Oncogenic Ras downregulates mdr1b expression through generation of reactive oxygen species

In the present study, we investigated the effect of oncogenic H-Ras on rat mdr1b expression in NIH3T3 cells. The constitutive expression of H-RasV12 was found to downregulate the mdr1b promoter activity and mdr1b mRNA expression. The doxorubicin-induced mdr1b promoter activity of the H-RasV12 expressing NIH3T3 cells was markedly lower than that of control NIH3T3 cells. Additionally, there is a positive correlation between the level of H-RasV12 expression and a sensitivity to doxorubicin toxicity. To examine the detailed mechanism of H-RasV12-mediated down-regulation of mdr1b expression, antioxidant N-acetylcysteine (NAC) and NADPH oxidase inhibitor diphenylene iodonium (DPI) were used. Pretreating cells with either NAC or DPI significantly enhanced the oncogenic H-Ras-mediated down-regulation of mdr1b expression and markedly prevented doxorubicin-induced cell death. Moreover, NAC and DPI treatment led to a decrease in ERK activity, and the ERK inhibitors PD98059 or U0126 enhanced the mdr1b-Luc activity of H-RasV12-NIH3T3 and reduced doxorubicin-induced apoptosis. These data suggest that RasV12 expression could downregulate mdr1b expression through intracellular reactive oxygen species (ROS) production, and ERK activation induced by ROS, is at least in part, contributed to the downregulation of mdr1b expression.

Oncogenic Ras downregulates mdr1b expression through generation of reactive oxygen species

In the present study, we investigated the effect of oncogenic H-Ras on rat mdr1b expression in NIH3T3 cells. The constitutive expression of H-RasV12 was found to downregulate the mdr1b promoter activity and mdr1b mRNA expression. The doxorubicin-induced mdr1b promoter activity of the H-RasV12 expressing NIH3T3 cells was markedly lower than that of control NIH3T3 cells. Additionally, there is a positive correlation between the level of H-RasV12 expression and a sensitivity to doxorubicin toxicity. To examine the detailed mechanism of H-RasV12-mediated down-regulation of mdr1b expression, antioxidant N-acetylcysteine (NAC) and NADPH oxidase inhibitor diphenylene iodonium (DPI) were used. Pretreating cells with either NAC or DPI significantly enhanced the oncogenic H-Ras-mediated down-regulation of mdr1b expression and markedly prevented doxorubicin-induced cell death. Moreover, NAC and DPI treatment led to a decrease in ERK activity, and the ERK inhibitors PD98059 or U0126 enhanced the mdr1b-Luc activity of H-RasV12-NIH3T3 and reduced doxorubicin-induced apoptosis. These data suggest that RasV12 expression could downregulate mdr1b expression through intracellular reactive oxygen species (ROS) production, and ERK activation induced by ROS, is at least in part, contributed to the downregulation of mdr1b expression.

Heat Shock Proteins and Autophagy in Rats with Cerulein-Induced Acute Pancreatitis

BACKGROUND/AIMS: Heat shock proteins (HSPs) protect rats from cerulein-induced acute pancreatitis (AP) by preventing the subcellular redistribution of cathepsin B and the activation of trypsinogen. Autophagy plays a critical role in the secretion of digestive enzymes and triggering of cerulein-induced AP via the colocalization of trypsinogen and lysosomes. Therefore, using a rat cerulein-induced AP model, we investigated whether HSPs prevent AP by regulating autophagy. METHODS: Twelve hours after fed standard laboratory chow and water, the experimental groups (cerulein, water-immersion [WI]-cerulein and heat-shock [HS]-cerulein) and the control groups (control, WI, and HS) received one intraperitoneal injection of cerulein (50 microg/kg) or saline, respectively. All of the rats were sacrificed at 6 hours after injection. The severity of the AP was assessed based on the serum amylase level and the histological and electron microscopy findings. Western blotting was also performed for HSP60/70 and LC3B-II. RESULTS: WI and HS induced HSP60 and HSP70, respectively. The induced HSP60/70 effectively prevented the development of cerulein-induced AP. Autophagy developed in the rats with cerulein-induced AP and was documented by the expression of LC3-II and electron microscopy findings. The WI-stressed rats and HS-treated rats did not develop cerulein-induced autophagy. CONCLUSIONS: HSPs exert protective effects against cerulein-induced AP in rats by inhibiting autophagy.

