Taurocholate Treatment Research Articles

Naringin Attenuated Acute Lung Injury in Rat Model with Acute Pancreatitis in Pregnancy through Inactivation of p38 MAPK Pathway

Acute pancreatitis in pregnancy can cause fetal lung injury. Naringin exhibits ant-inflammation effect against pulmonary injuries. However, whether naringin can alleviate lung injury associated with acute pancreatitis in pregnancy has not been elucidated. Establishment of acute pancreatitis in pregnancy model by sodium taurocholate showed that sodium taurocholate induced obvious pathological changes in pancreas. Histopathological changes in lungs were also aggravated post sodium taurocholate treatment with enhanced inflammation of neutrophils, thickened alveolar walls and alveolus collapse. Diagnostic blood tests for acute pancreatitis in pregnancy indicated that serum amylase and lipase were increased post sodium taurocholate treatment. Sodium taurocholate-induced rats were intragastrically administered with naringin to investigate the protective effect of naringin on acute lung injury induced by acute pancreatitis in pregnancy. Results revealed that administration of naringin could attenuate pathological changes in pancreas and lungs and decrease amylase and lipase. Moreover, naringin treatment attenuated sodium taurocholate-induced increase in inflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-6/1β in lungs. Sodium taurocholate-induced increase in phosphorylation of p38 was also reduced post naringin treatment. In conclusion, naringin could ameliorate acute lung injury and inflammation induced by acute pancreatitis in pregnancy by inhibiting the p38 pathway.

Regulatory mechanism of the gastric hyperemic response following barrier disruption: roles of cyclooxygenase-1, the prostaglandin E2/EP1 receptor and sensory neurons.

We herein reviewed the mechanism underlying the gastric hyperemic response following barrier disruption, with a focus on cyclooxygenase (COX) isozymes, prostaglandin (PG) E2, and capsaicin-sensitive afferent neurons. Mucosal damage was induced by exposing the stomach to 20 mM taurocholate (TC) with 50 mM HCl. The TC treatment disrupted surface epithelial cells, and then increased acid back-diffusion and mucosal blood flow (GMBF) in the stomachs of rats or wild-type mice. This hyperemic response in the rat stomach was inhibited by indomethacin without affecting acid back-diffusion, which resulted in the aggravation of lesions. The effect of indomethacin was mimicked by loxoprofen and the selective COX-1 inhibitor, SC-560, but not by the selective COX-2 inhibitor, celecoxib. The GMBF responses induced by TC were similarly observed in the stomachs of wild-type mice and EP3 receptor knockout mice, but not in mice lacking the EP1 receptor or pretreated with an EP1 antagonist. The increase in the GMBF response associated with acid back-diffusion after the TC treatment was also inhibited by the chemical ablation of capsaicin-sensitive afferent neurons, but not capsazepine, a TRPV1 antagonist. Thus, endogenous PGE2 produced by COX-1 plays a role in the gastric hyperemic response following barrier disruption of the stomach by interacting with capsaicin-sensitive afferent neurons, mainly through EP1 receptors, and facilitating the GMBF response to acid back-diffusion. These findings have also contributed to a deeper understanding of mucosal defensive mechanisms following barrier disruption and the development of new strategies for the treatment of gastrointestinal diseases.

Mechanisms of human hepatobiliary transporter gene regulation in the hepatocyte-like cell line HepaRG

Background&Aim: Functional studies on human hepatic gene regulation are limited due to the lack of suitable models. Currently used human hepatoma cell lines such as HepG2 or Huh7 are deficient in several transporters such as NTCP or BSEP whereas primary human hepatocytes and freshly prepared liver slices are limited in availability. The highly differentiated hepatic cell line HepaRG, which exhibits a hepatocyte-like equipment with various CYP P450s, nuclear receptors and a broad range of hepatobiliary transporters, represents an ideal model system to study human transporter gene regulation (LeVee et al. 2006, Aninat et al. 2006). The aim of the present study was to functionally characterize inflammatory and bile salt-induced mechanisms of human transporter gene regulation in the unique HepaRG cell system (kindly provided by Biopredic). Methods: Highly differentiated HepaRG cells maintained in DMSO containing medium were treated with either 100ng/ml LPS or 10ng/ml IL–1s or 10µM taurocholate (exemplary for inflammatory conditions or bile salt overload) for 16 hours. RNA and protein were prepared and analyzed by real-time RT-PCR and Western blotting. Results: Upon LPS-treatment NTCP mRNA expression decreased to 13% whereas OATP-C and BSEP expression showed a moderate reduction of 56% and 39%, respectively, compared to untreated controls. Effects of IL–1s treatment were even more pronounced (NTCP 4%, OATP-C 10% and BSEP 18%). MRP2 is down-regulated by inflammatory signals to 40–60% at the protein level whereas mRNA was 65–77% for IL–1s and LPS stimulation, respectively. MRP4 mRNA is increased around 2-fold while MRP3 expression remained stable under these conditions. Taurocholate treatment increased BSEP mRNA to 258%, slightly enhanced NTCP as well as MRP4 expression while OATP-C, MRP3 and MRP2 were unaffected. Conclusions: Human bile salt transporters NTCP and BSEP are suppressed by similar inflammatory mechanisms as their rat counterparts. Inflammation-induced MRP2 down-regulation occurs by posttranscriptional mechanisms. During bile salt accumulation MRP4 appears to be the primary human rescue system whereas other transporters are rather moderately suppressed or unaffected. Our data allow a comprehensive insight into cholestatic human transporter gene regulation and enable further mechanistic studies in the future.

