A possible role of neuroglobin in the retina after optic nerve injury: A comparative study of zebrafish and mouse retina

Neuroglobin (Ngb) is a new member of the family of heme proteins and is specifically expressed in neurons of the central and peripheral nervous systems in all vertebrates. In particular, the retina has a 100-fold higher concentration of Ngb than do other nervous tissues. The role of Ngb in the retina is yet to be clarified. Therefore, to understand the functional role of Ngb in the retina after optic nerve injury (ONI), we used two types of retina, from zebrafish and mice, which have permissible and non-permissible capacity for nerve regeneration after ONI, respectively. After ONI, the Ngb protein in zebrafish was upregulated in the amacrine cells within 3 days, whereas in the mouse retina, Ngb was downregulated in the retinal ganglion cells (RGCs) within 3 days. Zebrafish Ngb (z-Ngb) significantly enhanced neurite outgrowth in retinal explant culture. According to these results, we designed an overexpression experiment with the mouse Ngb (m-Ngb) gene in RGC-5 cells (retinal precursor cells). The excess of m-Ngb actually rescued RGC-5 cells under hypoxic conditions and significantly enhanced neurite outgrowth in cell culture. These data suggest that mammalian Ngb has positive neuroprotective and neuritogenic effects that induce nerve regeneration after ONI. © Springer International Publishing Switzerland 2016.[Book Chapter

Cell fate of müller cells during photoreceptor regeneration in an N-methyl-N-nitrosourea- induced retinal degeneration model of zebrafish

Zebrafish can regenerate several organs such as the tail fin, heart, central nervous system, and photoreceptors. Very recently, a study has demonstrated the photoreceptor regeneration in the alkylating agent N-methyl-N-nitrosourea (MNU)- induced retinal degeneration (RD) zebrafish model, in which whole photoreceptors are lost within a week after MNU treatment and then regenerated within a month. The research has also shown massive proliferation of Müller cells within a week. To address the question of whether proliferating Müller cells are the source of regenerating photoreceptors, which remains unknown in the MNU-induced zebrafish RD model, we employed a BrdU pulse-chase technique to label the proliferating cells within a week after MNU treatment. As a result of the BrdU pulse-chase technique, a number of BrdU+ cells were observed in the outer nuclear layer as well as the inner nuclear layer. This implies that regenerating photoreceptors are derived from proliferating Müller cells in the zebrafish MNU-induced RD model. © Springer International Publishing Switzerland 2016.[Book Chapter

Upregulation of anti-apoptotic factors in upper motor neurons after spinal cord injury in adult zebrafish

Unlike mammals, fish motor function can recover within 6-8 weeks after spinal cord injury (SCI). The motor function of zebrafish is regulated by dual control; the upper motor neurons of the brainstem and motor neurons of the spinal cord. In this study, we aimed to investigate the framework behind the regeneration of upper motor neurons in adult zebrafish after SCI. In particular, we investigated the cell survival of axotomized upper motor neurons and its molecular machinery in zebrafish brain. As representative nuclei of upper motor neurons, we retrogradely labeled neurons in the nucleus of medial longitudinal fasciculus (NMLF) and the intermediate reticular formation (IMRF) using a tracer injected into the lesion site of the spinal cord. Four to eight neurons in each thin sections of the area of NMLF and IMRF were successfully traced at least 1-15 days after SCI. TUNEL staining and BrdU labeling assay revealed that there was no apoptosis or cell proliferation in the axotomized neurons of the brainstem at various time points after SCI. In contrast, axotomized neurons labeled with a neurotracer showed increased expression of anti-apoptotic factors, such as Bcl-2 and phospho-Akt (p-Akt), at 1-6 days after SCI. Such a rapid increase of Bcl-2 and p-Akt protein levels after SCI was quantitatively confirmed by western blot analysis. These data strongly indicate that upper motor neurons in the NMLF and IMRF can survive and regrow their axons into the spinal cord through the rapid activation of anti-apoptotic molecules after SCI. The regrowing axons from upper motor neurons reached the lesion site at 10-15 days and then crossed at 4-6 weeks after SCI. These long-distance descending axons from originally axotomized neurons have a major role in restoration of motor function after SCI. © 2012 Elsevier Ltd. All rights reserved.Thesis of Kazuhiro Ogai / 大貝 和裕 博士論文 金沢大学医薬保健学総合研究科（保健学専攻

