithogenic diet. The biliary concentrations of cholesterol, phospholipids and bile acids were markedly lower in the ileectomized mice, with the decrease in cholesterol concentration being most significant. On the other hand, fecal excretion of sterols and bile acids increased in the ileectomized mice. The pool size of bile acids increased after the feeding of the lithogenic diet, but ileectomy decreased the pool size in mice fed the ordinary or lithogenic diets. The biliary concentration of cholic acid increased after the feeding of the lithogenic diet, but decreased with ileectomy. The biliary concentration and fecal excretion of deoxycholic acid markedly increased, while those of β-muricholic acid and its secondary bile acids, ω-muricholic acid and hyodeoxycholic acid, decreased. The increase in plasma and liver cholesterol levels after the feeding of the lithogenic diet was prevented by ileectomy. These data suggest that ileectomy prevents the formation of cholesterol gallstones after the feeding of a lithogenic diet due to a decrease in cholic acid absorption.     

The role of cystic duct resistance in the pathogenesis of cholesterol gallstones

Several recent clinical and laboratory observations suggest that impaired gallbladder emptying is important in the pathogenesis of cholesterol cholelithiasis. However, the exact mechanism by which gallbladder stasis occurs in the majority of patients who form gallstones has not been clear. We tested the hypothesis that impaired gallbladder emptying antedates cholelithiasis and results from increased resistance to bile flow. Using the prairie dog gallstone model, resistance to flow through the cystic duct (CD) and sphincter of Oddi (SO) was measured in control and cholesterol-fed animals. Prairie dogs were fed either a control (trace cholesterol) or a 0.4% cholesterol-enriched diet known to induce gallstones in 6 weeks. Resistance across the CD and SO was measured at 4 weeks (pregallstone) and 16 weeks (gallstone). Resistance was measured by infusing lactated Ringer's solution through the CD and SO at four separate flow rates while gallbladder and distal common bile duct pressures were recorded. Resistance to flow through the cystic duct increased prior to gallstone formation and continued to increase during the 16 weeks of cholesterol feeding. In comparison, sphincter of Oddi resistance remained normal despite chronic exposure to lithogenic bile and formation of stones within the gallbladder. The increased cystic duct resistance observed prior to gallstone formation provides a mechanism for diminished gallbladder emptying and suggests an etiological role for increased cystic duct resistance in the pathogenesis of cholesterol gallstones.     

Role of gallbladder mucus in the pathogenesis of cholesterol gallstones

Recent observations indicate that the hepatic secretion of lithogenic bile, gallbladder mucus hypersection, and gallbladder stasis are all critical factors in the pathogenesis of cholesterol gallstones. Using the prairie dog gallstone model, we investigated the interaction of these factors and the sequence in which they develop. The results of this study indicated that (1) gallbladder bile mucus concentration is elevated before cholesterol precipitation and increases progressively with the formation of cholesterol crystals, (2) cystic duct resistance increases in the presence of cholesterol crystals, but not fine, sonicated crystals increase cystic duct resistance. We conclude that these alterations trigger a self-perpetuating cycle of mucus hypersecretion, cholesterol crystallization, and gallbladder stasis which culminates in the formation of cholesterol gallstones.     

Biliary cholesterol and lithogeneity of bile in patients after ileal resection

For determination of the factors that regulate biliary cholesterol secretion and the lithogenity of bile in ileal dysfunction, plasma and biliary lipids and fecal excretion of bile acids were studied in 29 patients who had undergone ileal resection. Seven patients with ileal resection had normal bile acid excretion (less than 10 mg/kg/day), and 22 had various degrees of bile acid malabsorption. None of the patients had gallstones when examined with abdominal sonography. LDL cholesterol levels were decreased in bile acid malabsorption and demonstrated a positive correlation with the molar percentage of biliary cholesterol. Biliary cholesterol (mol percent) was inversely correlated with fecal bile acid excretion. This finding suggests that biliary cholesterol secretion decreases with increasing loss of bile acids to feces in ileal dysfunction, leading to an actual decrease in the lithogenic index and to hyposaturation of cholesterol in bile. The reduction in biliary cholesterol, regarded as protecting the gallbladder mucosa against the detergent properties of bile acids, may play an important role in the pathogenesis of increased gallstone formation in ileal dysfunction.     