Therapeutic effect of DA-9601 on chronic reflux gastritis induced by sodium taurocholate in rats

To investigate the therapeutic effects of DA-9601 on sodium taurocholate (TCA)-induced chronic reflux gastritis in SD rats. In this study, we have investigated the therapeutic effects of DA-9601 on chronic erosive and atrophic gastritis induced by 6 mo of TCA administration (5 mmol/L in drinking water) in SD rats. Four weeks of DA-9601 administration (0.065%, 0.216% in rat chow), following the withdrawal of TCA treatment, resulted in a significant decrease in total length of erosions in rats in a dose-dependent manner. Furthermore, the indicators of atrophic gastritis, such as reduced mucosal thickness and reduction in the number of parietal cells, were improved by the administration of DA-9601 in a dose-related manner. DA-9601 also attenuated inflammatory cell infiltration and the proliferation of collagenous fiber in the gastric mucosa. The improvement in the reduction of the gastric mucus was observed in the rats receiving a high dose of DA-9601 (0.216%). The therapeutic effect of DA-9601 on experimental chronic erosive gastritis was superior to that of rebamipide (1.08% in rat chow). Biochemical analyses showed increased mucosal prostaglandin E2 and reduced glutathione levels by DA-9601 treatment. We suggest that DA-9601 is a promising agent for the treatment of chronic erosive and atrophic gastritis with an etiological factor of bile reflux. Increased mucosal prostaglandin E2 and reduced glutathione by DA-9601 treatment may be therapeutic mechanisms for chronic erosive and atrophic gastritis.

Gastric ulcerogenic responses following barrier disruption in knockout mice lacking prostaglandin EP1 receptors.

Endogenous prostaglandins (PGs) are considered to play a pivotal role in maintaining the mucosal integrity of the stomach after injury. In the present study, we evaluated the mucosal ulcerogenic and mucosal blood flow (GMBF) responses in the stomach after damage by taurocholate (TC) in knockout mice lacking EP1 or EP3 receptors. Under urethane anaesthesia, a mouse stomach was mounted in an ex vivo chamber, exposed to 20 mmol/L TC for 20 min and treated with 20 mmol/L HCl before and after TC. GMBF was measured with a laser Doppler flowmeter. Mucosal exposure to TC in wild-type mice caused a marked decrease in potential difference (PD), followed by an increase in H+ loss and GMBF. The decreased PD was gradually normalized after removal of TC from the chamber, with minimal damage in the mucosa 1 h after TC treatment. This hyperaemic response was inhibited by indomethacin, resulting in severe lesions in the mucosa without any change in PD or H+ loss. None of these responses induced by TC were altered in EP3-/- mice. However, in mice lacking EP1 receptors, TC treatment did not increase GMBF, despite causing PD reduction and acid loss, and resulted in severe damage in the mucosa. These responses were closely similar to those observed in animals pretreated with ONO-8711, a EP1 receptor antagonist. Mucosal PGE2 content was significantly increased after TC, similarly in all groups of mice. These results confirm a mediator role for PGE2 in gastric hyperaemic response following mucosal exposure to TC and suggest that endogenous PGs may contribute to maintaining mucosal integrity after barrier disruption, mainly through activation of the EP1 receptor subtype.

