Biomedical subjects

S Ito

Publications and source records attributed to S Ito.

At least 451 records · Page 25Linked to original sources

PubMed1999

Transcriptional suppression of rat angiotensin AT1a receptor gene expression by interferon-gamma in vascular smooth muscle cells.

Angiotensin (Ang) II stimulates proliferation of vascular smooth muscle cells (VSMC) via its specific receptor AT1 subtype, possibly leading to atherosclerosis in hypertension. On the other hand, a cytokine interferon (IFN)-gamma has been shown to have an anti-atherosclerotic effect. In the present study, we examined a possible role of IFN-gamma in AT1 receptor gene regulation in VSMC. A firefly luciferase expression vector driven by the rat AT1a receptor gene promoter ( approximately 3.2 kb) was transfected into the cultured rat VSMC, and luciferase expression was determined to estimate the transcription function of the AT1a receptor gene promoter. RT-PCR was also carried out to determine mRNA expression of AT1a receptor in VSMC. IFN-gamma treatment decreased AT1a receptor mRNA expression as well as luciferase expression in a dose-dependent manner. The analysis with deletion DNA fragments showed that the IFN-responsive element was located between -987 and -331 positions, where multiple GAS (gamma interferon activated site)-like elements were identified. The expression suppression was reversed by either a MAPKK inhibitor PD98059 or a Jak-2 inhibitor AG-490. These results suggest that IFN-gamma can inhibit AT1 receptor expression at gene transcription level, and that the transcription suppression is dependent on MAP kinase and Jak-2. Inhibition of AT1a receptor expression may possibly be implicated in the anti-atherosclerotic action of IFN-gamma in VSMC.

Animals↗

PubMed1999

Cloning, expression profile, and genomic organization of the mouse STAP/A170 gene.

The preferential screening of cDNA libraries derived from the mouse osteoblastic cell line MC3T3-E1 has yielded a cDNA clone encoding a 442-amino-acid protein designated STAP (signal transduction and adaptor protein), which contains several motifs shared among transcription factors and adaptors such as a Zn-finger like motif, a proline-rich domain, and a PEST sequence. The amino acid sequence homology search also reveals that STAP is identical to a mouse oxidative stress protein, A170, and has 90% homology with a human p62 protein that binds to the tyrosine kinase p56(lck) SH2 domain. Northern blot analysis indicated a broad expression profile of STAP mRNA in various tissues and cell lines. In MC3T3-E1 cells, STAP mRNA was induced by treatment with TGF-beta, but not with BMP-2 or GDF-5. Analysis of the mouse STAP gene isolated from the genomic library revealed that the STAP gene spans a region of over 11 kb and comprises eight exons. The transcription start site was identified by primer extension analysis to be located 35 bp upstream from the translation initiation site. Sequencing analysis of the 5' flanking region of the STAP gene revealed multiple consensus motifs/sequences for several DNA binding transcription factors. The STAP gene had a TATA box, but no CCAAT box. Potential Sp1, AP-1, NF-E2, MyoD, and NF-kappaB binding sites were found in the 5' flanking region (1.4 kb) of the STAP gene.

3T3 Cells↗

PubMed1999

Expression cloning of a human alpha1, 4-N-acetylglucosaminyltransferase that forms GlcNAcalpha1-->4Galbeta-->R, a glycan specifically expressed in the gastric gland mucous cell-type mucin.

Among mucus-secreting cells, the gastric gland mucous cells, Brunner's glands, accessory glands of pancreaticobiliary tract, and pancreatic ducts exhibiting gastric metaplasia are unique in that they express class III mucin identified by paradoxical Con A staining composed of periodate oxidation, sodium borohydride reduction, Con A, and horseradish peroxidase reaction. Recently it was shown that these mucous cells secrete glycoproteins having GlcNAcalpha1-->4Galbeta-->R at nonreducing terminals of the carbohydrate moieties. Herein we describe the expression cloning of a cDNA encoding a human alpha1,4-N-acetylglucosaminyltransferase (alpha4GnT), a key enzyme for the formation of GlcNAcalpha1-->4Galbeta1-->R. COS-1 cells were thus cotransfected with a stomach cDNA library and a leukosialin cDNA. Transfected COS-1 cells were screened by using monoclonal antibodies specific for GlcNAcalpha1-->4Galbeta-->R and enriched by fluorescence-activated cell sorting. Sibling selection of recovered plasmids resulted in a cDNA clone that directs the expression of GlcNAcalpha1-->4Galbeta-->R. The deduced amino acid sequence predicts a type II membrane protein with 340 amino acids, showing no significant similarity with any other proteins. The alpha4GnT gene is located at chromosome 3p14.3, and its transcripts are expressed in the stomach and pancreas. An in vitro GlcNAc transferase assay by using a soluble alpha4GnT revealed that alpha1,4-linked GlcNAc residues are transferred most efficiently to core 2 branched O-glycans (Galbeta1-->4GlcNAcbeta1-->6(Galbeta1-->3)GalNAc), forming GlcNAcalpha1-->4Galbeta1-->4GlcNAcbeta1-->6(GlcNAca lpha1-->4Galbeta1- ->3)GalNAc. Transfection of alpha4GnT cDNA into gastric adenocarcinoma AGS cells produced class III mucin, indicating that alpha4GnT is responsible for the formation of class III Con A reactivity. These results indicate that the alpha4GnT is a glycosyltransferase that forms alpha1,4-linked GlcNAc residues, preferentially in O-glycans.

