Biomedical subjects

E Senba

Publications and source records attributed to E Senba.

At least 55 records · Page 3Linked to original sources

PubMed1999

Fetal liver development requires a paracrine action of oncostatin M through the gp130 signal transducer.

Fetal liver, the major site of hematopoiesis during embryonic development, acquires additional various metabolic functions near birth. Although liver development has been characterized biologically as consisting of several distinct steps, the molecular events accompanying this process are just beginning to be characterized. In this study, we have established a novel culture system of fetal murine hepatocytes and investigated factors required for development of hepatocytes. We found that oncostatin M (OSM), an interleukin-6 family cytokine, in combination with glucocorticoid, induced maturation of hepatocytes as evidenced by morphological changes that closely resemble more differentiated hepatocytes, expression of hepatic differentiation markers and intracellular glycogen accumulation. Consistent with these in vitro observations, livers from mice deficient for gp130, an OSM receptor subunit, display defects in maturation of hepatocytes. Interestingly, OSM is expressed in CD45(+) hematopoietic cells in the developing liver, whereas the OSM receptor is expressed predominantly in hepatocytes. These results suggest a paracrine mechanism of hepatogenesis; blood cells, transiently expanding in the fetal liver, produce OSM to promote development of hepatocytes in vivo.

Animals↗

PubMed1999

Gene expression of histamine H1 receptor in guinea pig primary sensory neurons: a relationship between H1 receptor mRNA-expressing neurons and peptidergic neurons.

Pharmacological studies have suggested that a subgroup of primary sensory neurons is responsive to histamine via the histamine H1 receptor. We addressed this issue using in situ hybridization histochemistry with a cRNA probe for the guinea pig H1 receptor gene. About 15% of the trigeminal and lumber dorsal root ganglion (DRG) neurons, but none of nodose ganglion neurons, were intensely labeled with this probe. The H1 receptor mRNA-positive neurons were exclusively small in size, and were demonstrated to give rise to unmyelinated fibers by ultrastructural analysis of isolectin B4-labeling. However, the H1 receptor mRNA-expressing DRG neurons were not immunoreactive to substance P (SP) and calcitonin gene-related peptide (CGRP). A marked increase in the number of mRNA-positive DRG neurons were observed 1-5 days after a crush injury of the sciatic nerve (3-4-fold of the control value). These neurons turned mRNA-positive after the nerve crush were also mainly small-sized. The mRNA signals were detected in many peptidergic (SP/CGRP) neurons, in contrast to the normal state. On the other hand, in the neurons which showed intense labeling in the normal condition, the mRNA signals were down-regulated. These results suggest that primary sensory neurons include two kinds of H1 receptor-expressing sensory neurons, one expressing H1 receptor mRNAs in the normal state and the other up-regulating the mRNAs following the peripheral nerve damage.

Animals↗

PubMed1999

Leukemia inhibitory factor, glial cell line-derived neurotrophic factor, and their receptor expressions following muscle crush injury.

Using in situ hybridization histochemistry, we characterized the spatiotemporal gene expression patterns of leukemia inhibitory factor (LIF) and glial cell line-derived neurotrophic factor (GDNF), and their receptor components (LIFR, GFR-alpha1, RET) induced in muscle cells, intramuscular nerves, and motoneurons in the regeneration processes of both muscle cells and nerves following muscle contusion. Muscle contusion induced upregulation of GDNF and GFR-alpha1 mRNAs in Schwann cell-like cells in the intramuscular nerves and of LIFR mRNA in damaged muscle cells. LIFR, GFR-alpha1, and RET mRNA expressions in motoneurons were upregulated following muscle contusion. Muscle contusion also induced more rapid, prominent transactivations of GFR-alpha1 and RET genes in motoneurons than did sciatic nerve axotomy. These findings suggest that rapid and prominent upregulation of the receptor components for LIF and GDNF in motoneurons is important for the regeneration of intramuscular motor nerves damaged by muscle contusion.

Animals↗

PubMed1999

Prostacyclin analog prevents stress-induced expression of immediate early genes and gastric mucosal lesions in the rat stomach.

