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Biomedical subjects

H Mizoguchi

Publications and source records attributed to H Mizoguchi.

At least 19 recordsLinked to original sources
PubMed2002

Antagonistic property of buprenorphine for putative epsilon-opioid receptor-mediated G-protein activation by beta-endorphin in pons/medulla of the mu-opioid receptor knockout mouse.

beta-Endorphin is a non-selective opioid peptide which binds mu-, delta- and putative epsilon (beta-endorphin-sensitive non-mu-, non-delta- and non-kappa(1)-)-opioid receptors. We have previously reported that beta-endorphin-produced G-protein activation is mediated by the stimulation of both mu- and putative epsilon-opioid receptors. The present study was designed to further characterize this putative epsilon-opioid receptor-mediated G-protein activation in the pons/medulla membrane obtained from mice lacking mu-opioid receptor, using a guanosine-5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS)-binding assay. beta-Endorphin and the mu-opioid receptor agonist [D-Ala(2),N-MePhe(4),Gly-ol(5)]enkephalin (DAMGO) increased the [(35)S]GTPgammaS binding in a concentration-dependent manner (0.001-10 microM), and at 10 microM beta-endorphin and DAMGO produced approximately 250 and 120% increases of [(35)S]GTPgammaS binding in the pons/medulla membrane obtained from wild-type mice, respectively. In the pons/medulla membrane obtained from mu-opioid receptor knockout mice, beta-endorphin-stimulated [(35)S]GTPgammaS binding was only partially attenuated and a more than 100% increase by 10 microM beta-endorphin still remained, while DAMGO failed to produce any increase in [(35)S]GTPgammaS binding. The residual increase in [(35)S]GTPgammaS binding by 10 microM beta-endorphin in mu-opioid receptor knockout mice was partially but significantly attenuated by the putative epsilon-opioid receptor partial agonist beta-endorphin (1-27), but not by the delta-opioid receptor antagonist naltrindole or the kappa(1)-receptor antagonist norbinaltorphimine. Furthermore, buprenorphine significantly attenuated the residual increase in [(35)S]GTPgammaS binding by 10 microM beta-endorphin in mu-opioid receptor knockout mice. The present results indicate that beta-endorphin activates G-protein by stimulation of putative epsilon-opioid receptors in the condition lacking the mu-opioid receptor, and buprenorphine acts as an antagonist for putative epsilon-opioid receptors in this condition.

Animals↗
PubMed2001

Release of [Met5]enkephalin from the spinal cord by intraventricularly administered endomorphin-2, but not endomorphin-1 in the anesthetized rat.

Effects of intraventricular injection of endomorphin-1, endomorphin-2 and beta-endorphin on the release of immunoreactive [Met(5)]enkephalin from the spinal cord were studied in pentobarbital anesthetized rats. Intraventricular injection of endomorphin-2, but not endomorphin-1, caused an increased release of immunoreactive [Met(5)]enkephalin in the spinal perfusates. Beta-endorphin given intraventricularly also increased the release of immunoreactive [Met(5)]enkephalin in an amount 15-fold higher than that produced by endomorphin-2. The increase of the release of immunoreactive [Met(5)]enkephalin induced by endomorphin-2 was blocked by mu-opioid receptor antagonist CTOP. Our result suggests that endomorphin-2 stimulates another subtype of mu-opioid receptor different from that acted by endomorphin-1 at the supraspinal site and subsequently increases the release of [Met(5)]enkephalin from the spinal cord.

Analgesics, Opioid↗
PubMed2001

Reduced hyperalgesia induced by nerve injury, but not by inflammation in mice lacking protein kinase C gamma isoform.

Protein kinase C is one of protein kinases which might be involved in the nerve injury- or inflammation-induced hyperalgesia. The present study was designed to investigate the hyperalgesia with thermal paw-withdrawal test induced by sciatic nerve ligation or by intraplantar injection of a complete Freund's adjuvant solution in protein kinase C gamma knockout and its wild-type mice. Either sciatic nerve ligation or intraplantar injection of a complete Freund's adjuvant caused a marked decrease of the paw-withdrawal latency only on the ipsilateral, but not on the contralateral side of the paw in wild-type mice. This ipsilateral hyperalgesia induced by sciatic nerve ligation was significantly attenuated in protein kinase C gamma knockout mice. On the other hand, the ipsilateral hyperalgesia induced by complete Freund's adjuvant remained about the same in protein kinase C gamma knockout mice as in wild-type mice. The results indicate that protein kinase C gamma is involved in the development of the thermal hyperalgesia induced by nerve ligation, but not by complete Freund's adjuvant-induced inflammation.