Seroreactivity of an Antigen of Leptospira interrogans Serovar Grippotyphosa

Srivastava, S.K. and Tiwari, V. 2000. Seroreactivity of an antigen of Leptospira interrogans serovar grippotyphosa. J. Appl. Anim. Pes., 18: 97–102. Antigen was extracted from L. interrogans sr. grippotyphosa by sodium taurocholate treatment and characterized. Using an ELISA the extracted antigen showed higher reactivity with the homologous antiserum than observed with antisera against serovars canicola, pomona, pyrogenes, hardjo, ballum, patoc and andamana. Fractionation of the extracted antigen employing ion-exchange chromatography resulted in the separation of relatively specific major protein along with non-reactive proteins. Use of the antigen for conducting ELISA for serodiagnosis of leptospirosis in field cattle indicated that, as compared to microscopic agglutination test, it was slightly less sensitive but was equally specific.

Increased susceptibility of gastric mucosa to ulcerogenic stimulation in diabetic rats--role of capsaicin-sensitive sensory neurons.

1. We examined the gastric mucosal blood flow (GMBF) and ulcerogenic responses following barrier disruption induced by sodium taurocholate (TC) in diabetic rats and investigated the role of capsaicin-sensitive sensory neurons in these responses. 2. Animals were injected streptozotocin (STZ: 70 mg kg(-1), i.p.) and used after 5, 10 and 15 weeks of diabetes with blood glucose levels of > 350 mg dl(-1). The stomach was mounted on an ex-vivo chamber under urethane anaesthesia and exposed to 20 mM TC plus 50 mM HCl for 30 min in the presence of omeprazole. Gastric transmucosal potential difference (PD), GMBF, and luminal acid loss (H+ back-diffusion) were measured before and after exposure to 20 mM TC, and the mucosa was examined for lesions 90 min after TC treatment. 3. Mucosal application of TC caused PD reduction in all groups; the degree of PD reduction was similar between normal and diabetic rats, although basal PD values were lower in diabetic rats. In normal rats, TC treatment caused luminal acid loss, followed by an increase of GMBF, resulting in minimal damage in the mucosa. 4. The increased GMBF responses associated with H+ back-diffusion were mitigated in STZ-treated rats, depending on the duration of diabetes, and severe haemorrhagic lesions occurred in the stomach after 10 weeks of diabetes. 5. Intragastric application of capsaicin increased GMBF in normal rats, but such responses were mitigated in STZ diabetic rats. The amount of CGRP released in the isolated stomach in response to capsaicin was significantly lower in diabetic rats when compared to controls. 6. The deleterious influences on GMBF and mucosal ulcerogenic responses in STZ-diabetic rats were partially but significantly antagonized by daily insulin (4 units rat(-1)) treatment. 7. These results suggest that the gastric mucosa of diabetic rats is more vulnerable to acid injury following barrier disruption, and this change is insulin-sensitive and may be partly accounted for by the impairment of GMBF response associated with acid back-diffusion and mediated by capsaicin-sensitive sensory neurons.

Cyclo-oxygenase isozymes in mucosal ulcergenic and functional responses following barrier disruption in rat stomachs.

1. We examined the effects of selective and nonselective cyclo-oxygenase (COX) inhibitors on various functional changes in the rat stomach induced by topical application of taurocholate (TC) and investigated the preferential role of COX isozymes in these responses. 2. Rat stomachs mounted in ex vivo chambers were perfused with 50 mM HCl and transmucosal potential difference (p.d.), mucosal blood flow (GMBF), luminal acid loss and luminal levels of prostaglandin E2 (PGE2) were measured before, during and after exposure to 20 mM TC. 3. Mucosal application of TC in control rats caused a reduction in p.d., followed by an increase of luminal acid loss and GMBF, and produced only minimal damage in the mucosa 2 h later. Pretreatment with indomethacin (10 mg kg[-1], s.c.), a nonselective COX-1 and COX-2 inhibitor, attenuated the gastric hyperaemic response caused by TC without affecting p.d. and acid loss, resulting in haemorrhagic lesions in the mucosa. In contrast, selective COX-2 inhibitors, such as NS-398 and nimesulide (10 mg kg[-1], s.c.), had no effect on any of the responses induced by TC and did not cause gross damage in the mucosa. 4. Luminal PGE2 levels were markedly increased during and after exposure to TC and this response was significantly inhibited by indomethacin but not by either NS-398 or nimesulide. The expression of COX-1-mRNA was consistently detected in the gastric mucosa before and after TC treatment, while a faint expression of COX-2-mRNA was detected only 2 h after TC treatment. 5. Both NS-398 and nimesulide significantly suppressed carrageenan-induced rat paw oedema, similar to indomethacin. 6. These results confirmed a mediator role for prostaglandins in the gastric hyperaemic response following TC-induced barrier disruption, and suggest that COX-1 but not COX-2 is a key enzyme in maintaining 'housekeeping' functions in the gastric mucosa under both normal and adverse conditions.

