Depression-like phenotypes in mice following common bile duct ligation: Insights into the gut-liver-brain axis via the vagus nerve.

Depression frequently occurs in patients with liver cirrhosis, yet the reasons for this correlation are not fully understood. Dysbiosis of gut microbiota has been implicated in depression through the gut-brain axis via the vagus nerve. This study explored the potential role of the gut-liver-brain axis via the vagus nerve in depression-like phenotypes in mice with liver cirrhosis. These mice underwent common bile duct ligation (CBDL), a method used to stimulate liver cirrhosis. To assess depression-like behaviors, behavioral tests were conducted 10 days following either sham or CBDL surgeries. The mice with CBDL displayed symptoms such as splenomegaly, elevated plasma levels of interleukin-6 and tumor necrosis factor-α, depression-like behaviors, decreased levels of synaptic proteins in the prefrontal cortex (PFC), disrupted gut microbiota balance, and changes in blood metabolites (or lipids). Additionally, there were positive or negative correlations between the relative abundance of microbiome and behavioral data or blood metabolites (or lipids). Significantly, these changes were reversed in CBDL mice by performing a subdiaphragmatic vagotomy. Intriguingly, depression-like phenotypes in mice with CBDL were improved after a single injection of arketamine, a new antidepressant. These results suggest that CBDL-induced depression-like phenotypes in mice are mediated through the gut-liver-brain axis via the subdiaphragmatic vagus nerve, and that arketamine might offer a new treatment approach for depression in liver cirrhosis patients.

Effect of Ageing on the Common Bile Duct Diameter.

INTRODUCTION: The aim of the study was to determine if the common bile duct (CBD) diameter increases physiologically with age and investigate whether gallstones lead to changes in CBD diameter. METHOD: Our study is composed of 721 patients in 2 groups: 517 asymptomatic patients and 204 gallstones patients who underwent MRCP. Their CBD diameter was measured at its widest visible portion on MRCP. Simple linear regression of the average of these measurements was used to investigate the relationship between age and CBD diameter in both populations. Subjects were further divided into 8 subgroups age-wise, respectively, and their means compared decade-wise using ANOVA. Furthermore, each subgroup mean from both populations was compared with each other using a t test. RESULTS: Among the 517 subjects, the mean CBD diameter was 5.3663 mm ± 1.43546 and correlated with age (p < 0.01), dilating at 0.07 mm/year. The mean diameter of our oldest group was 7.9 mm, resulting in a plausible upper limit of 8 mm for the asymptomatic population. The mean CBD diameter of the cholelithiasis population was 5.6738 mm ± 1.40986 and also correlated with age (p < 0.01). The mean CBD diameter of the age groups from the cholelithiasis population was larger than that from the asymptomatic population, but none were statistically significant. CONCLUSION: Although the CBD increases physiologically with age, there is no significant difference in CBD size between the general population and the cholelithiasis patients at any particular age. Gallstones do not independently dilate the CBD.

Clinical Impact of Common Bile Duct Angulation on the Recurrence of Common Bile Duct Stone: A Meta-analysis and Review.

Background/Aims: Local and systemic factors, such as diabetes, obesity, and hyperlipidemia, are considered risk factors for the recurrence of choledocholithiasis after successful endoscopic clearance. Local factors include the presence of bile sludge, common bile duct (CBD) diameter, and CBD angulation. Among them, it is unclear if acute CBD angulation is preferable to the recurrence of a CBD stone. Methods: PubMed, EMBASE, CINAHL, the Cochrane Library databases, and google website were searched for randomized controlled trials reported in English and undertaken until August 2019. Meta-analysis was performed on all randomized controlled trials for the recurrence of CBD stones between the patients with acute CBD angulation. Results: Eight randomized trials (1,776 patients) were identified, and the total recurrent rate of CBD stones was 18.8% (334/1,776). A CBD angle ≤145° was significantly associated with an increased risk of recurrent CBD stone (OR=2.65, p<0.01). In two prospective studies, acute CBD angulation was not proven to be associated with a recurrence (p=0.39). Conclusions: Approximately 20% of patients with a CBD stone showed recurrence after the complete clearance of the CBD stone, and a CBD angle ≤145° could increase the risk of recurrence. Overall, a large-scale prospective study should be necessary.

TGR5 is essential for bile acid-dependent cholangiocyte proliferation in vivo and in vitro.

