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In the brain, neurons, glial cells, vascular endothelial cells (ECs), and mural cells form a functional structure referred to as the neurovascular unit (NVU). The functions of the NVU become impaired with aging. To gain insight into the mechanism underlying the aging-related changes in the NVU, we characterized in the present study the gliovascular interface in transgenic mice expressing a dominant-negative form of the telomeric repeat-binding factor 2 (TERF2) specifically in ECs using the Tie2 promoter. In these transgenic mice, senescence occurred in the cerebral ECs and was accompanied by upregulation of the mRNAs of proinflammatory cell adhesion molecules and cytokines. It is noteworthy that in the deep layers of the cerebral cortex, astrocytes exhibited an increase in the signals for S100β as well as a decrease in the polarization of the water channel aquaporin-4 (AQP4) to the perivascular endfeet of the astrocytes. Mechanistically, the perivascular localization of dystroglycan and its ligand, laminin α2, was decreased, and their localization correlated well with the perivascular localization of AQP4, which supports the notion that their interaction regulates the perivascular localization of AQP4. The diminished perivascular localization of laminin α2 may be attributed to its proteolytic degradation by the matrix metalloproteinase-2 released by senescent ECs. Pericyte coverage was increased and negatively correlated with the decrease in the perivascular localization of AQP4. We propose that aging-related changes in ECs induce a mild morphological alteration of astrocytes and affect the localization of AQP4 at the gliovascular interface.

The efficacy of cisplatin (CDDP) has been demonstrated in the treatment of various cancers as monotherapy and combination therapy with immunotherapy. However, acquired CDDP resistance is a major obstacle to successful treatment. In the present study, the mechanisms underlying acquired CDDP resistance were examined using ACR20 cells, which are CDDP‑resistant cells derived from A549 lung cancer cells. CDDP induces cytotoxicity by binding nuclear DNA and generating reactive oxygen species (ROS). Contrary to our expectation, ROS levels were elevated in ACR20 cells not treated with CDDP. Pretreatment with an ROS inhibitor enhanced the sensitivity of ACR20 cells to CDDP and prevented the activation of nuclear factor (NF)‑кB signaling and upregulation of inhibitor of apoptosis proteins (IAPs). Notably, evaluation of the mitochondrial oxygen consumption rate and mitochondrial superoxide levels revealed a deterioration of mitochondrial function in ACR20 cells. Mitochondrial DNA PCR‑RFLP analysis revealed four mutations with varying percentage levels in ACR20 cells. In addition, in cytoplasmic hybrids with mitochondria from ACR20 cells, intrinsic ROS levels were elevated, expression of IAPs was increased, and complex I activity and sensitivity to CDDP were decreased. Analysis of three‑dimensional structure data indicated that a mutation (ND2 F40L) may impact the proton translocation pathway, thereby affecting mitochondrial complex I activity. Together, these findings suggest that intrinsic ROS levels were elevated by mitochondrial DNA mutations, which decreased the sensitivity to CDDP via activation of NF‑κB signaling and induction of IAP expression in ACR20 cells. These findings indicate that newly identified mutations in mitochondrial DNA may lead to acquired cisplatin resistance in cancer.

Here, we developed a novel in vitro co-culture model, in which process-bearing astrocytes and isolated cerebral microvessels from mice were co-cultured. Astrocytes formed contacts with microvessels from both adult and neonatal mice. However, concentrated localization of the immunofluorescence signal for aquaporin-4 (AQP4) at contact sites between perivascular endfoot processes and blood vessels was only detected with neonatal mouse microvessels. Contact between astrocytic processes and microvessels was retained, whereas concentrated localization of AQP4 signal at contact sites was lost, by knockdown of dystroglycan or α-syntrophin, reflecting polarized localization of AQP4 at perivascular regions in the brain. Further, using our in vitro co-culture model, we found that astrocytes predominantly extend processes to pericytes located at the abluminal surface of microvessels, providing additional evidence that this model is representative of the in vivo situation. Altogether, we have developed a novel in vitro co-culture model that can reproduce aspects of the in vivo situation and is useful for assessing contact formation between astrocytes and blood vessels.

Objective Prior to heart transplant, sensitization to human leukocyte antigen can occur after blood transfusions used during implantation of ventricular assist devices. The result is an increased risk of antibody-mediated rejection (AMR) after heart transplant. While plasmapheresis (PPH) treats serious AMR cases, what subsequent changes occur in the blood concentrations of immunosuppressive agents is still unknown. We investigated pre- and post-PPH changes in blood concentrations of tacrolimus (FK506) and mycophenolic acid (MPA) in a heart-transplant patient experiencing AMR. Case A 40-year-old woman with a history of dilated cardiomyopathy had heart transplantation for advanced heart failure. Since the patient was donor-specific antibody-positive and at risk for AMR, intravenous immunoglobulin therapy and PPH were performed just before transplantation. Triple combination immunosuppressive therapy was initiated, but 4 days after transplantation, panel-reactive antibody increased drastically, and AMR was diagnosed by biopsy. Multidisciplinary therapy, including PPH, was performed. Blood samples were collected to measure blood concentrations of FK506 and MPA before and after passage through the plasma separator. Results The elimination efficiency of FK506 from PPH was -6.25 - 2.25%, while the elimination efficiency of MPA was much greater at 32.35 - 51.43%. Conclusion These results show the necessity of carefully considering changes in blood concentrations that occur in immunosuppressive agents due to PPH, including the pharmacokinetics of the particular drug. However, proper timing of the PPH relative to drug administration can also minimize immunosuppressant loss. .