Regulation and translocation of ATP-dependent apical membrane proteins in rat liver.

The bile canalicular membrane contains four specific ATP-dependent transport processes that are involved in secretion of bile acids, non-bile acid organic anions (mrp1), phospholipids (mdr2), and organic cations (mdr3). The aim of this study was to determine how the canalicular presence of these transport proteins is regulated. Canalicular membrane vesicles (CMV) were prepared from livers of rats treated with taurocholate (TC) and/or dibutyryl-adenosine 3',5'-cycle monophosphate (DBcAMP) with and without pretreatment with colchicine. Transport studies were performed with radiolabeled substrates. Changes in the relative amounts of transport proteins were determined by Western blots. Compared with controls, the specific activity of each of the transport processes was enhanced 1.5- and 3-fold with TC and DBcAMP treatments, respectively. Western blots revealed the same increases with mdr2 and mdr3. Pretreatment of rats with colchicine prevented these responses fully with TC treatment, whereas only partial prevention was obtained with DBcAMP treatment. Besides the ATP-dependent transporters, the relative specific activities of the canalicular membrane ectoenzyme markers, leucine aminopeptidase and gamma-glutamyltranspeptidase, were also affected the same way. These results suggest that TC and DBcAMP increase the specific activity of the canalicular ATP-dependent transport proteins and some canalicular membrane ectoenzymes by stimulating an increase in the relative amounts of these proteins in the membrane.

Increased susceptibility of rat gastric mucosa to ulcerogenic stimulation with aging

We examined the influences of aging on gastric damage and gastric mucosal blood flow (GMBF) responses induced by acid back-diffusion, following the barrier disruption, and investigated the relation of capsaicin-sensitive sensory nerves to these changes. Male Fischer rats 3, 13, and 24 months old were used. Under urethane anesthesia, a rat stomach was mounted on a chamber, and gastric potential difference (PD), luminal H+ loss, and GMBF were measured before, during, and after exposure to 20 mM sodium taurocholate (TC) for 30 min, in the presence of 50 mM HCl. Mucosal exposure to TC caused surface cell damage, PD reduction, and acid back-diffusion (luminal H+ loss) in all groups of rats; delta PD reduction and the amount of H+ loss were not significantly different between young and aged rats. In young rats, a marked increase of GMBF was observed with luminal acid loss following TC treatment, yet it resulted in less damage in the gastric mucosa. In aged rats, however, such GMBF responses were apparently mitigated, leading to a significant worsening of gastric mucosal lesions induced by TC. Mucosal application of capsaicin (0.1 mg/ml) caused an increase of GMBF in young rats, but this response was significantly attenuated in aged rats. In addition, the amount of calcitonin gene-related peptide (CGRP) released in the isolated stomach in response to capsaicin (1 X 10(-5) M) was significantly lower in aged animals when compared to young rats. These findings suggest that the gastric mucosa of aged rats is more vulnerable to acid back-diffusion following the barrier disruption, partly because of dysfunction of GMBF responses mediated by capsaicin-sensitive sensory neurons in the acidic conditions.

Differing effects of cholesterol and taurocholate on steady state hepatic HMG-CoA reductase and cholesterol 7 alpha-hydroxylase activities and mRNA levels in the rat.

We investigated the effects of cholesterol, cholestyramine, and taurocholate feeding on steady state specific activities and mRNA levels of hepatic 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase and cholesterol 7 alpha-hydroxylase in the rat. Interruption of the enterohepatic circulation of bile acids (cholestyramine feeding) increased total HMG-CoA reductase activity 5-fold. Cholesterol and taurocholate administration suppressed total microsomal HMG-CoA reductase activities 87% and 65%, respectively. HMG-CoA reductase mRNA levels increased 3-fold with cholestyramine, did not decrease significantly with cholesterol feeding, but were markedly decreased after taurocholate treatment. Cholesterol 7 alpha-hydroxylase activity increased 4-fold with cholestyramine and 29% during cholesterol feeding, but decreased 64% with taurocholate. Cholesterol 7 alpha-hydroxylase mRNA levels rose 150% and 50% with cholestyramine and cholesterol feeding, respectively, but decreased 73% with taurocholate. The administration of cholesterol together with taurocholate prevented the decline in cholesterol 7 alpha-hydroxylase mRNA levels, but inhibition of enzyme activity persisted (-76%). Hepatic microsomal cholesterol concentrations increased 2-fold with cholesterol feeding but did not change with taurocholate or cholestyramine treatment. These results demonstrate that mRNA levels of HMG-CoA reductase are controlled by the hepatic taurocholate flux, whereas mRNA levels of cholesterol 7 alpha-hydroxylase are controlled by the cholesterol substrate supply. These end products, cholesterol and bile acids, exert post-transcriptional regulation on HMG-CoA reductase and cholesterol 7 alpha-hydroxylase, respectively.

