Involvement of interstitial cells of Cajal in nicotinic acetylcholine receptor-induced relaxation of the porcine lower esophageal sphincter.

The interstitial cells of Cajal (ICCs) play an important role in coordinated gastrointestinal motility. The present study aimed to elucidate whether or how ICCs are involved in the lower esophageal sphincter (LES) relaxation induced by stimulation of the nicotinic acetylcholine receptor. The application of 1,1-dimethyl-4-phenyl-piperazinium (DMPP; a nicotinic acetylcholine receptor agonist) induced a transient relaxation in the circular smooth muscle of the porcine LES. DMPP-induced relaxation was abolished by not only 1 µM tetrodotoxin but also the inhibition of ICC activity by pretreatment with 100 µM carbenoxolone (a gap junction inhibitor), pretreatment with 100 µM CaCCinh-A01 (an anoctamin-1 blocker acting as a calcium-activated chloride channel inhibitor), and pretreatment with Cl--free solution. However, pretreatment with 100 µM Nω-nitro-L-arginine methyl ester had little effect on DMPP-induced relaxation. Furthermore, DMPP-induced relaxation was inhibited by pretreatment with 1 mM suramin, a purinergic P2 receptor antagonist, but not by 1 µM VIP (6-28), a vasoactive intestinal peptide (VIP) receptor antagonist. Stimulation of the purinergic P2 receptor with adenosine triphosphate (ATP) induced relaxation, which was abolished by the inhibition of ICC activity by pretreatment with CaCCinh-A01. In conclusion, membrane hyperpolarization of the ICCs via the activation of anoctamin-1 plays a central role in DMPP-induced relaxation. ATP may be a neurotransmitter for inhibitory enteric neurons, which stimulate the ICCs. The ICCs act as the interface of neurotransmission of nicotinic acetylcholine receptor in order to induce LES relaxation.

Identification of evodiamine and rutecarpine as novel TMEM16A inhibitors and their inhibitory effects on peristalsis in isolated Guinea-pig ileum.

The transmembrane member 16A (TMEM16A)-encoded Ca2+-activated Cl- channel (CaCC) is expressed in interstitial cells of Cajal (ICCs) and involved in the generation of the slow-wave currents of gastrointestinal (GI) smooth muscles. TMEM16A modulators have been shown to positively or negatively regulate the contraction of gastrointestinal smooth muscle. Therefore, targeting the pharmacological modulation of TMEM16A may represent a novel treatment approach for gastrointestinal dysfunctions such as constipation and diarrhoea. In this study, evodiamine and rutecarpine were extracted from the traditional Chinese medicine Evodia rutaecarpa and identified as novel TMEM16A inhibitors with comparable inhibitory effects. Their effects on intestinal peristalsis were examined. Whole-cell patch clamp results show that evodiamine and rutecarpine inhibited TMEM16A Cl- currents in CHO cells. The half-maximal inhibition values (IC50) of evodiamine and rutecarpine on TMEM16A Cl- currents were 11.8 ± 1.3 µΜ and 9.2 ± 0.4 µM, and the maximal effect values (Emax) were 95.8 ± 5.1% and 99.1 ± 1.6%, respectively. The Lys384, Thr385, and Met524 in TMEM16A are critical for evodiamine and rutecarpine's inhibitory effects. Further functional studies show that both evodiamine and rutecarpine can significantly suppress the peristalsis in isolated guinea-pig ileum. These findings demonstrate that evodiamine and rutecarpine are new TMEM16A inhibitors and support the regulation effect of TMEM16A modulators on gastrointestinal motility.

Colonic Motility Is Improved by the Activation of 5-HT2B Receptors on Interstitial Cells of Cajal in Diabetic Mice.

BACKGROUND & AIMS: Constipation is commonly associated with diabetes. Serotonin (5-HT), produced predominantly by enterochromaffin (EC) cells via tryptophan hydroxylase 1 (TPH1), is a key modulator of gastrointestinal (GI) motility. However, the role of serotonergic signaling in constipation associated with diabetes is unknown. METHODS: We generated EC cell reporter Tph1-tdTom, EC cell-depleted Tph1-DTA, combined Tph1-tdTom-DTA, and interstitial cell of Cajal (ICC)-specific Kit-GCaMP6 mice. Male mice and surgically ovariectomized female mice were fed a high-fat high-sucrose diet to induce diabetes. The effect of serotonergic signaling on GI motility was studied by examining 5-HT receptor expression in the colon and in vivo GI transit, colonic migrating motor complexes (CMMCs), and calcium imaging in mice treated with either a 5-HT2B receptor (HTR2B) antagonist or agonist. RESULTS: Colonic transit was delayed in males with diabetes, although colonic Tph1+ cell density and 5-HT levels were increased. Colonic transit was not further reduced in diabetic mice by EC cell depletion. The HTR2B protein, predominantly expressed by colonic ICCs, was markedly decreased in the colonic muscles of males and ovariectomized females with diabetes. Ca2+ activity in colonic ICCs was decreased in diabetic males. Treatment with an HTR2B antagonist impaired CMMCs and colonic motility in healthy males, whereas treatment with an HTR2B agonist improved CMMCs and colonic motility in males with diabetes. Colonic transit in ovariectomized females with diabetes was also improved significantly by the HTR2B agonist treatment. CONCLUSIONS: Impaired colonic motility in mice with diabetes was improved by enhancing HTR2B signaling. The HTR2B agonist may provide therapeutic benefits for constipation associated with diabetes.

