bluuebunny/crossref_metadata_2025 huggingface dataset:
Intestinal anaphylaxis: mediation of the response of colonic longitudinal muscle in rat
Authors: Oliver M. R. , Tan D. T. , Scott R. B.
Published: December 2017

Colonic smooth muscle function may be altered in food protein hypersensitivity reactions and could contribute to the clinical manifestation of diarrhea. To characterize such functional changes and elucidate the mediators and mechanisms involved. Hooded-Lister rats were sensitized by intraperitoneal injection of egg albumin (10 micrograms), and controls were sham sensitized with saline. Fourteen days later the contractility of longitudinally oriented distal colonic segments (mucosa intact) were studied in standard tissue baths in response to antigen (Ag) or other agents. After Ag exposure, a contractile response was documented in animals that were sensitized [specific immunoglobulin E (IgE) antibody levels > or = 1:64] and was specific for the sensitizing Ag. Mast cell involvement was suggested by a significant reduction in the number of granulated mucosal mast cells in sensitized tissues after Ag challenge and in the magnitude of the Ag-induced contractile response in the presence of mast cell stabilizers. The antigen-induced response was significantly and independently inhibited by both cyclooxygenase and lipoxygenase enzyme inhibitors and by leukotriene D4 and platelet activating factor receptor antagonists. The Ag-induced response was resistant to histamine and the 5-hydroxytryptamine antagonists, atropine and tetrodotoxin. These results suggest that the food protein-induced contraction of colonic longitudinal smooth muscle in the sensitized rat is due to IgE-mediated mast cell activation with the subsequent production and release of membrane-derived mediators that, in vitro, act directly on the smooth muscle.
A rat gastrin-human gastrin chimeric transgene directs antral G cell-specific expression in transgenic mice
Authors: Wang T. C. , Babyatsky M. W. , Oates P. S. , Zhang Z. , Tillotson L. , Chulak M. , Brand S. J. , Schmidt E. V.
Published: December 2017

Gastrin gene expression in the gastrointestinal tract is under both developmental and spatial regulation. In the mature animal, gastrin, an important regulator of parietal acid secretion, is expressed primarily in G cells of the antrum. To determine whether specific promoter elements can direct expression to the gastric antrum in vivo, 450 nucleotides of the proximal rat gastrin promoter were cloned and used to construct a rat gastrin-human gastrin reporter chimeric transgene, which was injected into the mouse germ line. Northern blot analysis, in situ hybridization, and double-label immunocytochemistry studies demonstrated expression of the transgene specifically in antral G cells. Low levels of transgene expression were observed in the ileum and colon, where immunohistochemical studies demonstrated colocalization in enteroendocrine cells expressing peptide YY. The same 450-nucleotide rat gastrin promoter, when joined to the human growth hormone gene, did not result in antral expression. Similarly, a human gastrin-human gastrin reporter transgene also did not achieve antral expression, although it did express in the liver. These results suggest that cis-acting elements present in both the basal 450-nucleotide rat gastrin promoter and the intragenic sequences of the human gastrin gene are necessary to direct expression of a transgene specifically to antral G cells.
Phosphoinositide synthesis in desensitized rat pancreatic acinar cells
Authors: Lods J. S. , Rossignol B. , Dreux C. , Morisset J.
Published: December 2017

To help understand the possible role of phosphoinositide turnover in the desensitization process, the availability of phosphatidylinositol 4,5-bisphosphate was investigated in normal and desensitized pancreatic acinar cells treated with carbamylcholine (Cch), caerulein (Cae), and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). In control acini, incorporation of [myo-3H]inositol into total phosphoinositides was maximal at 120 min, was Cch and Cae dose dependent, and was insensitive to TPA. Cch stimulation increased the proportion of [myo-3H]inositol incorporated into phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2], whereas Cae specifically channeled [myo-3H]inositol incorporation into phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate. In the desensitized cells, preexposure to Cch and Cae, but not to TPA, increased the subsequent basal rate of [myo-3H]inositol incorporation into total phosphoinositol (PI) by 66 and 50% above control values. There were no subsequent responses to increasing concentrations of Cch, Cae, and TPA during a second incubation. Desensitization of the pancreatic secretory responses to Cch, Cae, and TPA does not seem to result from a decrease either in total PI or in specific PtdIns(4,5)P2 synthesis, which is needed for inositol trisphosphate and diacylglycerol production.
Facilitated DNA transfer to rat submandibular gland in vivo and GRP-Ca gene regulation
Authors: O'Connell B. C. , Ten Hagen K. G. , Lazowski K. W. , Tabak L. A. , Baum B. J.
Published: December 2017

The internalization of DNA can be facilitated by adenovirus infection. Using the replication-deficient adenovirus, Ad-dl312, and a plasmid-based firefly luciferase gene as a reporter, we have optimized the uptake and expression of DNA in rat submandibular glands in vivo. Luciferase expression is transient and peaked at approximately 18 h after infection. Luciferase activity increased with plasmid concentration and was greatest at 10(9) to 10(10) plaque-forming units of Ad-dl312 per gland. We next examined the expression in vivo of plasmids containing deletions of the glutamine/glutamic acid-rich protein (GRP-Ca isoform) gene upstream region linked to a chloramphenicol acetyltransferase (CAT) reporter. Constructs with 9.4, 6.3, and 2.7 kb and 17 base pairs of upstream sequence gave relative CAT activities of 100, 30, 7.6, and 38.5, respectively. With the 9.4-kb GRP-Ca construct, CAT was preferentially expressed in acinar cells, which is characteristic of GRP. This gene transfer approach should prove useful in the further study of gene expression in salivary glands and other organs.
Role of nitric oxide in restitution of injured guinea pig gastric mucosa in vitro
Authors: Yanaka A. , Muto H. , Fukutomi H. , Ito S. , Silen W.
Published: December 2017

