Characteristics of the cholecystokinin-induced depolarization of pacemaking activity in cultured interstitial cells of Cajal from murine small intestine

BACKGROUND/AIMS

In this study, we studied the effects of cholecystokinin (CCK) on pacemaker potentials in cultured interstitial cells of Cajal (ICCs) from mouse small intestine using the whole cell patch clamp technique.

METHODS

ICCs are pacemaker cells that exhibit periodic spontaneous depolarization, which is responsible for the production of slow waves in gastrointestinal smooth muscle, and generate periodic pacemaker potentials in current-clamp mode.

RESULTS

Exposure to CCK (100 nM-5 µM) decreased the amplitudes of pacemaker potentials and depolarized resting membrane potentials. To identify the type of CCK receptors involved in ICCs, we examined the effects of CCK agonists and found that the addition of CCK1 agonist (A-71323, 1 µM) depolarized resting membrane potentials, whereas exposure to CCK2 agonist (gastrin, 1 µM) had no effect on pacemaker potentials. To confirm these results, we examined the effects of CCK antagonists and found that pretreatment with CCK1 antagonist (SR 27897, 1 µM) blocked CCK-induced effects. However, pretreatment with CCK2 antagonist (LY 225910, 1 µM) did not. Furthermore, intracellular GDPβS suppressed CCK-induced effects. To investigate the involvements of phospholipase C (PLC), protein kinase C (PKC), and protein kinase A (PKA) in the effects of CCK in cultured ICCs, we used U-73122 (an active PLC inhibitor), chelerythrine (a PKC inhibitor), SQ-22536 (an inhibitor of adenylate cyclase), or mPKAI (an inhibitor of myristoylated PKA). All inhibitors blocked the CCK-mediated effects on pacemaker potentials. In addition, we found that transient receptor potential classical 5 (TRPC5) channel was involved in CCK-activated currents in cultured ICCs.

CONCLUSION

These results suggest that the CCK induced depolarization of pacemaking activity occurs in a G-protein-, PLC-, PKC-, and PKA-dependent manner via CCK1 receptor and TRPC5 channel is a candidate for CCK-activated currents in cultured ICCs in murine small intestine. Therefore, the ICCs are targets for CCK and their interaction can affect intestinal motility.

Effects of traditional Chinese herbal medicine San-Huang-Xie-Xin-Tang on gastrointestinal motility in mice

AIM

To investigate the effects of San-Huang-Xie-Xin-Tang (SHXXT), a herbal product used in traditional Chinese medicine, on gastrointestinal (GI) motility in mice.

METHODS

The in vivo effects of SHXXT on GI motility were investigated by measuring the intestinal transit rates (ITRs) using Evans blue in normal mice and in mice with experimentally induced GI motility dysfunction (GMD).

RESULTS

In normal ICR mice, ITRs were significantly and dose-dependently increased by SHXXT (0.1-1 g/kg). GMD was induced by injecting acetic acid or streptozotocin intraperitoneally. The ITRs of GMD mice were significantly reduced compared to normal mice, and these reductions were significantly and dose-dependently inhibited by SHXXT (0.1-1 g/kg).

CONCLUSION

These results suggest that SHXXT is a novel candidate for the development of a prokinetic agent that may prevent or alleviate GMD.

Reciprocal positive regulation between TRPV6 and NUMB in PTEN-deficient prostate cancer cells

Calcium acts as a second messenger and plays a crucial role in signaling pathways involved in cell proliferation. Recently, calcium channels related to calcium influx into the cytosol of epithelial cells have attracted attention as a cancer therapy target. Of these calcium channels, TRPV6 is overexpressed in prostate cancer and is considered an important molecule in the process of metastasis. However, its exact role and mechanism is unclear. NUMB, well-known tumor suppressor gene, is a novel interacting partner of TRPV6. We show that NUMB and TRPV6 have a reciprocal positive regulatory relationship in PC-3 cells. We repeated this experiment in two other prostate cancer cell lines, DU145 and LNCaP. Interestingly, there were no significant changes in TRPV6 expression following NUMB knockdown in DU145. We revealed that the presence or absence of PTEN was the cause of NUMB-TRPV6 function. Loss of PTEN caused a positive correlation of TRPV6-NUMB expression. Collectively, we determined that PTEN is a novel interacting partner of TRPV6 and NUMB. These results demonstrated a novel relationship of NUMB-TRPV6 in prostate cancer cells, and show that PTEN is a novel regulator of this complex.

Effects of Schisandra chinensis extract on gastrointestinal motility in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Schisandra chinensis (Turcz.) Baill. (SC) continues to be used as a traditional folk medicine in Asia, especially for the treatment of gastrointestinal (GI) disorders related to gastritis, diarrhea, enterocolitis and abnormal GI motility.

AIM OF THE STUDY

Because GI disorders, especially abnormal GI motility, are major lifelong problems, we investigated the effects of SC on the pacemaker activity of the interstitial cells of Cajal (ICCs) in murine small intestine and GI motility.