Salvia miltiorrhiza induces depolarization of pacemaker potentials in murine small intestinal interstitial cells of Cajal via extracellular Ca2+ and Na+ influx.

Interstitial cells of Cajal (ICCs) are pacemaker cells that control smooth muscle contraction in the gastrointestinal (GI) tract. The present study investigated the effects of Salvia miltiorrhiza (SM) on the pacemaker potentials of ICCs from the mouse small intestine in vitro and on GI motility in vivo. The whole­cell patch­clamp configuration was used to record pacemaker potential in ICCs in vitro, and GI motility was investigated in vivo by recording intestinal transit rate (ITR). Using the whole­cell patch­clamp configuration, SM depolarized the pacemaker potentials of ICCs in a dose­dependent manner. Fulvestrant blocked SM­induced effects but 1,3­dihydro­3,3­bis(4­hydroxyphenyl)-7-methyl­2H­indol­2­one did not. Additionally, 4­[2­phenyl-5,7­bis(trifluoromethyl) pyrazolo[1,5­a]pyrimidin­3­yl] phenol blocked SM­induced effects. Intracellular guanosine 5'­O­(2­thiodiphosphate), and pretreatment with extracellular Ca2+­ and Na+­free solutions also blocked SM­induced effects. Furthermore, ITR values were increased by SM in vivo and SM elevated the levels of motilin (MTL). The SM­induced increase in ITR was associated with increased protein expression levels of c­kit and the transmembrane protein 16A (TMEM16A) channel. In addition, SM induced pacemaker potential depolarization through estrogen receptor ß in a G protein­dependent manner via extracellular Ca2+ and Na+ regulation in the murine small intestine in vitro. Moreover, SM increased the ITR in vivo through the MTL hormone via c­kit and TMEM16A­dependent pathways. Taken together, these results suggested that SM may have the ability to control GI motility and could be used as a GI motility regulator.

Curcumin Alleviates the Side Effects of Cisplatin on Gastric Emptying of Mice by Inhibiting the Signal Changes of Acetylcholine and Interstitial Cells of Cajal.

Cisplatin is a widely used anticancer drug that has adverse effects on gastrointestinal function. Curcumin is a natural polyphenol extracted from the rhizome of turmeric that has a wide range of biological activities. The present study investigated the effects of cisplatin on gastric emptying in mice and examined whether these can be inhibited by curcumin. We found that pretreatment with curcumin (200 mg/kg/day) for 10-30 days partly inhibited the decreases in gastric emptying rate and body weight induced by cisplatin. Furthermore, cisplatin reduced acetylcholine (ACh) concentration and the messenger RNA (mRNA) level of ACh receptor (AChR) as well as acetylcholinesterase activity in the stomach of mice; caused ultrastructural damage to interstitial cells of Cajal (ICC); and altered the expression of c-kit/stem cell factor and the gap junction protein connexin 43 in ICC. Curcumin pretreatment inhibited the effects of cisplatin on ACh indicators and ICC. These results demonstrate that curcumin can protect against cisplatin-induced gastric emptying disorder and thus has therapeutic potential for alleviating this condition in cancer patients receiving cisplatin chemotherapy.

Leukocyte Nucleolus and Anisakis pegreffii-When Falling Apart Means Falling in Place.

The view of the nucleolus as a mere ribosomal factory has been recently expanded, highlighting its essential role in immune and stress-related signalling and orchestrating. It has been shown that the nucleolus structure, formed around nucleolus organiser regions (NORs) and attributed Cajal bodies, is prone to disassembly and reassembly correlated to various physiological and pathological stimuli. To evaluate the effect of parasite stimulus on the structure of the leukocyte nucleolus, we exposed rat peripheral blood mononuclear cells (PBMC) to the crude extract of the nematode A. pegreffii (Anisakidae), and compared the observed changes to the effect of control (RPMI-1640 media), immunosuppressive (MPA) and immunostimulant treatment (bacterial lipopolysaccharide (LPS) and viral analogue polyinosinic:polycytidylic acid (poly I:C)) by confocal microscopy. Poly I:C triggered the most accentuated changes such as nucleolar fragmentation and structural unravelling, LPS induced nucleolus thickening reminiscent of cell activation, while MPA induced disassembly of dense fibrillar and granular components. A. pegreffii crude extract triggered nucleolar segregation, expectedly more enhanced in treatment with a higher dose. This is the first evidence that leukocyte nucleoli already undergo structural changes 12 h post-parasitic stimuli, although these are likely to subside after successful cell activation.