Background Regulatory T cells (Tregs) are demonstrated to play a protective role in the development of atherosclerosis. However, their sites of action in atherosclerosis remain unclear. Although C-C chemokine receptor 4 (CCR4) has been shown to contribute to the accumulation of Tregs in inflamed tissues and prevention of experimental autoimmune diseases, the role of CCR4 in Treg migration to atherosclerotic lesions and suppression of plaque formation remains unknown. Methods and results We intraperitoneally injected 8-week-old apolipoprotein E–deficient mice fed a normal diet with vehicle (n=9) or a 4-μg dose of a CCR4 antagonist (n=10) 3 times weekly for 8 weeks and evaluated atherosclerotic lesions at 16 weeks old. Administration of the CCR4 antagonist significantly aggravated atherosclerotic plaque formation (aortic sinus plaque area: 2.91±0.87×104 μm2 versus 5.41±0.98×104 μm2 in control vehicle-treated and CCR4 antagonist-treated mice, respectively; P Conclusions Our findings indicate an important role for CCR4 in promotion of Treg recruitment into atherosclerotic lesions and subsequent prevention of early atherosclerosis and suggest CCR4 as a novel therapeutic target for atherosclerosis. Funding Acknowledgement Type of funding source: None

Cisplatin (CDDP) is widely used as an anti-cancer platinum agent but its therapeutic efficacy is limited by acquired drug resistance. To develop a new therapeutic strategy that could overcome this resistance, it is important to characterize CDDP-resistant cancer cells. Here we established human lung cancer A549 cell-derived low- and high-grade CDDP-resistant sublines, termed ACR4 and ACR20 cells, by stepwise increasing CDDP concentrations up to 4 and 20 μM, respectively. ACR4 and ACR20 cells showed 6- and 16-fold higher resistance to CDDP than A549 cells, respectively. Cell migration, invasion, and sphere formation were significantly decreased, whereas expression of the stem cell marker CD44v was increased in order of A549, ACR4, and ACR20 cells. The expression of the cystine-glutamate transporter xCT, which is encoded by SLC7A11, was upregulated because of the increased cell surface expression of CD44v in ACR20 cells. Treatment with the xCT inhibitor salazosulfapyridine and knockdown of SLC7A11 mRNA by a specific siRNA significantly improved sensitivity to CDDP in A549, ACR4, and ACR20 cells. Thus, our results suggest that CD44v overexpression is not involved in cancer stem cell properties but increases xCT expression, which leads to the acquisition of CDDP-resistance. This mechanism may contribute to the development of a new therapeutic strategy that can overcome resistance.

Background Exosomes, small-membrane vesicles, are secreted by cells and include several types of proteins and nucleic acids. Exosomes transfer cellular information derived from donor cells and are involved in various physiological and pathological events, such as organ-specific metastasis. Elucidating the exosome uptake mechanisms is important for understanding the progression processes of organ-specific metastasis. However, whether the exosomes secreted by the donor cells are selectively or non-selectively incorporated into the recipient cells is unknown. Methods In this study, three human carcinoma cell lines, A549 (lung), HCT116 and COLO205 (colon), were used. The exosome isolation efficiency was compared between three methods: ultracentrifugation, ExoQuick-TC and Total Exosome Isolation kits. Recipient cells were treated with Pitstop 2, an inhibitor of clathrin-dependent endocytosis, or genistein, an inhibitor of caveolae-dependent endocytosis, and then incubated with DiO-labeled exosomes. Results Among the three methods examined, ultracentrifugation was the most efficient and reproducible. Exosomes derived from a donor cell line are incorporated into the three cell lines, but the exosome uptake capability was different depending on the recipient cell type and did not depend on the donor cell type. Exosome uptake in COLO205 was inhibited by Pitstop 2 and genistein. Exosome uptake in HCT116 was inhibited by Pitstop 2, but not genistein, while that in A549 cells was not inhibited by these inhibitors. Taken together, these results suggest that the exosomes secreted by donor cells are non-selectively incorporated into recipient cells and that the exosome uptake mechanism is different depending on the recipient cells. Conclusions Different recipient cells’ exosome uptake capabilities may be involved in organ-specific metastasis.

Aims Vascular inflammation via T-cell-mediated immune responses has been shown to be critically involved in the pathogenesis of abdominal aortic aneurysm (AAA). T-cell coinhibitory molecule cytotoxic T-lymphocyte–associated antigen-4 (CTLA-4) is known to act as a potent negative regulator of immune responses. However, the role of this molecule in the development of AAA remains completely unknown. In the present study, we determined the effects of CTLA-4 overexpression on experimental AAA. Methods and results We continuously infused 12-week-old CTLA-4 transgenic (CTLA-4-Tg)/apolipoprotein E–deficient (Apoe−/−) mice (n=35) or control Apoe−/− mice (n=40) fed a high-cholesterol diet with angiotensin II by implanting osmotic mini-pumps and evaluated the development of AAA. Ninety percent of angiotensin II-infused mice developed AAA, with 50% mortality because of aneurysm rupture. Overexpression of CTLA-4 significantly reduced the incidence (66%), mortality (26%), and diameter (18%) of AAA (incidence: P=0.0104; mortality: P=0.031; diameter: P=0.011). These protective effects were associated with a decreased number of effector CD4+ T cells and the downregulated expression of costimulatory molecules CD80 and CD86, ligands for CTLA-4, on CD11c+ dendritic cells in lymphoid tissues. In addition, by performing in situ zymography of the abdominal aortic aneurysm lesions, we observed a trend toward a decrease in MMP activity in the aneurysmal lesion following overexpression of CTLA-4. Finally, CTLA-4-Tg/Apoe−/− mice had reduced macrophage and CD4+ T cell accumulation and MMP activity in the aneurysmal lesion, leading to attenuated aortic inflammation, preserved vessel integrity, and decreased susceptibility to AAA and aortic rupture. Conclusion Our findings suggest that CTLA-4 protects against AAA by suppressing immunoinflammatory responses and could be an attractive therapeutic target for AAA.