Gallstones, obesity, and jejunoileostomy

An attempt has been made to identify the causes of increased cholesterol gallstone formation in obese patients both before and following jejunoileostomy. The prime lithogenic mechanism in obesity seems to be increased cholesterol mobilization and excretion in the bile. In jejunoileal bypass, a host of factors, including possible limited bile salt synthesis, increased bile salt loss, and bacterial alteration of bile acids, along with the effects of rapid weight loss, may play a role. The identification and understanding of these factors will be important if attempts at prevention by administratin of antibiotics to reduce bacterial overgrowth, or by giving chenodeoxycholic or ursodeoxycholic acid to replenish the diminished bile acid pools, are to be carried out.     

Research progress on the immune microenvironment of the gallbladder in patients with cholesterol gallstones

Cholesterol gallstones are very common in hepatobiliary surgery and have been studied to a certain extent by doctors worldwide for decades. However, the mechanism of cholesterol gallstone formation is not fully understood, so there is currently no completely effective drug for the treatment and prevention of cholesterol gallstones. The formation and development of cholesterol gallstones are caused by a variety of genetic and environmental factors, among which genetic susceptibility, intestinal microflora disorders, impaired gallbladder motility, and immune disorders are important in the pathogenesis of cholesterol gallstones. This review focuses on recent advances in these mechanisms. We also discuss some new targets that may be effective in the treatment and prevention of cholesterol gallstones, which may be hot areas in the future.     

单个与多发胆固醇结石患者胆道细菌感染状况及与免疫球蛋白相关性的对照研究

目的 多发胆固醇结石患者胆囊炎症程度较高,可能与结石形成有关.对多发和单个胆固醇结石患者胆道细菌感染状况及与免疫球蛋白含量的相关性进行对照研究.方法 :用半定量PCR法测定分析38例胆囊结石患者胆石、胆汁和粘膜的细菌DNA阳性率和菌落数,并测定相应胆汁和粘膜IgA、IgG、IgM含量.结果 :单个和多发胆石组的胆汁细菌DNA阳性率分别为75.0%和73.7%,胆囊粘膜细菌DNA阳性率分别为66.7%和64.0%,结石核心的细菌DNA阳性率分别为57.1%和85.7%,结石外周细菌阳性率分别为71.4%和85.7%,两组间差异均无显著性.两组间胆汁和粘膜IgA、IgG、IgM含量差异无显著性,菌落数与免疫球蛋白含量不相关.多发胆石组粘膜细菌DNA阳性者的胆囊粘膜IgA、IgG含量高于阴性者(P<0.05).单个和多发胆石组胆汁胆固醇饱和指数(CSI)差异无显著性,各组内胆汁细菌阳性与阴性者的CSI差异也无显著性.结论 :多发和单个胆固醇结石患者胆囊细菌感染率相似,细菌感染不是多发胆固醇结石患者胆囊炎症严重的原因.多发胆固醇结石患者胆囊粘膜细菌与IgA、IgG含量增高有关,可能间接参与胆固醇结石的形成过程.     

骨桥蛋白在胆固醇结石患者胆汁中的表达及成核作用研究

目的 探讨骨桥蛋白在人胆固醇结石形成中的作用.方法 36例胆固醇结石患者为结石组,19例肝移植供体为正常组,分别测定骨桥蛋白、钙离子及脂质成分在胆囊胆汁中的含量,用成核时间法研究骨桥蛋白在胆汁中的成核作用.结果 骨桥蛋白呈剂量依赖性地抑制胆固醇自发成核.50 μg/ml的骨桥蛋白可分别使结石组和正常组胆汁的成核时间延缓48.90％和17.07％,100 μg/ml的骨桥蛋白可使成核时间延缓91.51％和32.93％;并可抑制钙离子诱导的促成核作用.50μg/ml骨桥蛋白+钙离子可分别使结石组和正常组胆汁成核时间延缓75.78％和33.96％,而100μg/ml骨桥蛋白+钙离子则使成核时间分别延缓125.90％和62.26％.结石组胆汁中胆固醇、磷脂、胆汁酸及胆固醇饱和指数均显著高于正常组胆汁(P＜0.05),而骨桥蛋白和钙离子含量则明显低于正常组胆汁中的含量(P＜0.05).结论 骨桥蛋白可抑制胆固醇成核,并参与胆结石的发生发展.     