OBJECTIVE: Cholestatic liver diseases in humans as well as bile acid (BA)-feeding and common bile duct ligation (CBDL) in rodents trigger hyperplasia of cholangiocytes within the portal fields. Furthermore, elevation of BA levels enhances proliferation and invasiveness of cholangiocarcinoma (CCA) cells in animal models, thus promoting tumour progression. TGR5 is a G-protein coupled BA receptor, which is highly expressed in cholangiocytes and postulated to mediate the proliferative effects of BA. DESIGN: BA-dependent cholangiocyte proliferation was examined in TGR5-knockout and wild type mice following cholic acid (CA)-feeding and CBDL. TGR5-dependent proliferation and protection from apoptosis was studied in isolated cholangiocytes and CCA cell lines following stimulation with TGR5 ligands and kinase inhibitors. TGR5 expression was analysed in human CCA tissue. RESULTS: Cholangiocyte proliferation was significantly reduced in TGR5-knockout mice in response to CA-feeding and CBDL. Taurolithocholic acid and TGR5-selective agonists induced cholangiocyte proliferation through elevation of reactive oxygen species and cSrc mediated epidermal growth factor receptor transactivation and subsequent Erk1/2 phosphorylation only in wild type but not in TGR5-knockout-derived cells. In human CCA tissue TGR5 was overexpressed and the pathway of TGR5-dependent proliferation via epidermal growth factor receptor and extracellular signal-regulated kinase (ERK)1/2 activation also translated to CCA cell lines. Furthermore, apoptosis was inhibited by TGR5-dependent CD95 receptor serine phosphorylation. CONCLUSIONS: TGR5 is an important mediator of BA-induced cholangiocyte proliferation in vivo and in vitro. Furthermore, TGR5 protects cholangiocytes from death receptor-mediated apoptosis. These mechanisms may protect cholangiocytes from BA toxicity under cholestatic conditions, however, they may trigger proliferation and apoptosis resistance in malignantly transformed cholangiocytes, thus promoting CCA progression.

Effects of thienorphine on contraction of the guinea pig sphincter of Oddi, choledochus and gall bladder.

Opioid analgesics are widely believed to cause spasm of the bile duct sphincter and so impede bile flow. Thienorphine is a partial opioid agonist that is a good candidate for the treatment of opioid dependence; however, to date, no studies have reported the effects of thienorphine on the function of the biliary tract. This study examined the in vivo effects of thienorphine on the guinea pig isolated sphincter of Oddi, choledochus and gall bladder and on bile flow. The area under the curve (AUC) of isolated sphincter of Oddi was not influenced by thienorphine or buprenorphine, whereas morphine increased the AUC of the isolated sphincter of Oddi in a concentration-dependent manner. Thienorphine and buprenorphine concentration-dependently decreased the AUC of isolated choledochus, while morphine increased the AUC of isolated choledochus. Thienorphine had no effect on the contractile amplitude or basal tension of isolated gall bladder muscle strips. In contrast, buprenorphine and morphine increased the contractile basal tension of isolated gall bladder muscle strips in a concentration-dependent manner. Thienorphine (0.01-1.0mg/kg) had no significant inhibitory effect on bile flow. However, morphine (1.0-10mg/kg) and buprenorphine (1.0mg/kg) significantly inhibited bile flow. The maximum inhibition of bile flow by buprenorphine was 63.9±12.9% and by morphine was 74.1±11.3%. In summary, thienorphine has little influence on the guinea pig isolated sphincter of Oddi, choledochus and gall bladder or on bile flow, which may result in a lack of adverse biliary colic effects.

Effects of cholecystectomy on the changes of motility of Beagle dogs' sphincter of Oddi.

PURPOSE: To observe the effect of cholecystectomy on the changes of motion pattern of Beagle dogs' sphincter of Oddi (SO), and investigate the modulatory role of nitric oxide (NO) and cholecystokinin (CCK) in the regulation of SO. METHODS: Pressure of common bile duct, SO motility, response to bolus injections of cholecystokinin (CCK, 20 ng/kg and 100 ng/kg), basal pressure (BP) and phasic contraction amplitude (PCA) were measured respectively by manometry in six Beagle dogs before and after cholecystectomy. RESULTS: After cholecystectomy, the pressure and diameter of common bile ducts (CBD) was significantly increased (p<0.01); BP and phasic contraction frequency (PCF) were also increased, however, no significant differences were found between the two groups; the SO motilities was not significantly changed. The relaxation responded to physiological dose of CCK (20ng/kg) was decreased, while bolus-dose of CCK (100ng/kg) induced rapid contractions and decreased PCA after cholecystectomy. The regulation pattern of SO pressure modulated by NO and its inhibitor had changed after cholecystectomy. CONCLUSION: After cholecystectomy in Beagle dogs, no obviously change of motion pattern of SO was observed through self-compensation, but these compensations may lead to some changes of regulation pattern of CCK and NO on SO.