Water immersion-restraint induced the expression of immediate early genes (IEGs) in the epithelial cells and smooth muscle cells of gastric wall of rats, in addition to its well-known effects of mucosal erosion. Pretreatment with a prostacyclin analog (beraprost), a proton pump inhibitor (lansoprazole) or a histamine H2 receptor antagonist (famotidine) prevented formation of gastric mucosal erosion, while only the prostacyclin analog inhibited expression of IEGs. The prostacyclin analog may prevent mucosal damages as well as molecular changes by ameliorating the mucosal microcirculation, and may have potential therapeutic applications.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed1999

Electrophysiological and morphological characterization of cytochemically-defined neurons in the caudal nucleus of tractus solitarius of the rat.

Morphological and electrophysiological properties of calbindin D-28k-, GABA- and dopamine-beta-hydroxylase-immunopositive neurons were investigated in the caudal nucleus of tractus solitarius of rats, using a patch-clamp whole-cell recording combined with intracellular staining and immunocytochemistry. Calbindin D-28K- and GABA-positive neurons had a small cell body (10.9+/-0.3 microm in diameter) and were distributed throughout the caudal nucleus of tractus solitarius. Double fluorescence immunocytochemistry revealed that calbindin- and GABA-positive neurons formed distinct subpopulations. Calbindin- and GABA-positive neurons double stained for biocytin showed extensive axon collaterals within the nucleus of tractus solitarius and some calbindin-positive, but not GABA-positive neurons, had also projection axons leaving the nucleus of tractus solitarius. Dopamine-beta-hydroxylase-immunopositive neurons had a small (10.8+/-0.3 microm) or large (17.2+/-0.4 microm) cell body. Neurons with a small cell body were observed in the dorsomedial nucleus at the level of the area postrema, and in the area postrema, while neurons with a large cell body were observed in the medial nucleus throughout the caudal nucleus of tractus solitarius. Double fluorescence immunocytochemistry revealed that almost all small dopamine-beta-hydroxylase-positive neurons were also immunoreactive for calbindin, while large dopamine-beta-hydroxylase-positive neurons were not. Double staining for dopamine-beta-hydroxylase and biocytin showed that neurons with a small cell body had moderate axon collaterals. On the contrary, neurons with a large cell body had few, if any, axon collaterals and a projection axon which could leave the nucleus of tractus solitarius. Following stimulation of the tractus solitarius, all neurons with a small cell body exhibited a polysynaptic excitatory response (type I neurons), while dopamine-beta-hydroxylase-immunopositive neurons with a large cell body exhibited a monosynaptic excitatory response (type II neurons) or an excitatory followed by an inhibitory response (type III neurons). Spontaneous and evoked excitatory postsynaptic currents of (type I neurons) calbindin- or GABA-positive neurons were reversibly blocked by 6-cyano-7-nitroquinoxaline-2,3-dione. Spontaneous and evoked inhibitory postsynaptic currents of type III neurons were reversibly blocked by bicuculline. Type II neurons showed no spontaneous excitatory nor inhibitory postsynaptic currents. It was concluded that the three kinds of chemically-defined neurons formed distinct neuronal subpopulations in the caudal nucleus of tractus solitarius in terms of synaptic responses and morphological characteristics such as cell size and axonal trajectory.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed1999

Emotional stress induces immediate-early gene expression in rat heart via activation of alpha- and beta-adrenoceptors.

We have studied the adrenergic mechanisms of immediate-early gene (IEG) induction in the discrete types of cardiac cells with the use of in situ hybridization histochemistry in an immobilization-stress model in conscious rats. Expression of c-fos, fos B, c-jun, jun B, NGFI-A, and NGFI-B mRNA was rapidly upregulated in the endothelial, myocardial, and smooth muscle cells of coronary vessels by 15-45 min after the onset of immobilization. Simultaneous blockade of both alpha- and beta-adrenoceptors completely abolished expression of IEGs in these cardiac cells. Application of an alpha-agonist or beta-agonist alone to the perfused rat heart under constant pressure elicited the upregulation of IEGs in a fashion similar to that of emotional stress. These data suggest that activation of either alpha- or beta-adrenoceptor is sufficient to evoke expression of these genes and that there may be cross talk in signal transduction downstream from alpha- and beta-adrenoceptors in cardiac cells.

