Nobuaki Matsui

Magnolol and honokiol prevent learning and memory impairment and cholinergic deficit in SAMP8 mice

The therapeutic use of neurotrophic factors to treat neurodegenerative disorders, including Alzheimers disease, is considered feasible. Magnolol and honokiol, constituents of the Magnolia plant, are small organic compounds with neurotrophic activity. We investigated whether magnolol and honokiol can prevent age-related learning and memory impairment and cholinergic deficits in senescence-accelerated mice (SAM). Magnolol (1, 10 mg/kg) or honokiol (0.1, 1 mg/kg) were orally administered to SAMP8 mice once a day for 14 days in 2-month-old mice. Learning and memory performance were evaluated by passive avoidance tests and location and object novelty recognition tests. SAMP8 mice showed significant impairment of learning and memory at 4 and 6 months of age. This age-related learning and memory impairment was prevented by pretreatment with either magnolol (10 mg/kg) or honokiol (1 mg/kg). Cholinergic neuron densities in the medial septum and vertical limb of the diagonal band of the forebrain were evaluated by an immunohistochemical analysis of choline acetyltransferase (ChAT). SAMP8 mice showed a significant cholinergic deficit at 6 months of age. These age-related cholinergic deficits were prevented by treatment with either magnolol (10 mg/kg) or honokiol (1 mg/kg). Moreover, SAMP8 mice showed decreased activity of Akt, a member of the prosurvival pathway, in the forebrain at 2 months of age. A 14-day treatment with either magnolol (10 mg/kg) or honokiol (1 mg/kg) enhanced phosphorylation of Akt in the forebrain at 2 months of age. These results suggest that magnolol and honokiol prevent age-related learning and memory impairment by preserving cholinergic neurons in the forebrain. These compounds may have potential therapeutic applications to various neurodegenerative disorders.

Bacterial components regulate the expression of Toll-like receptor 4 on human mast cells.

Abstract.Objectives and design:The aim of this study was to investigate whether the exposure of mast cells (MCs) to bacterial components affects the expression of Toll-like receptor (TLR) 4, and to elucidate the behavior of MCs during the early response to infection.Materials:Two human MC lines, HMC-1 and LAD2, were employed. Messenger RNA expression was observed by RT and real-time PCR. TLR4 expression was determined by Western blotting. TNF-α secretion was analyzed with ELISA. The degranulation ratio was measured with betahexosaminidase assay.Results:Although bacterial components increased TLR4 mRNA, only lipopolysaccharide (LPS) augmented the TLR4 protein expression. LAD2 pre-treated with LPS for 8 h resulted in 2-fold increased TNF-α secretion on LPS restimulation.Conclusion:These results suggest that the exposure of MCs to LPS may reinforce the innate immune system due to up-regulation of MC TLR4, followed by increased TNF-α release.

Does β-Hexosaminidase Function Only as a Degranulation Indicator in Mast Cells? The Primary Role of β-Hexosaminidase in Mast Cell Granules

β-Hexosaminidase, which is generally present in the lysosome, is essential for glycoprotein metabolism in the maintenance of cell homeostasis. In mast cells (MCs), large amounts of β-hexosaminidase are present in the granules as opposed to the lysosome, and the biological role of MC β-hexosaminidase has yet to be fully elucidated. Therefore, we investigated the biological role of β-hexosaminidase in MC granules. Bone marrow-derived MCs from C57BL/6 (BL/6-BMMC) or β-hexosaminidase gene–deficient (hexb−/−-BMMC) mice were transplanted into MC-deficient (WBB6F1/J-KitW/KitW-v [W/Wv]) mice to generate MC-reconstituted models. In asthma model experiments, no differences were observed in the symptoms of BL/6, W/Wv, BL/6-BMMC–reconstituted W/Wv, or hexb−/−-BMMC–reconstituted W/Wv mice. In Staphylococcus epidermidis experimental infection model experiments, the severity of symptoms and frequency of death were markedly higher in W/Wv and hexb−/−-BMMC–reconstituted W/Wv mice than in BL/6 and BL/6-BMMC–reconstituted W/Wv mice. The growth of S. epidermidis in an in vitro study was clearly inhibited by addition of BL/6-BMMC lysate, but not by addition of hexb−/−-BMMC lysate. Moreover, suppression of bacterial proliferation was completely recovered when bacteria were incubated with hexb−/−-BMMC lysate plus β-hexosaminidase. Transmission electron microscopy indicated that the cell wall of S. epidermidis was heavily degraded following coincubation of bacteria with BL/6-BMMC lysate, but not following coincubation with hexb−/−-BMMC lysate. These findings strongly suggest that MC granule β-hexosaminidase is crucial for defense against bacterial invasion, but is not involved in the allergic response. Our results also suggest that the bactericidal mechanism of β-hexosaminidase involves degradation of bacterial cell wall peptidoglycan.