Nonalcoholic steatohepatitis (NASH) progresses from nonalcoholic fatty liver disease (NAFLD), however, efficacious drugs for NASH treatment are lacking. Sodium alginate (SA), a soluble dietary fiber extracted from brown algae, could protect the small intestine from enterobacterial invasion. NASH pathogenesis has been suggested to be associated with enterobacterial invasion, so we examined the effect of SA on methionine- and choline-deficient (MCD) diet-induced steatohepatitis in mice (the most widely-used model of NASH). The mice (n = 31) were divided into three groups (mice fed with regular chow, MCD diet, and MCD diet premixed with 5% SA) for 4 and 8 weeks. The MCD diet increased lipid accumulation and inflammation in the liver, the NAFLD Activity Score and hepatic mRNA expression of tumor necrosis factor- and collagen 11, and induced macrophage infiltration. Villus shortening, disruption of zonula occludens-1 localization and depletion of mucus production were observed in the small intestine of the MCD-group mice. SA administration improved lipid accumulation and inflammation in the liver, and impaired barrier function in the small intestine. Collectively, these results suggest that SA is useful for NASH treatment because it can prevent hepatic inflammation and fatty degeneration by maintaining intestinal barrier function.

The liver and the small intestine are closely related in the processes of drug absorption, metabolism and excretion via the enterohepatic circulation. Small intestinal ulcers are a serious adverse effect commonly occurring in patients taking nonsteroidal anti-inflammatory drugs. However, the influence of small intestinal ulcers on drug metabolism has not been established. This study examined the expressional changes of cytochrome P450 (CYP) in the liver using an indomethacin-induced small intestinal ulcer rat model and in cultured cells. After the administration of indomethacin to rats, ulcers were observed in the small intestine and expression of CYP3A1, the major isoform of hepatic CYP, was significantly down-regulated in the liver, accompanied by increased expression of inducible nitric oxide synthase, tumor necrosis factor α, interleukin (IL)-1β and IL-6, in the small intestine and the liver. The indomethacin-induced small intestinal ulceration, the increase in inflammatory mediators in the small intestine and the liver, and the down-regulation of CYP3A1 expression in the liver were inhibited by co-administration of ampicillin, an antibacterial agent. In the human hepatic HepG2 cell line, IL-1β, IL-6 and NOC-18, an NO donor, caused down-regulation of CYP3A4, the major isoform of human CYP3A. Thus, this study suggests that after indomethacin treatment small intestinal ulcers cause the down-regulation of CYP3A1 in the rat liver through an increase in ulcer-derived inflammatory mediators. Copyright © 2016 John Wiley & Sons, Ltd.

Recent advances in diagnostic technologies have revealed that nonsteroidal anti-inflammatory drugs (NSAIDs) can cause serious mucosal injury in the upper and lower gastrointestinal tract (including the small intestine). A drug to treat NSAID-induced small-intestinal injury (SII) is lacking. Sodium alginate is a soluble dietary fiber extracted from brown seaweed and its solution has been used as a hemostatic agent to treat gastrointestinal bleeding due to gastric ulcers. Whether sodium alginate has therapeutic effects on NSAID-induced SII and its mechanism of action are not known. Here, we investigated if administration of two forms (high-molecular-weight (HMW) and low-molecular-weight (LMW)) of sodium alginate could ameliorate indomethacin-induced SII. Pretreatment with HMW sodium alginate or LMW sodium alginate before indomethacin administration improved ulceration and the resultant intestinal shortening was associated with reduced histological severity of mucosal injury and ameliorated mRNA expression of inflammation-related molecules in the small intestine. We found that mRNAs of secretory Muc2 and membrane-associated Muc1, Muc3 and Muc4 were expressed in the small intestine. mRNA expression of Muc1-4 was increased in indomethacin-induced SII, and these increases were prevented by sodium alginate. Thus, administration of sodium alginate could be a therapeutic approach to prevent indomethacin-induced SII.

In the central nervous system, astrocytes extend endfoot processes to ensheath synapses and microvessels. However, the mechanisms underlying this astrocytic process extension remain unclear. A limitation of the use of 2D cultured astrocytes for such studies is that they display a flat, epithelioid morphology, with no or very few processes, which is markedly different from the stellate morphology observed in vivo. In this study, we obtained 2D cultured astrocytes with a rich complexity of processes using differentiation of neurospheres in vitro. Using these process-bearing astrocytes, we showed that laminin, an extracellular matrix molecule abundant in perivascular sites, efficiently induced process formation and branching. Specifically, the numbers of the first- and second-order branch processes and the maximal process length of astrocytes were increased when cultured on laminin, compared with when they were cultured on poly-L-ornithine or type IV collagen. Knockdown of dystroglycan or α-syntrophin, constituent proteins of the dystrophin-glycoprotein complex that provides a link between laminin and the cytoskeleton, using small interference RNAs inhibited astrocyte process formation and branching, and down-regulated expression of the water channel aquaporin-4 (AQP4). Direct knockdown and a specific inhibitor of AQP4 also inhibited, whereas over-expression of AQP4 enhanced astrocyte process formation and branching. Knockdown of AQP4 decreased phosphorylation of focal adhesion kinase (FAK) that is critically implicated in actin remodeling. Collectively, these results indicate that the laminin-dystroglycan-α-syntrophin-AQP4 axis is important for process formation and branching of 2D cultured astrocytes. OPEN PRACTICES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/. Read the Editorial Highlight for this article on page 436.