The Expression of P53 and Phosphorylation of H2AX in Germ Cells of Varicocele Rats / 대한비뇨기과학회지

PURPOSE: To explore the expressions of P53 and phosphorylation-H2AX in varicocele-induced rat testes. MATERIALS AND METHODS: A total of 16 adult male Sprague-Dawley rats underwent an operation; 12 underwent an experimental varicocele and 4, as controls, were sham-operated. Groups of 4 varicocele-induced rats underwent a left orchiectomy after 2 or 3 weeks, or both orchiectomies after 4 weeks. The sham-operated rats underwent both orchiectomies after 4 weeks. Sections of both testes from each animal were studied. The changes in the expressions of P53 and phosphorylation of H2AX were determined using immunohistochemistry and western blot. RESULTS: Immunohistochemical staining of the left testes in the varicocele- induced rats showed that the expressions of P53 and phosphorylation of H2AX had not begun 2 weeks postoperatively, but remarkable results were observed after 3 and 4 weeks. Both testes of the varicocele-induced rats showed the expressions of P53 and phosphorylation of H2AX after 4 weeks, with the left testes being more distinctive in immunohistochemical staining compared to the right. Western blot of the left testes in the varicocele- induced rats also showed unclear expressions of P53 and gamma-H2AX after 2 weeks. Considerable distinction was seen after 3 and 4 weeks compared to the control group. CONCLUSIONS: Our results suggest that experimental varicocele is associated with increased sperm DNA damage. These changes may be related to abnormal spermatogenesis.

Inhibition of p65 Nuclear Translocation by KIOM-79 / 대한해부학회지

We demonstrate that KIOM-79, combined extracts isolated from Magnolia officinalis, Pueraria lobata, Glycyrrhiza uralensis, and Euphorbia pekinensis, inhibits LPS-induced expression of iNOS gene in RAW 264.7 cells. Treatment of RAW 264.7 cells with KIOM-79 inhibited LPS-stimulated nitric oxide production in a doserelated manner. Immunohisto-chemical staining of iNOS and RT-PCR analysis showed that the decrease of NO was due to the inhibition of iNOS gene expression. Immunostaining of p65 and EMSA showed that KIOM-79 inhibited NF-kappa/Rel nuclear translocation and DNA binding, respectively. Collectively, this series of experiments indicates that KIOM inhibits iNOS gene expression by blocking NF-kappa/Rel. Due to the critical role that NO release plays in mediating inflammatory responses, the inhibitory effects of KIOM-79 on iNOS suggest that KIOM-79 may represent a useful anti-inflammatory agent.

Activation of Macrophage by Polysaccharide Isolated from Salicornia herbacea L / 체질인류학회지

Salicornia herbacea L. is one of the halophytes that can grow in salt marshes, or salt fields along the seashores in Korea. The objective of this study is to investigate the mechanism by which Salicornia Polysaccharide, (SPS) activates macrophages. To analyze macrophage activation and iNOS gene expression, we performed nitrite generation assay, immunohistochemistry, and reverse transcriptase-polymerase chain reaction. A polysaccharide isolated from the Salicornia herbacea L. significantly induces nitric oxide (NO). Immunohistochemical staining of inducible NO synthase (iNOS) showed that the increase of NO was due to the induction of iNOS production. RT-PCR analysis showed that SPS produced significant induction of iNOS gene expression. Immunohistochemical staining of p65 showed that SPS produced strong induction of NF-kappa B/Rel nuclear translocation. Electrophoretic mobility shift assay further confirmed the activation of NF-kappaB/Rel by SPS. In conclusion, we demonstrate that SPS stimulates the macrophages to express iNOS gene via the activation of NF-kappa B/Rel.