Suppressive effect of Aurantii Fructus Immaturus and Atractylodis Macrocephalae Rhizoma on glutamic acid-induced autophagy of interstitial cells of Cajal.

OBJECTIVE: To investigate the effects of Aurantii Fructus Immaturus (Zhishi, ZS) and Atractylodis Macrocephalae Rhizoma (Baizhu, BZ)-containing serum on glutamate-induced autophagy in rat colonic interstitial cells of Cajal (ICCs) and to analyze the underlying mechanism. METHODS: Rat colonic ICCs cultured in vitro were identified by fluorescence and then stimulated with glutamic acid (5 mmol/L) for 24 h to establish a cell model of autophagy. The cells were then treated with different concentrations of ZSBZ-containing serum or rat serum. The viability of the ICCs was detected with cell counting kit-8 assays, and cell apoptosis rates were examined with flow cytometry. The ultrastructure and autophagosomes in the ICCs were observed using transmission electron microscopy. The effects of ZSBZ-containing serum on apoptosis-associated mediators were assessed by Western blotting and real-time quantitative polymerase chain reaction. In addition, microtubule-associated protein light chain 3 (LC3), p-phosphoinositide 3-kinase (p-PI3K), p-Akt and p-mammalian target of rapamycin (p-mTOR) expression was detected via Western blotting analysis. RESULTS: Compared to those in the model group, ICC viability and apoptosis rates were significantly increased by ZSBZ-containing serum (P < 0.05). In addition, the expression levels of Beclin-1, LC3, p-PI3K, p-Akt and p-mTOR were significantly lower (P < 0.05) and Bcl-2 expression was higher in the ZSBZ-containing serum treatment groups than in the model group (P < 0.05). CONCLUSION: Our findings demonstrated that ZSBZ protects glutamic acid-stimulated ICCs, and this beneficial effect may be mediated by a reduction in autophagy via inhibition of the PI3K/Akt/mTOR pathway.

Effects of Chaihu-Shugan-San on Small Intestinal Interstitial Cells of Cajal in Mice.

Chaihu-Shugan-San (CSS) has been widely used as an alternative treatment for gastrointestinal (GI) diseases in East Asia. Interstitial cells of Cajal (ICCs) are pacemakers in the GI tract. In the present study, we examined the action of CSS on pacemaker potentials in cultured ICCs from the mouse small intestine in vitro and on GI motility in vivo. We used the electrophysiological methods to measure the pacemaker potentials in ICCs. GI motility was investigated by measuring intestinal transit rates (ITR). CSS inhibited the pacemaker potentials in a dose-dependent manner. The capsazepine did not block the effect of CSS. However, the effects of CSS were blocked by glibenclamide. In addition, NG-nitro-L-arginine methyl ester (L-NAME) also blocked the CSS-induced effects. Pretreatment with SQ-22536 or with KT-5720 did not suppress the effects of CSS; however, pretreatment with ODQ or KT-5823 did. Furthermore, CSS significantly suppressed murine ITR enhancement by neostigmine in vivo. These results suggest that CSS exerts inhibitory effects on the pacemaker potentials of ICCs via nitric oxide (NO)/cGMP and ATP-sensitive K+ channel dependent and transient receptor potential vanilloid 1 (TRPV1) channel independent pathways. Accordingly, CSS could provide the basis for the development of new treatments for GI motility dysfunction.

Rikkunshito Depolarizes Pacemaker Potentials of Cultured Interstitial Cells of Cajal through Ghrelin Receptors in Murine Small Intestine.

BACKGROUND: Rikkunshito has been used to treat gastrointestinal (GI) disorders. The purpose of this study was to investigate the effects of Rikkunshito, a traditional Japanese herbal medicine, on the pacemaker potentials of interstitial cells of Cajal (ICCs) from the small intestines of mice. METHODS: We isolated ICCs from the small intestines of mice, and the whole-cell patch-clamp configuration was used to record the pacemaker potentials in cultured ICCs and membrane currents. RESULTS: Rikkunshito depolarized ICC pacemaker potentials in a dose-dependent manner. Pretreatment with GSK1614343 or (D-Lys3)-growth hormone-releasing peptide-6 inhibited Rikkunshito-induced depolarization of pacemaker potentials. Intracellular GDP-ß-S inhibited Rikkunshito-induced effects. In Ca2+-free solution or in the presence of thapsigargin, Rikkunshito did not depolarize pacemaker potentials. Moreover, in the presence of U-73122 or xestospongin C, Rikkunshito-induced effects were inhibited. However, in the presence of staurosporine, Go6976 or Rottlerin, Rikkunshito depolarized pacemaker potentials. Furthermore, Rikkunshito inhibited both transient receptor potentials melastatin 7 (TRPM7) and Ca2+-activated Cl- channels (ANO1) currents. CONCLUSION: Rikkunshito depolarized pacemaker potentials of ICCs via ghrelin receptor and G protein through internal or external Ca2+-, phospholipase C-, and inositol triphosphate-dependent and protein kinase C-, TRPM7-, and ANO1-independent pathways. The study shows that Rikkunshito may alleviate GI motility disorders through its depolarizing effects on ICCs.