Aims Cisplatin (CDDP) is a platinum-based drug that is widely used in cancer chemotherapy, but the development of resistance in tumor cells is a major weakness of these treatments. Several mechanisms have been proposed to explain cisplatin resistance, and disruption of certain cellular pathways could modulate drug sensitivity to cisplatin. A lower level of cross-resistance to cisplatin leads to better outcomes in clinical use. Main methods Cross-resistance was assessed using cisplatin resistant lung cancer cell line A549/CDDP. Cell cycle analysis was used to examine the effect of cisplatin on cell signaling pathways regulating G2/M transition in cisplatin resistant cells. Key findings A549/CDDP cells exhibited cross-resistance to carboplatin, but not oxaliplatin, which is often found in platinum analogues. Flow cytometry showed that nocodazole treatment caused a G2/M block in both A549/CDDP cells and cisplatin susceptible cells. However, A549/CDDP cells escaped the G2/M block following exposure to cisplatin. Activation of the Cdc2/CyclinB complex is required for transition from G2 to M phase, and the inactive form of phosphorylated Cdc2 is activated by Cdc25C dephosphorylation of Tyr15. In the cisplatin-treated susceptible cells, the levels of phosphorylated Cdc2 and Cdc25C were markedly decreased, leading to a loss of Cdc2 activity and G2/M arrest. In A549/CDDP cells, however, Cdc2 activity was supported by the expression of Cdc2 and Cdc25C after the addition of cisplatin, which resulted in G2/M progression. Significance The resistance phenotype of G2/M progression has been correlated with dysregulation of Cdc2 in a human lung cancer cell line selected for cisplatin.

Background: Non-steroidal anti-inflammatory drugs induce the serious side effect of small intestinal ulcerations (SIUs), but little information is available regarding the consequences to drug metabolism and absorption. Aim: We examined the existence of secondary hepatic inflammation in rats with indomethacin (INM)-induced SIUs and assessed its relationship to the cytochrome P450 (CYP) and P-glycoprotein (mdr1a), the major drug-metabolizing factors in the small intestine and the liver. Methods: Gene expression of the CYP family of enzymes and mdr1a was measured with quantitative real-time polymerase chain reaction (qPCR). Vancomycin (VCM), a poorly absorbed drug, was administered intraduodenally to rats with SIUs. Results: INM induced SIUs predominantly in the lower region of the small intestine with high expression of inflammatory markers. Liver dysfunction was also observed, which suggested a secondary inflammatory response in rats with SIUs. In the liver of rats with SIUs, the expression of CYP2C11, CYP2E1, and CYP3A1 was significantly decreased, and loss of CYP3A protein was observed. Although previous studies have shown a direct effect of INM on CYP3A activity, we could not confirm any change in hepatic CY3A4 expression (major isoform of human CYP3A) in vitro. The plasma VCM concentration was increased in rats with SIUs due to partial absorption from the mucosal injury, but not in normal mucosa. Conclusions: INM-induced SIUs had a subtle effect on intestinal CYP expression, but had an apparent action on hepatic CYP, which was influenced, at least in part, by the secondary inflammation. Furthermore, drug absorption was increased in rats with SIUs.

Vascular inflammation via T-cell-mediated immune responses has been shown to be critically involved in the pathogenesis of abdominal aortic aneurysm (AAA). T-cell coinhibitory molecule cytotoxic T-lymphocyte–associated antigen-4 (CTLA-4) is known to act as a potent negative regulator of immune responses. However, the role of this molecule in the development of AAA remains completely unknown. We determined the effects of CTLA-4 overexpression on experimental AAA. We continuously infused CTLA-4 transgenic (CTLA-4-Tg)/apolipoprotein E–deficient (Apoe−/−) mice or control Apoe−/− mice fed a high-cholesterol diet with angiotensin II by implanting osmotic mini-pumps and evaluated the development of AAA. Ninety percent of angiotensin II-infused mice developed AAA, with 50% mortality because of aneurysm rupture. Overexpression of CTLA-4 significantly reduced the incidence (66%), mortality (26%), and diameter of AAA. These protective effects were associated with a decreased number of effector CD4+ T cells and the downregulated expression of costimulatory molecules CD80 and CD86, ligands for CTLA-4, on CD11c+ dendritic cells in lymphoid tissues. CTLA-4-Tg/Apoe−/− mice had reduced accumulation of macrophages and CD4+ T cells, leading to attenuated aortic inflammation, preserved vessel integrity, and decreased susceptibility to AAA and aortic rupture. Our findings suggest T-cell coinhibitory molecule CTLA-4 as a novel therapeutic target for AAA.

Non-steroidal anti-inflammatory drugs (NSAIDs)-induced small intestinal injury is a serious clinical event with recent advances of diagnostic technologies, but a successful therapeutic method to treat such injuries is still lacking. Licorice, a traditional herbal medicine, and its derivatives have been widely used for the treatment of a variety of diseases due to their extensive biological actions. However, it is unknown whether these derivatives have an effect on NSAIDs-induced small intestinal damage. Previously, the anti-inflammatory effects of three compounds extracted from the licorice root, glycyrrhizin, 18β-glycyrrhetinic acid, and dipotassium glycyrrhizinate, were compared in vitro cell culture. The most prominent inhibitory effect on the tumor necrosis factor-α (TNF-α) production was observed with the administration of 18β-glycyrrhetinic acid as an active metabolite of glycyrrhizin. In this study, a complex compound of 18β-glycyrrhetinic acid and hydroxypropyl γcyclodextrin was examined to improve the oral bioavailability. After administration of this complex to indomethacin treated mice, a significantly high plasma concentration of 18β-glycyrrhetinic acid was detected using the tandem mass spectrometry coupled with the HPLC. Furthermore, the complex form of 18β-glycyrrhetinic acid and hydroxypropyl γcyclodextrin reduced mRNA expressions of TNF-α, interleukin (IL)-1β, and IL-6, which was histologically confirmed in the improvement of indomethacin-induced small intestinal damage. These results suggest that the complex of 18β-glycyrrhetinic acid and hydroxypropyl γcyclodextrin has the potential therapeutic value for preventing the adverse effects of indomethacin-induced small intestinal injury.