Changes of Calretinin-Immunoreactivities in the Rat Superior Collicuclus after Eye Enucleation / 체질인류학회지

Calcium-binding proteins play an important role in the protection, differentiation, and reorganization of the central nervous system. The effects of neonatal retinal deafferentiation on calretinin, and tracing of retinotectal pathway were examined immunohistochemically in the superficial layer of the rat superior colliculus. Tracing with cholera toxin was revealed on the superior colliculus contralateral to the ocular injection. On the contralateral side of superior colliculus, the calretinin-immunoreactive (IR) cells were dramatically increased, calretinin-IR fibers were markedly decreased in the superficial layer. These results show that retinal deafferentation results in an increase of calretinin-immunoreactive cells within the superficial layers of the superior colliculus, which suggest reorganization of neurons in superior colliculus.

iNOS Induction by Polysaccharide Isolated from Astragalus membranaceus / 체질인류학회지

Astragalus membranaceus is used as a natural herbal medicine in East Asia for preventing carcinogenesis and reducing side effects induced by chemotherapy in cancer patients. Although the mechanism of anti-tumor activity is not known, the polysaccharides may potentiate the host defense mechanism through the activation of immune system. The objective of this study is to investigate the mechanism by which APS activates macrophages. To analyze macrophage activation and iNOS gene expression, we performed nitrite generation assay, immunohistochemistry, and RT-PCR. In the present study we show that a polysaccharide isolated from the Astragalus membranaceus (Astragalus Polysaccharide, APS) significantly induces nitric oxide (NO). Immunohistochemical staining of inducible NO synthase (iNOS) showed that the increase of NO was due to the induction of iNOS production. To further study the mechanism responsible for the induction of iNOS, we investigated the effect of APS on the iNOS mRNA expression. RT-PCR analysis showed that APS produced significant induction of iNOS gene expression. In conclusion, we demonstrate that a polysaccharide isolated from Astragalus membranaceus stimulates macrophages to generate NO through the activation of iNOS gene expression.

Nuclear Translocation of NF-kappaB/Rel Component by PCSC22 Isolated from Poria cocos Sclerotium / 대한해부학회지

The sclerotium of Poria cocos Wolf, which grows on the roots of pine trees, has long been used as a sedative and diuretic (Chang and But, 1987). The accumulating data revealed that certain ingredients of the sclerotium of Poria cocos showed anti-tumor activities (Kanayama, 1986). Although the mechanism of anti-tumor activity is not known, the polysaccharides may potentiate the host defense mechanism through the activation of immune system. In the present study we show that PCSC22, a polysaccharide isolated from the sclerotium of Poria cocos with one percent sodium carbonate, significantly induces nitric oxide (NO) production and inducible NO synthase (iNOS) transcription. To further investigate the mechanism responsible for the induction of iNOS gene expression, we investigated the effect of PCSC22 on the activation of NF-kappaB/Rel, whose binding site was located in the promoter of iNOS gene. Immuno-histo-chemical staining of p65 and p50 showed that PCSC22 produced strong induction of NF-kappaB/Rel nuclear translocation. Electrophoretic mobility shift assay (EMSA) further confirmed the activation of NF-kappaB/Rel by PCSC22. In conclusion, we demonstrate that PCSC22 stimulates macrophages to express iNOS gene through the activation of NF-kappa B/Rel.

Expression of Bradykinin Receptors and Effects of Bradykinin in the Interstitial Cells of Cajal from Mouse Small Intestine / 체질인류학회지

Interstitial Cells of Cajal (ICC) are pacemaker cells that generates slow waves and drive spontaneous mechanical contractions of gastrointestinal smooth muscle. Slow waves are generated the periodic activation of spontaneous inward currents (pacemaker currents). We studied the modulation of pacemaker activities by bradykinin (10-8 M) in cultured ICC with the whole cell patch-clamp technique, and the localization of bradykinin-2 receptor-immunoreactivity using double labelling immunohistochemistry in the murine small intestine. Externally applied bradykinin produced membrane depolarization in current-clamping mode. At a -70 mV of holding potential bradykinin increased tonic inward pacemaker currents. Double labelling with bradykinin-2 receptor and and c-kit was shown that ICC expressed the bradykinin-2 receptor-immunoreactivity. These results suggest that bradykinin modulates electrical activities of ICC via bradykinin-2 receptor, which may regulate gastrointestinal motility.