The role of nitric oxide (NO) in restitution was examined in intact sheets of in vitro guinea pig gastric mucosae after mucosal injury induced by exposure of the luminal surface to 1.25 M NaCl for 10 min. The recovery of transmucosal electrical resistance and [3H]mannitol flux after the injury were significantly greater at luminal pH (pH1) 7.0 than 3.0. The recovery was abolished by pretreatment with 1 mM NG-nitro-L-arginine methyl ester (L-NAME), only at pHL 3.0, an effect reversed by 1 mM L-arginine. Enhancement of the recovery by L-arginine at pHL 3.0 was abolished by 50 microM methylene blue (MB), an effect restored by 1 mM N6,2'-O-dibutyryl guanosine 3',5'-cyclic monophosphate (DBcGMP). In L-arginine- but not L-NAME-treated tissues, recovery was enhanced further by an increase in serosal [HCO3-] and was inhibited by 5% N-acetyl-L-cysteine in the luminal solution or by the removal of serosal HCO3-. Morphological examination showed the formation of a thick "mucoid cap" in L-arginine-but not L-NAME-treated tissues. These results suggest that, in the presence of luminal acid, endogenous NO contributes to restitution in injured gastric mucosa at least in part by facilitating the formation of the mucoid cap.
Ectopic jejunal pacemakers after jejunal transection and their relationship to transit
Authors: Cullen J. J. , Eagon J. C. , Hould F. S. , Hanson R. B. , Kelly K. A.
Published: December 2017

The hypothesis was that orally moving pacesetter potentials distal to a site of jejunal transection and anastomosis would slow transit through jejunum containing them and that reoperation with excision of bowel containing these pacesetter potentials would restore transit to the control. In six conscious dogs with jejunal serosal electrodes for recording myoelectric activity and a jejunal perfusion/aspiration catheter for measuring transit, jejunal pacesetter potential frequency decreased distal to a midjejunal transection and anastomosis from 18.7 +/- 0.3 (SE) cycles/min (cpm) proximal to the site to 14.4 +/- 0.6 cpm distal to the site (P < 0.05). In addition, orally propagating pacesetter potentials occurred > 25% of the time in a 37 +/- 7 cm length of bowel distal to the site during fasting and after feeding. Transit through the segment with the orally moving pacesetter potentials was slowed during feeding (half time before and after transection, 7.7 +/- 1.1 and 13 +/- 2.0 min, respectively, P < 0.05). Resection of the segment with the abnormal pacesetter potentials shortened the length of bowel containing them to 24 +/- 2 cm (P > 0.05) and restored transit to the control. In conclusion, orally moving pacesetter potentials distal to a canine jejunal transection and anastomosis slowed transit through the segment of bowel containing them. Resection of the segment restored transit to the control.
Effect of orthotopic transplantation of liver on systemic and splanchnic hemodynamics in conscious rat
Authors: Kuznetsova L. V. , Zhao D. , Wheatley A. M.
Published: December 2017

The long-term cardiovascular effects of orthotopic liver transplantation (OLT) were studied in conscious Lewis rats with a radioactive microsphere technique. Three months after OLT with an all-suture technique for graft revascularization (s-OLT), all hemodynamic parameters were similar to control. OLT with "cuffs" fitted to the portal vein and infrahepatic inferior vena cava (c-OLT) led to prominent hemodynamic disturbances including 1) hyperkinetic circulation with increased cardiac index (CI; 22%; P < 0.05) and decreased mean arterial pressure (15%; P < 0.05) and total peripheral resistance (TPR; 28%; P < 0.05); 2) a slight increase in portal pressure (11.8 +/- 0.9 vs. 9.3 +/- 1.7 mmHg in control) and marked portal-systemic shunting (51 +/- 11 vs. 0.05 +/- 0.04% in control; P < 0.05); 3) increased hepatic arterial blood flow (0.49 +/- 0.06 vs. 0.27 +/- 0.04 ml.min-1.g liver wt-1; P < 0.05); 4) splanchnic vasodilation with vascular resistance significantly (P < 0.05) lower in the liver, stomach, and large intestine; and 5) increased blood flow and decreased vascular resistance in the kidneys and heart. Ganglionic blockade with chlorisondamine (5 mg/kg body wt iv) indicated that the increase in CI seen in the c-OLT rats was probably sympathetically mediated, whereas the increase in renal blood flow was a reflection of the increase in CI. After ganglionic blocker administration, TPR and regional vascular resistances decreased to approximately the same extent in the control and c-OLT groups, indicating that vascular sympathetic tone was unchanged in the c-OLT rats.(ABSTRACT TRUNCATED AT 250 WORDS)
Preservation of peristaltic reflex in hypertrophied ileum of guinea pig
Authors: Schulze-Delrieu K. , Brown B. , Herman B. , Brown C. K. , Lawrence D. , Shirazi S. , Palmieri T. , Raab J.
Published: December 2017