Adult↗

PubMed1999

Determining the site of the primary cancer in patients with skeletal metastasis of unknown origin: a retrospective study.

BACKGROUND: When skeletal metastasis is the presenting problem and the primary site is occult, there is a need to identify the primary site as soon as possible. However, the search for the primary tumor is often time-consuming and difficult. The purpose of this study was to analyze the efficacy of particular diagnostic approaches and to devise an efficient and optimal diagnostic strategy. METHODS: Among 213 patients with skeletal metastasis treated between 1990 and 1996 were 64 in whom skeletal lesions were the first manifestation of malignancy. The authors retrospectively analyzed both the final diagnosis and the process by which it was made in these 64 cases. RESULTS: The primary cancer was identified antemortem in 56 (88%) of the 64 patients by examination and in 3 patients at autopsy. Lung carcinoma, the most frequently observed primary lesion, was identified in 23 patients. Other primary lesions were prostate carcinoma in 11 patients, breast carcinoma in 5, and hepatocellular carcinoma in 5. The primary malignancy was not determined in 5 patients. Thoracic and abdominal computed tomography (CT) scans were useful, especially in the diagnosis of patients with lung, hepatocellular, renal cell, and pancreatic carcinomas. Tumor markers were abnormally elevated in 73% of patients with carcinomas. CONCLUSIONS: Although thoracic and abdominal CT scans were useful, examination of the gastrointestinal tract and pelvic CT scan seldom revealed the primary lesion and therefore should not be performed as an initial routine study in the absence of abdominal symptoms. Tumor markers are useful in differentiating carcinoma from hematologic malignancy and primary bone tumor.

Adult↗

PubMed1999

Low-Temperature Synthesis of Nanometer-Sized Crystalline TiO2 Particles and Their Photoinduced Decomposition of Formic Acid.

Anatase TiO2 particles with an average size of 2.7 nm in an as-grown state were obtained below 373 K from an H2O-EtOH mixed solution of TiOSO4 by a facile liquid phase method. The volume ratio of H2O to EtOH was revealed to be the key for crystallinity of the particles. The as-grown particles prepared from the H2O-EtOH solution (H2O/EtOH (mL/mL) = 150/100) showed a high photoreactivity in the TiO2 photoinduced decarboxylation of HCOOH under a deaerated condition. In contrast, under an aerated condition, the rate of the reaction increased with an increase in calcining temperature (Tc) due to the improvement of anatase crystallinity, going through a maximum at Tc = 873 K. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

A multinuclear NMR study of the active site of an endoglucanase from a strain of Bacillus. Use of Trp residues as structural probes.

In the hydrolytic reaction catalyzed by an endoglucanase from a Bacillus strain (endoglucanase K), 2 of 12 Trp residues, Trp174 and Trp243, are responsible for binding of the substrate and/or for the catalysis (Kawaminami, S., Ozaki, K., Sumitomo, N., Hayashi, Y., Ito, S., Shimada, I., and Arata, Y. (1994) J. Biol. Chem. 269, 28752-28756). Here we report results of a stable isotope-aided NMR analysis of the active site of endoglucanase K, using Trp174 and Trp243 as structural probes. Hydrogen-deuterium exchange experiments performed for the NH protons of main and side chains of Trp residues revealed that Trp174 and Trp243 are located in the hydrophilic and hydrophobic microenvironments in the active site, respectively. We also carried out pH titration experiments for indole C2 proton resonances of Trp residues and measured the pH dependence of specific activities for wild-type endoglucanase K and its mutants in which Glu or Asp residues are replaced with their respective amide forms. On the basis of the results obtained from the present study, we conclude that (a) Glu130 and Asp191, which are in spatial proximity to Trp174 and Trp243 in the active site, play a crucial role in the enzymatic activity; (b) Glu130 and Asp191 interact with each other in the active site, leading to an increase in the pKa values to 5.5 for both amino acid residues; and (c) the pKa values of Glu130 and Asp191 would lead to an unusually narrow pH-activity profile of the endoglucanase K.

