Daisuke Yamada

Pharmacological Discrimination of Extinction and Reconsolidation of Contextual Fear Memory by a Potentiator of AMPA Receptors

Conditioned fear memory, once formed through fear conditioning, is modulated by reexposure of individuals to a conditioned stimulus. The reexposure reactivates the fear memory, which induces reconsolidation of the memory first, and then extinction of the fear response. Both attenuating the former and facilitating the latter are effective in reducing the fear response, and these findings are potentially translatable to the enhancement of exposure therapy for complex anxiety disorders. Currently, there is no drug that is established to modulate either reconsolidation or extinction selectively, which are thought to be independent processes. Here, we report that an extinction-facilitating AMPA potentiator, 4-[2-(phenylsulfonylamino)ethylthio]-2,6-difluoro-phenoxyacetamide (PEPA), does not act on the reconsolidation of fear memory formed by contextual fear conditioning in mice. The freezing rates observed in contextually conditioned mice following short reexposure (3u2009min) to the context were not influenced by intraperitoneal or intra-amygdala administration of PEPA. The same short reexposure to the context enhanced freezing responses in mice that were similarly administered D-cycloserine (DCS), a drug that facilitates both extinction and reconsolidation, and this enhancement of freezing responses in mice intraperitoneally administered DCS was abolished by propranolol, a drug that suppresses reconsolidation. At the same doses used in the short reexposure experiments, PEPA and DCS facilitated extinction of the fear response induced by long reexposure to the context and suppressed reinstatement of the conditioned fear memory. PEPA and DCS did not affect reextinction. These results suggest that PEPA acts on extinction of contextual fear memory without having detectable influences on its reconsolidation.

Continuous flow synthesis

This article provides a brief outline of continuous flow synthesis including the advantages of the flow method, serial combinatorial synthesis in flow, space integration of reactions, and reactions that cannot be done in batch to show that continuous flow synthesis will be a powerful and indispensable technology for pharmaceutical research and production.

Loss of a Rho-Regulated Actin Nucleator, mDia2, Impairs Cytokinesis during Mouse Fetal Erythropoiesis

The small GTPase Rho and mDia2, a Rho-regulated actin nucleator, function as critical regulators of cytokinesis in cultured cells. However, their involvement in cytokinesis during mammalian development remains unknown. Here, we generated mice deficient in mDia2 and examined the role of Rho signaling in cytokinesis during development. mDia2-deficient mice survive until embryonic day 11.5 (E11.5), exhibit severe anemia with multinucleate erythroblasts, and die in utero by E12.5. mDia2-deficient erythroid cells differentiate normally, though in a delayed manner, but exhibit cytokinesis failure with decreased accumulation of F-actin in the cleavage furrow during late differentiation from proerythroblasts. On the other hand, inactivation of Rho induces cytokinesis failure from the earlier progenitor stage. mDia2-deficient erythroblasts, however, are able to enucleate their nuclei. Our findings have thus revealed that mDia2 functions critically in cytokinesis inxa0vivo during erythropoiesis and further suggest that the cytokinesis mechanism in development diverges downstream of Rho. They also demonstrate that cytokinesis and enucleation utilize different mechanisms.

Effect of β-lactotensin on acute stress and fear memory

Abstract β-Lactotensin (β-LT) is a bioactive peptide derived from bovine milk β-lactoglobulin and is a natural ligand for neurotensin receptors. We examined the effect of β-LT on restraint stress and fear memory in mice. Mice subjected to acute restraint stress exhibited a decreased number of head-dips and increased head-dip latency compared to non-stressed controls in the hole-board test, reflecting increased stress-induced behaviors. However, prior administration of β-LT improved the behaviors caused by stress. The anti-stress effect of β-LT was blocked by levocabastine, a neurotensin receptor subtype 2 (NTR2) antagonist. In the fear-conditioning test, the duration of freezing responses by cued fear conditioning was significantly reduced in mice administered β-LT compared with control mice. These results suggest that β-LT has an anti-stress effect and promotes the extinction of fear memory, which may be mediated by NTR2.