Vanilloid Receptor Type-1 Immunoreactivities in the Mouse Myenteric Plexus: Immunohistochemical and Electrophysiological Study / 체질인류학회지

The vanilloid receptor type-1 (VR1) is a nonselective cation channel activated by capsaicin and can be act as mediator of chemical and physical stimuli that elicit pain. The presence of VR1 in the dorsal root, trigeminal and nodose ganglia has been firmly established, but it unclear in the mouse intestinal wall. The distribution of VR1 receptors in mouse afferent neurons innervating the intestinal tract was investigated by immunohistochemistry. Also small and large intestines were dual-labelled with antibody for VR1 and marker for interstitial cells of Cajal (c-kit). VR1-immunopositive cells were localized on fine fibers in myenteric plexus and expressed weakly myenteric ganglia. The majority of VR1-immunopositive fibers are not colocalized with or apposed to c-kit positive interstitial cells of Cajal. Also electrophysiologically capsaicin had no effect on cultured interstitial cells of Cajal. It is concluded that VR1-immunoreactive intestinal nerves are mainly distributed in myenteric plexus of murine intestinal wall, and vanillod may be not directly related to interstitial cells of Cajal in regulation of intestinal motility.

Vanilloid Receptor Type-1 Immunoreactivities in the Mouse Myenteric Plexus: Immunohistochemical and Electrophysiological Study / 체질인류학회지

The vanilloid receptor type-1 (VR1) is a nonselective cation channel activated by capsaicin and can be act as mediator of chemical and physical stimuli that elicit pain. The presence of VR1 in the dorsal root, trigeminal and nodose ganglia has been firmly established, but it unclear in the mouse intestinal wall. The distribution of VR1 receptors in mouse afferent neurons innervating the intestinal tract was investigated by immunohistochemistry. Also small and large intestines were dual-labelled with antibody for VR1 and marker for interstitial cells of Cajal (c-kit). VR1-immunopositive cells were localized on fine fibers in myenteric plexus and expressed weakly myenteric ganglia. The majority of VR1-immunopositive fibers are not colocalized with or apposed to c-kit positive interstitial cells of Cajal. Also electrophysiologically capsaicin had no effect on cultured interstitial cells of Cajal. It is concluded that VR1-immunoreactive intestinal nerves are mainly distributed in myenteric plexus of murine intestinal wall, and vanillod may be not directly related to interstitial cells of Cajal in regulation of intestinal motility.

Calcitonin Gene-related Peptide Immunoreactivity in the Muscle Layer of Small Intestine; Its Action on Interstitial Cell / 체질인류학회지

In addition to the central and the peripheral nervous system, calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) has been identified throughout the enteric nervous system. Several functions of the CGRP in gastrointestinal (G-I) tract has been identified, but the effect of CGRP on G-I motility is unclear. The distribution of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) in the murine small bowel were studied by using immunohistochemistry, also analyzed functionally by using electrophysiological method. Immunohistochemical studies demonstrated that CGRP-LI is localized in both nerve fibers and myenteric ganglion cells in the whole-mount preparation of murine small intestine. Double labelling with CGRP and c-kit investigated by confocal microscope was shown that CGRP-LI enteric nerve fiber surrounded the c-kit positive interstitial cells of Cajal (ICC). Electrophysiological finding revealed that treatment of CGRP inhibited electrical activity on culture ICC. Our results suggest a CGRP innervation of murine small bowel ICC. The released CGRP from enteric nerve terminals may induce relaxation of small bowel through the inhibition of ICC.

Activation of Macrophage by PCSC22 Isolated from Poria cocos Sclerotium / 체질인류학회지

The sclerotium of Poria cocos Wolf, which grows on the roots of pine trees, has long been used as a sedative, diuretic, and anti-inflammatory agent. The accumulating data revealed that certain ingredients of the sclerotium of Poria cocos showed anti-tumor activities. Although the mechanism of anti-tumor activity is not known, the polysaccharides may potentiate the host defense mechanism through the activation of immune system. In the present study we show that PCSC22, a polysaccharide isolated from the sclerotium of Poria cocos with one percent sodium carbonate, significantly induces nitric oxide (NO). Immunohistochemical staining of inducible NO synthase (iNOS) showed that the increase of NO was due to the induction of iNOS production. To further study the mechanism responsible for the induction of iNOS gene expression, we investigated the effect of PCSC22 on the activation of p38 kinase, which is important in the gene expression of inflammatory cytokines including iNOS. Western blot assay showed that PCSC22 produced phosphorylation of p38 kinase. In conclusion, we demonstrate that PCSC stimulates macrophages to express iNOS gene through the activation of p38 kinase.