Amino Acid Sequence↗

PubMed1999

Biological and biochemical properties of Ret with kinase domain mutations identified in multiple endocrine neoplasia type 2B and familial medullary thyroid carcinoma.

Several mutations were identified in the kinase domain of the RET proto-oncogene in patients with multiple endocrine neoplasia (MEN) 2B, familial medullary thyroid carcinoma (FMTC) or sporadic medullary thyroid carcinoma. We introduced seven mutations (glutamic acid 768-->aspartic acid (E768D), valine 804-->leucine (V804L), alanine 883-->phenylalanine (A883F), serine 891-->alanine (S891A), methionine 918-->threonine (M918T), alanine 919-->proline (A919P) and E768D/A919P) into the short and long isoforms of RET cDNA and transfected the mutant cDNAs into NIH3T3 cells. The transforming activity of the long isoform of Ret with each mutation was much higher that that of its short isoform. Based on the levels of the transforming activity, these mutant RET genes were classified into two groups; a group with high transforming activity (A883F, M918T and E768D/A919P) and a group with low transforming activity (E768D, V804L, S891A and A919P) (designated high group and low group). Interestingly, the level of transforming activity correlated with clinical phenotypes; high group Ret with the A883F or M918T mutation and low group Ret with the E768D, V804L or S891A mutation were associated with the development of MEN 2B and FMTC, respectively. In addition, we found that substitution of phenylalanine for tyrosine 905 present in the kinase domain abolished both transforming and autophosphorylation activities of low group Ret whereas it did not affect the activities of high group Ret.

Amino Acid Substitution↗

PubMed1999

IL-12 induces IFN regulating factor-1 (IRF-1) gene expression in human NK and T cells.

IL-12 is a critical immunoregulatory cytokine that promotes cell-mediated immune responses and the differentiation of naive CD4+ cells to Th1 cells; however, relatively few IL-12 target genes have been identified. To better clarify the molecular basis of IL-12 action, we set out to characterize genes up-regulated by IL-12, first by contrasting IL-12- and IFN-alpha-inducible genes. We identified several genes up-regulated by IL-12, namely, MIP-1alpha, MIP-1beta, IL-1RA, and IFN regulatory factor-1 (IRF-1). IRF-1 is a transcription factor regulated by IFNs that is also essential for Th1 responses. We demonstrated that IL-12 directly up-regulates IRF-1 to the same extent as IFN-alpha in normal human T cells and in NK cells. We showed that IL-12 had a direct effect on IRF-1, an effect not mediated indirectly by the induction of IFN-gamma production. Furthermore, IL-2 and IL-12 synergistically induced IRF-1, whereas IFN-alpha and IL-12 did not. The participation of STAT4 in the regulation of IRF-1 was demonstrated in two ways. First, STAT4 was required for the IL-12-dependent transactivation of an IRF-1 reporter construct, and second, STAT4 binding to the IRF-1 promoter was shown using EMSA. In contrast to IL-12, no up-regulation of IRF-1 was found in IL-4-stimulated cells, and IL-4 did not block IL-12-dependent up-regulation of IRF-1. Therefore, IRF-1 may be an important contributor to IL-12 signaling, and we speculate that the defective IL-12 responses seen in IRF-1-/- mice might be attributable, in part, to the absence of this transcription factor.

3T3 Cells↗

PubMed1999

Thrombopoietin augments stem cell factor-dependent growth of human mast cells from bone marrow multipotential hematopoietic progenitors.