Adrenergic alpha-Agonists↗

PubMed1999

The novel analgesic compound OT-7100 (5-n-butyl-7-(3,4,5-trimethoxybenzoylamino)pyrazolo[1,5-a]pyrimid ine) attenuates mechanical nociceptive responses in animal models of acute and peripheral neuropathic hyperalgesia.

We investigated the effects of OT-7100, a novel analgesic compound (5-n-butyl-7-(3,4,5-trimethoxybenzoylamino)pyrazolo[1,5-a]pyrimidi ne), on prostaglandin E2 biosynthesis in vitro, acute hyperalgesia induced by yeast and substance P in rats and hyperalgesia in rats with a chronic constriction injury to the sciatic nerve (Bennett model), which is a model for peripheral neuropathic pain. OT-7100 did not inhibit prostaglandin E2 biosynthesis at 10(-8)-10(-4) M. Single oral doses of 3 and 10 mg/kg OT-7100 were effective on the hyperalgesia induced by yeast. Single oral doses of 0.1, 0.3, 1 and 3 mg/kg OT-7100 were effective on the hyperalgesia induced by substance P in which indomethacin had no effect. Repeated oral administration of OT-7100 (10 and 30 mg/kg) was effective in normalizing the mechanical nociceptive threshold in the injured paw without affecting the nociceptive threshold in the uninjured paw in the Bennett model. Indomethacin had no effect in this model. While amitriptyline (10 and 30 mg/kg) and clonazepam (3 and 10 mg/kg) significantly normalized the nociceptive threshold in the injured paw, they also increased the nociceptive threshold in the uninjured paw. These results suggest that OT-7100 is a new type of analgesic with the effect of normalizing the nociceptive threshold in peripheral neuropathic hyperalgesia.

Amitriptyline↗

PubMed1998

Novel alternative splicing in the 5' exon of the neurotrophin-3 gene.

The neurotrophin-3 (NT-3) gene has previously been reported to consist of three exons including two 5' short untranslated exons and a 3' long exon encoding the entire protein, and to give rise to two classes of transcripts by alternative splicing of the 5' exons to the 3' coding exon. In the present study, we demonstrated the presence of at least four new classes of transcripts of the NT-3 gene, in addition to the two known transcripts. The present finding proposes the further complexity of the regulational mechanism for NT-3 expression.

Alternative Splicing↗

PubMed1998

Glial cell line-derived neurotrophic factor and nerve growth factor receptor mRNAs are expressed in distinct subgroups of dorsal root ganglion neurons and are differentially regulated by peripheral axotomy in the rat.

We examined the colocalization of glial cell line-derived neurotrophic factor (GDNF) and nerve growth factor (NGF) receptor genes in rat dorsal root ganglion (DRG) neurons, and investigated the changes of the gene expression following sciatic nerve transection using in situ hybridization histochemistry. About 60% and 35% of the lumbar DRG neurons expressed c-ret and trkA, proto-oncogenes of the functional receptors for GDNF and NGF, respectively. Of the DRG neurons, however, only 9% was positive for both genes. A marked enhancement of the gene expression for GDNF receptor alpha (GDNFR alpha), which is a component of GDNF receptor, was observed in DRG neurons after sciatic nerve transection, but the percentage of c-ret mRNA-expressing neurons was not changed. The trkA mRNA-expressing neurons were decreased in number. These findings suggest that GDNF and NGF support distinct subgroups in intact DRG neurons, and that these receptor genes are differentially regulated when a peripheral nerve is injured.

Animals↗

PubMed1998

Induction of synaptosomal-associated protein-23 kD (SNAP-23) by various cytokines.

Cytokines manifest their function through regulation of gene expression. We searched for immediate-early cytokine responsive genes by the mRNA differential display technique using interleukin-3 (IL-3)-dependent OTT-1 cells, and have isolated a novel cDNA which encodes 210 amino acids and shows 87% amino acid identity to human SNAP-23 (synaptosomal-associated protein of 23 kD). The message for this protein (mouse SNAP-23) was induced in OTT-1 cells by IL-3, granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-5. The experiment using C-terminal deletion mutants of the common beta subunit (betac) of IL-3/GM-CSF/IL-5 receptors showed that expression of SNAP-23 was associated with the Ras-Raf-MAPK pathway, but not with the JAK-STAT pathway. Moreover, SNAP-23 was induced in response to a wide variety of cytokines, including IL-2, IL-3, IL-5, IL-10, stem cell factor, G-CSF, GM-CSF, leukemia inhibitory factor, and erythropoietin. Constitutive expression of SNAP-23 was seen in various tissues, including heart, lung, kidney, liver, spleen, and small intestine. Possible involvement of SNAP-23 in cytokine signal transduction is discussed.

