Guinea Pig Gallbladder Research Articles

Formononetin: A Phytoestrogen and Isoflavone, Relaxes Guinea Pig Gallbladder Strips

Formononetin: A Phytoestrogen and Isoflavone, Relaxes Guinea Pig Gallbladder Strips

Neutrophil depletion reduces interstitial cajal-like cell injury and alleviates inflammation-induced motor dysfunction in guinea-pig gallbladder during acute cholecystitis.

Objective(s):Gallbladder interstitial Cajal-like cells (ICLCs) are known as some of the players in the complex motility mechanisms affecting gallbladder motility. This study aims to explore the mechanism of guinea-pig gallbladder motility disorders during Acute Cholecystitis (AC), focusing on the relationships between neutrophil alterations, gallbladder ICLCs, and smooth muscle contractility.Materials and Methods:Forty-eight guinea pigs were randomly divided into four groups: normal, sham, common bile duct ligation (CBDL), and anti-PMN (anti-polymorphonuclear antibody treated +CBDL). Hematoxylin and eosin-stained slides from each gallbladder sample were examined for inflammation, and myeloperoxidase (MPO) activity was evaluated. The contractile response of gallbladder muscle to Ach, CCK-8, and KCl was registered by a tension transducer, and ultrastructure features of ICLCs were observed.Results:Pretreatment with anti-PMN significantly reduced the circulating neutrophils by 80% and also considerably decreased the gallbladder MPO activity by 52.9% compared with the CBDL group (P<0.05). After adding Ach, CCK-8, and KCl, the contraction ability in CBDL and anti-PMN groups was lower than those of normal and sham groups (P<0.05), and they were increased substantially in the anti-PMN group compared with the CBDL group (P<0.05). Transmission electron microscopy confirmed that the cytoplasm of the neutrophils was full of granules, and neutrophils contacted closely with ICLCs. The ultrastructure of ICLCs in the anti-PMN group was less inflamed and the endoplasmic reticulum was mildly dilated, and cell processes also increased.Conclusion:Anti-PMN could relieve the ultrastructure injury of ICLCs and alleviate gallbladder dysmotility during AC. Neutrophils may damage gallbladder ICLCs at first followed by dysmotility.

RNA Sequencing Analysis of Gene Expression by Electroacupuncture in Guinea Pig Gallstone Models.

Background Clinical studies have shown that electroacupuncture (EA) promotes gallbladder motility and alleviates gallstone. However, the mechanism underlying the effects of EA on gallstone is poorly understood. In this study, the mRNA transcriptome analysis was used to study the possible therapeutic targets of EA. Methods Hartley SPF guinea pigs were employed for the gallstone models. Illumina NovaSeq 6000 platform was used for the RNA sequencing of guinea pig gallbladders in the normal group (Normal), gallstone model group (Model), and EA-treated group (EA). Differently expressed genes (DEGs) were examined separately in Model vs. Normal and EA vs. Model. DEGs reversed by EA were selected by comparing the DEGs of Model vs. Normal and EA vs. Model. Biological functions were enriched by gene ontology (GO) analysis. The protein-protein interaction (PPI) network was analyzed. Results After 2 weeks of EA, 257 DEGs in Model vs. Normal and 1704 DEGs in EA vs. Model were identified. 94 DEGs reversed by EA were identified among these DEGs, including 28 reversed upregulated DEGs and 66 reversed downregulated DEGs. By PPI network analysis, 10 hub genes were found by Cytohubba plugin of Cytoscape. Quantitative real-time PCR (qRT-PCR) verified the changes. Conclusion We identified a few GOs and genes that might play key roles in the treatment of gallstone. This study may help understand the therapeutic mechanism of EA for gallstone.

Changes in the interstitial cells of Cajal in the gallbladder of guinea pigs fed a lithogenic diet.