Animals↗
PubMed2001

Up-regulation of spinal mu-opioid receptor function to activate G-protein by chronic naloxone treatment.

The effects of repeated s.c. administrations of an mu-opioid receptor antagonist naloxone on the G-protein activation induced by mu-opioid receptor agonists [D-Ala(2),N-MePhe(4),Gly-ol(5)]enkephalin (DAMGO), endomorphin-1 and endomorphin-2 in the mouse spinal cord was studied, monitoring guanosine-5'-o-(3-[35S]thio)triphosphate ([35S]GTPgammaS) binding. All mu-opioid receptor agonists concentration-dependently increased the [35S]GTPgammaS binding. The increases of [35S]GTPgammaS binding induced by agonists were significantly enhanced in mice pretreated with naloxone. Under the present condition, chronic treatment with naloxone significantly increased the density of [3H]DAMGO binding sites with an increase in K(d) values in spinal cord membranes, indicating an increase in mu-opioid receptors on the membrane surface. These findings suggest that chronic treatment with an mu-opioid receptor antagonist naloxone leads to the supersensitivity to activate G-protein by mu-opioid receptor agonists with an increase in mu-opioid receptors in membranes of the mouse spinal cord.

Analgesics, Opioid↗
PubMed2001

Partial agonistic action of endomorphins in the mouse spinal cord.

The partial agonistic properties of endogenous mu-opioid peptides endomorphin-1 and endomorphin-2 for G-protein activation were determined in the mouse spinal cord, monitoring the increases in guanosine-5'-o-(3-[35S]thio)triphosphate binding. The G-protein activation induced by endogenous opioid peptide beta-endorphin in the spinal cord was significantly, but partially, attenuated by co-incubation with endomorphin-1 or endomorphin-2. The data indicates that endomorphin-1 and endomorphin-2 are endogenous partial agonists for mu-opioid receptor in the mouse spinal cord.

Analgesics, Opioid↗
PubMed2001

Reversible integration of the dominant negative retinoid receptor gene for ex vivo expansion of hematopoietic stem/progenitor cells.

Since hematopoietic stem cells (HSCs) differentiate readily ex vivo resulting in the loss of self-renewal and engraftment abilities, the transient block of differentiation is essential to maintain those abilities during their ex vivo expansion culture. To this end, we developed a method of reversible integration of the dominant negative retinoic acid receptor (DN-RAR) gene, a differentiation-blocking gene, into cells utilizing the Cre/loxP-dependent gene recombination system. The murine immature hematopoietic 32D cells differentiate into mature neutrophils upon G-CSF treatment. However, 32D cells transduced with a retroviral vector expressing the DN-RAR gene put between two loxP sites continued to proliferate without showing differentiation even in the presence of G-CSF. After the cells were fully amplified, the cells were transduced with the Cre recombinase gene. The cells then restored the ability to differentiate into mature neutrophils upon G-CSF treatment. PCR analysis showed that the DN-RAR gene was efficiently removed from the genome by introduction of the Cre gene. This system may eventually be applicable to the ex vivo expansion of HSCs.

Animals↗
PubMed2001

Lack of the involvement of mu1-opioid receptor subtype on motivational effects induced by the endogenous mu-opioid receptor ligands endomorphin-1 and -2 in the mouse.