MATERIALS AND METHODS

Enzymatic digestions were used to dissociate ICCs from small intestines, and the whole-cell patch-clamp configuration was used to record potentials generated by cultured ICCs. In vivo effects of SC on GI motility were investigated by measuring the intestinal transit rate (ITR) of Evans blue in normal and GI motility dysfunction mice.

RESULTS

SC extracts depolarized the membrane potentials of ICCs in a dose dependent manner. Pretreatment with Ca(2+) free solution or thapsigargin (a Ca(2+)-ATPase inhibitor in the endoplasmic reticulum) abolished the generation of pacemaker potentials by ICCs, and under these conditions, SC extract did not depolarize the membrane potentials of ICCs. In addition, membrane depolarizations were inhibited by intracellular GDPβS and by U-73122 (an active phospholipase C (PLC) inhibitor). In normal mice, ITRs were significantly increased by SC extract (0.1-1g/kg, intragastrically (i.g.)) in a dose dependent manner. Also, SC extract significantly recovered the GI motility dysfunctions in acetic acid (AA)-injected and streptozotocin (STZ)-induced diabetic mice, which are the GI motility animal models.

MATERIALS AND METHODS

SC extract modulates pacemaker potentials in ICCs in a dose dependent manner via external and internal Ca(2+) regulations, and via G protein and the PLC pathway. In addition, SC extract increased ITRs in normal and abnormal GI motility mice models. This study shows that SC extract offers a basis for the development of a prokinetic agent that prevents or alleviates GI motility dysfunctions.

Autoantibodies in Sjögren's syndrome patients acutely inhibit muscarinic receptor function

OBJECTIVES

Autoantibodies from the sera of Sjögren's syndrome patients (SS IgG) have been suggested to inhibit muscarinic receptor function. However, the acute nature of such an inhibitory effect remains controversial. In this study, we investigated the acute effects of SS IgG on muscarinic receptor function in human submandibular gland (HSG) cells.

METHODS

The effects of autoantibodies on muscarinic receptor function were studied using microspectrofluorimetry, whole-cell patch clamp, immunofluorescence confocal microscopy, and a co-immunoprecipitation assay.

RESULTS

Carbachol (CCh) was found to consistently increase intracellular calcium concentration ([Ca(2+) ](i) ) and activate K(+) current in HSG cells. However, pretreatment of the cells with SS IgG for 5 or 30 min significantly attenuated these responses, with a substantially more prominent effect after 30 min of treatment. Like CCh, adenosine 5'-triphosphate (ATP) also increased [Ca(2+) ](i) and activated K(+) currents in HSG cells, although pretreatment with SS IgG did not affect the cellular response to ATP. CCh was found to reorganize α-fodrin in HSG cells in a Ca(2+) -dependent manner. However, pretreatment with SS IgG prevented the cytoskeletal reorganization of α-fodrin induced by CCh.

CONCLUSIONS

SS IgG acutely and reversibly inhibited muscarinic receptor function, thereby inhibiting the Ca(2+) mobilization necessary for the activation of K(+) currents and α-fodrin reorganization in HSG cells.

Inductions of Caspase-, MAPK- and ROS-dependent Apoptosis and Chemotherapeutic Effects Caused by an Ethanol Extract of Scutellaria barbata D. Don in Human Gastric Adenocarcinom Cells

OBJECTIVES

The crude extracts of Scutellaria barbata D. Don (SB) have traditionally demonstrated inhibitory effects on numerous human cancers both in vitro and in vivo. Gastric cancer is one of the most common types of cancer on world. The authors investigated the effects of an ethanol extract of Scutellaria barbata D. Don (ESB) on the growth and survival of MKN-45 cells (a human gastric adenocarcinoma cell line).

METHODS

The MKN-45 cells were treated with different concentrations of ESB, and cell death was examined using an MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. Analyses of sub-G1 peaks, caspase-3 and -9 activities, and mitochondrial membrane depolarizations were conducted to determine the anti-cancer effects of SB on MKN-45 cells. Also, intracellular reactive oxygen species (ROS) generation was investigated.

RESULTS

ESB inhibited the growth of MKN-45 cells, caused cell cycle arrest, and increased the sub-G1 population. In addition, ESB markedly increased mitochondrial membrane depolarization and the activities of caspase-3 and -9. ESB exerted anti-proliferative effects on MKN-45 cells by modulating the mitogen-activated protein kinase (MAPK) signaling pathway and by increasing the generation of ROS. Furthermore, combinations of anti-cancer drugs plus ESB suppressed cell growth more than treatments with an agent or ESB, and this was especially true for cisplatin, etoposide, and doxorubicin.

CONCLUSION

ESB has a dose-dependent cytotoxic effect on MKN-45 cells and this is closely associated with the induction of apoptosis. ESB-induced apoptosis is mediated by mitochondria- , caspase- and MAPK dependent pathways. In addition, ESB enhances ROS generation and increases the chemosensitivity of MKN-45 cells. These results suggest that treatment with ESB can inhibit the proliferation and promote the apoptosis of human gastric adenocarcinoma cells by modulating the caspase-, MAPK- and ROS-dependent pathway.