Cholesterol cholelithiasis is a common disease and gallbladder hypomotility may underlie its pathogenesis. Interstitial cells of Cajal (ICCs) in the gallbladder serve vital roles in regulating gallbladder motility. The aim of the present study was to investigate changes in gallbladder ICCs during the development of cholesterol cholelithiasis. A total of 40 male guinea pigs were randomly assigned to four groups and fed a standard diet (SD) or lithogenic diet (LD) for 2 or 8 weeks. The LD significantly increased the total cholesterol levels in the serum and bile, as well as the serum levels of high-density lipoprotein-cholesterol and low-density lipoprotein-cholesterol after 2 and 8 weeks. The LD also significantly increased and decreased the number of gallbladder ICCs at 2 and 8 weeks, respectively, by regulating the stem cell factor/C-kit pathway. Moreover, the ultrastructure of gallbladder ICCs was significantly altered after 8 weeks, and the protein expression levels of connexin 43 in the gallbladder were differentially altered after 2 and 8 weeks. Finally, cholecystokinin receptor type A (CCK1R) expression in the gallbladder was assessed. In gallbladder ICCs, its expression was significantly increased and decreased after 2 and 8 weeks, respectively. In conclusion, these results demonstrate that the density, ultrastructure and CCK1R expression levels of gallbladder ICCs are differentially altered at various stages of cholesterol cholelithiasis progression, indicating that gallbladder ICCs may be considered a potential therapeutic target for treatment of cholesterol cholelithiasis.

Cholesterol gallstones: Focusing on the role of interstitial Cajal-like cells.

Cholesterol gallstone (CG) is a common, frequent biliary system disease in China, with a complex and multifactorial etiology. Declined gallbladder motility reportedly contributes to CG pathogenesis. Furthermore, interstitial Cajal-like cells (ICLCs) are reportedly present in human and guinea pig gallbladder tissue. ICLCs potentially contribute to the regulation of gallbladder motility, and aberrant conditions involving the loss of ICLCs and/or a reduction in its pacing potential and reactivity to cholecystokinin may promote CG pathogenesis. This review discusses the association between ICLCs and CG pathogenesis and provides a basis for further studies on the functions of ICLCs and the etiologies of CG.

Monochloramine effects on gallbladder contractility.

Digestive inflammatory processes induce motility alterations associated with an increase in reactive oxygen species production, including monochloramine (NH2 Cl). The aim of the study was to characterize the effects of the naturally occurring oxidant monochloramine in the guinea pig gallbladder. We used standard in vitro contractility technique to record guinea pig gallbladder strips contractions. NH2 Cl caused a concentration-dependent contraction which was reduced by inhibition of extracellular Ca2+ influx and tyrosine kinase pathways. The PKC antagonist GF109203X also reduced the response but not after previous tyrosine kinase inhibition, suggesting that PKC is activated by tyrosine kinase activity. The NH2 Cl contractile effect was also reduced by inhibitors of mitogen-activated protein kinase (MAPK), nitric oxide synthase, phospholipase A2 and cyclooxygenase. In addition, NH2 Cl impaired the responses to CCK, tissue depolarization and electrical field stimulation. In conclusion, we present new evidence that monochloramine impairs not only the gallbladder response to CCK but also to membrane depolarization and nervous plexus stimulation, and that tyrosine kinase, PKC, MAPK and NO pathways are involved in the contractile direct effect of monochloramine.

Effect of cholesterol on in vitro cultured interstitial Cajal-like cells isolated from guinea pig gallbladders.

BACKGROUNDLoss and/or dysfunction of interstitial Cajal-like cells (ICLCs) in the gallbladder may promote cholesterol gallstone formation by decreasing gallbladder motility.AIMTo study the effect of cholesterol on the proliferation and apoptosis of ICLCs from guinea pig gallbladders.METHODSGuinea pig gallbladder ICLCs were isolated and cultured in vitro. The cells were exposed to cholesterol solutions at different concentrations (0, 25, 50, and 100 mg/L) for 24 h. Then, cell proliferation was detected by the CCK-8 method and the apoptosis rate was detected by flow cytometry. Further, the expression of the c-Kit protein was detected by Western blot and the expression level of c-Kit mRNA in the cells was detected by real-time quantitative PCR.RESULTSAfter ICLCs were cultured with cholesterol at concentrations of 25, 50, and 100 mg/L, the proliferation rates decreased significantly (P < 0.05), whereas the apoptosis rates increased significantly (P < 0.05). Moreover, the expression of c-Kit protein and mRNA decreased significantly (P < 0.05).CONCLUSIONHigh cholesterol concentrations can inhibit the proliferation of ICLCs and promote apoptosis. This decrease in the ICLC proliferation rate might be caused by the inhibition of the stem cell factor/c-Kit signaling pathway.