Chronic obstruction of the guinea pig ileum leads to distension and muscular hypertrophy, but how this affects passive biomechanical and nerve-mediated contractions and clearance known as peristaltic reflex is unclear. Ileum of controls had a diameter of 3.0 +/- 1.1 mm and a circular muscle thickness of 37.2 +/- 11.2 microns; 4 wk after placement of a nonconstricting Gore-Tex band, the ileum was distended to 10.0 +/- 0.19 mm, and its muscle had hypertrophied to 195.0 +/- 61.2 microns. Hypertrophied segments exceeded controls in capacity (e.g., 5.1 +/- 1.1 vs. 1.1 +/0 0.2 ml at 6 cm), compliance, and hysteresis. Threshold volumes and pressures that triggered the reflex were 3.3 +/- 1.3 ml and 3.1 +/- 0.01 mmHg in hypertrophied vs. 0.7 +/- 0.2 ml and 1.5 +/- 0.2 mmHg in controls. The diameter increase that triggered the reflex was 1.4 +/- 0.1 mm in hypertrophied segments and 0.6 +/- 0.1 mm in controls. Hypertrophied segments generated fewer contractions of virtually double the amplitude and failed to generate a pressure differential between up- and downstream sites as controls did. Hypertrophied segments generated larger stroke volumes and cumulative clearance than controls. The ratio of antegrade to retrograde clearance was similar in hypertrophied and control segments. The length of the occluding segment in hypertrophied preparations exceeded that of controls. Control contractions indented the antimesenteric border and propagated antegrade from their site of origin; bizarre writhing movements of hypertrophied segments made their contractions difficult to monitor. Thus distension and muscular hypertrophy do not interfere with the ability of the chronically obstructed guinea pig ileum to generate a peristaltic reflex at least as readily and as powerful and as effective in clearing the lumen as controls.
Interleukin-1 beta in the dorsal vagal complex inhibits TRH analogue-induced stimulation of gastric contractility
Authors: Morrow N. S. , Quinonez G. , Weiner H. , Tache Y. , Garrick T.
Published: December 2017

The effect of murine interleukin-1 beta (mIL-1 beta) microinjected into the dorsal vagal complex (DVC) on thyrotropin-releasing hormone (TRH) analogue (RX-77368)-induced stimulation of gastric contractility was examined in fasted, urethan-anesthetized rats. Gastric corpus contractions were measured with extraluminal force transducers and analyzed by computer. Microinjection of RX-77368 (30 ng) into the right DVC with mIL-1 beta microinjected either into the right (100, 250 pg) or into the left (100, 500 pg) DVC inhibited gastric contractility for 30-120 min postinjection. Peak suppression of gastric contractility (64-78%) occurred at 50-60 min postinjection. Microinjection of mIL-1 beta into the DVC at a lower dose (10 pg) or into sites adjacent to the DVC (100-500 pg) did not suppress the stimulated gastric contractility pattern. Injection of mIL-1 beta (250 pg) or 0.1% bovine serum albumin into the DVC alone did not alter basal gastric contractility. Intracisternal injection of the IL-1 receptor antagonist (250 ng/10 microliters) abolished the inhibitory effect of mIL-1 beta (250 pg) on gastric contractility. These results demonstrate that mIL-1 beta acts in the DVC to inhibit vagally stimulated gastric contractility, and its action is mediated by IL-1 receptors.
NO mediates gastric relaxation after brief vagal stimulation in anesthetized dogs
Authors: Meulemans A. L. , Eelen J. G. , Schuurkes J. A.
Published: December 2017

In vitro studies showed that relaxations induced after vagal stimulation of the guinea pig stomach are mediated via nitric oxide (NO). The role of NO in canine gastric relaxation in response to vagal stimulation has as yet not been studied. The present study examined the influence of NG-nitro-L-arginine (L-NNA) on gastric relaxations after vagal nerve stimulation in the anesthetized dog. In beagle dogs (n = 7), the ventral and dorsal abdominal vagal nerves were connected to a pair of platinum electrodes. Gastric tone was measured by means of a barostat. Changes in gastric motility were measured with force transducers sutured on the fundus and the antrum. The cervical vagi were sectioned, and dogs were given atropine (0.2 mg/kg i.v.) and guanethidine (5 mg/kg i.v.). Electrical stimulation of the vagal trunks (19 V, 1-ms duration, for 15 s every 2 min, 1-30 Hz) induced frequency-dependent increases in volume. On the fundus, frequency-dependent relaxations could be observed (maximal effect at 5 mmHg and at 10 Hz). During electrical stimulation, the spontaneous antral contractions were completely blocked. After cessation of the stimulus, "rebound" contractions could be observed. L-NNA (5 mg/kg i.v.) completely blocked the increases in gastric volume and the relaxations on the fundus. On the antrum, however, contractions were observed during the electrical stimulation. L-Arginine (250 mg/kg i.v.) gradually restored the relaxations on electrical stimulation. This study demonstrates that NO mediates short-lasting vagally induced gastric relaxations in the anesthetized dog.
Microinjection of TRH analogue into the dorsal vagal complex stimulates pancreatic secretion in rats
Authors: Okumura T. , Taylor I. L. , Pappas T. N.
Published: December 2017

Thyrotropin-releasing hormone (TRH) stimulates pancreatic exocrine secretion through the vagus nerve when injected into rat cerebrospinal fluid. However, little is known about the exact site of action of TRH in the brain to stimulate pancreatic secretion. Recent neuroimmunochemical and neurophysiological studies suggest that TRH could be a neurotransmitter in the dorsal vagal complex, which sends fibers to the pancreas through the vagus nerve. We therefore hypothesized that TRH may act centrally in the dorsal vagal complex to stimulate pancreatic exocrine secretion. To address this question, a TRH analogue, [1-methyl-(S)-4,5-dihydroorotyl]-L-histidyl-L-prolinamide- NH2, was microinjected into the dorsal vagal complex, and basal pancreatic fluid flow and protein secretion were measured in urethan-anesthetized rats. Microinjection of TRH analogue (0.2-2 ng/site) into the dorsal vagal complex significantly stimulated pancreatic flow and protein output in a dose-dependent manner. As a control, microinjection of the TRH analogue into the brain stem outside the vagal complex failed to stimulate pancreatic secretion. Either bilateral subdiaphragmatic vagotomy or atropine abolished the ability of the TRH analogue to stimulate pancreatic secretion. Our data suggest that TRH acts in the dorsal vagal complex to stimulate pancreatic secretion through vagus-dependent and cholinergic pathways. The dorsal vagal complex may play an important role as a central site for control of the exocrine pancreas.
Modulation of smooth muscle contraction by sphingosylphosphorylcholine
Authors: Bitar K. N. , Yamada H.
Published: December 2017