Cholelithiasis in mice: effects of different chemicals upon formation and prevention of gallstones

Prevention of gallstones induced in mice by 1% cholesterol and 0.5% cholic acid (lithogenic diet) for 8 weeks was obtained by simultaneously feeding sulfaguanidine (1.5%) and dodecyl sodium sulfate (0.5–1.0%) along with the lithogenic diet. Citrus pectin (3%), egg lecithin (1%), n-octyl alcohol (1%), neomycin sulfate (0.2–0.5%) and l-ascorbic acid (5%) added to the lithogenic diet did not prevent gallstone formation. The condition of the liver, fatty or normal, in the experiment could not be correlated with the stone formation. Lower serum and liver cholesterol levels and an elevation of lecithin concentrations in serum was noticed in mice fed the sulfaguanidine and dodecyl sodium sulfate diet.     

An experimental study on preventing gallstone formation by exogenous cholecystokinin

It is well known that stasis of lithogenic bile in the gallbladder is an important factor in cholesterol gallstone formation. In this study, hamsters fed with standard lithogenic diet were given physiologic dose of exogenous cholecystokinin-octapeptide daily to facilitate emptying of the gallbladder. It was found that there was significant reduction in the gallstone formation. This study suggests that gallbladder motility is closely correlated with cholesterol gallstone formation, and administration of exogenous cholecystokinin-octapeptide can effectively prevent gallbladder stasis and reduce the incidence of cholelithiasis. This method may be useful for gallstone prophylaxis in high-risk individuals.     

Dissolution of gallstones--when and how?

Availability of bile acid therapy for gallstone dissolution adds another therapeutic choice for treatment of gallstone disease. Because dissolution is slow and eventual outcome uncertain, surgery remains the treatment of choice for most patients who have experienced symptoms clearly related to their gallstones. Patients with only dyspeptic or no gastrointestinal symptoms, especially if significant associated cardiac or pulmonary disease exists, may be candidates for bile acid therapy with chenodeoxycholic acid or its 7-beta epimer, ursodeoxycholic acid, when available. Fifty to 75 per cent of patients, depending on individual criteria, may anticipate complete dissolution. Radiolucent gallstones and gallbladder opacification are basic requirements for cholelitholytic therapy. Periodic assessment of laboratory parameters is necessary at routine visits and when unexpected symptoms occur. In a few patients, evidence of obstructive gallstone disease will develop during bile acid therapy and surgery will be required. The value of bild acid therapy for the relief of dyspeptic symptoms, the role of bile analysis, and optimal long-term therapy remain to be established.     

家族性胆固醇结石患者肝组织CYP7A1 mRNA的表达

目的:研究家族遗传性胆囊胆固醇结石患者、散发性胆固醇结石患者和非结石患者肝组织CYP7A1基因mRNA的表达改变及其与胆汁成石性变化的关系.方法:应用逆转录-聚合酶链反应(RT-PCR)技术,研究了28例具有家族遗传性胆囊胆固醇结石患者、30例散发性结石患者和32例非结石患者肝组织CYP7A1 mRNA的表达变化;并采用生物化学技术行胆汁脂质分析,计算成石指数.结果:家族遗传性和散发性胆固醇结石组CYP7A1 mRNA表达水平较非胆固醇结石组降低,差异有显著性;在家族遗传性和散发性胆固醇结石组两组间无统计学差别;各组肝组织CYP7A1 mRNA表达与胆汁成石指数(LI)呈负相关.结论:胆囊胆固醇结石患者肝组织CYP7A1 mRNA水平降低,因而CYP7A1 mRNA表达下调可能是胆囊胆固醇结石形成的重要原因之一;CYP7A1是决定胆汁成石性和胆囊胆固醇结石发生的一个重要基因.     

紧密连接蛋白2缺失对小鼠胆汁及胆固醇结石形成的影响分析

目的 旨在探究紧密连接蛋白2（Cldn2）在胆汁分泌中的相关作用。方法 实验将受试小鼠分为Cldn2^-/-基因敲除组（Cldn2^-/-组）与Cldn2^+/+野生型组（Cldn2^+/+组）,进行4周致石饮食,两组小鼠分别获得肝脏及胆管组织,通过组织学、生物化学、电生理学分析等分析两组小鼠肝脏和胆管内水及相关离子渗透压梯度运动差异;评价两组小鼠胆结石的形成情况。结果 Cldn2 ^+/+组小鼠的胆汁流速为[（58.0±4.4）μL/ （min·kg）],约为Cldn2^-/-组[29.0±3.3 μL/（min·kg）]的2倍,Cldn2^-/-组胆汁中总胆固醇、磷脂、总胆汁酸及总胆红素均显著高于Cldn2+/+组（P＜0.01）。当将Cldn2^+/+组的肝内胆管单位（IBDU）置于低渗缓冲液中时,腔内空间立即增加且持续至90 s;相反,当IBDU置于高渗缓冲液中时,Cldn2^+/+组腔内空间立即降低并且持续收缩至90 s;Cldn2^-/-组具有相同的趋势,但变化幅度显著低于Cldn2^+/+组,表现为90 s低渗时[（1.20±0.02）% vs（1.34±0.02）%,P=0.035],高渗时[（0.67±0.01）% vs（ 0.82±0.01）%,P=0.025]。与Cldn2^+/+组比,Cldn2^-/-组Na⁺浓度降低,但K⁺浓度升高,跨上皮电传导速度显著降低。致石饮食后所有Cldn2^-/-组肉眼均可见明显的胆结石形成,结石的主要成分是胆固醇（＞98%）,而Cldn2^+/+组中仅1 只小鼠有结石形成。结论 Cldn2 可能通过调控胆汁中的水分、胆固醇含量以及离子浓度,进而影响胆汁流速和成分,该蛋白的缺失会导致胆固醇结石发生的风险增加。     