The Traditional Medicine Banhasasim-Tang Depolarizes Pacemaker Potentials of Cultured Interstitial Cells of Cajal through M3 Muscarinic and 5-HT3 Receptors in Murine Small Intestine.

BACKGROUND: Banhasasim-tang (BHSST) is a classic herbal formulation in traditional Chinese medicine widely used for gastrointestinal (GI) tract motility disorder. We investigated the effects of BHSST on the pacemaker potentials of cultured interstitial cells of Cajal (ICCs) in small intestine in vitro and its effects on GI motor functions in vivo. METHODS: We isolated ICCs from the small intestines and recorded pacemaker potentials in cultured ICCs with the whole-cell patch-clamp configuration in vitro. Intestinal transit rates (ITR%) were investigated in normal mice and GI motility dysfunction (GMD) mouse models in vivo. RESULTS: BHSST (20-50 mg/mL) depolarized pacemaker potentials and decreased their amplitudes in a concentration-dependent manner. Pretreatment with methoctramine (a muscarinic M2 receptor antagonist) did not inhibit BHSST-induced pacemaker potential depolarization. However, when we applied 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide (4-DAMP; a muscarinic M3 receptor antagonist), BHSST-induced effects were blocked. Pretreatment with Y25130 (a 5-HT3 receptor antagonist) blocked BHSST-induced effects in ICCs. In addition, when we applied 4-DAMP and Y25130 together, BHSST-induced effects were completely blocked. Pretreatment with Ca2+-free solution or thapsigargin inhibited BHSST-induced effects. Moreover, BHSST blocked both the transient receptor potential melastatin (TRPM) 7 and voltage-sensitive calcium-activated chloride (anoctamin-1, ANO1) channels. In normal mice, ITR% values were significantly increased by BHSST in a dose-dependent manner. The ITR% of GMD mice was significantly reduced relative to those of normal mice, which were significantly reversed by BHSST in a dose-dependent manner. CONCLUSION: These results suggested that BHSST depolarizes the pacemaker potentials of ICCs in a dose-dependent manner through the M3 and 5-HT3 receptors via internal and external Ca2+-dependent and TRPM7- and ANO1-independent pathways in vitro. Moreover, BHSST increased ITR% in vivo in normal mice and GMD mouse models. Taken together, the results of this study showed that BHSST had the potential for development as a prokinetic agent in GI motility function.

Depolarization of pacemaker potentials by caffeic acid phenethyl ester in interstitial cells of Cajal from the murine small intestine.

Interstitial cells of Cajal (ICCs) are pacemaker cells in the gastrointestinal (GI) tract and generate pacemaker potentials. In this study, we investigated the effects of caffeic acid phenethyl ester (CAPE) on the pacemaker potentials of ICCs from the mouse small or large intestine. Using the whole-cell patch-clamp configuration, we found that CAPE depolarized the pacemaker potentials of cultured ICCs from the murine small intestine in a dose-dependent manner. The estrogen receptor (ER) ß antagonist PHTPP completely inhibited CAPE-induced depolarization, but the ERα antagonist BHPI did not. Intracellular GDP-ß-S and pretreatment with Ca2+-free solution or thapsigargin also blocked CAPE-induced depolarization. To investigate the mechanisms of CAPE-mediated depolarization of ICCs, we used the nonselective cation channel (NSCC) inhibitor flufenamic acid, the Cl- channel blocker, mitogen-activated protein kinase (MAPK) inhibitors PD98059, SB203580, or SP600125, and PI3 kinase inhibitor LY294002. All inhibitors blocked the CAPE-induced pacemaker potential depolarization of ICCs. These results suggest that CAPE induces pacemaker potential depolarization through ERß in a G protein, NSCC, Cl- channel, MAPK- and PI3 kinase dependent manner via intracellular and extracellular Ca2+ regulation in the murine small intestine. CAPE may therefore modulate GI motility by acting on ICCs in the murine small intestine.

Effects of Morphine on Interstitial Cells of Cajal in Rabbit Colon and Small Intestinal Transit: An Experimental Study.