We have investigated the effect of sphingosylphosphorylcholine (SPC), a synthetic product that was implicated in the sphingomyelin cycle, and have assessed its role in intracellular signaling. SPC induced a dose-dependent contractile effect of smooth muscle cells isolated from the rectosigmoid of the rabbit. Maximal contraction occurred at 10(-6) M. The response started early, 25.4 +/- 6% shortening at 15 s, peaked at 30 s (32.5 +/- 2%), and remained sustained at 8 min (30.0 +/- 3.5%). Preincubation of the cells with thapsigargin had no effect on contraction induced by SPC. The response to a combination of threshold concentrations of inositol 1,4,5-trisphosphate (IP3) and SPC was additive and was significantly different from the maximal response elicited by each agent alone. SPC also induced activation of mitogen-activated protein kinase (MAP kinase). This study demonstrates that SPC is important in cellular signaling of gastrointestinal smooth muscle cells through a mechanism that is independent of IP3-sensitive calcium release and probably through activation of a protein kinase C-mediated activation of MAP kinase.
Effect of kinin inhibition in experimental acute pancreatitis
Authors: Lerch M. M. , Weidenbach H. , Gress T. M. , Adler G.
Published: December 2017

Activation of the endogenous kinin system is a consistent observation in acute pancreatitis and has repeatedly been implicated in the pathophysiology of the disease. We have studied the effect of a potent bradykinin antagonist on the onset and development of acute pancreatitis in four unrelated animal models. Pancreatitis was induced in rats by either supramaximal stimulation with caerulein, intraductal injection of sodium taurocholate, or pancreatic duct ligation with secretin infusion, and in mice by feeding a choline-deficient, ethionine-supplemented diet. The potent, long-acting bradykinin antagonist HOE-140 was administered subcutaneously (0.1 mg/kg every 5 h). Effective kinin inhibition had no effect on pancreatitis-associated mortality, the extent of morphological damage and inflammation, or the intracellular distribution of lysosomal hydrolases. Pancreatic edema was only reduced in caerulein-induced pancreatitis, the only model in which edema formation was paralleled by increased vascular permeability. We conclude that, contrary to previous suggestions, kinins do not play a predominant role in the development of acute pancreatitis. Their participation is strictly limited to vascular events and does not involve the early cell biological alterations in pancreatic acinar cells.
L-glutamine and L-asparagine stimulate ODC activity and proliferation in a porcine jejunal enterocyte line
Authors: Kandil H. M. , Argenzio R. A. , Chen W. , Berschneider H. M. , Stiles A. D. , Westwick J. K. , Rippe R. A. , Brenner D. A. , Rhoads J. M.
Published: December 2017

We studied the effect of L-glutamine (Gln), the principal intestinal fuel, on proliferation of a porcine jejunal cell line, IPEC-J2. In cells synchronized by serum deprivation for 4 h, Gln stimulated ornithine decarboxylase (ODC; EC 4.1.1.17) in a dose- and time-dependent manner, with maximal effects at 10 mM in 3 h (P < 0.01). Similar effects were seen for the structurally related amino acid L-asparagine and serum. The Gln effect on ODC was specific, as isosmolar mannitol, glucose, methyl-beta-D-glucoside, L-phenylalanine, ammonia, and aminoisobutyric acid were ineffective. The alanine aminotransferase inhibitor aminooxyacetate (AO) inhibited the ODC stimulation by Gln in a dose-dependent manner (half-maximal inhibitory concentration = 0.5 mM). AO was not toxic to cells, as determined by propidium iodide uptake into nuclei. In addition, Gln stimulated a twofold increase of cellular 24-h [3H]thymidine incorporation above rates of control cells bathed in standard media (P < 0.01); this effect was also blocked by AO. Gln and phorbol 12-myristate 13-acetate stimulated ODC in a synergistic manner. The Na+/H+ exchange inhibitor methylisobutyl amiloride blocked the enhancement of ODC by Gln. Gln also induced the mRNA of the immediate-early gene c-jun. Gln stimulates proliferation in a porcine jejunal cell line through a mechanism requiring transamination and intact Na+/H+ exchange. This stimulation of enterocyte proliferation by Gln suggests that therapeutic Gln administration could facilitate epithelial recovery in the injured small intestine.
Cholecystokinin receptors
Authors: Wank S. A.
Published: December 2017