Synthesis of neurotransmitter GABA via the neuronal tricarboxylic acid cycle is elevated in rats with liver cirrhosis consistent with a high GABAergic tone in chronic hepatic encephalopathy.

Hepatic encephalopathy (HE) is a neuropsychiatric complication to liver disease. It is known that ammonia plays a role in the pathogenesis of HE and disturbances in the GABAergic system have been related to HE. Synthesis of GABA occurs by decarboxylation of glutamate formed by deamidation of astrocyte-derived glutamine. It is known that a fraction of glutamate is decarboxylated directly to GABA (referred to as the direct pathway) and that a fraction undergoes transamination with formation of alpha-ketoglutarate. The latter fraction is cycled through the neuronal tricarboxylic acid cycle, an energy-generating pathway, prior to being employed for GABA synthesis (the indirect pathway). We have previously shown that ammonia induces an elevation of the neuronal tricarboxylic acid cycle activity. Thus, the aims of the present study were to determine if increased levels of ammonia increase GABA synthesis via the indirect pathway in a rat model of HE induced by bile-duct ligation and in co-cultures of neurons and astrocytes exposed to ammonia. Employing (13) C-labeled precursors and subsequent analysis by mass spectrometry, we demonstrated that more GABA was synthesized via the indirect pathway in bile duct-ligated rats and in co-cultures subjected to elevated ammonia levels. Since the indirect pathway is associated with synthesis of vesicular GABA, this might explain the increased GABAergic tone in HE.

Viscosity of human bile sampled from the common bile duct.

Cholestasis is a frequent gastroenterological problem, which is tackled by endoscopic procedures. Little is known about bile viscosity, a major determinant of its flow. We measured the viscosity of bile from the common bile duct during endoscopic retrograde cholangiography. Bile was aspirated immediately after cannulation of the papilla and deep-frozen. Viscosity was measured with a rotational viscometer at 37 degrees C and a broad range of shear rates (0.08-69.5 s(-1)). The majority of the 138 patients (64.5%) had bile viscosities between water (0.7 mPa.s) and the lower limit of plasma (1.1 mPa.s). In 20 patients (14.5%) it was above that of plasma (>1.4 mPa.s), and showed a non-Newtonian behaviour, i.e. the viscosity increased exponentially with decreasing shear rate. Cholecystectomized patients had a lower bile viscosity. Bile viscosities did not differ between patient groups with either choledocholithiasis, sludge, cholangitis, biliary pancreatitis, pancreatic carcinoma, or cholangiocarcinoma. We conclude that bile viscosity in the common bile duct is usually lower than that of plasma, in 15% it is higher and increases exponentially with decreasing flow rate, which may lead to a vicious cycle.

The common bile duct: size, course, relations.

The common bile duct may present a number of anatomical peculiarities regarding its size, course and relations, which should be taken into consideration by the anatomists and by the surgeons as well, during the surgery of the gallbladder, pancreas and duodenum. In the present study, we have analyzed the anatomical peculiarities of the common bile duct in 150 adult corpses of both sexes from the Anatomy Department and 22 human fetuses from the Pathology Department, University of Medicine and Pharmacy Cluj-Napoca.

[The relationship between age and biomechanical properties in porcine common bile duct].

The aim of this study was to detect the relationship between age and biomechanical properties in porcine common bile duct (CBD). The CBDs of 50 Hubei white pigs aged 3-12 months were obtained. The experiment of pressure-diameter was conducted on the biomechanical experiment stand for soft tissues, and then the elastic modulus and compliance were calculated. The materials were transversely extracted, refrigerated, and sliced up before HE staining. The diameter and wall thickness of the CBD were measured by a computer image analysis system. The results showed that there was statistically significant difference in regard to the compliance of the porcine CBDs of different months (F = 59.69, P = 0.00). The compliance of the porcine CBD increased gradually with monthly age. However, after the pigs being aged 10 months, the compliance decreased gradually with monthly age. The compliance of the CBD of pigs aged 7-10 months was not significantly different (P > 0.05), but the compliance of the CBDs of pigs' aged 3-6 months and 11-12 months was significantly lower than that of pigs aged 7-10 months (P < 0.01). The changes in elastic modulus of porcine CBD with age were opposed to the changes in compliance. The results of the present study suggests that the in biomechanical properties of pigs' CBDs change with their ages, and the CBDs of pigs aged 7-10 months have good compliance. Thus, for the pig-to-human liver xenotransplantation, the livers of pigs aged 7-10 months, being chosen as donators, may be more conducive to matching.