OBJECTIVE: This study aims to investigate the effect of morphine with naloxone on intestinal peristalsis and the number of interstitial cells of Cajal (ICC) in colon tissues of rabbits. METHODS: Thirty rabbits were randomly divided into five groups (n=6, each group): saline control group (NS group), low concentration of morphine group (L group), medium concentration of morphine group (M group), high concentration of morphine group (H group), medium concentration of morphine and naloxone mixed with antagonist group (NM group). Rabbits in these five groups were administered with an epidural puncture tube and dorsal epidural analgesia pump, and were continuously infused for seven days. Fecal characteristics were observed, and the ink propulsion rate was calculated. The expression level of ICC C-kit protein in colon tissues was tested by western blot. RESULTS: The stool characteristics in the L, M and H groups were more severe than those in the NS and NM groups. Furthermore, the intestinal propulsion rate in the L, M and H groups was lower than that in the NS and NM groups. The C-kit mRNA and protein expression in the colon of rabbits were significantly lower in the L, M and H groups, when compared to the NS and NM groups. CONCLUSION: Naloxone blocked the mRNA and protein expression of C-kit, and improved intestinal motor function.

QUERCETIN SUPPLEMENTATION PREVENTS CHANGES IN THE SEROTONIN AND CASPASE-3 IMMUNOREACTIVE CELLS OF THE JEJUNUM OF DIABETIC RATS.

BACKGROUND: Serotonin (5-HT) is present in the epithelial enterochromaffin cells (EC), mast cells of the lamina propria and enteric neurons. The 5-HT is involved in regulating motility, secretion, gut sensation, immune system and inflammation. OBJECTIVE: Evaluate the effects of diabetes and quercetin supplementation on serotoninergic cells and its cell loss by apoptosis in jejunal mucosa of streptozotocin-induced diabetic rats (STZ-rats). METHODS: Twenty-four male Wistar rats were divided into four groups: normoglycemic (C), normoglycemic supplemented with 40 mg/day quercetin (Q), diabetic (D) and diabetic supplemented with 40 mg/day quercetin (DQ). After 120 days, the jejunum was collected and fixated in Zamboni's solution for 18 h. After obtaining cryosections, immunohistochemistry was performed to label 5-HT and caspase-3. Quantification of 5-HT and caspase-3 immunoreactive (IR) cells in the lamina propria, villi and crypts were performed. RESULTS: The diabetic condition displayed an increase of the number of 5-HT-IR cells in villi and crypts, while decreased number of these cells was observed in lamina propria in the jejunum of STZ-rats. In the diabetic animals, an increased density of apoptotic cells in epithelial villi and crypts of the jejunum was observed, whereas a decreased number of caspase-3-IR cells was observed in lamina propria. Possibly, quercetin supplementation slightly suppressed the apoptosis phenomena in the epithelial villi and crypts of the STZ-rats, however the opposite effect was observed on the 5-HT-IR cells of the lamina propria. Quercetin supplementation on healthy animals promoted few changes of serotoninergic function and apoptotic stimuli. CONCLUSION: These results suggest that quercetin supplementation mostly improved the serotonergic function affected by diabetes maybe due to antioxidant and anti-inflammatory properties of quercetin.

A suplementação com quercetina previne mudanças em células imunorreativas à serotonina e caspase-3 do jejuno de ratos diabéticos / Quercetin supplementation prevents changes in the serotonin and caspase-3 immunoreactive cells of the jejunum of diabetic rats

ABSTRACT BACKGROUND: Serotonin (5-HT) is present in the epithelial enterochromaffin cells (EC), mast cells of the lamina propria and enteric neurons. The 5-HT is involved in regulating motility, secretion, gut sensation, immune system and inflammation. OBJECTIVE: Evaluate the effects of diabetes and quercetin supplementation on serotoninergic cells and its cell loss by apoptosis in jejunal mucosa of streptozotocin-induced diabetic rats (STZ-rats). METHODS: Twenty-four male Wistar rats were divided into four groups: normoglycemic (C), normoglycemic supplemented with 40 mg/day quercetin (Q), diabetic (D) and diabetic supplemented with 40 mg/day quercetin (DQ). After 120 days, the jejunum was collected and fixated in Zamboni's solution for 18 h. After obtaining cryosections, immunohistochemistry was performed to label 5-HT and caspase-3. Quantification of 5-HT and caspase-3 immunoreactive (IR) cells in the lamina propria, villi and crypts were performed. RESULTS: The diabetic condition displayed an increase of the number of 5-HT-IR cells in villi and crypts, while decreased number of these cells was observed in lamina propria in the jejunum of STZ-rats. In the diabetic animals, an increased density of apoptotic cells in epithelial villi and crypts of the jejunum was observed, whereas a decreased number of caspase-3-IR cells was observed in lamina propria. Possibly, quercetin supplementation slightly suppressed the apoptosis phenomena in the epithelial villi and crypts of the STZ-rats, however the opposite effect was observed on the 5-HT-IR cells of the lamina propria. Quercetin supplementation on healthy animals promoted few changes of serotoninergic function and apoptotic stimuli. CONCLUSION: These results suggest that quercetin supplementation mostly improved the serotonergic function affected by diabetes maybe due to antioxidant and anti-inflammatory properties of quercetin.