The cholecystokinin (CCK) and gastrin families of peptides act as hormones and neuropeptides on central and peripheral CCK receptors to mediate secretion and motility in the gastrointestinal (GI) tract in the physiological response to a normal meal. CCK and its receptors are also widely distributed in the central nervous system (CNS) and contribute to the regulation of satiety, anxiety, analgesia, and dopamine-mediated behavior. Although the wide distribution, myriad number of functions, and reported pharmacological heterogeneity of CCK receptors would suggest a large number of receptor subtypes, the application of modern molecular biological techniques has identified two CCK receptors, CCK-A receptor (CCK-AR) and CCK-B receptor (CCK-BR), that mediate the actions of CCK and gastrin; gastrin receptors have been found to be identical to CCK-BR. CCK-AR, found predominantly in the GI system and select areas of the CNS, have high affinity for CCK and the nonpeptide antagonist L-364,718, whereas CCK-BR, found predominantly in the CNS and select areas of the GI system, have high affinity for CCK and gastrin and the nonpeptide antagonist L-365,260. Both CCK-AR and CCK-BR are highly conserved between species, although there is some tissue-specific variation in expression. Recombinant receptor expression faithfully reproduces the native receptor pharmacology and signal transduction pathways, allowing direct comparisons of receptor function between species as well as serving as a convenient source of receptor. Our present knowledge of the chromosomal localization, receptor gene structure, and primary sequence will allow further studies in disease association, receptor regulation, and structure-function analysis.
Tonic suppression of gastric acid secretion by endogenous peptides in neonatal rats
Authors: Rao R. K. , Pepperl S. , Porreca F.
Published: December 2017

Stimulation of gastric acid secretion by secretagogues was measured in developing rats by in vivo and in vitro techniques. Basal acid outputs in vivo were very low in 8- and 14-day-old rats compared with those in 20- and 30-day-old rats. In 20-day-old rats, all secretagogues increased acid output in vivo, whereas only carbachol, pentagastrin, and sulfated cholecystokinin octapeptide (CCK-8S) were active in 14-day-old rats. In contrast, basal acid output in vitro and stimulation by secretagogues did not differ significantly with age. CCK-8S-stimulated acid output in vitro in 14-day-old rats was blocked by L-365,260, L-364,718, tetrodotoxin, and atropine, but not by hexamethonium, whereas gastrin-stimulated acid output was blocked only by L-365,260. Furthermore, acid output in vivo was elevated three- to fourfold by subcutaneous naloxone-methiodide or L-364,718, but not by L-365,260, in 14-day-old rats; none of these antagonists produced an effect in 20-day-old rats. These studies show that low basal gastric acid output in neonatal rats is caused by tonic inhibitory regulation by endogenous regulatory peptides.
Trehalase gene expression during postnatal development of rabbit intestine and kidney: effects of glucocorticoids
Authors: Galand G. , L'Horset F. , Longis Y. , Perret C.
Published: December 2017

Rabbit trehalase is a 75-kDa glycosyl phosphatidylinositol-anchored glycoprotein of the microvillus membrane of the enterocyte and kidney proximal tubule epithelial cells. The purpose of this work was to try to elucidate the molecular basis of trehalase gene expression in intestine and kidney during normal postnatal development and after hydrocortisone injection in suckling rabbits. Trehalase cDNA isolated, sequenced, and characterized by J. Ruf, H. Wacker, P. James. M. Maffia, P. Seiler, G. Galand, A. Kieckebusch, G. Semenza, and N. Mantei (J. Biol. Chem. 265: 15034-15039, 1990) was used to quantify trehalase mRNA. To measure the amount of trehalase mRNA encoding for trehalase, poly(A)+ mRNA was isolated and analyzed by Northern blot hybridization. This cDNA hybridized to a 1.8-kb mRNA in the small intestine and kidney. In developing rabbit intestine, after a slow decrease between 4 and 10 days, there is a sharp and parallel rise of both trehalase specific activity (28x) and mRNA (10x) between 10 and 30 days after birth. In contrast, in the kidney, between 4 and 30 days, the general developmental profile of both parameters is very different. There is an overall significant and parallel increase of both trehalase specific activity (3.3x) and mRNA (4.3x). In intestine the longitudinal gradient of trehalase activity and mRNA expression is different in adult and 16-day cortisol-treated suckling rabbits. In intestine, between 10 and 14 days, cortisol induces a coordinate increase of both trehalase activity (26x) and mRNA (19x), but at 16 days the two parameters diverge markedly. Daily injections of cortisol between 10 and 16 days do not induce significantly trehalase mRNA over controls at 16 days. In only 2 days, between 14 and 16 days, there is a clear loss of trehalase mRNA responsiveness to glucocorticoids. On the contrary, in the kidney, daily injections of cortisol between 10 and 16 days have no significant effect on trehalase mRNA but induce a small and significant increase of trehalase specific activity at 16 days (1.8x). Therefore we conclude that, with respect to the distribution along the small intestine, normal development in kidney and intestine, and after induction with glucocorticoid in intestine, alteration in the steady-state levels of trehalase mRNA is a major mechanism for the regulation of trehalase gene expression.
Immunocytes and abnormal gastrointestinal motor activity during ileitis in dogs
Authors: Jouet P. , Sarna S. K. , Singaram C. , Ryan R. P. , Hillard C. J. , Telford G. L. , Fink J. , Henderson J. D.
Published: December 2017

Infiltration of specific immunocytes and stimulation of abnormal gastrointestinal motor activity during ileal inflammation induced by mucosal exposure to ethanol and acetic acid were investigated in 17 dogs. Ileal inflammation significantly increased the frequency of giant migrating contractions (GMCs) and decreased the frequency of migrating motor complexes (MMCs). The frequency of retrograde giant contractions (RGCs) increased only on the day of ethanol and acetic acid treatment. Diarrhea, urgency of defecation, and apparent abdominal discomfort were related to the increased frequency of GMCs. Ileal inflammation also prolonged the duration of postprandial MMC disruption. Histological and immunohistochemical findings indicated transmural inflammation with marked increase in polymorphonuclear cells in the lamina propria and muscularis externa layers. Myeloperoxidase activity increased severalfold in both layers. Cells containing interleukin-2 receptor (IL-2R) increased in the lamina propria. Other immunocytes, such as B and T lymphocytes, dendritic cells, and human leukocyte antigen DR-1 (HLADR)-positive cells, did not exhibit a significant increase in the inflamed ileum compared with the normal proximal jejunum. We conclude that stimulation of GMCs may be the major motility marker of intestinal inflammation.
Regulation of lineage-specific transcription of the sucrase-isomaltase gene in transgenic mice and cell lines
Authors: Markowitz A. J. , Wu G. D. , Bader A. , Cui Z. , Chen L. , Traber P. G.
Published: December 2017