Microflow System Controlled Carbocationic Polymerization of Vinyl Ethers

A cation pool of an N- acyliminium ion was found to serve as an effective initiator of cationic polymerization of vinyl ethers in a microflow system consisting of two micromixers (IMM micromixer) and two microtube reactors. The cationic polymerization of n-butyl vinyl ether in CH(2)Cl(2) at -78 degrees C led to very narrow molecular weight distribution (M(w)/M(n)=1.14). The molecular weight (M(n)) increased linearly with an increase in monomer/initiator ratio. The carbocationic polymer end was effectively trapped by allyltrimethylsilane. Additionally, the synthesis of block polymers was accomplished by the present microflow system controlled method. The polymerization was also conducted using commercially available trifluoromethanesulfonic acid (TfOH) as an initiator. A high level of molecular weight control was attained even at -25 degrees C. The TfOH-initiated polymerization could be conducted using a microflow system based on T-shaped micromixers, which serves as a practical tool for microflow system controlled carbocationic polymerization.

Efficient green emission from (112¯2) InGaN∕GaN quantum wells on GaN microfacets probed by scanning near field optical microscopy

Nanoscopic optical characterization using scanning near field optical microscopy was performed on a (112¯2) microfacet quantum well (QW). It was revealed that the carrier diffusion length in the (112¯2) QW is less than the probing fiber aperture of 160nm, which is shorter than that of the (0001) QWs and is attributed to much faster radiative recombination processes in the (112¯2) QW due to a reduced internal electric field. Owing to this short diffusion length, the correlation between the internal quantum efficiency (IQE) and emission wavelength is elucidated. The highest IQE is ∼50% at 520nm, which is about 50nm longer than in (0001) QWs, suggesting that the (112¯2) QW is a suitable green emitter.

Generation and Reactions of Pyridyllithiums via Br/Li Exchange Reactions Using Continuous Flow Microreactor Systems

A continuous flow microreactor method for generating and carrying out reactions on pyridyllithiums has been developed based on Br/Li exchange reactions of bromopyridines and dibromopyridines. The reactions can be carried out without using cryogenic conditions by virtue of short residence times and efficient heat transfer, while very low temperatures such as –78 or –110°C are required for conventional batch macro methods. Moreover, sequential introduction of two different electrophiles has been successfully achieved using dibromopyridines in an integrated flow microreactor system composed of four micromixers and four microtube reactors.

mDia and ROCK Mediate Actin-Dependent Presynaptic Remodeling Regulating Synaptic Efficacy and Anxiety

Here, we show neuronal inactivation-induced presynaptic remodeling and involvement of the mammalian homolog of Diaphanous (mDia) and Rho-associated coiled-coil-containing kinase (ROCK), Rho-regulated modulators of actin and myosin, in this process. Wexa0find that social isolation induces inactivation ofxa0nucleus accumbens (NAc) neurons associated with elevated anxiety-like behavior, and that mDia in NAc neurons is essential in this process. Upon inactivation of cultured neurons, mDia induces circumferential actin filaments around the edge of the synaptic cleft, which contract the presynaptic terminals in a ROCK-dependent manner. Social isolation induces similar mDia-dependent presynaptic contraction at GABAergic synapses from NAc neurons in the ventral tegmental area (VTA) associated with reduced synaptic efficacy. Optogenetic stimulation of NAc neurons rescues the anxiety phenotype, and injection of a specific ROCK inhibitor, Y-27632, into the VTA reverses both presynaptic contraction and the behavioral phenotype. mDia-ROCK signaling thus mediates actin-dependent presynaptic remodeling in inactivated NAc neurons, which underlies synaptic plasticity in emotional behavioral responses.