RESUMO CONTEXTO: A serotonina (5-HT) está presente nas células epiteliais enterocromafins (CE), nos mastócitos da lâmina própria e nos neurônios entéricos. A 5-HT está envolvida na regulação da motilidade, secreção, nocepção intestinal, sistema imunológico e inflamação. Objetivo: Avaliar os efeitos do diabetes e da suplementação de quercetina sobre a função serotoninérgica e a perda celular por apoptose na mucosa jejunal de ratos diabéticos induzidos por estreptozotocina (ratos STZ). MÉTODOS: Vinte e quatro ratos Wistar machos foram divididos em quatro grupos: normoglicêmico (C), normoglicêmico suplementado com quercetina 40 mg/dia (Q), diabético (D) e diabético suplementado com quercetina 40 mg/dia (DQ). Após 120 dias, o jejuno foi coletado e fixado na solução de Zamboni por 18 horas. Após a obtenção de cortes em criostato, a imuno-histoquímica foi realizada para marcar 5-HT e caspase-3. A quantificação de células imunorreativas (IR) à 5-HT e caspase-3 foram realizadas na lâmina própria, vilosidades e criptas. RESULTADOS: A condição diabética ocasionou um aumento do número de células 5-HT-IR nas vilosidades e criptas, enquanto que na lâmina própria houve uma redução dessas células, no jejuno de ratos STZ. Nos animais diabéticos, foi observada uma densidade aumentada de células apoptóticas no epitélio do jejuno, tanto nas vilosidades quanto nas criptas, por outro lado um número reduzido de células caspase-3-IR foi observado na lâmina própria. Possivelmente, a suplementação de quercetina suprimiu ligeiramente os fenômenos de apoptose no epitélio de vilosidades e criptas do jejuno de ratos STZ, no entanto, o efeito oposto foi observado nas células 5-HT-IR da lâmina própria. A suplementação com quercetina em animais saudáveis promoveu poucas alterações na função serotoninérgica e nos estímulos apoptóticos. CONCLUSÃO: Estes resultados sugerem que a suplementação de quercetina melhorou principalmente a função serotoninérgica afetada pelo diabetes, talvez devido às propriedades antioxidantes e anti-inflamatórias da quercetina.

The Mechanism of Action of Ghrelin and Motilin in the Pacemaker Potentials of Interstitial Cells of Cajal from the Murine Small Intestine.

Interstitial cells of Cajal (ICCs) are pacemaker cells that exhibit periodic spontaneous depolarization in the gastrointestinal (GI) tract and generate pacemaker potentials. In this study, we investigated the effects of ghrelin and motilin on the pacemaker potentials of ICCs isolated from the mouse small intestine. Using the whole-cell patch-clamp configuration, we demonstrated that ghrelin depolarized pacemaker potentials of cultured ICCs in a dose-dependent manner. The ghrelin receptor antagonist [D-Lys] GHRP-6 completely inhibited this ghrelin-induced depolarization. Intracellular guanosine 5'-diphosphate-ß-S and pre-treatment with Ca2+free solution or thapsigargin also blocked the ghrelin-induced depolarization. To investigate the involvement of inositol triphosphate (IP3), Rho kinase, and protein kinase C (PKC) in ghrelin-mediated pacemaker potential depolarization of ICCs, we used the IP3 receptor inhibitors 2-aminoethoxydiphenyl borate and xestospongin C, the Rho kinase inhibitor Y-27632, and the PKC inhibitors staurosporine, Go6976, and rottlerin. All inhibitors except rottlerin blocked the ghrelin-induced pacemaker potential depolarization of ICCs. In addition, motilin depolarized the pacemaker potentials of ICCs in a similar dose-dependent manner as ghrelin, and this was also completely inhibited by [D-Lys] GHRP-6. These results suggest that ghrelin induced the pacemaker potential depolarization through the ghrelin receptor in a G protein-, IP3-, Rho kinase-, and PKC-dependent manner via intracellular and extracellular Ca2+ regulation. In addition, motilin was able to depolarize the pacemaker potentials of ICCs through the ghrelin receptor. Therefore, ghrelin and its receptor may modulate GI motility by acting on ICCs in the murine small intestine.

Effects of epidural infusion of morphine combined with small-dose naloxone on gastrointestinal interstitial cells of Cajal in rabbits.