Amino Acid Sequence↗

PubMed1998

Gene expression of neurotrophins and their receptors in cultured rat vascular smooth muscle cells.

Most previous researches on neurotrophins including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) have focused on the nervous system, because their receptors are widely distributed in neuronal tissues. Recently, however, the participation of neurotrophins in inflammation and atherosclerosis has been proposed. Therefore, the gene expression of neurotrophins is now an urgent issue is to be investigated in nonneuronal tissues. Here, we evaluated the gene expression of neurotrophins and their receptors in rat cultured vascular smooth muscle cells (VSMCs) by the reverse transcriptase-polymerase chain reaction method. The transcripts of NGF, NT-3, and TrkC (high-affinity receptor for NT-3), and two BDNF alternative spliced transcript variants with exons 3 and 4 were clearly detected in VSMCs cultured under conventional culture conditions. The upregulation of mRNA levels for NGF, two BDNF variants with exons 1 and 2, low-affinity neurotrophin receptor, and high-affinity receptors, TrkA (for NGF) and TrkB (for BDNF), was observed in response to the treatment with serum and phorbol-ester following the serum-starvation. In contrast, the expression of NT-3 and TrkC genes was downregulated under these conditions. Co-expression of these factors and their receptors and the characteristic regulation of their gene transcriptions suggest that these factors play crucial roles in the function of VSMCs through an autocrine mechanism.

Alternative Splicing↗

PubMed1998

Localization of leukemia inhibitory factor and interleukin-6 messenger ribonucleic acids in regenerating rat skeletal muscle.

In the present study, we characterized both temporal and spatial expression patterns of leukemia inhibitory factor (LIF) and interleukin-6 (IL-6) messenger ribonucleic acids (mRNAs) in injured skeletal muscle using in situ hybridization. LIF and IL-6 mRNAs were expressed in mononucleated cells and damaged muscle cells. Further, signals for LIF mRNA were also detected in Schwann cell-like cells of intramuscular nerves. These results suggest that the earliest events involved in the repair of injured muscles and nerves may be triggered by these cytokines.

Animals↗

PubMed1998

Immunolocalization of proto-oncogene products in keratocytes after epithelial ablation, alkali burn and penetrating injury of the cornea in rats.

BACKGROUND: We examined the immunolocalization of proto-oncogene products, including c-Fos and c-Jun, in the rat cornea during epithelial and stromal wound healing after simple epithelial ablation, penetrating injury or alkali burn. METHODS: Eighty-four male Wistar rats were divided into three groups and subjected to treatments as follows: (a) ablation of central corneal epithelium leaving basement membrane intact, (b) alkali burn in the central cornea with 1 N NaOH and (c) penetrating injury at the central cornea. The affected eyes were then enucleated after various intervals of healing. The frozen sections were immunohistochemically stained with the antibodies against proto-oncogene products. RESULTS: c-Fos- and c-Jun-immunoreactive cells were detected in the epithelium around the epithelial defect from 60 to 120 min after these treatments. The distribution of these cells were varied in these three types of injury. The immunoreactivities for these proteins were also detected in keratocytes after epithelial ablation. In the corneas with alkali burn, the immunoreactivities were detected in the keratocytes in the whole corneal stroma, and these immunoreactions were stronger than those observed in simple epithelial ablation. In the corneas with penetrating injury, such immunoreaction was seen only in keratocytes around the wound. CONCLUSION: These findings indicate that activator protein 1-mediated transcriptional activation for epithelial migration is initiated in the early phase after each injury, and that stromal keratocytes are also transcriptionally activated not only by alkali burn or penetrating injury but also by simple epithelial ablation in which basement membrane was not affected.

Animals↗

PubMed1998

Histamine-induced internalization of substance P receptors in myoepithelial cells of the guinea pig nasal glands.