Hominis Placenta facilitates hair re-growth by upregulating cellular proliferation and expression of fibroblast growth factor-7

BACKGROUND

Hominis Placenta (HP) known as a restorative medicine in Traditional Chinese Medicine (TCM), has been widely applied in the clinics of Korea and China as an anti-aging agent to enhance the regeneration of tissue. This study was conducted to investigate whether topical treatment of HP promotes hair regrowth in the animal model.

METHODS

The dorsal hairs of 8-week-old C57BL/6 mice were depilated to synchronize hair follicles to the anagen phase. HP was applied topically once a day for 15 days. Hair growth was evaluated visually and microscopically. The incorporation of bromodeoxyuridine (BrdU) and expression of proliferating cell nuclear antigen (PCNA), fibroblast growth factor-7 (FGF-7) in dorsal skin tissue was examined by immunohistochemical analysis. Reverse transcription polymerase chain reaction (RT-PCR) was used to measure the mRNA expression of FGF-7.

RESULTS

HP exhibited potent hair growth-promoting activity in C57BL/6 mice. Gross examination indicated that HP markedly increased hair regrowth as well as hair density and diameter. Histologic analysis showed that HP treatment enhanced the anagen induction of hair follicles. Immunohistochemical analysis revealed that BrdU incorporation and the expressions of PCNA were increased by treatment of HP. HP treatment significantly increased the expression of FGF-7, which plays pivotal roles to maintain anagen phase both protein and mRNA levels.

CONCLUSIONS

Taken together, our results indicate that HP has a potent hair growth-promoting activity; therefore, it may be a good candidate for the treatment of alopecia.

A tough nanofiber hydrogel incorporating ferritin

We have developed tough nanofiber hydrogels incorporating ferritin nanoparticles with a core-shell structure that is suitable for stress concentration reduction. The swelling properties of the nanocomposite hydrogel under external forces were enhanced, leading to fast water absorption. The elastic modulus, tensile strength, and elongation at break of the nanocomposite hydrogel measured in solutions were dramatically enhanced as compared to those of the bare polymer hydrogel. During the tensile tests, the strong bonding between the nanofiller and polymer matrix played an important role in enhancing the toughness of the composite hydrogel fibers.

Effects of the roots of Liriope Platyphylla Wang Et tang on gastrointestinal motility function

ETHNOPHARMACOLOGICAL RELEVANCE

Liriope platyphylla Wang et Tang continues to be used in Korea as a traditional medicine for the treatment of gastrointestinal (GI) disorders related to constipation and abnormal GI motility.

AIM OF THE STUDY

Because GI disorders, especially GI motility dysfunctions, are major lifelong problems, the authors investigated the effects of a water extract of the roots of L. platyphylla Wang et Tang (LPE) on the pacemaker potentials (PPTs) of interstitial cells of Cajal (ICCs) and on GI motility in male ICR mice.

MATERIALS AND METHODS

Enzymatic digestions were used to dissociate ICCs from small intestines, and the whole-cell patch-clamp configuration was used to record PPTs generated by cultured ICCs in vitro. In vivo effects of LPE on GI motility were investigated by measuring intestinal transit rates (ITRs) of Evans blue in normal mice and in acetic acid (AA) and streptozotocin (STZ)-induced diabetic mouse models of GI motility dysfunction.

RESULTS

LPE dose-dependently depolarized PPTs in ICCs. Pretreatment with methoctramine (a muscarinic M2 receptor antagonist) did not block LPE-induced PPT depolarization. However, pretreatment with 4-DAMP (a muscarinic M3 receptor antagonist) blocked LPE-induced PPT depolarization. In addition, treatment with LY294002 (a phosphoinositide 3-kinase (PI3K) inhibitor) also blocked LPE-induced PPT depolarization. Intracellular GDPβS inhibited LPE-induced PPT depolarization, and LPE-induced PPT depolarization was found to occur in a phospholipase C (PLC)- and a protein kinase C (PKC)-dependent manner. Pretreatment with Ca(2+)free solution or thapsigargin (a Ca(2+)-ATPase inhibitor in endoplasmic reticulum) abolished PPTs, and under these conditions, LPE did not depolarize ICC PPTs. In normal mice, ITRs were significantly and dose-dependently increased by LPE (0.01-1g/kg administered intragastrically (i.g.)). In addition, LPE (i.g.) significantly recovered GI motility dysfunctions in both animal models.

CONCLUSION

LPE dose-dependently depolarizes ICC PPTs through M3 receptors via external and internal Ca(2+)regulation and via G protein-, PI3K-, PLC- and PKC- dependent pathways in vitro. Also, in vivo, LPE increased ITRs in treatment naïve mice and our two mouse models of GI dysfunction. Therefore, this study shows that LPE offers a basis for the development of a prokinetic agent that prevents or alleviates GI motility dysfunctions.