OBJECTIVE: To study the effect of epidural infusion of morphine combined with small-dose naloxone on gastrointestinal interstitial cells of Cajal (ICC) in rabbits. MATERIALS AND METHODS: A total of 80 healthy New Zealand rabbits were selected as objects of study, and divided into normal saline control group (Group NS, n=20), morphine group (Group M, n=20), naloxone group (Group N, n=20), and morphine + naloxone group (Group NM, n=20). Rabbits in four the groups received epidural catheterization for continuous drug infusion for 7 d, and epidural analgesia pump was connected. Visual analogue scale (VAS) score, intestinal propulsion rate, c-kit expression, and ICC count were detected and compared among four groups of rabbits. RESULTS: No statistical differences of occurrence rates regarding constipation as well as expressions of c-kit and ICC count in the proximal colon were shown among rabbits in Group NS, Group N, and Group NM during drug administration (p>0.05). However, the occurrence rates of constipation of rabbits in Group M at 3-7 d were statistically higher than those in Group NS, Group N, and Group NM, and the differences were statistically significant (p<0.05). Moreover, the VAS scores in Group NS and Group N were significantly higher than those in Group M and Group NM, while the scores in Group M were also significantly increased compared to that in Group NM (p<0.05). The intestinal propulsion rates, expressions of c-kit and ICC counts of rabbits in Group NS, Group N, and Group NM were statistically higher than that in Group M (p<0.05). CONCLUSIONS: Epidural infusions of morphine combined with small-dose naloxone effectively inhibit the gastrointestinal motility of rabbits via the reduction of ICC in the proximal colon of the gastrointestinal tract of rabbits. Moreover, small-dose of naloxone enhances the analgesic effect and reduces the risk of adverse reactions.

Tonic inhibition of murine proximal colon is due to nitrergic suppression of Ca2+ signaling in interstitial cells of Cajal.

Spontaneous excitability and contractions of colonic smooth muscle cells (SMCs) are normally suppressed by inputs from inhibitory motor neurons, a behavior known as tonic inhibition. The post-junctional cell(s) mediating tonic inhibition have not been elucidated. We investigated the post-junctional cells mediating tonic inhibition in the proximal colon and whether tonic inhibition results from suppression of the activity of Ano1 channels, which are expressed exclusively in interstitial cells of Cajal (ICC). We found that tetrodotoxin (TTX), an inhibitor of nitric oxide (NO) synthesis, L-NNA, and an inhibitor of soluble guanylyl cyclase, ODQ, greatly enhanced colonic contractions. Ano1 antagonists, benzbromarone and Ani9 inhibited the effects of TTX, L-NNA and ODQ. Ano1 channels are activated by Ca2+ release from the endoplasmic reticulum (ER) in ICC, and blocking Ca2+ release with a SERCA inhibitor (thapsigargin) or a store-operated Ca2+ entry blocker (GSK 7975 A) reversed the effects of TTX, L-NNA and ODQ. Ca2+ imaging revealed that TTX, L-NNA and ODQ increased Ca2+ transient firing in colonic ICC. Our results suggest that tonic inhibition in the proximal colon occurs through suppression of Ca2+ release events in ICC. Suppression of Ca2+ release in ICC limits the open probability of Ano1 channels, reducing the excitability of electrically-coupled SMCs.

Effects of Ca2+-Activated Cl- Channel ANO1inhibitors on Pacemaker Activity in Interstitial Cells of Cajal.

BACKGROUND/AIMS: Anoctamin1 (Ca2+-activated Cl- channel, ANO1) is a specific marker of the interstitial cells of Cajal (ICC) in the gastrointestinal tract, and are candidate proteins that can function as pacemaker channels. Recently, novel selective ANO1 inhibitors were discovered and used to study Ca2+-activated Cl- channels. Therefore, to investigate whether ANO1 channels function as pacemaker channels, selective ANO1 inhibitors were tested with respect to the pacemaker potentials in ICC. METHODS: Whole-cell patch-clamp recording, RT-PCR, and intracellular Ca2+ ([Ca2+]i) imaging were performed in cultured ICC obtained from mice. RESULTS: Though CaCCinh-A01 (5 µM), T16Ainh-A01 (5 µM), and MONNA (5 µM) (selective ANO1 inhibitors) blocked the generation of pacemaker potentials in colonic ICC, they did not do so in small intestinal ICC. Though nifulmic acid (10 µM) and DIDS (10 µM) (classical Ca2+-activated Cl- channel inhibitors) also had no effect in small intestinal ICC, they suppressed the generation of pacemaker potentials in colonic ICC. In addition, knockdown of ANO1 reduced the pacemaker potential frequency in colonic ICC alone. Though ANO1 inhibitors suppressed [Ca2+]i oscillations in colonic ICC, they did not do so in small intestinal ICC. T-type Ca2+ channels were expressed in the both the small intestinal and colonic ICC, but mibefradil (5 µM) and NiCl2 (30 µM) (T-type Ca2+ channel inhibitors) inhibited the generation of pacemaker potentials in colonic ICC alone. CONCLUSION: These results indicate that though ANO1 and T-type Ca2+ channels participate in generating pacemaker potentials in colonic ICC, they do not do so in small intestinal ICC. Therefore, the mechanisms underlying pacemaking in ICC might be different in the small intestine and the colon.