Immunohistochemical Study on Platelet-Derived Growth Factor alpha-Receptor (PDGF -alpha R) in Developing Canine CNS / 대한해부학회지

Platelet-derived growth factor (PDGF) was initially described for its mitogenic activity on smooth muscle cells, fibroblast, and glial cells. The biological activities of PDGF include stimulation of mitogenesis, differentiation, wound healing, inflammation, and tumor formation. The localization of platelet-derived growth factor-alpha Receptor (PDGF-alpha R) in central nervous system was commonly restricted to oligodendrocyte progenitors during late embryonic and postnatal development. However, several studies recently demonstrated that postnatal neurons could also synthesize PDGF-alpha R in rodents. In the present study, to analyze the distributional pattern of PDGF-alpha R during postnatal development of the canine CNS, we used immunohistochemical method on sections of canine brain tissue. We found that neurons of various CNS regions, including cerebral cortex, striatum, diencephalon, nuclei of brain stem, cerebellum, spinal cord, exhibited the immunoreactivity to PDGF-alpha R as early as postnatal day 0. Generally PDGF-alpha R immunoreactivity was well localized in the dendrites and axons of neuron during the postnatal day 14 and postnatal day 28, and then showed diminished pattern. But neuronal immunoreactivity to PDGF-alpha R were maintained postnatal 6 month. These results suggest that the localization of PDGF-alpha R in postnatal developing neurons supports the several roles of PDGF for neurons including maturation and survival.

Degenerative Change of Cerebellar Purkinje Cells by Harmaline Treatment / 체질인류학회지

The indole alkaloid harmaline has been to cause tremor and ataxia, and produce cerebellar neurotoxicity in rat. Degeneration of Purkinje cell alligned in narrow parasagittal bands result from excitation of inferior olivary nucleus in harmaline-treated rats. The objective of this study was to investigate the hypothesis that excitation of climbing fiberinduced by harmaline mediates Purkinje cell injury or degeneration. For this purpose, the inferior olive of rats was chemically ablated by using 3-acetyl pyridine, a neurotoxic chemical, and cerebellar damage followed by administration of harmaline was analyzed using immunohistochemical markers for neurons, glial cells. The results demonstrated that a subset of Purkinje cell in the vermis and paravermis degenerated after harmaline treatment, but harmaline produced little or no Purkinje cell degeneration after inferior olivary ablation. These results suggested that harmalineinduced activation of inferior olivary neurons may lead to release of glutamate from climbing fiber synaptic terminal distributed over the Purkinje cells, and may lead to cytotoxic degeneration of Purkinje cells.

Plasticity of Interstitial Cells of Cajal (ICC) and Intestinal Motility in Murine Small Bowel Obstruction / 체질인류학회지

Interstitial cells of Cajal (ICC) are the pacemakers in gastrointestinal slow wave, and also transduce signal inputs from the enteric nervous system to smooth muscle. The abnormal motility corresponded to a lack or decreasing of ICC and a disruption of electrical slow waves. So we developed partial obstruction model in murine small intestine, and found that ICC and electrical slow wave were absent or decreased oral to the occlusion site in previous study. In an additional series of experiments, we examined the ability of tissue regenerate the ICC phenotype and normal electrical slow waves after surgical treatment to relieve the mechanical obstruction, and the animals were allowed to recover for 1~2 months. Removal of the obstruction led to the normal gross appearance and the redevelopment of ICC and recovery of slow wave activity within 30 days. These data demonstrate the plasticity of ICC networks in response to partial obstruction, and suggest that adult tissue retain the ability to regenerate functional ICC. This model may be useful for estimating molecular factors responsible for the regulation of the ICC phenotype. More work is needed to find out the factors in ICC for the therapy of intestinal motility disorders.