Characteristics of gintonin-mediated membrane depolarization of pacemaker activity in cultured interstitial cells of Cajal

BACKGROUND/AIMS

Ginseng regulates gastrointestinal (GI) motor activity but the underlying components and molecular mechanisms are unknown. We investigated the effect of gintonin, a novel ginseng-derived G protein-coupled lysophosphatidic acid (LPA) receptor ligand, on the pacemaker activity of the interstitial cells of Cajal (ICC) in murine small intestine and GI motility.

MATERIALS AND METHODS

Enzymatic digestion was used to dissociate ICC from mouse small intestines. The whole-cell patch-clamp configuration was used to record pacemaker potentials and currents from cultured ICC in the absence or presence of gintonin. In vivo effects of gintonin on gastrointestinal (GI) motility were investigated by measuring the intestinal transit rate (ITR) of Evans blue in normal and streptozotocin (STZ)-induced diabetic mice.

RESULTS

We investigated the effects of gintonin on pacemaker potentials and currents in cultured ICC from mouse small intestine. Gintonin caused membrane depolarization in current clamp mode but this action was blocked by Ki16425, an LPA1/3 receptor antagonist, and by the addition of GDPβS, a GTP-binding protein inhibitor, into the ICC. To study the gintonin signaling pathway, we examined the effects of U-73122, an active PLC inhibitor, and chelerythrine and calphostin, which inhibit PKC. All inhibitors blocked gintonin actions on pacemaker potentials, but not completely. Gintonin-mediated depolarization was lower in Ca(2+)-free than in Ca(2+)-containing external solutions and was blocked by thapsigargin. We found that, in ICC, gintonin also activated Ca(2+)-activated Cl(-) channels (TMEM16A, ANO1), but not TRPM7 channels. In vivo, gintonin (10-100 mg/kg, p.o.) not only significantly increased the ITR in normal mice but also ameliorated STZ-induced diabetic GI motility retardation in a dose-dependent manner.

CONCLUSIONS

Gintonin-mediated membrane depolarization of pacemaker activity and ANO1 activation are coupled to the stimulation of GI contractility through LPA1/3 receptor signaling pathways in cultured murine ICC. Gintonin might be a ingredient responsible for ginseng-mediated GI tract modulations, and could be a novel candidate for development as a prokinetic agent that may prevent or alleviate GI motility dysfunctions in human patients.

Ginsenoside Re inhibits pacemaker potentials via adenosine triphosphate-sensitive potassium channels and the cyclic guanosine monophosphate/nitric oxide-dependent pathway in cultured interstitial cells of Cajal from mouse small intestine

BACKGROUND

Ginseng belongs to the genus Panax. Its main active ingredients are the ginsenosides. Interstitial cells of Cajal (ICCs) are the pacemaker cells of the gastrointestinal (GI) tract. To understand the effects of ginsenoside Re (GRe) on GI motility, the authors investigated its effects on the pacemaker activity of ICCs of the murine small intestine.

METHODS

Interstitial cells of Cajal were dissociated from mouse small intestines by enzymatic digestion. The whole-cell patch clamp configuration was used to record pacemaker potentials in cultured ICCs. Changes in cyclic guanosine monophosphate (cGMP) content induced by GRe were investigated.

RESULTS

Ginsenoside Re (20-40μM) decreased the amplitude and frequency of ICC pacemaker activity in a concentration-dependent manner. This action was blocked by guanosine 5'-[β-thio]diphosphate [a guanosine-5'-triphosphate (GTP)-binding protein inhibitor] and by glibenclamide [an adenosine triphosphate (ATP)-sensitive K(+) channel blocker]. To study the GRe-induced signaling pathway in ICCs, the effects of 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (a guanylate cyclase inhibitor) and RP-8-CPT-cGMPS (a protein kinase G inhibitor) were examined. Both inhibitors blocked the inhibitory effect of GRe on ICC pacemaker activity. L-NG-nitroarginine methyl ester (100μM), which is a nonselective nitric oxide synthase (NOS) inhibitor, blocked the effects of GRe on ICC pacemaker activity and GRe-stimulated cGMP production in ICCs.

CONCLUSION

In cultured murine ICCs, GRe inhibits the pacemaker activity of ICCs via the ATP-sensitive potassium (K(+)) channel and the cGMP/NO-dependent pathway. Ginsenoside Re may be a basis for developing novel spasmolytic agents to prevent or alleviate GI motility dysfunction.