The liver and the small intestine are closely related in the processes of drug absorption, metabolism and excretion via the enterohepatic circulation. Small intestinal ulcers are a serious adverse effect commonly occurring in patients taking nonsteroidal anti-inflammatory drugs. However, the influence of small intestinal ulcers on drug metabolism has not been established. This study examined the expressional changes of cytochrome P450 (CYP) in the liver using an indomethacin-induced small intestinal ulcer rat model and in cultured cells. After the administration of indomethacin to rats, ulcers were observed in the small intestine and expression of CYP3A1, the major isoform of hepatic CYP, was significantly down-regulated in the liver, accompanied by increased expression of inducible nitric oxide synthase, tumor necrosis factor α, interleukin (IL)-1β and IL-6, in the small intestine and the liver. The indomethacin-induced small intestinal ulceration, the increase in inflammatory mediators in the small intestine and the liver, and the down-regulation of CYP3A1 expression in the liver were inhibited by co-administration of ampicillin, an antibacterial agent. In the human hepatic HepG2 cell line, IL-1β, IL-6 and NOC-18, an NO donor, caused down-regulation of CYP3A4, the major isoform of human CYP3A. Thus, this study suggests that after indomethacin treatment small intestinal ulcers cause the down-regulation of CYP3A1 in the rat liver through an increase in ulcer-derived inflammatory mediators. Copyright © 2016 John WileySons, Ltd.

Duodenal HCO3− secretion increases in response to luminal acid, mediated by endogenous nitiric oxide (NO) as well as prostaglandins (PGs). In this study, we examined the effects of various inhibitors of cyclooxygenase (COX) or NO synthase (NOS) on the acid-induced HCO3− secretion in rats and determined the enzyme isoforms responsible for this response. A proximal duodenal loop was perfused with saline under urethane anesthesia, and the HCO3− secretion was measured at pH 7.0 using a pH-stat method and by adding 10 mM HCl. Mucosal acidification was performed by exposing the loop to 10 mM HCl for 10 min. Indomethacin, SC-560 (a selective COX-1 inhibitor) and rofecoxib (a selective COX-2 inhibitor) were given intraduodenally 1 hr before exposure to 10 mM HCl, while NG-nitro-l-arginine methyl ester (l-NAME: a nonselective NOS inhibitor) and aminoguanidine (a relatively selective inhibitor of iNOS) were given subcutaneously 3 hr before the acidification. The mucosal acidification increased the HCO3− secretion, with a rise in mucosal PGE2 content and luminal release of NO. The HCO3− secretory and PGE2 biosynthetic responses were significantly inhibited by indomethacin and SC-560, while rofecoxib had no effect on these responses. On the other hand, l-NAME, but not aminoguanidine, attenuated NO release following the acidification, resulting in inhibition of the acid-induced HCO3− secretion in a l-arginine-sensitive manner. Neither COX-2 nor iNOS mRNAs were observed in the mucosa before and 1 hr after acidification, while the gene expression of COX-1 and nNOS was constitutively detected in the mucosa and appeared to be slightly up-regulated after the acid stimulation. These results suggest that COX-1 and cNOS play as the respective key enzyme responsible for producing PG and NO following the duodenal acidification, both of which are involved in the mechanism for the acid-induced HCO3− secretion in the duodenum.

Body temperature dependency in gastric functional responses to baclofen, a GABA B agonist, such as acid secretion, mucosal blood flow (GMBF) and motor activity, was examined in urethane-anesthetized rats under normal (37±1 °C) and hypothermic (31±1 °C) conditions. A rat stomach was mounted in an ex-vivo chamber, perfused with saline, and the acid secretion was measured using a pH-stat method, simultaneously with GMBF by a laser Doppler flowmeter. Gastric motility was measured using a miniature balloon as intraluminal pressure recordings. Intravenous administration of baclofen significantly increased acid secretion at the doses > 0.3 mg/kg under hypothermic conditions, yet it caused a significant stimulation only at doses >10 mg/kg under normothermic conditions. The increases in gastric motility and GMBF were similarly induced by baclofen, irrespective of whether the animals were subjected to normothermic or hypothermic conditions. These functional responses to baclofen under hypothermic conditions were totally attenuated by either bilateral vagotomy or atropine (3 mg/kg, s.c.). Baclofen at a lower dose (1 mg/kg i.v.) significantly increased the acid secretion even under normothermic conditions when the animals were subjected to chemical deafferenation of capsaicin-sensitive neurons or pretreatment with intracisternal injection of CGRP 8-37 (30 ng/rat). These results suggest that 1) gastric effects of baclofen are dependent on body temperature in stimulating acid secretion but not GMBF or motor activity, 2) the acid stimulatory action of baclofen is enhanced under hypothermic conditions, and 3) the suppression of baclofen-induced acid response under normothermic conditions may be related to capsaicin-sensitive afferent neuronal activity, probably mediated by central release of CGRP.

Nizatidine, a histamine H(2)-antagonist, is known to inhibit acetylcholinesterase (AChE) activity and is used clinically as a gastroprokinetic agent as well as the anti-ulcer agent. We examined whether or not nizatidine stimulates duodenal HCO(3)(-) secretion in rats through vagal-cholinergic mechanisms by inhibiting AChE activity. Under pentobarbital anesthesia, a proximal duodenal loop was perfused with saline, and the HCO(3)(-) secretion was measured at pH 7.0 using a pH-stat method and by adding 10 mM HCl. Nizatidine, neostigmine, carbachol, famotidine or ranitidine was administered i.v. as a single injection. Intravenous administration of nizatidine (3-30 mg/kg) dose-dependently increased the HCO(3)(-) secretion, and the effect at 10 mg/kg was equivalent to that obtained by carbachol at 0.01 mg/kg. The HCO(3)(-) stimulatory action of nizatidine was observed at the doses that inhibited the histamine-induced acid secretion and enhanced gastric motility. This effect was mimicked by neostigmine (0.03 mg/kg) and significantly attenuated by bilateral vagotomy and pretreatment with atropine but not indomethacin. The IC(50) of nizatidine for AChE of rat erythrocytes was 1.4 x 10(-6) M, about 12 times higher than that of neostigmine. Ranitidine showed the anti-AchE activity and increased duodenal HCO(3)(-) secretion, similar to nizatidine, whereas famotidine had any influence on neither AChE activity nor the HCO(3)(-) secretion. On the other hand, duodenal damage induced by acid perfusion (100 mM HCl for 4 h) in the presence of indomethacin was significantly prevented by nizatidine and neostigmine, at the doses that increased the HCO(3)(-) secretion. These results suggest that nizatidine increases HCO(3)(-) secretion in the rat duodenum, mediated by vagal-cholinergic mechanism, the action being associated with the anti-AChE activity of this agent.