Evaluation of constituents of Piper retrofractum fruits on neurotrophic activity.

Three new compounds, 1-3, together with 22 known compounds, were isolated from the fruits of Piper retrofractum. The structures of the new compounds were elucidated on the basis of spectroscopic data analysis and comparison with literature values. Compound 1 was found to enhance the neurite outgrowth of NGF-mediated PC12 cells at concentrations ranging from 0.1 to 10 μM.

Inhibitory Effect of Egualen Sodium: A New Stable Derivative of Azulene on Histamine Release from Mast Cell-Like Cells in the Stomach

We studied the inhibitory effect of egualen sodium (ES) (sodium 3-ethyl-7-isopropyl-1-azulenesulfonate 1/3 hydrate, KT1–32), a new derivative and more stable compound than azulene, on histamine release from the mucosal histaminocytes and elucidated the mechanism for this action. ES prevented the histamine release from isolated mast cell-like cells of the guinea pig stomach induced by A23187 in a dose-dependent fashion. ES dose-dependently inhibited the histamine release from lung pieces of sensitized guinea pigs induced by an antigen-antibody reaction. ES also inhibited histamine release from rat peritoneal mast cells induced by compound 48/80 or antigen-antibody reaction. ES exhibited the membrane stabilizing activity on DPPC liposomes. These findings suggest that ES may prevent histamine release from histaminocytes induced by various stimuli and the stabilizing action of the cell membrane may be responsible for the inhibition of histamine release.

Roles of Superoxide Dismutase in Rat Mast Cell Granules

Background: It has been suggested that in the granules of rat mast cells there is some kind of superoxide dismutase (SOD), but details of this SOD in mast cells remain unclear. In the present study, we studied the mode of existence of SOD in mast cells and its releasing mechanism from the granules. In addition, we discussed the physiological role of SOD in allergic events. Methods: Purified rat mast cells were disrupted with a sonic disrupter and granules (sample I) were separated from supernatant (sample II) by centrifugation. The granules were treated with 1 mM Ca2+, and the supernatant (sample III) was separated from the pellet (sample IV). Sample III was applied to a heparin column and the eluate was used as sample V. SOD activity was measured in these samples. Results: SOD existed in mast cell granules as a heparin-binding and an inactive form. However, when granules were released and exposed to high Ca2+ concentration, SOD was discharged from heparin and shifted to the active form. The expression of macrophage inflammatory protein-1 alpha mRNA was enhanced when hydrogen peroxide (H2O2) or sample III with the xanthine-xanthine oxidase system were added to the culture media. Conclusions: These findings suggest that in stimulated rat mast cells, the released SOD may transform the generated superoxide anion into H2O2, and the generated H2O2 may enhance the expression of chemokine mRNA in the mast cells.

Magnolol Enhances Hippocampal Neurogenesis and Exerts Antidepressant-Like Effects in Olfactory Bulbectomized Mice

Magnolol is the main constituent of Magnolia bark and has been reported to exhibit antidepressant effects in rodent models. Hippocampal neurogenesis and neurotrophins such as brain‐derived neurotrophic factor are integrally involved in the action of conventional antidepressants. Here, we investigated the effects of magnolol on depressive behaviours, impaired hippocampal neurogenesis and neurotrophin‐related signal transduction in an olfactory bulbectomy (OBX) mouse model of depression. Mice were submitted to OBX to induce depressive behaviour, which was evaluated in the tail suspension test. Magnolol was administered orally by gavage needle. Neurogenesis was assessed by analysis of cells expressing NeuN, a neuronal marker, and 5‐bromo‐2′‐deoxyuridine (BrdU) uptake. Phosphorylation levels of protein kinase B (Akt), extracellular signal‐regulated kinase and cyclic AMP‐responsive element‐binding protein were evaluated by Western blot. Fourteen day treatment with magnolol (50 or 100 mg/kg/day) significantly improved OBX‐induced depressive behaviour in tail suspension test. In agreement, magnolol significantly rescued impairments of hippocampal neurogenesis. Moreover, single treatments with magnolol (50 mg/kg) significantly increased phosphorylation of Akt, extracellular signal‐regulated kinase and cyclic AMP‐responsive element‐binding protein after 3 h. The present data indicate that magnolol exerts antidepressant‐like effects on behaviours by enhancing hippocampal neurogenesis and neurotrophin‐related intracellular signalling in OBX mice. Copyright