A Comparison of the Effects of Several Agents Found in Common Foodstuffs on Cholecystokinin‐induced Tension in Guinea Pig Gallbladder Strips

17beta‐estradiol (E2) has an inhibitory effect on the contractility of gastrointestinal smooth muscle, including the gallbladder. The inhibition of extracellular Ca2+ entry mediated E2‐induced relaxation of either CCK‐ or KCl‐induced tension in male and female guinea pig gallbladder strips. Chrysin, an endocrine disrupter, and luteolin are flavones. Resveratrol is a non‐flavonoid phytoestrogen, quercetin a phytoestrogen, and curcumin a diarylheptanoid. All are natural constituents of common foodstuffs. All relaxed CCK‐induced tension in male guinea pig gallbladder strips. Luteolin, quercetin, curcumin, resveratrol, and chrysin relaxed the CCK‐induced tension in the gallbladder strips by blocking extracellular Ca2+ entry and intracellular Ca2+ release. The effect of luteolin was also mediated by the PKA/cAMP system while quercetin also involved NO. In addition to the Ca2+ effects, the effects of curcumin and chrysin involved the PKC system. The purpose of this study was to determine which of these agents was most potent in relaxing the CCK‐induced tension in gallbladder strips. Luteolin was the most potent (98.2±2.0%), chrysin (45.4±3.7%), resveratrol (41.1±4.0%), quercetin (42.9±3.0%), curcumin (39.4±4.0%), and E2 (64.5±2.3%) when using 50 mM of each agent. Luteolin had the largest effect at all the other concentrations used (10, 25, 50, and 100 mM) in relaxing CCK‐induced tension. Curcumin was the least potent. There was no significant difference in the amount of relaxation induced by chrysin, resveratrol, and quercetin were compared. The effect of E2 was second only to luteolin.Support or Funding InformationThis research did not receive any specific grant from funding agencies in the public, commercial, or not‐for‐profit sectors.

Polydatin Attenuates Carbachol-induced Contraction of Guinea Pig Gallbladder

The aim of this study was to determine whether polydatin, a glucoside of resveratrol isolated from the root of Polygonum cuspidatum, warranted development as a potential therapeutic for ameliorating the pain originating from gallbladder spasm disorders and the underlying mechanisms. Guinea pig gallbladder smooth muscles were treated with polydatin and specific inhibitors to explore the mechanisms underpinning polydatin-induced relaxation of carbachol-precontracted guinea pig gallbladder. Our results shown that polydatin relaxed carbachol-induced contraction in a dose-dependent manner through the nitric oxide/cyclic guanosine monophosphate/protein kinase G and the cyclic adenosine monophosphate/protein kinase A signaling pathways as well as the myosin light chain kinase and potassium channels. Our findings suggested that there was value in further exploring the potential therapeutic use of polydatin in gallbladder spasm disorders.

The Flavone Luteolin, an Endocrine Disruptor, Relaxed Male Guinea Pig Gallbladder Strips.

BackgroundLuteolin (3',4',5,7-tetrahydroxyflavone) is a flavone with a yellow crystalline appearance present in numerous plants such as broccoli, green chili, and carrot. Luteolin is considered to be an endocrine disruptor with potent estrogen agonist activity and potent progesterone antagonist activity. Luteolin has effects on smooth muscle. Luteolin relaxed guinea pig trachea smooth muscle as it inhibited both phosphodiesterase and reduced intracellular Ca2+. Luteolin also caused vasorelaxation in rat thoracic aorta smooth muscle by inhibiting intracellular Ca2+ release, inhibition of sarcolemmal Ca2+ channels, and activation of K+ channels. Luteolin or its glycosides from artichoke extracts may have an ameliorating effect on irritable bowel syndrome. The purpose of this study was to determine if luteolin had an effect on gallbladder motility.MethodsAn in vitro pharmacologic technique was utilized. Either cholecystokinin octapeptide (CCK) or KCl were used to induce tension in male guinea pig gallbladder strips maintained in Sawyer-Bartlestone chambers. Luteolin relaxed either the CCK- or KCl-induced tension in a concentration dependent manner. Various blockers were added to the chambers to determine which second messenger system(s) mediated the observed relaxation. Paired t-tests were used for statistical analysis. Differences between mean values of P < 0.05 were considered significant.ResultsTreatment of the gallbladder strips with luteolin prior to either KCl or CCK significantly (P < 0.001) decreased the amount of either KCl- or cholecystokinin-induced tension. The 2-aminoethoxydiphenylborane was used to ascertain if the release of intracellular Ca2+ mediated the luteolin-induced relaxation. It significantly (P < 0.001) decreased the amount of luteolin-induced relaxation. To ascertain if PKA mediated the luteolin-induced relaxation, PKA inhibitor 14-22 amide myristolated was used. It significantly (P < 0.01) reduced the amount of luteolin-induced relaxation. Neither KT5823, NG-methyl-L-arginine acetate salt, genistein, tetraethylammonium, nor fulvestrant had a significant effect. To ascertain if PKC mediated the luteolin-induced relaxation, the PKC inhibitors bisindolymaleimide IV and chelerythrine Cl- were used together. They had no significant effect.ConclusionsLuteolin relaxed cholecystokinin- or KCl-induced tension by blocking extracellular Ca2+ entry as well as intracellular Ca2+ release. In addition, the actions of PKA are also involved in mediating the luteolin effect.