The present article overviews the regulatory mechanism of acid secretion in the stomach after damage with taurocholate (TC), one of the bile acids. Mucosal exposure of a rat stomach to 20 mmol/L TC for 30 min caused a decrease of acid secretion with a concomitant increase in nitric oxide (NO) and prostaglandin (PG) E2 (PGE2) as well as Ca2+ in the luminal contents. Prior administration of N(G)-nitro-L-arginine methyl ester (L-NAME), as well as indomethacin, significantly attenuated the reduction of acid secretion by TC and acid secretion was even increased in the presence of L-NAME. The acid stimulatory effect of L-NAME in the damaged stomach was not mimicked by aminoguanidine and was antagonized by co-administration of L-arginine but not D-arginine. Increased NO release in the damaged stomach was suppressed by pretreatment with L-NAME or co-application of EGTA and the latter also inhibited the increase in luminal Ca2+. The enhanced acid secretory response in the presence of L-NAME was also inhibited by cimetidine, FPL-52694 (a mast cell stabilizer) or sensory deafferentation. Mucosal exposure to TC caused an increase in luminal histamine output, together with a decrease in the number of mucosal mast cells in the stomach. These changes were prevented by FPL-52694 and sensory deafferentation and were also partly suppressed by indomethacin. In addition, the acid stimulatory action of L-NAME in the damaged stomach was significantly mitigated when indomethacin was administered together with L-NAME. We conclude that: (i) damage in the stomach may activate acid a stimulatory pathway in addition to a PG-, NO- and Ca2+-dependent inhibitory mechanism, but the latter effect overcomes the former, resulting in a decrease in acid secretion; (ii) acid stimulation in the damaged stomach is mediated by histamine released from the mucosal mast cell, a process interacting with capsaicin-sensitive sensory nerves; (iii) the increase in luminal Ca2+ plays a role in increasing NO production and, hence, in regulating acid secretion; and (iv) PG may have a dual role in the regulation of acid secretion in the damaged stomach: an inhibitory effect at the parietal cell and an excitatory effect, probably through enhancing the release of mucosal histamine.

Summary Background: The acid inhibitory mechanism in the damaged stomach is known to involve endogenous nitric oxide (NO) as well as prostaglandin (PG). Aim: To investigate the interaction between PG and NO in regulation of acid secretion in the stomach following damage. Methods: Under urethane anaesthesia, a rat stomach was mounted in an ex vivo chamber and perfused with saline. Acid secretion, luminal PGE2, NO metabolites (NOx) and histamine output were measured before and after application of 20 m m taurocholate Na (TC) for 30 min, with or without pre-treatment with indomethacin and/or NG-nitro- l-arginine methyl ester (L-NAME). Results: Exposure of the stomach to TC caused a decrease in acid secretion, with concomitant increase of both luminal NOx and PGE2. Either L-NAME or indomethacin reduced the decrease in acid secretion in response to TC, but only L-NAME allowed acid secretion to increase over basal values. L-NAME prevented the increase of luminal NOx after TC treatment, while indomethacin inhibited PGE2 release during and after exposure to TC. The increase in acid secretion in the presence of L-NAME was prevented when indomethacin was given concomitantly. TC treatment increased histamine output in the lumen, a process that was enhanced by L-NAME but reduced by indomethacin. Conclusions: Damage to the stomach increases both NO and PG in the lumen, and decreases acid secretion. Inhibiting NO production increases acid secretion in the damaged stomach, but only when PG biosynthesis is intact. It is assumed that endogenous PG has a dual role in the regulation of acid secretion in the damaged stomach: an inhibitory effect at the parietal cell and an excitatory effect probably through enhancing the release of mucosal histamine.

We compared gastric acid secretion in response to various stimuli in normal and streptozotocin (STZ)-induced diabetic rats, in an attempt to characterize the alteration of acid secretory response in diabetic conditions. Animals were injected STZ (70 mg x kg(-1), i.p.) and used after 5 weeks of diabetes with blood glucose350 mg x dL(-1). Under urethane anesthesia, a rat stomach was mounted on an ex vivo chamber, perfused with saline and acid secretion was measured at pH 7.0 using a pH-stat method and by adding 100 mM NaOH. The acid secretion was stimulated by i.v. infusion of either histamine (4 mg x kg(-1) x h(-1)), pentagastrin (60 microg x kg(-1) x h(-1)) or carbachol (20 microg x kg(-1) x h(-1)) or i.v. injection of YM-14673 (0.3 mg x kg(-1)), an analog of thyrotropin-releasing hormone, or vagal electrical stimulation (2 ms, 3 Hz, 0.5 mA). In normal rats, gastric acid secretion was increased in response to either histamine, pentagastrin, carbachol, YM-14673 or electrical vagal stimulation. In STZ diabetic rats, however, changes in acid secretion varied depending on the stimuli; the acid secretory responses to histamine remained unchanged, those to YM-14673 and vagal electrical stimulation significantly decreased, but the responses to both pentagastrin and carbachol were significantly enhanced as compared to normal rats. Luminal release of histamine in response to both pentagastrin and carbachol was increased in STZ-diabetic rats as compared to normal animals. The altered acid secretory responses in STZ diabetic rats were partially reversed by daily injection of insulin with amelioration of high blood glucose levels. These results suggest that STZ-diabetic rats showed different changes in gastric acid secretory responses to various stimuli; no change in response to histamine, a decrease to both YM-14673 and vagal electrical stimulation and an increase to both pentagastrin and carbachol. The increased acid secretory response may be associated with an enhanced release of mucosal histamine, while the decreased response may be due to vagal neuropathy.