Generation of Mast Cells from Mouse Fetus: Analysis of Differentiation and Functionality, and Transcriptome Profiling Using Next Generation Sequencer

While gene knockout technology can reveal the roles of proteins in cellular functions, including in mast cells, fetal death due to gene manipulation frequently interrupts experimental analysis. We generated mast cells from mouse fetal liver (FLMC), and compared the fundamental functions of FLMC with those of bone marrow-derived mouse mast cells (BMMC). Under electron microscopy, numerous small and electron-dense granules were observed in FLMC. In FLMC, the expression levels of a subunit of the FcεRI receptor and degranulation by IgE cross-linking were comparable with BMMC. By flow cytometry we observed surface expression of c-Kit prior to that of FcεRI on FLMC, although on BMMC the expression of c-Kit came after FcεRI. The surface expression levels of Sca-1 and c-Kit, a marker of putative mast cell precursors, were slightly different between bone marrow cells and fetal liver cells, suggesting that differentiation stage or cell type are not necessarily equivalent between both lineages. Moreover, this indicates that phenotypically similar mast cells may not have undergone an identical process of differentiation. By comprehensive analysis using the next generation sequencer, the same frequency of gene expression was observed for 98.6% of all transcripts in both cell types. These results indicate that FLMC could represent a new and useful tool for exploring mast cell differentiation, and may help to elucidate the roles of individual proteins in the function of mast cells where gene manipulation can induce embryonic lethality in the mid to late stages of pregnancy.

Bangle (Zingiber purpureum) Improves Spatial Learning, Reduces Deficits in Memory, and Promotes Neurogenesis in the Dentate Gyrus of Senescence-Accelerated Mouse P8

Bangle (Zingiber purpureum) is a tropical ginger that is used as a spice in Southeast Asia. Phenylbutenoid dimers isolated from Bangle have exhibited neurotrophic effects in primary cultured rat cortical neurons and PC12 cells. Furthermore, chronic treatment with phenylbutenoid dimers enhances hippocampal neurogenesis in olfactory bulbectomized mice. In this study, we investigated the effects of Bangle extract on behavior and hippocampal neurogenesis in vivo. SAMP8 mice, which are an established model for accelerated aging, with age-related learning and memory impairments, were given a Bangle-containing diet for 1 month, and subsequent behavioral tests and immunohistochemistry for Ki67, a proliferating cell marker, were performed. We found that the Bangle-containing diet improved spatial learning and memory deficits in the Morris water maze and significantly increased the numbers of Ki67-positive cells in the dentate gyrus of the SAMP8 mice. In addition, the Bangle extract exhibited a neurotrophin-like activity as indicated by the induction of neurite sprouting in PC12 cells. Our results suggest that Bangle is beneficial for the prevention of age-related progression of cognitive impairment.

Compound 48/80, a Mast Cell Stimulator, Enhances Synthesis of IgE and IgG Induced by Intranasal Application of Ovalbumin in Mice.

Mast cells are well established effector cells of type I hypersensitivity reactions such as allergic rhinitis. However, recent studies have suggested that activated mast cells enhance local immunoglobulin E (IgE) synthesis in the nasal mucosa of allergic rhinitis patients. Therefore, we hypothesized that non-immunological mast cell activators may have the potential to enhance local IgE synthesis. Here, we examined the effect of compound 48/80 (C48/80), a mast cell activator, on IgE and immunoglobulin G (IgG) synthesis. Female Balb/c mice were intranasally administered a mixture of ovalbumin (OVA) (1-10 µg/nose) and C48/80 (1-100 µg/nose) on days 0, 7, 14 and 21 and on consecutive days from day 28 to day 42. Intranasal administration of C48/80 with OVA increased serum OVA-specific IgE and IgG. Double staining with fluorescent-labeled OVA and fluorescent-labeled IgE- or IgG-specific antibody demonstrated the presence of OVA-specific IgE- or IgG-producing cells in the nasal mucosa of sensitized mice. Moreover, intranasal administration of C48/80 with OVA increased the nasal mucosal interleukin (IL)-4 level and enhanced the OVA-induced symptom of sneezing. These results suggested that simultaneous activation of mast cells with antigen exposure enhances local IgE and IgG synthesis.