Mo1378 - Inflammation can Injure Interstital Cells of Cajal in Acute Cholecystitis of Guinea Pig Gallbladders

Mo1378 - Inflammation can Injure Interstital Cells of Cajal in Acute Cholecystitis of Guinea Pig Gallbladders

Luteolin Relaxes Cholecystokinin‐Induced Tension in Guinea PIg Gallbladder Strips

Luteolin, a flavone, is found in celery, broccoli, green pepper, parsley, carrots, and olive oil. Luteolin was shown to relax rat aortic rings by stimulating the release of nitric oxide (NO) and rat thoracic aortic strips by blocking intracellular Ca2+ release and activating K+ channels. The purpose of this study was to determine if luteolin had an effect on gallbladder motility. An in vitro technique was used to determine which system(s) mediated the relaxation. Both paired t‐tests and analysis of variance were used for statistical analysis; differences between mean values of p&lt;0.05 were considered significant. Luteolin relaxed cholecystokinin octapeptide (CCK)‐induced tension in male guinea pig gallbladder strips in a concentration‐dependent manner. Adding luteolin prior to either CCK or KCl produced a significant decrease in the amount of tension (0.99±0.07 g vs. 0.82+0.09 g CCK [p&lt;0.02]; 1.1±0.09 g vs. 0.97±0.08 g KCl [p&lt;0.001]. The protein kinase A blocker, PKA inhibitor 14–22 amide myristolated, significantly (p&lt;0.01) reduced the amount of luteolin‐induced relaxation (53.9±3.9% vs. 46.5±4.3%). The blocker of intracellular Ca2+ release, 2‐APB, significantly (p&lt;0.001) decreased the amount of luteolin‐induced relaxation (55.9±5.3% vs. 28.9±4.6%). Neither tetraethylammonium (TEA), a non‐selective K+ channel blocker; NO synthase blocker, L‐NAME; KT5823, blocker of protein kinase G; bisindolymaleimide IV and chelerythrine Cl− were used together and are blockers of PKC; fulvestrant, an estrogen receptor blocker; nor genistein, a protein tyrosine kinase blocker had a significant effect on the luteolininduced relaxation. The luteolin‐induced relaxation of CCK‐ or KCl‐induced tension was mediated by blocking extracellular Ca2+ entry which affected downstream events such as intracellular Ca2+ release, and the activation of protein kinase A. Th.Support or Funding InformationThis research did not receive any specific grant from funding agencies in the public, commercial, or not‐for‐profit sectors.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Mechanism of resveratrol-induced relaxation in the human gallbladder

BackgroundResveratrol is a polyphenolic compound extracted from plants and is also a constituent of red wine. Resveratrol produces relaxation of vascular smooth muscle and may prevent cardiovascular diseases. Although resveratrol has been reported to cause relaxation of the guinea pig gallbladder, limited data are available about the effect of resveratrol on the gallbladder smooth muscle in humans. The purpose of this study was to investigate the relaxation effects of resveratrol in human gallbladder muscle strips.MethodsWe studied the relaxant effects of resveratrol in human gallbladder. In addition, we also investigated mechanism of resveratrol-induced relaxation in human gallbladder by tetraethylammonium (a non-selective potassium channels blocker), iberiotoxin (an inhibitor of large conductance calcium-activated potassium channel), glibenclamide (an ATP-sensitive potassium channel blocker), charybdotoxin (an inhibitor of large conductance calcium-activated potassium channels and slowly inactivating voltage-gated potassium channels), apamine (a selective inhibitor of the small conductance calcium-activated potassium channel), KT 5720 (a cAMP-dependent protein kinase A inhibitor), KT 5823 (a cGMP-dependent protein kinase G inhibitor), NG-Nitro-L-arginine (a competitive inhibitor of nitric oxide synthase), tetrodotoxin (a selective neuronal Na+ channel blocker), and ω-conotoxin GVIA (a selective neuronal Ca2+ channel blocker).ResultsThe present study showed that resveratrol has relaxant effects in human gallbladder muscle strips. In addition, we found that resveratrol-induced relaxation in human gallbladder is associated with nitric oxide, ATP-sensitive potassium channel, and large conductance calcium-activated potassium channel pathways.ConclusionsThis study provides the first evidence concerning the relaxant effects of resveratrol in human gallbladder muscle strips. Furthermore, these results demonstrate that resveratrol is a potential new drug or health supplement in the treatment of biliary colic.