Optimized immunohistochemical analysis of cerebellar purkinje cells using a specific biomarker, calbindin d28k

Cerebellar Purkinje cells (PCs) play a crucial role in motor functions and their progressive degeneration is closely associated with spinocerebellar ataxias. Although immunohistochemical (IHC) analysis can provide a valuable tool for understanding the pathophysiology of PC disorders, the method validation of IHC analysis with cerebellar tissue specimens is unclear. Here we present an optimized and validated IHC method using antibodies to calbindin D28k, a specific PC marker in the cerebellum. To achieve the desired sensitivity, specificity, and reproducibility, we modified IHC analysis procedures for cerebellar tissues. We found that the sensitivity of staining varies depending on the commercial source of primary antibody. In addition, we showed that a biotin-free signal amplification method using a horseradish peroxidase polymer-conjugated secondary antibody increases both the sensitivity and specificity of ICH analysis. Furthermore, we demonstrated that dye filtration using a 0.22 microm filter eliminates or minimizes nonspecific staining while preserving the analytical sensitivity. These results suggest that our protocol can be adapted for future investigations aiming to understand the pathophysiology of cerebellar PC disorders and to evaluate the efficacy of therapeutic strategies for treating these diseases.

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-β-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.

Ethanol Extract of Oldenlandia diffusa - an Effective Chemotherapeutic for the Treatment of Colorectal Cancer in Humans: -Anti-Cancer Effects of Oldenlandia diffusa

OBJECTIVES

Oldenlandia diffusa is traditionally used to relieve the symptoms of and to treat various diseases, but its anti-cancer activity has not been well studied. In the present study, the authors investigated the anti-cancer effects of an ethanol extract of Oldenlandia diffusa (EOD) on HT-29 human adenocarcinoma cells.

METHODS

Cells were treated with different concentrations of an EOD, and cell death was assessed by using a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Analyses of the sub G1 peak, the caspase-3 and -9 activities, and the mitochondrial membrane depolarizations were conducted to confirm cell death by apoptosis. Also, intracellular reactive oxygen species (ROS) generation was determined using carboxy-H2DCFDA (5-(and-6)-carboxy-20,70-dichlorodihydrofluorescein diacetate).

RESULTS

EOD inhibited the proliferation of HT-29 cells for 24 hours by 78.6% ± 8.1% at 50 μg/mL, 74.4% ± 4.6% at 100 μg/mL, 65.9% ± 5.2% at 200 μg/mL, 51.4% ± 6.2% at 300 μg/mL, and by 41.7% ± 8.9% at 400 μg/mL, and treatment for 72 hours reduced the proliferation at the corresponding concentrations by 43.3% ± 8.8%, 24.3 ± 5.1 mV, 13.5 ± 3.2 mV, 6.5 ± 2.3 mV, and by 2.6 ± 2.3 mV. EOD increased the number of cells in the sub-G1 peak in a dose-dependent manner. The mitochondrial membrane depolarization was elevated by EOD. Also, caspase activities were dose-dependently elevated in the presence of EOD, and these activities were repressed by a pan-caspase inhibitor (zVAD-fmk). The ROS generation was significantly increased by EOD and N-acetyl-L-cysteine (NAC; a ROS scavenger) remarkably abolished EOD-induced cell death. In addition, a combination of sub-optimal doses of EOD and chemotherapeutic agents noticeably suppressed the growth of HT-29 cancer cells.

CONCLUSION

These results indicate that EOD might be an effective chemotherapeutic for the treatment of human colorectal cancer.

SK&F 96365 induces apoptosis and autophagy by inhibiting Akt-mTOR signaling in A7r5 cells

SK&F 96365 has been widely used as an inhibitor of transient receptor potential (TRP) calcium channels in various physiological settings. However, growing evidence suggests that SK&F 96365 affects several cellular and molecular processes via uncharacterized off-target mechanisms. In this study, we showed that SK&F 96365 induces apoptosis and autophagy in A7r5 vascular smooth muscle cells. The combined suppression of apoptosis and autophagy provoked necrosis rather than rescued cell death in the cells treated with SK&F 96365. In addition, we found that SK&F 96365 inhibits Akt-mTOR signaling pathways, which is comparable with the efficacy of other known Akt inhibitors. Our findings suggest that SK&F 96365 can be a useful agent for delineating the molecular mechanisms underlying crosstalk among cell death pathways.

Effects of San-Huang-Xie-Xin-tang, a traditional Chinese prescription for clearing away heat and toxin, on the pacemaker activities of interstitial cells of Cajal from the murine small intestine

ETHNOPHARMACOLOGICAL RELEVANCE

San-Huang-Xie-Xin-Tang (SHXXT) is a traditional Chinese medicinal formula composed of Coptidis rhizoma (Coptis chinesis Franch), Scutellariae radix (Scutellaria baicalensis Georgi), and Rhei rhizoma (Rheum officinale Baill) and is widely used in Eastern Asia, especially to ameliorate the symptoms of gastrointestinal (GI) disorders related to gastritis, gastric bleeding, peptic ulcers, and abnormal GI motility

AIM OF THE STUDY

Interstitial cells of Cajal (ICCs) are pacemaker cells in the GI tract that generate rhythmic oscillations in membrane potentials known as slow waves. Because GI disorders, especially abnormal GI motility, are major lifelong problems, the authors investigated the effects of SHXXT on mouse small intestine ICCs, and sought to identify the receptors and the action mechanisms involved.