Soluble dietary fiber protects against cholesterol gallstone formation.

BACKGROUND: Epidemiological studies have suggested that soluble dietary fibers are hypocholesterolemic and may inhibit cholelithiasis. METHODS: Thirty prairie dogs were placed on a cholesterol-supplemented lithogenic diet. Ten animals received 5% psyllium (PSY) and 10 animals received 5% cellulose. After 6 weeks all gallbladders were inspected for stones; blood and bile were collected for analysis. RESULTS: Cholesterol stones were present in 8 of 10 of the control animals, in 6 of 10 of the cellulose group, and 3 of 10 of the PSY animals (P <0.05). Concentrations of cholesterol and chenodeoxycholic acid (CDCA) were significantly lower in the PSY group compared with controls (0.49 versus 0.88 mM and 4.2 versus 9.2 mM, respectively) leading to a significant reduction in the cholesterol saturation index (0.62 versus 1.2). CONCLUSIONS: A dietary soluble fiber (PSY) inhibits cholesterol stone formation by reducing the biliary cholesterol saturation index. This protective effect is associated with a selective decrease in biliary cholesterol and CDCA.     

Stasis before gallstone formation: Altered gallbladder compliance or cystic duct resistance?

Gallbladder stasis occurs before gallstone formation and provides the link between the hepatic secretion of supersaturated bile and cholesterol cholelithiasis. We recently observed that cystic duct resistance increases while sphincter of Oddi resistance is unchanged in the presence of lithogenic bile without gallstones. Whether alterations in gallbladder function also lead to gallbladder stasis has been unclear. Therefore, we tested the hypothesis that before gallstone formation, stasis results from increased cystic duct resistance and altered gallbladder compliance. Adult, male prairie dogs were fed either a trace cholesterol (control) or a 0.4 percent cholesterol-enriched diet. Cystic duct resistance increased but gallbladder compliance was unchanged before gallstone formation. A significant correlation (p < 0.001) was found between the lithogenic index and cystic duct resistance in pregallstone animals. We conclude that increased resistance to flow across the cystic duct, and not altered gallbladder compliance, is etiologically related to bile stasis, an important event in gallstone formation.     

小鼠胆囊胆固醇结石模型的建立

目的建立简单、可靠、高效的小鼠胆囊胆固醇结石模型,为研究胆石成因及防治提供重要手段。方法C57BL／6小鼠随机分为对照组和模型组,对照组喂饲基础饲料,模型组喂饲致石饲料（基础饲料加10％猪油、1％胆固醇及0．5％胆酸）。两组小鼠分别于喂养4周和8周后,计算小鼠存活率,同时各取一半数量小鼠在乙醚吸入麻醉下手术取胆囊及血液标本,分别检测成石率、血脂浓度及胆汁胆固醇饱和度。结果对照组小鼠8周存活率100％,模型组小鼠死亡1只,存活率95％。对照组8周成石率为零,模型组4周成石率80％,8周成石率100％。血脂分析表明,与对照组比较,模型组4周和8周总胆固醇及低密度脂蛋白显著升高（P〈0．01）,甘油三酯浓度轻度升高（P〈0．05）,高密度脂蛋白显著降低（P〈0．01）。4周和8周时胆汁胆固醇饱和度测定,对照组分别为0．48±0．29和0．58±0．21,模型组分别为1．36±0．36和1．52±0．37,模型组胆固醇浓度处于过饱和状态。结论本模型方法简单、成石率高、动物死亡率低,可作为研究胆石成因及防治的备选模型。