Formononetin Relaxes Cholecystokinin‐ and KCl‐induced Tension in Guinea Pig Gallbladder Strips

Formononetin, a phytoestrogen and isoflavone, relaxed cholecystokinin octapeptide‐ (CCK) and KCl‐induced tension in a concentration dependent manner. An in vitro technique was used to determine which system(s) mediated the relaxation. Paired t‐tests were used; differences between mean values of p&lt;0.05 were considered significant. Adding formononetin prior to CCK or KCl produced a significant decrease in the amount of tension {1.2±0.07 vs. 0.81±0.05 g CCK, (p&lt;0.001); 0.84±0.04 vs. 0.74±0.05 g KCl, p&lt;0.01}. When the PKC inhibitors bisindolymaleimide IV and chelerythrine Cl− were used together, a significant (p&lt;0.01) reduction in the formononetin‐induced relaxation (78.1±4.5 vs. 69.7±3.4%) was observed. Genistein, a protein tyrosine kinase inhibitor, significantly (p&lt;0.01) decreased the amount of formononetin‐induced relaxation (72.2±6.5 vs. 59.3±6.5%). To determine if PKA mediated the formononetin‐induced relaxation, PKA inhibitor 14–22 amide myristolated (PKA‐IM) was used. PKA‐IM had no significant effect on the amount of formononetin‐induced relaxation. Neither the use of 2‐APB, a blocker of intracellular Ca2+ release; KT5823, a blocker of PKG; or L‐NMMA, a nitric oxide synthase inhibitor, had a significant effect on the amount of formononetin‐induced relaxation. The formononetin‐induced relaxation of CCK‐ or KCl‐induced tension was mediated by blocking extracellular Ca2+ entry which then affected downstream events such as activation of PKC and protein tyrosine kinase.

Quercetin relaxes guinea pig gallbladder strips

Quercetin, a phytoestrogen and flavonoid, relaxes intestinal and vascular smooth muscle. The purpose of this study was to determine if quercetin had an effect on gallbladder smooth muscle. An in vitro technique was used to determine the effects of quercetin on gallbladder strips and which system(s) mediated the relaxation. Paired t tests were used; differences between means of P < .05 were considered significant. Adding quercetin before cholecystokinin or KCl produced a significant (P < .001) decrease in the amount of tension (0.80 ± 0.04 vs 0.48 ± 0.04 g cholecystokinin octapeptide and 0.8 ± 0.06 vs 0.54 ± 0.05 g KCl, respectively). When the protein kinase C (PKC) inhibitors bisindolymaleimide IV and chelerythrine Cl− were simultaneously, a significant (P < .001) reduction in the quercetin-induced relaxation (45.7% ± 4.3% vs 27.6% ± 3.4%) was observed. To determine if protein kinase A (PKA) mediated the quercetin-induced relaxation, PKA inhibitor 14-22 amide myristolated was used. It significantly (P < .05) decreased the amount (40.4% ± 3.7% vs 34.5% ± 3.3%) of quercetin-induced relaxation. The use of 2-APB also significantly (P < .001) reduced the amount of quercetin-induced relaxation (51.2% ± 3.5% vs 14.8% ± 3.6%). l-NG-methyl-l-arginine acetate salt, a nitric oxide synthase inhibitor, significantly (P < 001) decreased the quercetin-induced relaxation (45.7% ± 4.2% vs 35.2% ± 3.6%). KT5823, a PKC inhibitor, had no effect on the quercetin-induced relaxation. Quercetin blocked extracellular Ca2+ entry which affected downstream events such as activation of PKC, PKA, intracellular Ca2+ release, and activation of nitric oxide synthase. Quercetin relaxed cholecystokinin octapeptide and KCl-induced tension in a concentration dependent manner. Thus quercetin-induced relaxation was mediated by multiple signaling pathways.

