NAKAHARA Keiko

写真a

Title

Professor

Research Fields, Keywords

Life science

Mail Address

E-mail address

Graduating School 【 display / non-display

  •  
    -
    1997.03

    University of Miyazaki   Faculty of Agriculture   Veterinary Physiology   Graduated

Graduate School 【 display / non-display

  •  
    -
    1999.03

    University of Miyazaki  United Graduate School, Division of Veterinary Medicine  Doctor's Course  Unfinished Course

Field of expertise (Grants-in-aid for Scientific Research classification) 【 display / non-display

  • Veterinary medical science

  • Neurophysiology / General neuroscience

  • General physiology

 

Papers 【 display / non-display

  • Comparison of glucose tolerance between wild-type mice and mice with double knockout of neuromedin U and neuromedin S.

    Ensho T, Maruyama K, Qattali AW, Yasuda M, Uemura R, Murakami N, Nakahara K

    The Journal of veterinary medical science     2019.07  [Refereed]

    Joint Work

     View Summary

    <p>Recently, it has been proposed that neuromedin U (NMU) is "decretin", which suppresses insulin secretion from the pancreas <i>in vitro</i>. Here we examined the possible involvement of NMU in insulin secretion <i>in vivo</i> by comparing the plasma glucose and insulin levels of wild-type mice with those of double knockout (D-KO) of the NMU and neuromedin S (NMS) genes, as NMS binds to the neuromedin U receptor. If NMU is, in fact, "decretin", which inhibits insulin secretion from the pancreas, then NMU-deficient mice might result in higher plasma insulin levels than is the case in wild-type mice, or injection of NMU lead to suppression of plasma insulin level. In this study, we found that the fasting plasma level of insulin was not increased in D-KO mice. Glucose tolerance tests revealed no significant difference in plasma insulin levels between wild-type mice and D-KO mice under non-fasting conditions. After peripheral injection of NMU, plasma glucose and insulin levels did not show any significant changes in either wild-type or D-KO mice. Glucose tolerance testing after 3 weeks of high fat feeding revealed no significant difference in plasma insulin levels during 60 min after glucose injection between wild-type and D-KO mice. These results suggest that even if NMU is a decretin candidate, its physiological involvement in suppression of insulin secretion may be very minor <i>in vivo</i>.</p>

    DOI PubMed CiNii

  • Immunostimulatory effect of kumquat (: Fortunella crassifolia) and its constituents, β-cryptoxanthin and R -limonene

    Terao R., Murata A., Sugamoto K., Watanabe T., Nagahama K., Nakahara K., Kondo T., Murakami N., Fukui K., Hattori H., Eto N.

    Food and Function   10   38 - 48   2019.01  [Refereed]

    Joint Work

     View Summary

    © 2019 The Royal Society of Chemistry. Natural killer (NK) cells play an important role in the innate immune system by eliminating cancer cells and virally infected cells. Aging and stress attenuate the activity of NK cells, thereby increasing the risk of various diseases. In this study, we demonstrated that the consumption of a small number of kumquats in an in vivo model could suppress elevated plasma corticosterone levels and reverse the decline in splenocyte cytotoxicity caused by restraint stress. Our results identified β-cryptoxanthin (BCX) as an active kumquat component with a NK cell-activating effect, and R-limonene as an active component that mediates not only the anti-stress effect but also NK cell activation by oral administration. In addition, BCX, R-limonene, and R-limonene metabolites were found to enhance IFN-γ production in KHYG-1 cells, a human NK cell line. Collectively, our findings suggest that the ingestion of a few kumquats on a daily basis can help to combat stress and enhance NK cell activity.

    DOI PubMed

  • Purification and identification of native forms of goldfish neuromedin U from brain and gut

    Maruyama K., Kaiya H., Miyazato M., Murakami N., Nakahara K., Matsuda K.

    Biochemical and Biophysical Research Communications     2019  [Refereed]

    Joint Work

     View Summary

    © 2019 Neuromedin U (NMU) plays important roles in energy homeostasis in rodents and birds. Previously, our group has isolated four cDNAs encoding precursor proteins of NMU from the goldfish brain and gut, and it was assumed that these transcripts are produced by alternative splicing. We have also demonstrated that intracerebroventricular (ICV) injection of putative goldfish NMU inhibits food intake. However, as native goldfish NMU has not yet been identified, we attempted to purify it from goldfish brain and gut extracts. To assess NMU activity in fractions at each purification step, we measured changes in the intracellular concentrations of Ca2+ using HEK293 cells expressing goldfish NMU-R1 or -R2. We isolated a 25-amino-acid peptide (NMU-25) from the brain and gut and found that its primary structure is similar to that of mammalian NMU. Another 21-amino-acid peptide (NMU-21) was purified from the brain, but not from the gut. Furthermore, a 9-amino-acid peptide (NMU-9) identical to the C-terminus of NMU-21 and -25 was also isolated from the brain and gut. Treatment with synthetic NMU-9, -21 and -25 dose-dependently increased the intracellular Ca2+ concentration in mammalian cells expressing goldfish NMU-R1 and -R2. We also examined the effect of ICV-administered synthetic goldfish NMUs on goldfish food intake. NMU-25 inhibited food intake to the same degree as NMU-21. However, the inhibitory effect of NMU-9 was slightly weaker than those of NMU-21 and -25. These results indicate that several molecular forms of NMU exist in the goldfish brain and gut, and that all of them play physiological roles via NMU-R1 and NMU-R2.