Numerous substance P (SP) immunoreactive nerve fibers were located around submucosal glands in the guinea pig nasal mucosa. Since these SP positive nerve fibers were also positive for vasoactive intestinal polypeptide, and to a lessor extent for neuropeptide Y, they were presumed to be parasympathetic fibers. SP receptor positive structures were observed exclusively on the membrane of myoepithelial cells in normal nasal mucosa, suggesting that myoepithelial cells are targets of SP positive fibers. SP receptor-like immunoreactivity was observed associated with intracellular organella of myoepithelial cells 5 min after intranasal histamine challenge, which may indicate the molecular basis for histamine-induced nasal discharge.

Animals↗

PubMed1998

Water immersion-restraint stress induces expression of immediate-early genes in gastrointestinal tract of rats.

The aims of this study were to determine 1) which cells are involved in stress-induced acute gastric mucosal lesion and 2) what kinds of molecular alterations are induced by stress, using immediate-early genes (IEG) as tools for detection of cellular activation. Male Wistar rats were exposed to acute water immersion-restraint stress. Protein and mRNA for IEG were detected by immunohistochemistry and in situ hybridization, respectively. This stress induced the expression of c-fos and nerve growth factor-induced gene (NGFI-A) mRNA in gastric epithelial cells, the smooth muscle layer of small blood vessels, and the stomach wall. Stress upregulated the mRNA levels of these IEG in the duodenal epithelial cells and induced de novo expression of IEG in the smooth muscle layer of small blood vessels and the duodenal wall. These findings indicate that these cells are activated in response to stress. Expression of these IEG and/or transcriptional factors may reflect an initiation of mechanisms for repairing the lesions induced by stress as well as an adaptation to the stress.

Animals↗

PubMed1997

Noradrenaline-mediated lateral inhibition in the sympathetic ganglion.

Intracellular recordings were made from neurons of denervated superior cervical ganglion (SCG) of the rat. Focal electrical stimulation near the recording site evoked a monosynaptic inhibitory postsynaptic potential (IPSP) in about 15% of SCG neurons. The IPSP was reversibly abolished by alpha2-adrenoceptor antagonist, yohimbine. The ionic mechanism of the IPSP appeared to be due to an increase of potassium conductance following the activation of alpha2-adrenoceptor. Electron microscopic observations confirmed that these cells received synapses of intrinsic type. It was concluded that some SCG neurons were under an inhibitory control from neighboring neurons via noradrenergic synapses.

Animals↗

PubMed1997

Relationship between BDNF- and trk-expressing neurones in rat dorsal root ganglion: an analysis by in situ hybridization.

Brain-derived neurotrophic factor (BDNF) is synthesized in sensory neurones and suggested to operate on these same neurones by an autocrine mechanism, but it is unclear whether these neurones express the functional receptor (TrkB) for BDNF. We therefore examined the co-localization of BDNF and neurotrophin receptor mRNAs in adult rat dorsal root ganglion (DRG) neurones by in situ hybridization histochemistry. BDNF mRNA signals were detected in about 40-50% of DRG neurones (L4-5). Almost all the trkA mRNA-expressing neurones (95%) were positive for BDNF mRNA, while no trkB mRNA- and few trkC mRNA-expressing neurones displayed BDNF mRNA signals. These findings suggest that BDNF is mainly synthesized in the sensory neurones that are responsive to nerve growth factor but not to BDNF or neurotrophin-3. It is unlikely that BDNF is involved in an autocrine loop in sensory ganglia.

Animals↗

PubMed1997

Immobilization stress reduced the expression of neurotrophins and their receptors in the rat brain.

Exposure to stressful events and elevated level of stress hormones are associated with impaired spatial memory and neuronal damage in the hippocampus. These neurons are considered to be maintained by neurotrophins such as nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) and trk family of neurotrophin receptors. Male Wistar rats (6 weeks old) were exposed to immobilization stress for 8 h and their brains were processed for in situ hybridization histochemistry. Exposure to long-lasting immobilization stress reduced mRNA levels for neurotrophins and their high affinity receptors in the brain, especially in the hippocampus. Our results provide, some new information that may be relevant to the pathogenesis of stress-induced disturbances of memory and learning.

Animals↗