Change of Interstitial Cells of Cajal (ICC) and Intestinal Motility in Murine Small Bowel Obstruction / 대한해부학회지

Interstitial cells of Cajal (ICC) are the pacemakers in gastrointestinal slow wave, and also transduce signal inputs from the enteric nervous system to smooth muscle. The abnormal motility corresponded to a lack or decreasing of ICC and a disruption of electrical slow waves. So we developed partial obstruction model in murine small intestine and investigated changes in the ICC networks and electrical activity in the obstructed bowel using c-kit immunohistochemistry and intracelluar electrophysiological techniques. Two weeks following the onset of a partial obstruction, the small intestine increased in diameter and muscular hypertrophy was developed oral to the obstruction site. ICC were absent or only weak at 1 ~25 mm oral to the occlusion site, and this disruption was accompanied by the loss of electrical slow wave. ICC networks and slow waves were normal appearance aboral to the clip. In conclusion, The present results showed that partial intestinal obstruction induced the loss of ICC networks and slow waves. These result will provide a valuable aid for understanding pathogenesis of intestinal motility disorder, and this model may be an important tool for evaluating genetic or molecular factor for the therapeutic opportunities of motility disorder in human.

Postnatal Development of Parvalbumin and Calbindin D-28k Immunoreactivities in the Canine Anterior Cingulate Cortex: Transient Expression in Layer V Pyramidal Cells / 대한해부학회지

We have examined the ontogeny of parvalbumin and calbindin D-28k immunoreactivities in the canine anterior cingulate cortex from the day of birth (P0) through P180. At P7, parvalbumin immunoreactivity appears firstly in layer VI multipolar cells. The parvalbumin immunoreactivity in GABAergic interneurons appears to follow an 'inside-out' gradient of radial mergence and reaches an adult-like pattern by the end of the 6th postnatal month. Immunoreactivity is limited mainly to developing nonpyramidal cells, whereas pyramid-like parvalbumin immunoreactive cells are transiently observed in layer V from the P14 to the P90. The developmental pattern of calbindin D-28k immunoreactivity differs from that of parvalbumin immunoreactivity. Calbindin D-28k immunoreactivity develops firstly in layer V pyramidal cells from P0, which continues through the third postnatal month. Calbindin D-28k immunoreactive interneurons are located in the infragranular layers and white matter at P0 and increase in both the supragranular and infragranular layers by P14. This is followed by an adult-like pattern at the P180. These data suggested that parvalbumin and calbindin D-28k may play a role in protecting immature neurons from intracelluar calcium influx during postnatal development.

The Morphological Study of the Protein Gene Product (PGP) 9.5-like Immunoreactive Enteric Nervous System in Murine Ileum: Close Relation to Interstitial Cells of Cajal (ICC) in Confocal Laser Scanning Microscopy / 대한해부학회지

This study was performed to investigate the morphology of the enteric nervous system and interstitial cells of Cajal (ICC) in the murine ileum. The PGP9.5-like immunoreactive (PGP9.5-LI) neurons and the c-Kit-like immunoreactive (c-Kit-LI) ICCs were stained by indirect immunofluorescence method and were observed under the confocal laser scanning microscopy. According to three dimensional reconstruction study, it was found that the PGP9.5-LI neurons and the c-Kit-LI ICCs were widely distributed in the intestinal wall : (1) In circular muscle layer, PGP9.5-LI nerve fibers were paralell to circular muscle layer. (2) In the myenteric plexus, the PGP9.5-LI nerve were closely apposed to the adjacent PGP9.5-LI nerve, constituting the networks. (3) In double-labeling immunohistochemistry using anti-PGP9.5 and anti-c-Kit antibodies, the c-Kit-LI networks encircled around the neural strands. The characteristic arrangement of the PGP9.5-LI enteric nervous system and the ICC containing c-Kit-positive cells provide a morphological basis upon the mechanism regulating gastro-intestinal motility and the pathogenesis of gatro-intestinal disorders.