The present study was designed to investigate the role of mu-opioid receptor subtypes in the motivational effect of endogenous mu-opioid receptor ligands, endomorphin-1 and -2. In C57BL/6J mice, endomorphin-1 produced a significant place preference, whereas endomorphin-2 exhibited a significant place aversion. These effects were abolished by a mu1/mu2-opioid receptor antagonist beta-funaltrexamine. Under these conditions, both endomorphin-1 and -2 produced their motivational effects in mu1-opioid receptor-deficient CXBK mice, indicating the mu2-opioid receptor involvement. Furthermore, in the lower midbrain including ventral tegmental area, both endomorphin-1 and -2 equally produced dose-related increases in guanosine-5'-o-(3-[35S] thio) triphosphate bindings in C57BL/6J and CXBK mice. These findings indicate that endomorphin-1 and -2 may produce distinct motivational effects via respective mu2-opioid receptor isoforms in the mouse. Furthermore, endomorphin-1 and -2 produced the mu1-resistant G-protein activation in the mouse lower midbtrain.

Analgesics, Opioid↗
PubMed2001

Antisera against endogenous opioids increase the nocifensive response to formalin: demonstration of inhibitory beta-endorphinergic control.

The roles of endogenous opioid peptides in the brain in the modulation of nocifensive responses to formalin in ICR mice were studied. Mice were pretreated intracerebroventricularly (i.c.v.) with rabbit antiserum against beta-endorphin, [Leu5]enkephalin, [Met5]enkephalin or dynorphin A-(1-17) 1 h prior to intraplantar injection of formalin (0.5%, 25 microl) and the nocifensive licking responses were then observed. Pretreatment of mice with antiserum against beta-endorphin enhanced the second phase, but not the first phase of the nocifensive responses to formalin. Pretreatment with antiserum against [Leu5]enkephalin also caused a small but statistically significant enhancement of the second phase, but not the first phase of nocifensive responses to formalin. On the other hand, pretreatment with antiserum against [Met5]enkephalin or dynorphin A-(1-17) did not affect the nocifensive response to formalin. Our results indicate that beta-endorphinergic, and to a lesser extent, [Leu5]enkephalinergic systems are activated at the supraspinal sites to attenuate the nocifensive responses to formalin stimulation.

Animals↗
PubMed2001

Involvement of spinal protein kinase Cgamma in the attenuation of opioid mu-receptor-mediated G-protein activation after chronic intrathecal administration of [D-Ala2,N-MePhe4,Gly-Ol(5)]enkephalin.

The present study was designed to investigate the role of a protein kinase C (PKC) isoform in the uncoupling of the mu-opioid receptor from G-proteins after repeated intrathecal injection of a selective mu-receptor agonist, [D-Ala(2),N-MePhe(4),Gly-ol(5)]enkephalin (DAMGO), in the spinal cord of mice. The activation of G-proteins by opioids was measured by monitoring the guanosine-5'-o-(3-[(35)S]thio)triphosphate ([(35)S]GTPgammaS) binding. Mice were injected intrathecally with saline or DAMGO once a day for 1-7 d. At 24 hr after every injection the spinal cord membranes were prepared for the assay. The enhanced [(35)S]GTPgammaS binding by mu-agonists DAMGO, endomorphin-1, or endomorphin-2 was attenuated clearly in spinal cord membranes obtained from mice that were treated intrathecally with DAMGO for 5 and 7 d, but not for 1 or 3 d. By contrast, no change in levels of [(35)S]GTPgammaS binding induced by the delta-receptor agonist SNC-80 or kappa-receptor agonist U-50,488H was noted in membranes obtained from mice that were treated with DAMGO. Concomitant intrathecal administration of a specific PKC inhibitor Ro-32-0432 with DAMGO blocked the attenuation of DAMGO-induced G-protein activation that was caused by chronic DAMGO treatment. Western blotting analysis showed that chronic DAMGO treatment increased the levels of PKCgamma, but not PKCalpha, PKCbetaI, and PKCbetaII isoforms, in spinal cord membranes. Furthermore, mice lacking PKCgamma failed to exhibit the desensitization of the DAMGO-stimulated [(35)S]GTPgammaS binding after repeated DAMGO injection. These findings indicate that repeated intrathecal administration of DAMGO may activate the PKCgamma isoform and in turn cause a desensitization of mu-receptor-mediated G-protein activation in the mouse spinal cord.

Animals↗
PubMed2001

Enhanced mu-opioid responses in the spinal cord of mice lacking protein kinase Cgamma isoform.