Background: The antiulcer drug ecabet 2Na (12-sulfodehydroabietic acid disodium salt) exhibits a gastroprotective activity, mainly through a local action, involving endogenous prostaglandins (PGs) and nitric oxide (NO). In the present study, we examined the effect of ecabet on the epithelial restitution of the bullfrog gastric mucosa in vitro following injury by hypertonic NaCl. Methods: Bullfrog fundic mucosa was mounted in an Ussing chamber. The tissue injury was induced by exposure of the mucosa to 1.25 M NaCl for 5 min, and transmucosal potential difference (PD) and electrical resistance (R) were measured during a 4-hour test period. Ecabet (3–30 mg/ml) was added to the luminal solution for 10 min before or after NaCl, while 16,16-dimethyl PGE2 (dmPGE2: 1× 10–6 M) or NOR-3 (a NO donor: 1 × 10–4 M) was added to the nutrient solution 10 min before NaCl. Results: Mucosal application of 1.25 M NaCl caused an immediate reduction of PD and R, followed by a gradual normalization, reaching about 70% of the pre-exposure levels within 4 h. Ecabet, added before NaCl, significantly expedited the recovery of PD and R in a concentration-dependent manner; this effect was mimicked by posttreatment with ecabet and significantly mitigated by prior addition of indomethacin (1 × 10–5 M) or NG-nitro-L-arginine methyl ester (L-NAME: 1 × 10–3 M). The epithelial restitution was also significantly promoted by serosal application of either dmPGE2 or NOR-3. The mucosal exposure to ecabet significantly increased the luminal release of PGE2 and NO metabolites, the effects being attenuated by indomethacin and L-NAME, respectively. The mucous secretion was increased by ecabet as well as dmPGE2 and NOR-3, and the effect of ecabet was significantly suppressed by both indomethacin and L-NAME. The inhibitory effects of L-NAME on the ecabet action were all significantly antagonized by concurrent addition of L-arginine. Conclusion: These results suggest that ecabet significantly expedited the restitution following gastric surface cell injury, and this action is mediated by endogenous NO as well as PGs and may be functionally associated with an increase of mucous secretion.

In our previous study, it was found that linoleoyl ethanolamide (LE) is present in sake lees, which are produced as a byproduct during the making of Japanese sake. LE is a fatty acid ethanolamide, which have been demonstrated to exert a variety of biological functions, and in this study, the anti-inflammatory effects of LE were examined using in vitro cell culture and in vivo animal experiments. In mouse RAW264.7 macrophages, LE suppressed the lipopolysaccharide (LPS)-induced expression of pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6. In addition, LE inhibited LPS-induced increases in the levels of cyclooxygenase enzyme-2 and prostaglandin E(2), which are indicators of inflammation. The inhibitory effect of LE on the release of TNF-α was stronger than that of dipotassium glycyrrhizinate, which is widely used in external human skin care treatments. LE also suppressed the LPS-induced activation of Toll-like receptor 4 signaling and nuclear translocation of nuclear factor-κB (NF-κB) p65. In a contact dermatitis animal model, applying LE to affected ear skin ameliorated 2,4-dinitrofluorobenzene-induced contact dermatitis and pro-inflammatory cytokine expression at inflamed sites. These results indicate that LE exerts anti-inflammatory effects by inhibiting NF-κB signaling, and LE is proposed to be a useful therapeutic agent against contact dermatitis.

Duodenal HCO3- secretion increases in response to luminal acid, mediated by endogenous nitric oxide (NO) as well as prostaglandins (PGs). In this study, we examined the effects of various inhibitors of cyclooxygenase (COX) or NO synthase (NOS) on the acid-induced HCO3- secretion in rats and determined the enzyme isoforms responsible for this response. A proximal duodenal loop was perfused with saline under urethane anesthesia, and the HCO3- secretion was measured at pH 7.0 using a pH-stat method and by adding 10 mM HCl. Mucosal acidification was performed by exposing the loop to 10 mM HCl for 10 min. Indomethacin, SC-560 (a selective COX-1 inhibitor) and rofecoxib (a selective COX-2 inhibitor) were given intraduodenally 1 hr before exposure to 10 mM HCl, while N(G)-nitro-L-arginine methyl ester (L-NAME: a nonselective NOS inhibitor) and aminoguanidine (a relatively selective inhibitor of iNOS) were given subcutaneously 3 hr before the acidification. The mucosal acidification increased the HCO3- secretion, with a rise in mucosal PGE2 content and luminal release of NO. The HCO3- secretory and PGE2 biosynthetic responses were significantly inhibited by indomethacin and SC-560, while rofecoxib had no effect on these responses. On the other hand, L-NAME, but not aminoguanidine, attenuated NO release following the acidification, resulting in inhibition of the acid-induced HCO3- secretion in a L-arginine-sensitive manner. Neither COX-2 nor iNOS mRNAs were observed in the mucosa before and 1 hr after acidification, while the gene expression of COX-1 and nNOS was constitutively detected in the mucosa and appeared to be slightly up-regulated after the acid stimulation. These results suggest that COX-1 and cNOS play as the respective key enzyme responsible for producing PG and NO following the duodenal acidification, both of which are involved in the mechanism for the acid-induced HCO3- secretion in the duodenum.