Common bile duct anteroposterior movement synchronized with inferior vena cava pulsation observed by cine magnetic resonance imaging.

PURPOSE: To reveal the phenomenon of common bile duct (CBD) anteroposterior movement caused by inferior vena cava (IVC) pulsation depending on the cardiac cycle using cine magnetic resonance imaging. MATERIALS AND METHODS: A breath-hold trans-axial cine segmented true fast imaging with steady-state precession (trueFISP) sequence was prospectively performed on 11 healthy volunteers to observe CBD anteroposterior movement and IVC pulsation during the cardiac cycle. Changes in IVC anterior-posterior diameter and CBD location were compared using Pearson rank correlation analysis. RESULTS: Nine (81.8%) of 11 CBDs moved back and forth in synchronicity with IVC anterior wall motion depending on the cardiac cycle; the mean maximum and minimum IVC diameters were 16.2+/-2.7 and 12.9+/-3.1 mm, respectively. Two (18.2%) of 11 CBDs and IVC walls did not move; the mean unchanged IVC diameter was 5.3+/-2.1 mm. There were significant correlations between the mean change in IVC diameter and distance of CBD anteroposterior movement (2.7+/-2.1 and 1.8+/-1.4 mm, respectively, r=0.911, P<.05). CONCLUSION: Many CBDs move back and forth in synchronicity with IVC pulsation depending on the cardiac cycle.

In vivo confocal laser laparoscopy allows real time subsurface microscopy in animal models of liver disease.

BACKGROUND/AIMS: Histopathology is essential in the diagnostic workup of most liver diseases. However, biopsy sampling might carry risks, is subject to sampling error, and does not provide dynamic tissue imaging. Therefore a newly developed miniaturised confocal probe was evaluated for in vivo microscopic imaging in rodent models of human liver diseases. METHODS: The handheld laparoscopy probe used a 488nm single line laser for fluorophore excitation. Optical slice thickness was 7 microm, lateral resolution 0.7 microm. Imaging depth was 0-250 microm below the tissue surface. Imaging using different fluorescent staining protocols was performed in healthy mice, IFN-gamma- and IL-12-induced hepatitis, after bile duct ligation, and in ob/ob mice. RESULTS: Confocal imaging permitted microscopic imaging of the liver in vivo at high resolution. Landmarks of liver diseases such as inflammatory infiltration, steatosis, bile duct proliferation, pericellular fibrosis and perfusion anomalies could be characterised, localised and differentiated in vivo. CONCLUSIONS: In vivo confocal microscopy with this newly developed probe allows real-time subsurface imaging and characterisation of normal and pathologic liver tissue at high resolution. Since this technology is suited for laparoscopy in humans, it has the potential to impact on the diagnostic workup of liver diseases and to permit dynamic monitoring of (patho-)physiologic events in vivo.

Hepatobiliary transporter expression in intercellular adhesion molecule 1 knockout and Fas receptor-deficient mice after common bile duct ligation is independent of the degree of inflammation and oxidative stress.