Sucrase-isomaltase (SI), a gene expressed exclusively in absorptive enterocytes, was used to examine the molecular mechanisms that regulate cell-specific gene expression in the intestinal epithelium. Transgenic mice were made with a construct containing nucleotides -8,500 to +54 of the mouse SI gene linked to a human growth hormone reporter gene. In adult transgenic animals, high-level transgene expression was limited to the small intestine, with low levels of ectopic expression in the colon. In contrast to the endogenous gene that is expressed only in enterocytes, the transgene was expressed in all four cell lineages, including enterocytes, enteroendocrine, goblet, and Paneth cells. To examine this process of lineage-specific expression further we studied Caco-2 and COLO DM cell lines, which model enterocytes and enteroendocrine cells, respectively. Reminiscent of results in transgenic animals, only Caco-2 cells transcribed the endogenous SI gene, whereas both Caco-2 and COLO DM cells supported transcription from chimeric SI reporter gene constructs. Taken together, these data suggest that each intestinal cell lineage has the cellular machinery to transcribe the SI gene. Moreover, these findings imply that transcription is normally repressed in nonenterocytic cells, possibly via a transcriptional silencer residing outside of the region of the SI gene examined in these studies.
Bile salt-dependent inhibition of gallbladder emptying
Authors: Lin H. C. , Zhao X. T. , Kwok G. M. , Gu Y. G. , Elashoff J. D.
Published: December 2017

Little is known about the inhibitory controls of gallbladder emptying. Since cholestyramine, a binding agent that reduces luminal concentration of bile salt, has been reported to accelerate gallbladder emptying, suggesting that bile salt is inhibitory, we hypothesized that fat-stimulated gallbladder emptying is inhibited by a bile salt-dependent mechanism. To test this idea, we compared gallbladder emptying in 10 dogs equipped with duodenal and jejunal fistulas that allowed for complete diversion of the native bile while varying concentrations of bile salt were perfused into the small intestine. In six dogs, 30 mM oleate and 5, 10, or 20 mM sodium taurocholate was perfused into the whole intestine. Since bile salt availability alters fat absorption, in a separate experiment in seven dogs we also compared gallbladder emptying while 30 mM oleate and 5 mM taurocholate were perfused between fistula and 0, 5, 10, or 20 mM taurocholate were perfused beyond jejunal fistula to separate fat from varying concentrations of bile salt. We found that intestinal taurocholate inhibited fat-stimulated gallbladder emptying in a dose-dependent fashion (P < 0.01; analysis of variance, significant linear dose effect) and that the inhibitory effect of bile salt persisted when 5-20 mM taurocholate was perfused beyond the jejunal fistula (0 vs. average of 5-20 mM taurocholate, P < 0.05, paired t-test). We conclude that fat-stimulated gallbladder emptying is inhibited by a bile salt-dependent inhibitory mechanism.
Effect of ethanol on cholecystokinin-stimulated zymogen conversion in pancreatic acinar cells
Authors: Katz M. , Carangelo R. , Miller L. J. , Gorelick F.
Published: December 2017

Exocrine pancreatic zymogens are proteolytically processed to active forms after they are secreted into the small intestine. However, intracellular conversion of zymogens to active forms can be stimulated by treating pancreatic acinar cells with high doses of cholecystokinin (0.1 microM) or carbamylcholine (0.1 mM). The high doses of cholecystokinin are unlikely to be achieved physiologically. The ability of ethanol to sensitize the acinar cell to zymogen conversion Induced by cholecystokinin or carbamylcholine was examined. Ethanol (10-200 mM) had no effect alone or when combined with carbamylcholine. However, ethanol (25 mM) added with low-dose cholecystokinin (0.1 nM) generated zymogen conversion that was 1) sixfold higher than cholecystokinin alone and 2) equivalent to that generated by highdose cholecystokinin (10 microM). The ability of ethanol to enhance cholecystokinin-induced zymogen conversion was dependent on the dose of ethanol and the duration of ethanol treatment. The cholecystokinin receptor antagonist, L-364,718, blocked the conversion stimulated by the addition of ethanol with cholecystokinin. This effect of ethanol did not change the affinity or number of cholecystokinin receptors, suggesting an effect more distal in the stimulus-activation cascade. These findings demonstrate that ethanol selectively sensitizes the pancreatic acinar cell to cholecystokinin-stimulated zymogen proteolysis.
Induction of hepatoma cell apoptosis by c-myc requires zinc and occurs in the absence of DNA fragmentation
Authors: Xu J. , Xu Y. , Nguyen Q. , Novikoff P. M. , Czaja M. J.
Published: December 2017