The effects of thrombopoietin (TPO) and/or stem cell factor (SCF) on the development of human mast cells from CD34(+) bone marrow (BM) cells were investigated using a serum-deprived liquid culture system. Mast cells were identified by measurement of intracellular histamine content, immunocytochemical staining, and flow cytometric analysis. Whereas SCF alone generated only a small number of tryptase+ cells, the addition of TPO to the culture containing SCF resulted in an apparent production of mast cells from 3 weeks until at least 15 weeks. Some of the cells reacted with an antichymase monoclonal antibody as well. Based on the effects of growth factor(s) on a later phase of the mast cell growth, TPO may stimulate an early stage of mast cell development in combination with SCF, whereas subsequent growth seems to be supported by SCF alone. Single-cell culture studies indicated that the CD34(+)CD38(-)c-kit+ cells and CD34(+)CD38(+)c-kit+ cells were responsible for the SCF + TPO-dependent mast cell production. Two-step culture assays clearly showed that mast cells originated from multilineage colony-forming cells that had potential to differentiate into neutrophil/mast cell lineages, neutrophil/macrophage/mast cell lineages, or neutrophil/macrophage/mast cell/erythroid lineages. These results suggest that TPO plays an important role in the development of human mast cells from CD34(+) BM cells in concert with SCF, and provide direct evidence of the differentiation into the mast cell lineage of human multipotential BM-derived progenitors.

Cell Differentiation↗

PubMed1999

Circadian-regulated expression of a nuclear-encoded plastid sigma factor gene (sigA) in wheat seedlings.

The activity of a light-responsive psbD promoter in plastids is known to be regulated by a circadian clock. However, the mechanism of the circadian regulation of the psbD light-responsive promotor, which is recognized by an Escherichia coli-type RNA polymerase, is not yet known. We examined the time course of mRNA accumulation of two E. coli-type RNA polymerase subunit genes, sigA and rpoA, under a continuous light condition after 12 h light/12 h dark entrainment. Accumulation of the sigA mRNA was found to be regulated by a circadian clock, while rpoA mRNA did not show any significant oscillation throughout the experiment.

Amino Acid Sequence↗

PubMed1999

Uricase-catalyzed oxidation of uric acid using an artificial electron acceptor and fabrication of amperometric uric acid sensors with use of a redox ladder polymer.

Electrochemical oxidation of uric acid catalyzed by uricase (uric acid oxidase, UOx; EC 1.7.3.3) was studied using several redox compounds including 5-methylphenazinium (MP) and 1-methoxy-5-methylphenazinium (MMP) as electron acceptors for UOx, which does not contain any redox cofactor. It was found that MP and MMP were useful to mediate electrons from UOx to an electrode in the enzymatic oxidation of uric acid. A novel redox polymer, poly(N-methyl-o-phenylenediamine)(poly-MPD), containing the MP units was also found to possess the mediation ability for UOx, and poly-MPD was immobilized together with UOx onto an electrode substrate covered with a self-assembled monolayer of 2-aminoethanethiolate with use of glutaraldehyde as a binding agent. The resulting electrode (poly-MPD/UOx/Au) exhibited amperometric responses to uric acid with very fast response of approximately 30 s, allowing reagentless amperometric determination in a concentration range covering that in the blood of a healthy human being. Kinetic parameters of the apparent Michaelis constant and the maximum current response obtained at the poly-MPD/UOx/Au suggested that electrochemical oxidation of uric acid was controlled by diffusion of uric acid into the enzyme film and that the redox polymer worked well in mediating between active sites of UOx molecules and the electrode substrate.

Candida↗

PubMed1999

Identification of human, rat and mouse nocistatin in brain and human nocistatin in brain and human cerebrospinal fluid.

Nocistatin was recently isolated from bovine brain and shown to block hyperalgesia and allodynia induced by nociceptin and prostaglandin (PG) E2. The counterparts of human, rat and mouse are deduced from their precursor prepronociceptin to be 30, 35, and 41 residue peptide respectively. To identify these mature forms of nocistatin, three peptides were synthesized and a detection program for nocistatin was developed, using high pressure liquid chromatography (HPLC) along with specific radioimmunoassay (RIA). Nocistatin extracted from human, rat and mouse brain were subjected to HPLC and nocistatin-like immunoreactivity (NST-IR) was determined. All three species showed two NST-IR peaks, one of which coincided with that of the corresponding putative nocistatin. The same NST-IR was also detected in human cerebrospinal fluid (CSF).

Amino Acid Sequence↗

PubMed1999

Enzymatic properties and deduced amino acid sequence of a high-alkaline pectate lyase from an alkaliphilic Bacillus isolate.