    DOI PubMed

  • Identification of neuromedin U precursor-related peptide and its possible role in the regulation of prolactin release

    Mori K., Ida T., Fudetani M., Mori M., Kaiya H., Hino J., Nakahara K., Murakami N., Miyazato M., Kangawa K.

    Scientific Reports   7   10468   2017.12  [Refereed]

    Joint Work

     View Summary

    © 2017 The Author(s). The discovery of neuropeptides provides insights into the regulation of physiological processes. The precursor for the neuropeptide neuromedin U contains multiple consensus sequences for proteolytic processing, suggesting that this precursor might generate additional peptides. We performed immunoaffinity chromatography of rat brain extracts and consequently identified such a product, which we designated neuromedin U precursor-related peptide (NURP). In rat brain, NURP was present as two mature peptides of 33 and 36 residues. Radioimmunoassays revealed NURP immunoreactivity in the pituitary, small intestine, and brain of rats, with the most intense reactivity in the pituitary. Intracerebroventricular administration of NURP to both male and female rats robustly increased plasma concentrations of prolactin but not of other anterior pituitary hormones. In contrast, NURP failed to stimulate prolactin release from dispersed anterior pituitary cells. Pretreatment of rats with bromocriptine, a dopamine receptor agonist, blocked the prolactin-releasing activity of NURP. In rats pretreated with the antagonist sulpiride, intracerebroventricular administration of NURP did not increase plasma prolactin concentrations more than administration of saline. These data suggest that NURP induces prolactin release by acting indirectly on the pituitary; dopamine from the hypothalamus, which inhibits prolactin release, may be involved in this activity of NURP.

    DOI PubMed

  • Neuromedin U precursor-related peptide (NURP) exerts neuromedin U-like sympathetic nerve action in the rat

    Ensho T., Maruyama K., Mori K., Miyazato M., Kangawa K., Nakahara K., Murakami N.

    Biochemical and Biophysical Research Communications   492   412 - 418   2017.10  [Refereed]

    Joint Work

     View Summary

    © 2017 It has been suggested that novel peptide that is produced from the neuromedin U (NMU) precursor may exist, as this precursor contains multiple consensus sequences for proteolytic processing. Recently, we identified two mature novel peptides comprising 33 and 36 residues in the rat brain, which were designated neuromedin U precursor-related peptide (NURP) 33 and 36. In the present study, we compared the roles of NURP33 and 36 with that of NMU, as neither activates the NMU receptors. Immunoreactivity for NMU and NURPs was widely present in the central nervous system and showed a similar distribution. Intracerebroventricular (icv) injection of NURP33 in rats increased locomotor activity, energy expenditure, heart rate and back surface temperature (BS-T), similarly to NMU or NURP36. NMU treatment reduced food intake, but NURP33 did not. Pretreatment with the β3 blocker, SR59230A, and the cyclooxygenase blocker, indomethacin, inhibited the NURP33- or NMU-induced increase of BS-T. In addition, icv injection of NURP33 or NMU increased the expression of mRNA for cyclooxygenase 2 in the hypothalamus and for uncoupling protein 1 in the brown adipose tissue. These results suggest that although NURP33 and 36 do not activate the NMU receptors, they might exert NMU-like sympathetic nerve action in the brain.

    DOI PubMed

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Books 【 display / non-display

  • Functions of Dietary Valine, as Revealed by Dietary Valine-Deficiency

    Kenji Nagao, Makoto Bannai, Keiko Nakahara, Noboru Murakami (Part: Joint Work )

    Nova Science Publishers, Inc. NY  2012.04

Presentations 【 display / non-display

  • The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers

    M Bannai, N Kawai, K Ono, K Nakahara, N Murakami

    Society for Endocrinology Annual Meeting  2013.06  -  2013.06  Society for Endocrinology

  • Des-acyl ghrelin protects against body damage by heat stroke in rats

    Y. Hayashi, Y. Inoue, K. Nakahara, K. Maruyama, Y. Suzuki1, K. Kangawa, N. Murakami

    Society for Endocrinology Annual Meeting  2013.06  -  2013.06  Society for Endocrinology

  • VOLUNTARY AND REINFORCED WHEEL RUNNING IN MICE: CONTRIBUTION OF VMH

    Makoto Bannai, Keiko Nakahara, NoboruMurakami, Michio Takahasi

    Society for Neuroscience 37th Annual Meeting  2007.11  -  2007.11  Society for Neuroscience

  • Effects of running wheel deprivation on food consumption and coticosterone secretion in rats

    M. Bannai, K. Nakahara, M.Takahashi, N. Murakami

    Society for Neuroscience 36th Annual Meeting  2006.10  -  2006.10  Society for Neuroscience

  • Effects of ghrelin and des-acylghrelin on neurogenesis of the rat fetal spinal cord.

    Shintaro Goto,Miho Sato, Keiko Nakahara, Hiroyuki Kaiya, Mikiya Miyazato, Kenji Kangawa Noboru Murakami

    21世紀COE国際シンポジウム  2006.08  -  2006.08  宮崎大学

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