Effect of emodin on mobility signal transduction system of gallbladder smooth muscle in Guinea pig with cholelithiasis.

To study the effect of emodin on protein and gene expressions of the massagers in mobility signal transduction system of cholecyst smooth muscle cells in guinea pig with cholesterol calculus. The guinea pigs were randomly divided into 4 groups, such as control group, gall-stone (GS) group, emodin group and ursodeoxycholic acid (UA) group. Cholesterol calculus models were induced in guinea pigs of GS, emodin and UA groups by lithogenic diet, while emodin or UA were given to the corresponding group for 7 weeks. The histomorphological and ultrastructure change of gallbladder were detected by microscope and electron microscope, the content of plasma cholecystokinin (CCK) and [Ca2+]i were analyzed successively by radioimmunoassay and flow cytometry. The protein and mRNA of Gsα, Giα and Cap in cholecyst cells were determined by western blotting and real time polymerase chain reaction (RT-PCR). Emodin or UA can relieve pathogenic changes in epithelial cells and muscle cells in gallbladder of guinea pig with cholesterol calculus by microscope and transmission electron microscope. In the cholecyst cells of GS group, CCK levels in plasma and [Ca2+]i decreased, the protein and mRNA of GS were down-regulated, the protein and mRNA of Gi and Cap were up-regulated. Emodin significantly decreased the formative rate of gallstone, improved the pathogenic change in epithelial cells and muscle cells, increased CCK levels in plasma and [Ca2+]i in cholecyst cells, enhanced the protein and mRNA of Gs in cholecyst cells, reduced the protein and mRNA of Gi and Cap in cholecyst cells in guinea pig with cholesterol calculus. The dysfunction of gallbladder contraction gives rise to the disorders of mobility signal transduction system in cholecyst smooth muscle cells, including low content of plasma CCK and [Ca2+]i in cholecyst cells, abnormal protein and mRNA of Gs, Gi and Cap. Emodin can enhance the contractibility of gallbladder and alleviate cholestasis by regulating plasma CCK levels, [Ca2+]i in cholecyst cells and the protein and mRNA of Gs, Gi and Cap.

C-Kit expression in the gallbladder of guinea pig with chronic calculous cholecystitis and the effect of Artemisia capillaris Thunb on interstitial cells of Cajal.

To study the c-Kit expression in the gallbladder of cholesterol lithogenic guinea pig model and the effect of Artemisia capillaris Thunb on interstitial cells of Cajal (ICCs). A total of 45 guinea pigs were randomly assigned into three groups: the control group (guinea pigs fed a standard diet, normal group); the model group (guinea pigs fed a cholesterol gallstone-inducing diet); and the Chinese medicine group (guinea pigs fed the cholesterol gallstone-inducing diet and treated with A. capillaris through intragastric administration, therapy group). Each group had 15 guinea pigs. The gallbladders of the guinea pigs were harvested after 8 weeks. C-Kit expression was detected using an immunohistochemistry staining, real-time PCR, and Western blot analyses. The effect of A. capillaris on ICCs was evaluated by muscle strip contraction experiments. C-Kit expression significantly decreased in the gallbladder of model group, but increased in the Chinese medicine group. The Contractility of guinea pig gallbladder muscle strip significantly improved in the Chinese medicine group. Our results indicated that A. capillaris improves gallbladder impairment by up-regulating c-Kit expression, and it also can improve the contractile response of in vitro guinea pig gallbladder muscle strips.