The protein kinase C (PKC)gamma isoform is a major pool of the PKC family in the mammalian spinal cord. PKCgamma is distributed strategically in the superficial layers of the dorsal horn and, thus, may serve as an important biochemical substrate in sensory signal processing including pain. Here we report that mu-opioid receptor-mediated analgesia/antinociception and activation of G-proteins in the spinal cord are enhanced in PKCgamma knockout mice. In contrast, delta- and kappa-opioidergic and ORL-1 receptor-mediated activation of G-proteins in PKCgamma knockout mice was not altered significantly relative to the wild-type mice. Deletion of PKCgamma had no significant effect on the mRNA product of spinal mu-opioid receptors but caused an increase of maximal binding of the mu-opioid receptor agonist [3H][d-Ala(2),N-Me-Phe(4),Gly(5)-ol]enkephalin in spinal cord membranes obtained from PKCgamma knockout mice. These findings suggest that deletion of PKCgamma genes protects the functional mu-opioid receptors from degradation by phosphorylation. More importantly the present data provide direct evidence that PKCgamma constitutes an essential pathway through which phosphorylation of mu-opioid receptors occurs.

Analgesics↗
PubMed2001

Successful treatment of refractory anemia by high-dose methylprednisolone associated with an increment in CD68-positive cells in bone marrow.

Refractory anemia has a relatively low incidence of the subsequent development of acute leukemia and a relatively long survival among the myelodysplastic syndromes (MDS). We observed hematological improvement due to high-dose methylprednisolone in 9 of 18 patients with refractory anemia. The patients' age range was from 28 to 78 years old (mean age: 54), including 14 male and 4 females. A complete response was obtained in 5 patients, minimal response in 4 patients, and no response in 9 patients. Laboratory data of peripheral blood counts and differential counts of bone marrow aspirates were not different, except that fewer chromosomal abnormalities (P = 0.086) were observed in the responder group. Side effects were seen in two patients but were controllable. Overall survival was significantly longer in the responder group (Log-rank P = 0.040, Wilcoxon P = 0.045). The overall survival of responders did not reach the median and 85% of the patients were alive after 180 months, while the median overall survival of the nonresponders was 61.8 months. Disease progression was more frequently seen in the non-responder group (P = 0.045). Furthermore, we investigated retrospectively immunohistochemical bone marrow staining, and a significantly higher percentage of CD68-positive (22.6% +/- 7.1%) and CD45RA-positive cells was observed in the responder group compared to the non-responder group (6.5% +/- 1.3%). Our present results indicate that high-dose methylprednisolone is valuable as a primary treatment before other immunosuppressive treatments, because of its ease of use. High efficacy with high-dose methylprednisolone is expected, especially in patients in which increments in CD68-positive cells in bone marrow are observed.

Adult↗
PubMed2001

Anti-lymphoma effect of naproxen and indomethacin in a patient with relapsed diffuse large B-cell lymphoma.

A 77-year-old man with relapsed non-Hodgkin's lymphoma, diffuse large B-cell type, was treated with naproxen, a nonsteroidal anti-inflammatory drug (NSAID), for paraneoplastic fever. A dramatic disappearance of not only the fever but also generalized lymphadenopathy was observed. Naproxen was continued, and he maintained remission for 10 months. When relapse of lymphoma occurred in spite of continuous naproxen administration, indomethacin, another type of NSAID, was tried. Surprisingly, rapid regression of lymphoma occurred again and was maintained for almost 1 year. These results indicate that NSAIDs are effective in some patients with non-Hodgkin's lymphoma.

Aged↗
PubMed2001

Primary chronic myelofibrosis: clinical and prognostic evaluation in 336 Japanese patients.

We retrospectively analyzed 336 patients with primary chronic myelofibrosis from 203 medical institutes in Japan. Notwithstanding their heterogeneous treatments, the median survival in 298 patients that could be evaluated was 10.0 years. Average age at onset was 60.7 years. Men were affected 1.4 times more frequently than women. The factors associated with shorter survival included anemia, leukocytosis/leukocytopenia, thrombocytopenia, and increased blasts in the peripheral blood, and sex (male), age (>60), and the presence of symptoms. A new scoring system based on the peripheral blood findings (hemoglobin [Hb] level, platelet count, and rate of blast formation) at initial diagnosis clearly correlated with survival rate. Accordingly, patients could be categorized into 3 groups by severity grading. Through stepwise multivariate survival analysis, the significant prognostic factors were identified as the severity grading based on the new scoring system (P = .0002), age (P = .0024), sex (P = .0153), and Hb (P = .0198). Chromosomal abnormalities were found in 58 of 154 patients (38%), although these did not influence survival.