A detailed protocol for perspiration monitoring using a novel, small, wireless device

Perspiration monitoring can be utilized for the detection of certain diseases, such as thermoregulation and mental disorders, particularly when the patients are unaware of such disorders or are having difficulty expressing their symptoms. Until now, several devices for perspiration monitoring have been developed; however, such devices tend to have a relatively large exterior, considerable power consumption, and/or less sensitivity. Recently, we developed a small, wireless device for perspiration monitoring. The device consists of a temperature/relative humidity (T/RH) sensor, battery-driven small data logger, and silica gel as a desiccant in a small cylindrical exterior. The T/RH sensor is placed between the detection windows (through which the water vapor from the skin enters) and the silica gel. The underlying principle of the perspiration monitoring device is based on Fick\u27s law of diffusion, which means that water vapor flux from the skin to the silica gel (i.e. transepidermal water loss and perspiration) can be captured by change in humidity at the T/RH sensor. In addition, a baseline subtraction method was adopted to distinguish perspiration and transepidermal water loss. As shown in the previous report, the developed device can monitor the perspiration at any sites of the body in an easy, wireless manner. However, detailed methods of how to use the device have not been disclosed yet. In this article, therefore, we would like to show the point-by-point tutorials of how to use the device for perspiration monitoring, by showing the sympathetic activity test with the sympathetic skin response monitoring as an example. © 2016 Journal of Visualized Experiments.Embargo Period 24 month

Development of a small wireless device for perspiration monitoring

A small and wireless device that can capture the temporal pattern of perspiration by a novel structure of water vapor collection combined with reusable desiccant has been developed. The novel device consists of a small cylindrical case with a temperature/relative humidity sensor, battery-driven data logger, and silica gel (desiccant). Water vapor of perspiration was detected by the change in relative humidity and then adsorbed by silica gel, allowing continuous recording of perspiration within a closed and wireless chamber, which has not been previously achieved. By comparative experiments using the commercially-available perspiration monitoring device, the developed device could measure perspiration as efficiently as the conventional one, with a normalized cross coefficient of 0.738 with 6 s delay and the interclass correlation coefficient [ICC(2, 1)] of 0.84. These results imply a good agreement between the conventional and developed devices, and thus suggest the applicability of the developed device for perspiration monitoring. © 2015 IPEM.Embargo Period 12 month

Function of Sox2 in ependymal cells of lesioned spinal cords in adult zebrafish.

The sex-determining region Y-box 2 (Sox2) is related not only to pluripotency, but also to cell proliferation. Zebrafish can regain their motor function after spinal cord injury (SCI). Following SCI, new motor neurons are produced from proliferating ependymal cells. Here, we investigated the expression and function of Sox2 after SCI in zebrafish. Sox2 was upregulated as early as 1 day post-lesion (dpl) in ependymal cells, which was followed by cell proliferation. Sox2 knockdown significantly decreased the number of proliferating cells at 5 dpl. The results of this study suggest a role of Sox2 as one of the proliferation initiators in ependymal cells after SCI. © 2014 Elsevier Ireland Ltd and the Japan Neuroscience Society.12 months Embargo Perio

Upregulation of Leukemia Inhibitory Factor (LIF) during the Early Stage of Optic Nerve Regeneration in Zebrafish.