MATERIALS AND METHODS

Enzymatic digestions were used to dissociate ICCs from small intestines, and the whole-cell patch-clamp configuration was used to record potentials generated by cultured ICCs.

RESULTS

SHXXT produced membrane depolarization in current-clamp mode, and Y25130 (a 5-HT3 receptor antagonist) and RS39604 (a 5-HT4 receptor antagonist) blocked SHXXT-induced membrane depolarizations, whereas SB269970 (a 5-HT7 receptor antagonist) did not. However, during external Ca2+ free conditions or in the presence of thapsigargin, SHXXT did not exhibit membrane depolarization. Furthermore, the application of flufenamic acid (a nonselective cation channel (NSCC) blocker) or DIDS (a chloride channel blocker) abolished pacemaker potential generation and blocked SHXXT-induced membrane depolarizations. In addition, SHXXT-induced membrane depolarizations, which are dependent on G-protein, in ICCs were blocked by PD 98059 (a p42/44 mitogen-activated protein kinase (MAPK) inhibitor), SB203580 (a p38 MAPK inhibitor), and by a c-jun NH2-terminal kinase (JNK) II inhibitor. Regarding the components of SHXXT, Coptidis rhizome and Rhei rhizoma modulated ICC pacemaking activity, whereas Scutellariae radix did not.

CONCLUSION

SHXXT modulates pacemaker potentials via 5-HT3 and 5-HT4 receptor-mediated pathways, external Ca2+ influx, and Ca2+ release from internal stores. Furthermore, NSCCs and Cl- channels play important roles in the regulation of pacemaking activity in a MAPK dependent manner in ICCs. The regulation of pacemaking activity by SHXXT may be due to the activity of Coptidis rhizome and Rhei rhizome. The study shows SHXXT can modulate the pacemaking activity of ICCs in the GI tract, and thus, suggests SHXXT has potential pharmacological relevance for the treatment of GI motility disorders.

Effect of lithospermi radix on contact dermatitis induced by dinitrofluorobenzene in mice

OBJECTIVE

The root of Lithospermum erythrorhizon Sieb. et Zucc. (Lithospermi Radix, LR) is a kind of heat clearing and blood cooling medicinal herbs. It can clear away heat and cool the blood, reduce toxins and disperse maculae. LR has long been used as efficacious therapy for inflammation, burns, frostbite and skin diseases such as eczema and psoriasis.

METHODS

In the present study, we investigate anti-allergic and anti-inflammatory effects of LR by using the 1-fluoro-2, 4- dinitrofluorobenzene (DNFB)-induced contact dermatitis mouse model.

RESULTS

Topical application of 10 mg/mL of LR effectively inhibited skin lesions induced by repeated paintings with DNFB. Topical application of LR also inhibited hyperplasia, edema, spongiosis and infiltrations of mononuclear cells. In addition, production levels of total immunoglobulin and IgG1 in serum were decreased by using LR in vivo.

CONCLUSION

These data suggest that LR acts as an antiinflammatory agent, improving skin lesions in CD mice.

Sphingosine and FTY720 modulate pacemaking activity in interstitial cells of Cajal from mouse small intestine

Interstitial cells of Cajal (ICCs) are the pacemakers of the gastrointestinal tract, and transient receptor potential melastatin type 7 (TRPM7) and Ca(2+) activated Cl(-) channels (ANO1) are candidate the generators of pacemaker potentials in ICCs. The effects of D-erythro-sphingosine (SPH) and structural analogues of SPH, that is, N,N-dimethyl-Derythro-sphingosine (N,N-DMS), FTY720, and FTY720-P on the pacemaking activities of ICCs were examined using the whole cell patch clamp technique. SPH, N,N-DMS, and FTY720 decreased the amplitudes of pacemaker potentials in ICC clusters, but resting membrane potentials displayed little change. Also, perfusing SPH, N,N-DMS, or FTY720 in the bath reduced both inward and outward TRPM7-like currents in single ICCs, and inhibited ANO1 currents. The another structural analogue of SPH, FTY720-P was ineffective at the pacemaker potentials in ICC clusters and the TRPM7-like currents in single ICCs. Furthermore, FTY720-P had no effect on ANO1. These results suggest that SPH, N,N-DMS, and FTY720 modulate the pacemaker activities of ICCs, and that TRPM7 and ANO1 channels affect intestinal motility.

Functional characteristics of TRPC4 channels expressed in HEK 293 cells

The classical type of transient receptor potential (TRPC) channel is a molecular candidate for Ca(2+)-permeable cation channels in mammalian cells. Because TRPC4 and TRPC5 belong to the same subfamily of TRPC, they have been assumed to have the same physiological properties. However, we found that TRPC4 had its own functional characteristics different from those of TRPC5. TRPC4 channels had no constitutive activity and were activated by muscarinic stimulation only when a muscarinic receptor was co-expressed with TRPC4 in human embryonic kidney (HEK) cells. Endogenous muscarinic receptor appeared not to interact with TRPC4. TPRC4 activation by GTPgammaS was not desensitized. TPRC4 activation by GTPgammaS was not inhibited by either Rho kinase inhibitor or MLCK inhibitor. TRPC4 was sensitive to external pH with pK (a) of 7.3. Finally, TPRC4 activation by GTPgammaS was inhibited by the calmodulin inhibitor W-7. We conclude that TRPC4 and TRPC5 have different properties and their own physiological roles.