Mechanism of protective effects of ouren-gedoku-to and san'ou-syashin-to on the gastric mucosa

Ouren-Gedoku-To (OGT) and San'ou-Syashin-To (SST), traditional Chinese prescriptions, have been used to treat peptic ulcer. In order to elucidate the mechanism of the protective effects of OGT and SST on the gastric mucosa, we studied their effects on gastric mucosal lesions, ion permeability and prostaglandin synthesis using ulcer experimentally induced in rats by saturation with acidic test solution after taurocholate treatment. Both OGT and SST inhibited taurocholate-induced gastric mucosal lesions in a dose-related manner. These prescriptions dose-dependently inhibited not only the increase of hydrogen and sodium ion net fluxes but also possible hydrogen ion back diffusion into the gastric mucosa during saturation with acidic test solution. SST induced a significant increase in gastric mucosal prostaglandins synthesized from 14C labeled arachidonate. These results suggest that both OGT and SST by strengthening the gastric mucosal barrier demonstrate their protective effects on the gastric mucosa and that this effect of SST is attributable to the increased ability of the gastric mucosa to synthesize prostaglandin.

Further Study of Mucosal Repair by Sofalcone in Experimental Gastritis

The effect of sofalcone on the glandular structure and cell proliferation in the gastric mucosa of rats with gastritis induced by the administration of sodium taurocholate (TCA) for 6 months was examined by histoquantitative analysis and [3H]thymidine autoradiography. Morphometric observation revealed that, with TCA treatment, mucosal thickness, parietal cell mass, and the ratios of the length of the glandular portion/total length of the gastric gland were decreased in both the fundic and pyloric glands. Inflammatory cell infiltration and collagenous fiber proliferation were present in the gastric mucosa following TCA and indicated the presence of atrophic gastritis. These atrophic changes and inflammatory cell infiltration were reversed by a 3 week administration of sofalcone. Cellular proliferative activity assessed by the labeling indices of the gastric mucosa increased in TCA-induced gastritis in rats. The administration of sofalcone to rats with TCA-induced gastritis significantly increased labeling indices, particularly in the pyloric glands. From these results, it appears that sofalcone stimulates the compensatory increase in proliferative activity of generative cells, which then may become available to heal the gastritis.

Taurocholate increases the biliary output of bilirubin pigments in the rat, due to haemolysis

In order to investigate the effect of bile salts on the biliary transport of bilirubin, we infused rats with taurocholate at 1–3 μmol/min/kg body weight. When administered in saline, taurocholate induced haemolysis, and a dosedependent increase in biliary excretion and serum concentration of all bilirubin pigments. The addition of human or rat serum albumin to the infusate, at an albuminataurocholate molar ratio equal to or above 200, completely prevented haemolysis and the above-mentioned alterations in bilirubin transport, without any change in the bile acid output. In order to mimic a haemolytic condition, an erythrocyte haemolysate was further added to the taurocholate-alburnin solution. This again resulted in an increased bilirubin output. We suggest that taurocholate treatment increases bilirubin output due to the increased load of the pigment on the liver, as a result of the bile acid-induced haemolysis.

Lysophosphatidylcholine and taurodeoxycholate increase stomach permeability to different-sized molecules.

The influence of lysophosphatidylcholine (LPC), taurocholate (TC), and taurodeoxycholate (TDC) on gastric mucosal permeability was studied in a rat experimental model, with different-sized polyethylene glycols (PEGs) in the 722-1206-dalton range as permeability markers. Gastric mucosal morphology was also studied by transmission electron microscopy. We found that 2.5 mM and 5 mM LPC and TDC, but not TC, caused an increase in the passage of PEGs across the gastric mucosa. LPC altered the permeability significantly more than did TDC. Morphologically damaged intercellular microvillous structures could be seen after LPC treatment, whereas no obvious changes could be seen after TC or TDC treatment. These findings indicate that LPC and TDC may damage the gastric mucosa and enable permeation of molecules in the 722-1206-dalton range. Molecules within this range could potentially be toxic or antigenic, and this therefore represents an aspect of interest in the pathology of enterogastric reflux. Furthermore, the results indicate that dihydroxy secondary bile acids (TDC) have a more pronounced effect on gastric mucosal permeability than trihydroxy primary bile acids (TC).