Rational identification of a novel soy-derived anxiolytic-like undecapeptide acting via gut-brain axis after oral administration

Abstract Here we found that the chymotryptic digest of soy &bgr;‐conglycinin, a major storage protein, exhibited anxiolytic‐like effects in mice. We then searched for anxiolytic‐like peptides in the digest. Based on a comprehensive peptide analysis of the chymotryptic digest by high performance liquid chromatograph connected to an LTQ Orbitrap mass spectrometer and the structure‐activity relationship of known peptides, we explored anxiolytic‐like peptides present in the digest. FLSSTEAQQSY, which corresponds to 323–333 of the &bgr;‐conglycinin &agr; subunit [&bgr;CG&agr;(323–333)] emerged as a candidate. Oral administration of synthetic &bgr;CG&agr;(323–333) exhibited anxiolytic‐like effects in the elevated plus‐maze and open‐field test in male mice. Orally administered &bgr;CG&agr;(323–333) exhibited anxiolytic‐like effects in sham‐operated control mice but not in vagotomized mice. In addition, oral administration of &bgr;CG&agr;(323–333) increased the expression of c‐Fos, a marker of neuronal activity, in the nucleus of the solitary tract, which receives inputs from the vagus nerve. These results suggest that the anxiolytic‐like effects were mediated by the vagus nerve. The anxiolytic‐like effects of &bgr;CG&agr;(323–333) were also blocked by antagonists of the serotonin 5‐HT1A, dopamine D1 and GABAA receptors. However &bgr;CG&agr;(323–333) had no affinity for these receptors, suggesting it stimulates the release of endogenous neurotransmitters to activate the receptors. Taken together, a soy‐derived undecapeptide, &bgr;CG&agr;(323–333), may exhibit anxiolytic‐like effects after oral administration via the vagus nerve and 5‐HT1A, D1 and GABAA systems. HighlightsThe chymotryptic digest of soy &bgr;‐conglycinin exhibited anxiolytic‐like effect in mice.We found a novel anxiolytic soy undecapeptide based on a global analysis of the digest.The soy undecapeptide exhibited potent anxiolytic‐like effect after oral administration.The anxiolytic‐like effect was blocked by the 5‐HT1A, D1and GABAA antagonists.This is the first soy anxiolytic‐like peptide coupled to the gut‐brain communication.

Characterization of soy-deprestatin, a novel orally active decapeptide that exerts antidepressant-like effects via gut–brain communication

We found that the orally administered thermolysin digest of β‐conglycinin exhibits antidepressant‐like effects in tail suspension and forced swim tests in mice. A comprehensive peptide analysis of the digest using liquid chromatography/mass spectrometry was performed, and LSSTQAQQSY emerged as a candidate antidepressant‐like peptide. Orally administered synthetic LSSTQAQQSY exhibited antidepressant‐like effects at a dose of 0.3 mg/kg; therefore, we named the decapeptide soy‐deprestatin. In contrast, intraperitoneally administered soy‐deprestatin was ineffective. We then hypothesized that it acted on the gut, and its signal was transferred to the brain. Indeed, orally administered soy‐deprestatin exhibited antidepressant‐like activity in sham‐treated, but not vagotomized, mice. Oral administration of soy‐deprestatin also increased the c‐Fos expression in the nucleus of the solitary tract, which receives inputs from the vagus nerve. These results suggested that the antidepressant‐like effects were mediated by the vagus nerve. Thermolysin digest‐ and soy‐deprestatin–induced antidepressant‐like effects were also blocked by antagonists of serotonin 5‐HT1A, dopamine D1, or GABAA receptors. We also clarified the order of receptor activation as 5‐HT1A, D1, and GABAA, using selective agonists and antagonists. Taken together, soy‐deprestatin may exhibit antidepressant‐like effects after oral administration via a novel pathway mediated by 5‐HT1A, followed by D1 and GABAA systems. This is the first orally active peptide demonstrating antidepressant‐like effects via gut–brain communication.—Mori, Y., Asakura, S., Yamamoto, A., Odagiri, S., Yamada, D., Sekiguchi, M., Wada, K., Sato, M., Kurabayashi, A., Suzuki, H., Kanamoto, R., Ohinata, K. Characterization of soy‐deprestatin, a novel orally active decapeptide that exerts antidepressant‐like effects via gut–brain communication. FASEB J. 32, 568–575 (2018). www.fasebj.org