Since c-myc expression is increased during apoptosis in toxin-induced liver injury in vivo, the role of c-myc in liver cell apoptosis was investigated. The human hepatoma cell line HuH-7, which constitutively expresses c-myc, was stably transfected with sense and antisense c-myc expression vectors under the control of the zinc-inducible metallothionein promoter. None of the three cell types (wild-type, sense c-myc, or antisense c-myc) underwent apoptosis when cultured in serum-free medium (SFM). With the addition of SFM plus 37.5 microM zinc, wild-type and sense c-myc-expressing cells underwent rapid cell death, whereas antisense c-myc-expressing cells exhibited increased survival. This cell death had the light, fluorescent, and electron microscopic appearance of apoptosis, but did not result in DNA fragmentation. This apoptosis could be terminated by the addition of medium containing 2% fetal calf serum or the overexpression of bcl-2 but not by supplementation with specific growth factors. Altering c-myc expression did not affect cellular metallothionein mRNA levels or the rate of cell death from copper or cadmium. The requirement for zinc and absence of DNA fragmentation in c-myc-induced hepatoma cell apoptosis under serum-free conditions provides further evidence of the complex regulation of apoptosis in different cell types.
Apolipoprotein A-IV synthesis in proximal jejunum is stimulated by ileal lipid infusion
Authors: Kalogeris T. J. , Tsuchiya T. , Fukagawa K. , Wolf R. , Tso P.
Published: December 2017

Biosynthesis of apolipoprotein A-IV (apo A-IV) is stimulated by dietary lipid, but the precise mechanisms involved are not clearly understood. Using an intestinally infused rat model, we compared the effect of delivery of lipid into different intestinal sites on mucosal synthesis of apo A-IV in the jejunum and ileum to determine 1) the effect of lipid delivered to one region of the intestine on apo A-IV synthesis in another region of the gut, and 2) whether any such effect is dependent on the presence of lipid in the latter region. Duodenal infusion of triolein emulsion (40 mumol/h) increased jejunal apo A-IV synthesis and mRNA levels by two- to threefold but had no effect on ileal apo A-IV synthesis or mRNA abundance. Ileal infusion of lipid emulsion containing monoolein (20 mumol/h) + oleic acid (40 mumol/h) stimulated apo A-IV synthesis in both ileum and proximal jejunum. Retrograde (orad) transport of ileally infused lipid was not a likely explanation for the ileal effect on jejunal apo A-IV synthesis, because there was negligible luminal and mucosal recovery of [14C]oleic acid in the jejunum after ileal infusion. Total bile diversion did not block the effect of ileal lipid on jejunal apo A-IV synthesis. Ileal, but not duodenal, lipid infusion stimulated apo A-IV synthesis in a jejunal Thiry-Vella fistula, and perfusion of an ileal Thiry-Vella fistula marginally stimulated proximal jejunal apo A-IV synthesis. Thus administration of lipid to the distal gut produces an increase in mucosal synthesis of apo A-IV in both proximal and distal gut. This effect appears to be independent of direct jejunal presence of lipid, suggesting that lipid in the distal intestine may elicit a signal capable of stimulating jejunal synthesis of apo A-IV.
Impaired intracellular signal transduction in gastric smooth muscle of diabetic BB/W rats
Authors: Takahashi T. , Kojima Y. , Tsunoda Y. , Beyer L. A. , Kamijo M. , Sima A. A. , Owyang C.
Published: December 2017

The pathophysiological mechanisms responsible for diabetic gastroparesis remain unclear. Diabetes mellitus occurs spontaneously in 90% of a partially inbred colony of BB/W rats. This animal model resembles human insulin-dependent diabetes and is suitable for investigating the mechanism of diabetic gastroparesis. Diabetic BB/W rats were killed 6 mo after the onset of diabetes. Muscle contraction experiments and [3H]acetylcholine release studies were performed with muscle strips of the gastric body. Biochemical measurements of inositol trisphosphate (IP3) and protein kinase C (PKC) in gastric muscle were performed to characterize abnormalities of the intracellular signal transduction system in gastric myocytes. Circular muscle contractions in response to direct myogenic stimulants, carbachol (10(-7) - 10 (-3)M) or substance P (10(-7) - 10(-5)M), were significantly impaired in diabetic BB/W rats compared with controls. Similarly, muscle contractions in response to NaF (10 mM), a direct stimulant of G proteins, were also impaired in diabetic BB/W rats. In contrast, muscle contractions in response to KCl (25-75 mM) were similar between control and diabetic BB/W rats, indicating normal voltage-dependent Ca2+ entry in muscle strips obtained from diabetics BB/W rats. [3H]acetylcholine release from gastric myenteric plexus in response to electrical transmural stimulation remained intact in diabetic BB/W rats. In separate studies, we demonstrated that carbachol (10(-6) - 10(-4)M) -induced IP3 responses were significantly reduced in diabetic rats compared with control. In addition, there was also impairment of translocation of PKC in diabetic BB/W rats. These observations indicate that myogenic impairment occurred in diabetic BB/W rats. This resulted from altered intracellular signal transduction involving abnormal IP3 production and PKC translocation.
Electrophysiological effects of cholinergic agonists in surface epithelium of Necturus gastric antrum
Authors: Gadacz A. E. , Klingensmith M. E. , Soybel D. I.
Published: December 2017

Intracellular microelectrode techniques were used to characterize voltage and conductance properties of the basolateral membrane of surface epithelial cells in in vitro Necturus antral mucosa. Flux studies confirmed that this tissue secretes HCO3- under resting conditions and during response to cholinergic stimulation. In studies using intracellular microelectrodes, exposure to cholinergic agonists such as acetylcholine, bethanechol, or carbachol elicited an initial hyperpolarization followed by depolarization of the basolateral cell membranes associated with up to fourfold increases in basolateral membrane conductance. Effects of acetylcholine were dose dependent (10(-6) - 10(-4) M) and prevented by pretreatment of tissues with the nonselective muscarinic receptor blocker atropine. Some variation in this response to cholinergic stimulation was observed and appeared to be related to the season (fall/winter/early spring vs. late spring/summer). Despite such variability, circuit analysis and ion substitution studies indicated that the carbachol-induced increases in basolateral conductance were due to increases in conductance to K+ and Cl- . These increases in basolateral transport processes may serve to stabilize cell ion composition and membrane electrical properties during cholinergic stimulation of mucus and HCO3- secretions.
Comparison between activation of ornithine decarboxylase and histidine decarboxylase in rat stomach
Authors: Ding X. Q. , Chen D. , Rosengren E. , Persson L. , Hakanson R.
Published: December 2017