Pituitary adenylate cyclase activating polypeptides (PACAP) stimulate duodenal HCO3- secretion in the rat. The present study was performed to determine whether endogenous PACAP is involved in the mechanism of acid-induced HCO3- response in the duodenum, using a PACAP antagonist, PACAP6-27. Under urethane anaesthetised conditions, a duodenal loop that was made between the pylorus and the area just above the outlet of the common bile duct was perfused with saline, and the HCO3- secretion was measured at pH 7.0 using a pH-stat method and by adding 10 mM HCl. Duodenal HCO3- secretion was significantly stimulated by i.v. administration of PACAP-27 (8 nmol kg-1) as well as vasoactive intestinal polypeptide (VIP: 8 nmol kg-1). The effect of PACAP-27 (8 nmol kg-1) was equivalent to that induced by prostaglandin E2 (300 micrograms kg-1, i.v.) and significantly suppressed by either PACAP6-27 (40 nmol kg-1, i.v.) or VIP antagonist (Ac-Tyr1, D-Phe2-VIP: 40 nmol kg-1, i.v.). These peptide antagonists suppressed duodenal HCO3- secretory response to VIP but did not have any effect on either basal or PGE2-stimulated HCO3- secretion. On the other hand, the duodenal mucosa responded to acidification by increasing HCO3- secretion in a indomethacin-sensitive manner, and this process was also significantly suppressed by both PACAP6-27 and VIP-antagonist. Duodenal damage induced by acid perfusion (100 mM HCl for 4 h) was significantly worsened by PACAP6-27, VIP antagonist as well as indomethacin at the doses that suppressed acid-induced HCO3- secretion. These findings suggest that PACAP may play a role in local modulation of the duodenal mucosal integrity, by mediating the HCO3- secretory response induced by mucosal acidification.

Background & Aim. The circulating peptide leptin produced by the fat cells, acts on central receptors to control food intake and body weight homeostasis. Contrary to initial reports, leptin expression has also been detected in the human placenta, the muscles and recently rat gastric chief cells. Here we investigate the possible presence of leptin and leptin receptor in human stomach. Methods. Immunohistochemistry, reverse transcriptase (RT-PCR) and western blot analysis on biopsy samples from 24 normal individuals was used to investigate leptin and leptin receptor expressions. These individuals were randomly selected from the files of our Gastroenterology Department. They included 15 healthy volunteers and 9 patients with non-ulcer dyspepsia (n=24) who gave informed consent for upper endoscopy and gastric secretory tests. Secretory studies upon pentagastrin (6J,Lg/kg/hr) or secretin (3Ul/kg.hr) infusions, available for 22 subjects (mean age 46.7::':: 3.lyears; range 15-67,9 women, l3 men) were analyzed. At the time of study, all had normal endoscopy and normal gastric mucosa on histological examination. Plasma, gastric juice and fundic mucosa leptin were determined by radioimmunoassay. Results. In fundic biopsies from normal individuals, immunoreactive leptin cells were found in the lower half of the fundic glands at the site of chief cells. mRNA encoding ob-protein was detected in the corpus of human stomach. The amount of fundic content of leptin was 10.4 ::':: 3.7 ng leptin/g mucosa as determined by radioimmunoassay. Intravenous infusions of pentagastrin or secretin caused an increase in circulating leptin levels and leptin release into the gastric juice from 24.5 ::'::.3.5 in basal condition to 109 ::':: 26 ng/h under pentagastrin and 1556 ::':: 107 ng/hr under secretin. Gel filtration of leptin incubated with stimulated gastric juice at pH 2 showed an only limited degradation of this peptide. Immunohistochemistry and immunoblotting detected leptin receptor protein and mRNA encoding Ob-RL in the corpus and the antrum. Conclusion. These data provide the first evidence for the presence of leptin and leptin receptors in human stomach. We suggest that gastric epithelial cells be direct targets of leptin. However, the physiological and/or pathophysiological meanings of these findings remain so far unknown.

AIM:To examine whether nizatidine stimulates duodenal HCO(3)(-) secretion in rats by inhibiting AChE activity.METHODS:Under pentobarbital anesthesia, a proximal duodenal loop was perfused with saline, and the HCO(3)(-) secretion was measured at pH 7.0 using a pH-stat method and by adding 10mM HCl. Nizatidine, neostigmine, carbachol or famotidine was administered i.v. as a single injection.RESULTS:Intravenous administration of nizatidine (3-30mg/kg) dose-dependently increased duodenal HCO(3)(-) secretion, and the effect at 10mg/kg was equivalent to that obtained by carbachol at 0.01mg/kg. This nizatidine action was observed at the same dose range that inhibited acid secretion and enhanced gastric motility, mimicked by i.v. injection of neostigmine(0.03mg/kg), and significantly attenuated by bilateral vagotomy and prior s.c. administration of atropine but not by indomethacin, a cyclooxygenase inhibitor, or NG-nitro-L-arginine methyl ester, a NO synthase inhibitor. The HCO(3)(-) secretory response to acetylcholine (0.001mg/kg) was significantly potentiated by the concurrent administration of nizatidine (3mg/kg,i.v.). The IC(50) of nizatidine for AChE of rat erythrocytes was 1.4·10(-6) M, about 12 times higher than that of neostigmine. Neither famotidine (10(-3) M, 30mg/kg, i.v.) nor cisapride (10(-3) M,3mg/kg, i.v.) had any influence on AChE activity or duodenal HCO(3)(-) secretion. Duodenal damage induced by acid perfusion (100mM HCl for 4h) in the presence of indomethacin was significantly prevented by nizatidine and neostigmine, at the doses that increased the HCO(3)(-)secretion.CONCLUSION:Nizatidine stimulates duodenal HCO(3)(-) secretion, in both vagal dependent and atropine sensitive manners, and the action is associated with the anti-AChE activity of this agent.