Association of a Methanol Extract of Rheum undulatum L. Mediated Cell Death in AGS Cells with an Intrinsic Apoptotic Pathway

OBJECTIVES

Rheum undulatum L. has traditionally been used for the treatment of many diseases in Asia. However, its anti-proliferative activity in cancer has still not been studied. In the present study, we investigated the anti-cancer effects of methanol extract of Rheum undulatum L. (MERL) on human adenocarcinoma gastric cell lines (AGS).

METHODS

To investigate the anti-cancer effect of MERL on AGS cells, we treated the AGS cells with varying con¬centrations of MERL and performed 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assays. Cell cycle analyses, measurements of the mitochondrial membrane potential (MMP), caspase activity assays and Western blots were conducted to determine whether AGS cell death occurred by apoptosis.

RESULTS

Treatment with MERL significantly inhibited growth of AGS cells in a concentration dependent manner. MERL treatment in AGS cells leaded to increased accumulation of apoptotic sub G1 phase cells in a concentration dependent manner. In control cultures, 5.38% of the cells were in the sub G1 phase. In MERL treated cells, however, this percentage was significantly increased (9.95% at 70 μg/mL, 15.94% at 140 μg/mL, 26.56% at 210 μg/mL and 38.08% at 280 μg/mL). MERL treatment induced the decreased expression of pro-caspase-8 and -9 in a concentration dependent manner, whereas the expression of the active form of caspase-3 was increased. A subsequent Western blot analysis revealed increased cleaved levels of poly (ADP-ribose) polymerase (PARP) protein. Also, treatment with MERL increased the activities of caspase-3 and -9 compared with the control. MERL treatment increased the levels of the pro-apoptotic truncated Bid (tBid) and Bcl2 Antagonist X (Bax) proteins and decreased the levels of the anti-apoptotic B-cell lymphoma 2 (Bcl-2) protein, whose is the stabilization of mitochondria. However, inhibitions of p38, extracellular signal regulated kinases (ERKs) and C-Jun N-terminal kinases (JNK) by MERL treatment did not affect cell death.

CONCLUSION

These results suggest that MERL mediated cell death is associated with an intrinsic apoptotic pathway in AGS cells.

Berberine induces pacemaker potential inhibition via cGMP-dependent ATP-sensitive K+ channels by stimulating mu/delta opioid receptors in cultured interstitial cells of Cajal from mouse small intestine

Berberine is traditionally used to treat gastrointestinal (GI) motility disorders. The interstitial cells of Cajal (ICCs) are the pacemaker cells of the gastrointestinal tract, which are responsible for the production of gut movements. The present study aimed to investigate the effects of berberine on pacemaker potentials (PPs) in cultured ICC clusters from the mouse small intestine, and sought to identify the receptors involved and the underlying mechanisms of action. All experiments were performed on cultured ICCs, and a whole‑cell patch‑clamp configuration was used to record PPs from ICC clusters (current clamp mode). Under current clamp mode, berberine was shown to decrease the amplitude and frequency of PPs. However, these effects were suppressed by treatment with glibenclamide, a specific ATP‑sensitive K+ channel blocker. Nor‑binaltorphimine dihydrochloride (a kappa opioid receptor antagonist) did not suppress berberine‑induced PP inhibition, whereas ICI 174,864 (a delta opioid receptor antagonist) and CTOP (a mu opioid receptor antagonist) did suppress the inhibitory effects of berberine. Pretreatment with SQ‑22536 (an adenylate cyclase inhibitor) or with KT‑5720 (a protein kinase A inhibitor) did not suppress the effects of berberine; however, pretreatment with 1H‑[1,2,4] oxadiazolo [4,3‑a] quinoxalin‑1‑one (a guanylate cyclase inhibitor) or KT‑5823 [a protein kinase G (PKG) inhibitor] did. In addition, berberine stimulated cyclic guanosine monophosphate (cGMP) production in ICCs. These observations indicate that berberine may inhibit the pacemaker activity of ICC clusters via ATP‑sensitive K+ channels and the cGMP‑PKG‑dependent pathway by stimulating mu and delta opioid receptors. Therefore, berberine may provide a basis for the development of novel agents for the treatment of GI motility dysfunction.

Effects of Gamisoyo-San Decoction, a Traditional Chinese Medicine, on Gastrointestinal Motility

BACKGROUND

Gamisoyo-San decoction (GSS), a traditional Chinese medicine, has been used to treat various gastrointestinal (GI) symptoms and diseases such as functional dyspepsia. The purpose of this study was to investigate the effect of GSS on GI motility functions in mice.