A high-alkaline pectate lyase (pectate trans-eliminase, EC 4.2.2.2.) from alkaliphilic Bacillus sp. strain KSM-P7, designated Pel-7, was purified to homogeneity. The purified Pel-7 had a molecular mass of approximately 33 kDa as determined by SDS-polyacrylamide gel electrophoresis. The isoelectric point was close to or higher than pH 10.5. In the presence of Ca2+ ions, Pel-7 trans-eliminated polygalacturonate in random manner to generate oligogalacturonides; it exhibited optimal activity at pH 10.5 and around at 60 to 65 degrees C in glycine-NaOH buffer. Mn2+ and Sr2+ ions can serve as cofactors at almost the same level of Ca2+ ions. It also exhibited a protopectinase-like activity, liberating soluble pectin and/or oligogalacturonides from cotton fibers. The pel gene was cloned and sequenced, and the deduced amino acid sequence of mature Pel-7 (302 amino acids, 33, 355 Da) showed some conserved regions in Pel superfamily, although homology to amino acid sequences of known Pels with 27 to 32% identity. Furthermore, Pel-7 appears to have similar core structure of parallel beta-helix and active site topology with other Pels as revealed by secondary structure prediction in the Pel proteins. These results suggest that Pel-7 is basically grouped into Pel superfamily although the enzymatic and molecular properties are different.

Amino Acid Sequence↗

PubMed1999

Functional integrity of mitochondrial genomes in human platelets and autopsied brain tissues from elderly patients with Alzheimer's disease.

To determine whether pathogenic mutations in mtDNA are involved in phenotypic expression of Alzheimer's disease (AD), the transfer of mtDNA from elderly patients with AD into mtDNA-less (rho0) HeLa cells was carried out by fusion of platelets or synaptosomal fractions of autopsied brain tissues with rho0 HeLa cells. The results showed that mtDNA in postmortem brain tissue survives for a long time without degradation and could be rescued in rho0 HeLa cells. Next, the cybrid clones repopulated with exogenously imported mtDNA from patients with AD were used for examination of respiratory enzyme activity and transfer of mtDNA with the pathogenic mutations that induce mitochondrial dysfunction. The presence of the mutated mtDNA was restricted to brain tissues and their cybrid clones that formed with synaptosomes as mtDNA donors, whereas no cybrid clones that isolated with platelets as mtDNA donors had detectable mutated mtDNA. However, biochemical analyses showed that all cybrid clones with mtDNA imported from platelets or brain tissues of patients with AD restored mitochondrial respiration activity to almost the same levels as those of cybrid clones with mtDNA from age-matched normal controls, suggesting functional integrity of mtDNA in both platelets and brain tissues of elderly patients with AD. These observations warrant the reassessment of the conventional concept that the accumulation of pathogenic mutations in mtDNA throughout the aging process is responsible for the decrease of mitochondrial respiration capacity with age and with the development of age-associated neurodegenerative diseases.

Aged↗

PubMed1999

Amperometric determination of total cholesterol at gold electrodes covalently modified with cholesterol oxidase and cholesterol esterase with use of thionin as an electron mediator.

Immobilization of cholesterol oxidase (EC 1.1.3.6) (ChOx) on a gold electrode was attempted by cross-linking using glutaraldehyde between ChOx molecules and a self-assembled monolayer of 2-aminoethanethiolate. The resulting electrode (ChOx/Au) exhibits an amperometric response to free cholesterol in the presence of thionin as an electron mediator, and a steady-state response is obtained approximately 60 s after injection of cholesterol into the electrolyte solution. Coimmobilization of cholesterol esterase (EC 3.1.1.13) (ChE) and ChOx (ChE/ChOx/Au) allows the amperometric determination of both esterified cholesterol and free cholesterol. Cyclic voltammetry of the ChE/ChOx/Au and the dependence of the amperometric response to cholesterol on the concentration of thionin suggest that thionin is encapsulated in the enzyme film on the electrode surface. Apparent Michaelis constants of the ChOx/Au and the ChE/ChOx/Au electrodes suggest that the amperometric response was controlled by penetration of the reaction substrate into the films of the enzyme(s). The concentration of total (free and esterified) cholesterol in human serum samples, determined by using the techniques developed in the present study, is in good agreement with that determined by the well-established technique using colorimetry.

Cholesterol↗

PubMed1999

Interleukin-10 inhibits expression of both interferon alpha- and interferon gamma- induced genes by suppressing tyrosine phosphorylation of STAT1.