Liver injury in intercellular adhesion molecule 1 knockout (ICAM(-/-)) and Fas receptor-deficient (lpr) mice is markedly reduced after common bile duct ligation (CBDL) due to significantly reduced inflammation and oxidative stress. Liver injury in CBDL rodents is counteracted by adaptive hepatobiliary transporter induction. Since hepatobiliary transporter expression in obstructive cholestasis may be regulated not only by accumulating bile acids but also by inflammatory mediators and oxidative stress, we hypothesized that differences in the inflammatory response may affect hepatobiliary transporter expression in CBDL, which would contribute to reduced liver injury. Therefore, expression of major hepatobiliary transporters (Ntcp, Bsep, Mrp2-4, Ost alpha/beta) was determined by Taqman RT-PCR and Western blotting in sham-operated animals and 3 days after CBDL in wild-type, ICAM(-/-) and lpr mice of the endotoxin-sensitive C57BL/6 and the endotoxin-resistant C3H/HeJ strains. CBDL resulted in a significant decrease of Ntcp in all genotypes. Canalicular transporters Bsep and Mrp2 were repressed only in the endotoxin-sensitive strain regardless of the genotype. Mrp3 was moderately induced in ICAM(-/-), lpr, and endotoxin-resistant mice, whereas Mrp4 was only induced in the endotoxin-resistant strain. Ost beta was massively induced in all CBDL mice, whereas Ost alpha was reduced. In conclusion, markedly reduced inflammation and oxidative stress in CBDL ICAM(-/-) and lpr mice does not profoundly affect hepatobiliary transporter expression. Therefore, transporter expression does not account for reduced liver injury in ICAM(-/-) and lpr mice. Induction of the adaptive transporter response after CBDL is independent of the degree of the inflammatory response. Rather, retention of biliary constituents may determine transporter expression in CBDL.

Mannose-6-phosphate/insulin-Like growth factor-II receptors may represent a target for the selective delivery of mycophenolic acid to fibrogenic cells.

PURPOSE: The insulin-like growth factor axis plays an important role in fibrogenesis. However, little is known about mannose-6-phosphate/Insulin-like growth factor-II receptor (M6P/IGF-IIR) expression during fibrosis. When expressed preferentially on fibrogenic cells, this receptor may be used to selectively deliver drugs to these cells. METHODS: We investigated M6P/IGF-IIR expression in livers of bile duct-ligated (BDL) rats and in renal vascular walls of renin transgenic TGR(mRen2)27 rats. Both models are characterized by fibrogenic processes. Furthermore, we studied whether drug delivery via M6P/IGF-II-receptor-mediated uptake is possible in fibroblasts. RESULTS: M6P/IGF-IIR mRNA expression was investigated 3, 7 and 10 days after BDL. At all time-points hepatic M6P/IGF-IIR expression was significantly increased compared to healthy controls. Moreover, immunohistochemical staining revealed that alpha-sma-positive cells were M6P/IGF-IIR-positive. In kidneys of TGR(mRen2)27 rats, the number of M6P/IGF-IIR-positive arteries per microscopic field was increased 5.5 fold over healthy controls. To examine whether M6P/IGF-IIRs could be used as a port of entry for drugs, we coupled mycophenolic acid (MPA) to mannose-6-phosphate-modified human serum albumin (M6PHSA). M6PHSA-MPA inhibited 3T3-fibroblast proliferation dose-dependently, which was reversed by co-incubation with excess M6PHSA, but not by HSA. CONCLUSIONS: M6P/IGF-IIRs are expressed by fibrogenic cells and may be used for receptor-mediated intracellular delivery of the antifibrogenic drug MPA.

Pancreatobiliary afferent recordings in the anaesthetised Australian possum.

The sensory innervation to the pancreatobiliary system is poorly characterized. Afferent signals from the gastrointestinal tract and biliary tree are transmitted to the central nervous system via the vagus and spinal nerves. We aimed to record afferent discharge in order to characterize the vagal and splanchnic afferent signals from the possum upper gastrointestinal tract, biliary tree and pancreas. In 21 anaesthetised possums nerve fibres were teased from the vagus or splanchnic nerve for multi-unit recording. Mechanical stimuli consisted of balloon distension of the gallbladder and duodenum (2-7 ml) and fluid distension (0-20 mm Hg) of the bile or pancreatic ducts. Approximately 60% of fibres from all nerves displayed spontaneous discharge. Spinal afferent responses to mechanical stimuli were infrequent (n=13). Increased discharge occurred in response to duodenal (12/99 fibres) or gallbladder (7/96 fibres) distension, but not to bile duct (0/73 fibres) or pancreatic duct (0/51 fibres) distension. Vagal afferent responses to distension of the duodenum or stomach (5-30 ml) were more common (n=8). Increased discharge was recorded in response to duodenal (49/134 fibres), or gastric (22/70 fibres) distension. Responses to gallbladder distension were less frequent (6/99 fibres) and as with the spinal afferent no response to bile duct (0/66) or pancreatic duct (0/70) distension were recorded. We conclude that mechanosensitive afferents in the pancreatobiliary system are relatively rare, particularly within the ducts, and/or that they are adapted to monitor stimuli other than luminal distension.