Estrogen and G protein-coupled estrogen receptor agonist G-1 cause relaxation of human gallbladder

ObjectiveEstrogen interacts with a membrane receptor, G protein-coupled estrogen receptor (GPER). It was reported that 17β-estradiol was able to inhibit contraction of the human colon and cause relaxation of the guinea pig gallbladder, however, the involvement of GPER was not clarified. The aim of the present study was to investigate the effect of estrogen on human gallbladder motility and the possible role of GPER. Materials and MethodsRelaxation of human gallbladder strips were measured using isometric transducers. Expression of GPER was evaluated by reverse transcription polymerase chain reaction (PCR), real-time PCR, and immunohistochemistry. ResultsIn human gallbladder strips, 17β-estradiol and G-1 elicited marked and rapid relaxation, whereas tamoxifen produced mild concentration-dependent relaxation. The relative efficacies to cause relaxation were as follows: 17β-estradiol = G-1 > tamoxifen. The relaxant response of 17β-estradiol was not attenuated by tetrodotoxin or conotoxin GVIA. This implies that nerve stimulation was not involved in the 17β-estradiol-induced gallbladder relaxation. Analysis by reverse transcription PCR and real-time PCR showed that GPER was expressed in the human gallbladder. Further analysis by immunohistochemistry revealed that GPER was expressed in the gallbladder muscle. This suggests that 17β-estradiol relaxes the human gallbladder via GPER. ConclusionThese results demonstrate for the first time that 17β-estradiol and GPER agonist G-1 cause relaxation of the human gallbladder, probably through GPER. Estrogen might play an important role in the control of human gallbladder motility.

The Role of Interstitial Cells of Cajal in Acute Cholecystitis in Guinea Pig Gallbladder

Background/Aims: Acute cholecystitis is common in gallbladder motility disorder. Interstitial cells of Cajal (ICCs) in the gallbladder are involved in the regulation of gallbladder motility. The aim of this study was to explore the change of gallbladder ICCs in acute cholecystitis. Methods: Thirty adult guinea pigs were randomly divided into 3 groups: a sham-operated group (healthy controls) and 2 study groups. The animals in the study group were subjected to bile duct ligation and then to laparotomy and cholecystectomy at 24 and 48 hours after surgery. Immunohistochemistry, immunohistofluorescence, and laser confocal microscopy were performed to observe the shape, size, morphology, and density of gallbladder ICCs. Western blot and real-time PCR were performed to detect stem cell factor and c-kit protein and mRNA expression, respectively. Results: There were no differences in the shape, size, and morphology of the gallbladder ICCs in the control and the two acute cholecystitis groups. Density of gallbladder ICCs, SCF level, and c-kit protein and mRNA expression all decreased in the acute cholecystitis groups. Further, SCF level and c-kit protein and mRNA expression decreased with progress of acute cholecystitis (all P < 0.05). Conclusion: Acute cholecystitis can decrease ICCs through repression of SCF and c-kit expression and that ICCs loss play a role in acute cholecystitis.

The role of TRPP2 in agonist-induced gallbladder smooth muscle contraction.

TRPP2 channel protein belongs to the superfamily of transient receptor potential (TRP) channels and is widely expressed in various tissues, including smooth muscle in digestive gut. Accumulating evidence has demonstrated that TRPP2 can mediate Ca(2+) release from Ca(2+) stores. However, the functional role of TRPP2 in gallbladder smooth muscle contraction still remains unclear. In this study, we used Ca(2+) imaging and tension measurements to test agonist-induced intracellular Ca(2+) concentration increase and smooth muscle contraction of guinea pig gallbladder, respectively. When TRPP2 protein was knocked down in gallbladder muscle strips from guinea pig, carbachol (CCh)-evoked Ca(2+) release and extracellular Ca(2+) influx were reduced significantly, and gallbladder contractions induced by endothelin 1 and cholecystokinin were suppressed markedly as well. CCh-induced gallbladder contraction was markedly suppressed by pretreatment with U73122, which inhibits phospholipase C to terminate inositol 1,4,5-trisphosphate receptor (IP3) production, and 2-aminoethoxydiphenyl borate (2APB), which inhibits IP3 recepor (IP3R) to abolish IP3R-mediated Ca(2+) release. To confirm the role of Ca(2+) release in CCh-induced gallbladder contraction, we used thapsigargin (TG)-to deplete Ca(2+) stores via inhibiting sarco/endoplasmic reticulum Ca(2+)-ATPase and eliminate the role of store-operated Ca(2+) entry on the CCh-induced gallbladder contraction. Preincubation with 2 μmol L(-1) TG significantly decreased the CCh-induced gallbladder contraction. In addition, pretreatments with U73122, 2APB or TG abolished the difference of the CCh-induced gallbladder contraction between TRPP2 knockdown and control groups. We conclude that TRPP2 mediates Ca(2+) release from intracellular Ca(2+) stores, and has an essential role in agonist-induced gallbladder muscle contraction.