We compared the responses of rat stomach ornithine decarboxylase (ODC) and histidine decarboxylase (HDC) to food intake, oral treatment with antisecretagogues, NaHCO3, and hypertonic NaCl, antrectomy, intravenous infusion of gastrin-17, the selective cholecystokinin (CCK)-B/gastrin receptor antagonist L-365,260, and the somatostatin analogue RC-160. The serum gastrin concentration and oxyntic mucosal ODC and HDC activities were higher in freely fed rats than in fasted rats. Food intake in fasted rats raised the serum gastrin concentration and the ODC and HDC activities. Ranitidine, omeprazole, and NaHCO3 raised the serum gastrin concentration and activated ODC and HDC. Hypertonic NaCl raised the ODC activity 200-fold, whereas circulating gastrin and HDC activity were increased only moderately. Infusion of gastrin-17 activated HDC but not ODC. L-365,260 prevented the activation of HDC but not of ODC in response to food intake and treatment with omeprazole, NaHCO3, or hypertonic NaCl. Antrectomy prevented the food- and omeprazole-evoked rise in oxyntic mucosal HDC activity but not the rise in ODC activity. RC-160 suppressed HDC activity after food intake and treatment with omeprazole, NaHCO3, or NaCl. In contrast, RC-160 suppressed omeprazole- and NaHCO3-evoked ODC activation but not that evoked by food intake or NaCl. The results support the view that HDC in the oxyntic mucosa is activated by gastrin and suppressed by somatostatin. The induction of ODC is not mediated by gastrin; ODC activation appears to be related to acid inhibition per se or to mucosal maintenance and repair; somatostatin, or rather the lack of it, might contribute to the induction of ODC after acid blockade. The mechanism behind the activation of rat stomach ODC seems to differ depending on the type of stimulus.
Evidence for VIP-induced increase in NO production in myenteric neurons of opossum internal anal sphincter
Authors: Chakder S. , Rattan S.
Published: December 2017

A significant interaction between vasoactive intestinal polypeptide (VIP) and nitric oxide (NO) has been reported in neurotransmission of the gastrointestinal tract, including the internal anal sphincter (IAS). The exact site of this NO release from the IAS in response to VIP is not known. Studies were carried out to determine the site of this VIP-induced NO release in opossum IAS. NO synthase (NOS) activity was quantitated by determining L--3H-citrulline production from L[3H]arginine in isolated myenteric ganglia and smooth muscle cells of the IAS. L-[3H]citrulline production was determined before and after treatment with either the ganglionic stimulant 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP), VIP, or peptide histidine isoleucine (PHI) in the absence and presence of the neurotoxin tetrodotoxin and the NOS inhibitor NG-nitro-L-arginine (L-NNA). Smooth muscle cells and ganglia were preloaded with L-[3H]arginine for 5 min and treated with VIP for 1 and 5 min. DMPP and VIP caused a significant increase in L-[3H]citrulline formation in myenteric ganglia at both time periods, whereas in smooth muscle cells there was a moderate but significant increase in L-[3H]citrulline production only at 5 min of VIP treatment. VIP-induced relaxation of isolated smooth muscle cells of the IAS was not affected by L-NNA. The increase in NOS activity of myenteric ganglia by DMPP and VIP was sensitive to neurotoxin and the NOS inhibitor. The data suggest that the increase in NO production in response to VIP in the IAS occurs mainly from the myenteric neurons, with some contribution from the smooth muscle cells.
Kupffer cell prostaglandin E2 stimulates parenchymal cell O2 consumption: alcohol and cell-cell communication
Authors: Qu W. , Zhong Z. , Goto M. , Thurman R. G.
Published: December 2017

Several studies have demonstrated that ethanol can increase hepatic O2 uptake (e.g., produce a hypermetabolic state); however, a complete explanation of this important phenomenon remains unclear. Here, the effect of conditioned media from Kupffer cells isolated from rats chronically exposed to ethanol on O2 consumption of normal parenchymal cells was studied to evaluate the possibility that cell-cell communication participates in the mechanism of the hepatic hypermetabolic state. Kupffer cells were isolated from rats fed either a liquid control diet or a diet containing ethanol. Kupffer cells were cultured for 4 h, and conditioned media were incubated with parenchymal cells isolated from untreated rats in a closed chamber with an O2 electrode. O2 consumption of parenchymal cells incubated in fresh media or conditioned media from Kupffer cells from untreated rats was approximately 30 microliters.h-1. 10(6) cells-1; however, values were increased by > 30% by conditioned media from Kupffer cells isolated from rats treated with ethanol. Indomethacin, nisoldipine, and boiling the conditioned media blocked this stimulation, suggesting the involvement of eicosanoids. Indeed, prostaglandin E2 (PGE2) added directly to parenchymal cells increased O2 consumption in a dose-dependent manner by nearly 60%. Furthermore, PGE2 levels in conditioned media from Kupffer cells isolated from ethanol-treated rats were elevated about twofold. The addition of endotoxin to cultured cells caused a similar phenomenon. Taken together, these data support the hypothesis that Kupffer cells are activated by ethanol treatment to release mediators such a PGE2, which stimulate O2 consumption in parenchymal cells, possibly by mechanisms involving bacterial endotoxin.