Clostridium butyricum promotes intestinal motility by regulation of TLR2 in interstitial cells of Cajal.

OBJECTIVE: Clostridium butyricum (C. butyricum) as a probiotic has been reported to have an important role in the pathogenesis of gastrointestinal diseases. However, the effects of C. butyricum on regulation of intestinal motility of ulcerative colitis (UC) remain unclear. Our study aimed to explore the cross-regulation effect of C. butyricum and toll-like receptor 2 (TLR-2) on UC. MATERIALS AND METHODS: Interstitial cells of Cajal (ICCs) were treated by C. butyricum for 2 h, the mRNA and protein levels of TLR-2, IL-6, and IL-8 were detected by RT-qPCR and Western blot. Then, TLR2-specific small interfering RNA (si-TLR2) was transfected into ICCs, and the relative expressions of IL-6 and IL-8, SCF, cell viability, ghrelin, SP, and ET were measured by RT-qPCR, Western blot, CCK-8, and ELISA. Besides, the signal pathways of NF-κB and JNK were determined by Western blot. RESULTS: C. butyricum significantly increased TLR2, IL-6, and IL-8 expressions in ICCs. However, TLR2 silence alleviated C. butyricum-induced IL-6 and IL-8 expressions. Moreover, TLR2 silence significantly inhibited C. butyricum-induced cell viability in ICCs. Additionally, C. butyricum significantly increased SCF expression and promoted the secretion of ghrelin and SP. However, a significant reduction in the levels of SCF, ghrelin, and SP was evident in the silence of TLR2 expression. Besides, TLR2 silence reduced C. butyricum-activation NF-κB and JNK signal pathways in ICCs. CONCLUSIONS: These findings revealed that C. butyricum promoted intestinal motility by regulation of TLR2 in ICCs, which contributed to understand the molecular mechanisms of C. butyricum on UC.

Expression of TRPV1 channels by Cajal-Retzius cells and layer-specific modulation of synaptic transmission by capsaicin in the mouse hippocampus.

KEY POINTS: By taking advantage of calcium imaging and electrophysiology, we provide direct pharmacological evidence for the functional expression of TRPV1 channels in hippocampal Cajal-Retzius cells. Application of the TRPV1 activator capsaicin powerfully enhances spontaneous synaptic transmission in the hippocampal layers that are innervated by the axons of Cajal-Retzius cells. Capsaicin-triggered calcium responses and membrane currents in Cajal-Retzius cells, as well as layer-specific modulation of spontaneous synaptic transmission, are absent when the drug is applied to slices prepared from TRPV1- /- animals. We discuss the implications of the functional expression of TRPV1 channels in Cajal-Retzius cells and of the observed TRPV1-dependent layer-specific modulation of synaptic transmission for physiological and pathological network processing. ABSTRACT: The vanilloid receptor TRPV1 forms complex polymodal channels that are expressed by sensory neurons and play a critical role in nociception. Their distribution pattern and functions in cortical circuits are, however, much less understood. Although TRPV1 reporter mice have suggested that, in the hippocampus, TRPV1 is predominantly expressed by Cajal-Retzius cells (CRs), direct functional evidence is missing. As CRs powerfully excite GABAergic interneurons of the molecular layers, TRPV1 could play important roles in the regulation of layer-specific processing. Here, we have taken advantage of calcium imaging with the genetically encoded indicator GCaMP6s and patch-clamp techniques to study the responses of hippocampal CRs to the activation of TRPV1 by capsaicin, and have compared the effect of TRPV1 stimulation on synaptic transmission in layers innervated or non-innervated by CRs. Capsaicin induced both calcium responses and membrane currents in ∼50% of the cell tested. Neither increases of intracellular calcium nor whole-cell currents were observed in the presence of the TRPV1 antagonists capsazepine/Ruthenium Red or in slices prepared from TRPV1 knockout mice. We also report a powerful TRPV1-dependent enhancement of spontaneous synaptic transmission onto interneurons with dendritic trees confined to the layers innervated by CRs. In conclusion, our work establishes that functional TRPV1 is expressed by a significant fraction of CRs and we propose that TRPV1 activity may regulate layer-specific synaptic transmission in the hippocampus. Lastly, as CR density decreases during postnatal development, we also propose that functional TRPV1 receptors may be related to mechanisms involved in CR progressive reduction by calcium-dependent toxicity/apoptosis.