Interleukin-10 (IL-10) helps maintain polarized T-helper cells in a T-helper lymphocyte 2 (Th2) phenotype. Part of this process involves the prevention of the development of Th1 cells, which are a primary source of interferon gamma (IFNgamma), a potent activator of monocytes and an inhibitor of Th2 proliferation. Because monocytes and macrophages are important mediators of Th1-type responses, such as delayed-type hypersensitivity, we sought to determine if IL-10 could directly mediate inhibition of IFNgamma- and IFNalpha-induced gene expression in these cells. Highly purified monocytes were incubated with IL-10 for 60 to 90 minutes before the addition of IFNgamma or IFNalpha. IL-10 preincubation resulted in the inhibition of gene expression for several IFN-induced genes, such as IP-10, ISG54, and intercellular adhesion molecule-1. The reduction in gene expression resulted from the ability of IL-10 to suppress IFN-induced assembly of signal transducer and activator of transcription (STAT) factors to specific promoter motifs on IFNalpha- and IFNgamma-inducible genes. This was accomplished by preventing the IFN-induced tyrosine phosphorylation of STAT1, a component of both IFNalpha- and IFNgamma-induced DNA binding complexes. Therefore, IL-10 can directly inhibit STAT-dependent early response gene expression induced by both IFNalpha and IFNgamma in monocytes by suppressing the tyrosine phosphorylation of STAT1. This may occur through the ability of IL-10 to induce expression of the gene, suppressor of cytokine signaling 3 (SOCS3).

Cells, Cultured↗

PubMed1999

Characteristics of 5-HT-containing chemoreceptor cells of the chicken aortic body.

1. Voltage-dependent and oxygen-sensitive currents in 5-HT-containing epithelioid cells isolated from chicken thoracic aorta were examined using the whole-cell patch clamp technique. 5-HT immunoreactive cells were identified with Neutral Red. The release of 5-HT from chicken thoracic aorta in the presence of excess KCl and veratridine was also examined using HPLC. 2. At a holding potential of -70 mV with CsCl pipette solution, depolarizing steps between -30 and +60 mV produced inward currents that were blocked by tetrodotoxin (0.2 microM). In the presence of tetrodotoxin and BaCl2 (5 mM), depolarizing steps evoked slow inward currents that were sensitive to CoCl2 (2 mM). Nifedipine (1 microM) decreased the currents to 79.4 +/- 1.7 %, and omega-conotoxin GVIA (1 microM) to 20.2 +/- 3.8 %. 3. When KCl pipette solution was used, depolarizing potentials positive to -40 mV caused outward currents that were inhibited by tetraethylammonium chloride. The K+ currents evoked by depolarizing steps to +20 mV were reduced to 90.3 +/- 0.8 % by hypoxia in five out of seven cells. Two cells failed to respond to hypoxia. The K+ current response was partly decreased by Neutral Red (20 microM). 4. Excess KCl (60 mM) and veratridine (30 microM) both caused the release of 5-HT from aortic strips. 5-HT outputs induced by both stimuli were partly inhibited by nifedipine (1 microM) and by omega-conotoxin GVIA (1 microM), and were abolished by these drugs in combination and by extracellular Ca2+ removal. 5. These results suggest that epithelioid cells containing 5-HT act as chemoreceptor cells in the chicken aortic body, having voltage-dependent Na+, K+, and L- and N-type Ca2+ channels, and oxygen-sensitive K+ channels.

Animals↗

PubMed1999

Lack of tactile pain (allodynia) in lipocalin-type prostaglandin D synthase-deficient mice.

Prostaglandin (PG) D2 is the most abundant prostanoid produced in the central nervous system of mammals and has been implicated in the modulation of neural functions such as sleep induction, nociception, regulation of body temperature, and odor responses. We generated gene-knockout mice for lipocalin-type PGD2 synthase (L-PGDS) and found that the intrathecal administration of PGE2, an endogenous pain-producing substance, failed to elicit allodynia (touch-evoked pain), which is one typical phenomenon of neuropathic pain, whereas it evoked thermal hyperalgesia, in L-PGDS-/- mice. We also found that the allodynic response induced by the gamma-aminobutyric acid (GABA)A receptor antagonist bicuculline was selectively abolished in the L-PGDS-/- mice, among excitatory and inhibitory agents that induced allodynia in wild-type mice. Interestingly, simultaneous injection of a femtogram amount of PGD2 with PGE2 or bicuculline induced allodynia in L-PGDS-/- mice to the same extent as in wild-type mice. The PGE2- or bicuculline-evoked allodynia in wild-type and in PGD2-supplemented L-PGDS-/- mice was blocked by a PGD2 receptor antagonist given in a femtogram amount. These results reveal that endogenous PGD2 is essential for both PGE2- and bicuculline-induced allodynia.

Anesthesia↗