Fish retinal ganglion cells (RGCs) can regenerate their axons after optic nerve injury, whereas mammalian RGCs normally fail to do so. Interleukin 6 (IL-6)-type cytokines are involved in cell differentiation, proliferation, survival, and axon regrowth; thus, they may play a role in the regeneration of zebrafish RGCs after injury. In this study, we assessed the expression of IL-6-type cytokines and found that one of them, leukemia inhibitory factor (LIF), is upregulated in zebrafish RGCs at 3 days post-injury (dpi). We then demonstrated the activation of signal transducer and activator of transcription 3 (STAT3), a downstream target of LIF, at 3–5 dpi. To determine the function of LIF, we performed a LIF knockdown experiment using LIF-specific antisense morpholino oligonucleotides (LIF MOs). LIF MOs, which were introduced into zebrafish RGCs via a severed optic nerve, reduced the expression of LIF and abrogated the activation of STAT3 in RGCs after injury. These results suggest that upregulated LIF drives Janus kinase (Jak)/STAT3 signaling in zebrafish RGCs after nerve injury. In addition, the LIF knockdown impaired axon sprouting in retinal explant culture in vitro; reduced the expression of a regeneration-associated molecule, growth-associated protein 43 (GAP-43); and delayed functional recovery after optic nerve injury in vivo. In this study, we comprehensively demonstrate the beneficial role of LIF in optic nerve regeneration and functional recovery in adult zebrafish

Protective action of nipradilol mediated through S-nitrosylation of Keap1 and HO-1 induction in retinal ganglion cells

Nipradilol (Nip), which has α1- and β-adrenoceptor antagonist and nitric oxide (NO)-donating properties, has clinically been used as an anti-glaucomatous agent in Japan. NO mediates cellular signaling pathways that regulate physiological functions. The major signaling mechanisms mediated by NO are cGMP-dependent signaling and protein S-nitrosylation-dependent signalings. Nip has been described as having neuroprotective effects through cGMP-dependent pathway in retinal ganglion cells (RGCs). However, the effect seems to be partial. On the other hand, whether Nip can prevent cell death through S-nitrosylation is not yet clarified. In this study, we therefore focused on the neuroprotective mechanism of Nip through S-nitrosylation. Nip showed a dramatic neuroprotective effect against oxidative stress-induced death of RGC-5 cells. However, denitro-nipradilol, which does not have NO-donating properties, was not protective against oxidative stress. Furthermore, an NO scavenger significantly reversed the protective action of Nip against oxidative stress. In addition, we demonstrated that α1- or β-adrenoceptor antagonists (prazosin or timolol) did not show any neuroprotective effect against oxidative stress in RGC-5 cells. We also demonstrated that Nip induced the expression of the NO-dependent antioxidant enzyme, heme oxygenase-1 (HO-1). S-nitrosylation of Kelch-like ECH-associated protein by Nip was shown to contribute to the translocation of NF-E2-related factor 2 to the nucleus, and triggered transcriptional activation of HO-1. Furthermore, RGC death and levels of 4-hydroxy-2-nonenal (4HNE) were increased after optic nerve injury in vivo. Pretreatment with Nip significantly suppressed RGC death and accumulation of 4HNE after injury through an HO-1 activity-dependent mechanism. These data demonstrate a novel neuroprotective action of Nip against oxidative stress-induced RGC death in vitro and in vivo. © 2012 Elsevier Ltd. All rights reserved

Anti-inflammatory effects of lipoic acid through inhibition of GSK-3β in lipopolysaccharide-induced BV-2 microglial cells

Activated microglial cells play an important role in immune and inflammatory responses in CNS and play a role in neurodegenerative diseases. We examined the effects of lipoic acid (LA) on inflammatory responses of BV-2 microglial cells activated by lipopolysaccharide (LPS), and explored the underlying mechanisms of action of LA. BV-2 cells treated with LPS showed an up-regulation of mRNA of the pro-inflammatory molecules, inducible nitric oxide synthase (iNOS). LA suppressed the expression of iNOS and furthermore, LPS-induced production of nitrite. Moreover, LA suppressed the nuclear translocation of RelA, a component of nuclear factor-kappa B (NF-κB) that contains transcriptional activator domain for LPS. The mechanisms of LA-mediated anti-inflammatory effects on microglia remain unknown, and we suggested an involvement of Akt/glycogen synthase kinase-3β (GSK-3β) phosphorylation. The results showed that inhibitor of phosphatidylinositol 3-kinase prevented LA-mediated suppression of LPS induction of RelA and expression of iNOS. Furthermore, these inflammatory actions were prevented by GSK-3β inhibitors. These data demonstrate a role for LA as a chemical modulator of inflammatory responses by microglia, and thus may be a therapeutic strategy for treating neurodegenerative diseases with an inflammatory component. © 2013 Elsevier Ireland Ltd and the Japan Neuroscience Society