Actuarial Analysis↗
PubMed2001

Different motivational effects induced by the endogenous mu-opioid receptor ligands endomorphin-1 and -2 in the mouse.

The present study was designed to investigate the motivational effects of the newly discovered endogenous mu-opioid receptor ligands, endomorphin-1 and endomorphin-2, using the conditioned place preference paradigm in mice. The binding properties of these peptides were first examined using an opioid binding assay. In membranes obtained from the mouse whole brain, the binding of [3H][D-Ala2, NMePhe4, Gly(ol)5]enkephalin (DAMGO; mu), but not of [3H][D-Phe2, D-Phe5]enkephalin (DPDPE; delta) or [3H]U69593 (kappa) selectively and concentration-dependently competed with that of endomorphin-1 and endomorphin-2, indicating that both endomorphin-1 and endomorphin-2 are specific ligands for mu-opioid receptors in the brain. Endomorphin-1 (1-30 nmol/mouse) given i.c.v. produced a dose-related place preference. This effect was abolished by pre-treatment with the mu-opioid receptor antagonist beta-funaltrexamine but not the delta-opioid receptor antagonist naltrindole or the kappa-opioid receptor antagonist nor-binaltorphimine. In contrast, endomorphin-2 (5.6 nmol/mouse) produced place aversion. This aversive effect was inhibited by nor-binaltorphimine as well as beta-funaltrexamine, but not by naltrindole. The place aversion produced by endomorphin-2 was also attenuated by pre-treatment with antiserum against the endogenous kappa-opioid receptor ligand dynorphin A (1-17). These findings indicate that endomorphin-1 may produce its rewarding effect via mu-opioid receptors. On the other hand, the aversive effect induced by endomorphin-2 may be associated with the stimulation of endomorphin-1-insensitive mu-opioid receptors and the activation of dynorphinergic systems in the mouse brain.

Animals↗
PubMed2001

Lack of gastric toxicity of nitric oxide-releasing indomethacin, NCX-530, in experimental animals.

The effects of a nitric oxide (NO) releasing derivative of indomethacin (NCX-530) on gastric ulcerogenic and healing responses were evaluated in rats and mice, in comparison with the parent compound indomethacin. Indomethacin (per os) produced damage in the rat stomach in a dose-dependent manner. NCX-530 (per os) itself, however, was not ulcerogenic and even showed a dose-dependent protection against HCl/ethanol-induced lesions in the rat stomach. Likewise, indomethacin given repeatedly delayed healing of gastric ulcers induced in mice by thermal cauterization, while NCX-530 did not affect the healing response and significantly promoted the healing as compared to indomethacin. These actions of NCX-530 were mimicked by the combined administration of a NO donor NOR-3 with indomethacin. The amount of NO metabolites was increased in both the gastric contents and serum when NCX-530, but not indomethacin, was given in pylorus-ligated stomachs. Neither indomethacin nor NCX-530 influenced gastric acid secretion and transmucosal potential difference, yet NCX-530 caused a marked increase of gastric mucosal blood flow, which was preventable by carboxy-PTIO, a scavenger of NO. Gastric motility was increased by indomethacin but not by NCX-530. In addition, NCX-530 inhibited PGE2 generation in both the intact and ulcerated gastric mucosa and showed antiinflammatory action on carrageenan-induced rat paw edema, as effectively as indomethacin. These results suggest that unlike indomethacin, NCX-530 caused neither an irritating action on the stomach nor healing impairment effect on the preexisting gastric ulcers, but conferred gastric protection against HCl/ethanol, despite causing cyclooxygenase inhibition and antiinflammatory action, as effectively as indomethacin. This NO-releasing indomethacin, probably by releasing NO, exerts protective influences, such as an increase of gastric mucosal blood flow, that counteract the potential damaging effects of cyclooxygenase inhibition by indomethacin.

Acetates↗