METHODS

Percent intestinal transit rate (ITR%) and gastric emptying (GE) values were measured using Evans Blue and phenol red, respectively, in normal mice and in mice with experimentally induced GI motility dysfunction (GMD).

RESULTS

In normal mice, GSS (0.01-1 g/kg) induced higher GE values than non-treated controls. Also, GSS could increase GE in loperamide-induced and cisplatin-induced GE delay models. In addition, GSS increased ITR% in a dose-dependent manner. Loperamide decreased ITR% and GSS recovered this loperamide-induced decrease in ITR%. To examine the effect of GSS on GMD, we used acetic acid (AA)-induced and streptozotocin (STZ)-induced mouse GMD models. The AA mouse model showed a significant decrease in ITR%. However, intragastric treatment with GSS significantly recovered this inhibition. Furthermore, STZ-induced diabetic mice showed a significant reduction in ITR%, which was also significantly inhibited by GSS.

CONCLUSION

These results demonstrate that GSS can modulate bowel activity and that it could be used as a gastroprokinetic agent in the treatment of GI motility diseases.

Apoptotic effects of alisol B 23‑acetate on gastric cancer cells

Alisol B 23‑acetate (AB23A) is a natural triterpenoid isolated from Alismatis rhizoma, which exhibits a number of pharmacological activities. In the present study, AB23A‑induced anticancer efficacy was examined in AGS gastric cancer cells. Cell viability assay, cell cycle analysis, caspase activity assay, western blotting and reactive oxygen species (ROS) assay were used to investigate the anticancer effects of AB23A on AGS cells. AB23A reduced the viability of AGS cells, increased the sub‑G1 cell fraction and depolarized the mitochondrial membrane. Notably, AB23A‑induced cell death was associated with downregulation of the B‑cell lymphoma 2 and survivin proteins, and upregulation of the Bax protein. In addition, AB23A increased caspase‑3 and ‑9 activities, and regulated the activation of mitogen‑activated protein kinases (MAPK). Moreover, AB23A increased the production of reactive oxygen species. These results suggested that AB23A may induce apoptosis through cell cycle arrest and the mitochondrial pathway, accompanied by the caspase and MAPK signaling cascades. In conclusion, AB23A may have potential as a novel anticancer drug for the treatment of gastric cancer.

Radix Sophorae Flavescentis induces apoptosis through by Caspase, MAPK Activation and ROS Signaling Pathways in 5637 Human Bladder Cancer Cells

The anti-cancer mechanisms of Radix Sophorae Flavescentis were investigated in 5637 bladder cancer cells. Radix Sophorae Flavescentis extract (RSF) (50‑400 µg/ml) inhibited the proliferation of 5637 cells and increased sub‑G1 phase ratios. RSF‑induced cell death was associated with the down-regulation of B‑cell lymphoma 2 (Bcl‑2) and the up-regulation of Bcl‑2 X‑associated protein (Bax). RSF also activated caspase‑3 and -9 and regulated the activations of mitogen-activated protein kinases (MAPKs). In addition, RSF increased intracellular reactive oxygen species (ROS) levels and depolarized the mitochondrial membrane potential. These findings suggest RSF induces apoptosis in 5637 bladder cancer cells and that it has potential use as a novel anti-cancer drug for bladder cancer.

Effects of Lizhong Tang on cultured mouse small intestine interstitial cells of Cajal

AIM

To investigate the effects of Lizhong Tang, an herbal product used in traditional Chinese medicine, on mouse small intestine interstitial cells of Cajal (ICCs).

METHODS

Enzymatic digestions were used to dissociate ICCs from mouse small intestine tissues. The ICCs were morphologically distinct from other cell types in culture and were identified using phase contrast microscopy after verification with anti c-kit antibody. A whole-cell patch-clamp configuration was used to record potentials (current clamp) from cultured ICCs. All of the experiments were performed at 30-32 °C.

RESULTS

ICCs generated pacemaker potentials, and Lizhong Tang produced membrane depolarization in current-clamp mode. The application of flufenamic acid (a nonselective cation channel blocker) abolished the generation of pacemaker potentials by Lizhong Tang. Pretreatment with thapsigargin (a Ca²⁺-ATPase inhibitor in the endoplasmic reticulum) also abolished the generation of pacemaker potentials by Lizhong Tang. However, pacemaker potentials were completely abolished in the presence of an external Ca²⁺-free solution, and under this condition, Lizhong Tang induced membrane depolarizations. Furthermore, When GDP-β-S (1 mmol/L) was in the pipette solution, Lizhong Tang still induced membrane depolarizations. In addition, membrane depolarizations were not inhibited by chelerythrine or calphostin C, which are protein kinase C inhibitors, but were inhibited by U-73122, an active phospholipase C inhibitors.

CONCLUSION

These results suggest that Lizhong Tang might affect gastrointestinal motility by modulating pacemaker activity in interstitial cells of Cajal.