研究者業績

佐々木 典康

ササキ ノリヤス  (Noriyasu Sasaki)

基本情報

所属
日本獣医生命科学大学 獣医学科 獣医生化学研究室 准教授
学位
博士(獣医学)(1998年3月 北海道大学)
学士(獣医学)(1994年3月 酪農学園大学)

J-GLOBAL ID
200901085122883977
researchmap会員ID
6000014205

委員歴

 2

論文

 26
  • Ichiro Yamamoto, Masaki Michishita, Koki Fujita, Tamami Sakai, Noriyasu Sasaki, Koh Kawasumi
    General and comparative endocrinology 353 114520-114520 2024年4月18日  査読有り
    G protein-coupled receptor 84 (GPR84) was cloned as an orphan receptor, and medium-chain fatty acids were then revealed as endogenous ligands. GPR84 is expressed in immune cells and is believed to protect liver function from lipotoxicity caused by overeating and high-fat diet intake. This study aimed to present the molecular characterization of GPR84 in domestic cats. The deduced amino acid sequence of the feline GPR84 shows high sequence homology (83-89 %) with the orthologues from other mammalians by cDNA cloning of feline GPR84. Remarkably high mRNA expression was observed in the bone marrow by Q-PCR analysis. The inhibition of intracellular cAMP concentration was observed in cells transfected with feline GPR84 and treated with medium-chain fatty acids. Immunostaining of GPR84 and free fatty acid receptor 2 (FFAR2)/GPR43 in the bone marrow, where high mRNA expression was observed, showed reactions in macrophages and myeloid cells. To clarify whether the receptor formed homo/hetero-merization, GPR84 and FFARs were analyzed using Nano-Luc binary technology and NanoLuc bioluminescence resonance energy transfer technologies, which revealed that GPR84 formed more heteromers with FFAR2 than homomers with each other. In addition, when GPR84 and FFAR2/GPR43 were cotransfected in the cell, their localization on the cell membrane was reduced compared with that when single receptors were transfected. These results indicated that GPR84 is a functional receptor protein that is expressed in cat tissues and may have a protein-protein interaction with FFAR2/GPR43 on the cell membrane.
  • Hisako Kaneda, Misa Hori, Haruka Shinomiya, Ayaka Nakajima, Shingo Yamazaki, Noriyasu Sasaki, Tsuyoshi Sato, Takeharu Kaneda
    Journal of Food Biochemistry 2022年3月21日  査読有り
  • Kaneda H, Otomo R, Sasaki N, Omi T, Sato T, Kaneda T
    Journal of pharmacological sciences 140(1) 48-53 2019年5月  査読有り
  • Saga S, Sasaki N, Arai T
    Journal of advanced veterinary and animal research 6(1) 1-8 2019年3月  査読有り
  • Takeharu Kaneda, Noriyasu Sasaki, Norimoto Urakawa, Kazumasa Shimizu
    Journal of Pharmacological Sciences 136(1) 26-30 2018年1月1日  査読有り
    Chlorogenic acid (CGA) is a polyphenol found in coffee and medicinal herbs such as Lonicera japonica. In this study, the effect of CGA-induced relaxation on carbachol (CCh)-induced contraction of mouse urinary bladder was investigated. CGA (30–300 μg/ml) inhibited CCh- or U46619-induced contraction in a concentration-dependent manner. SQ22536 (adenylyl cyclase inhibitor) recovered CGA-induced relaxation of CCh-induced contraction however, ODQ (guanylyl cyclase inhibitor) did not have the same effect. In addition, 3-isobutyl-1-methylxanthine (IBMX) enhanced CGA-induced relaxation however, forskolin or sodium nitroprusside did not have the same effect. Moreover, Ro 20–1724, a selective phosphodiesterase (PDE) 4 inhibitor, enhanced CGA-induced relaxation, but vardenafil, a selective PDE5 inhibitor, did not have the same effect. In the presence of CCh, CGA increased cyclic adenosine monophosphate (cAMP) level, whereas SQ22536 inhibited the increase of cAMP levels. Moreover, higher cAMP levels were obtained with CGA plus IBMX treatment than the total cAMP levels obtained with separate CGA and IBMX treatments. In conclusion, these results suggest that CGA inhibited CCh-induced contraction of mouse urinary bladder by partly increasing cAMP levels via adenylyl cyclase activation.
  • Hidenori Kanda, Takeharu Kaneda, Akira Kawaguchi, Noriyasu Sasaki, Tsuyoshi Tajima, Norimoto Urakawa, Kazumasa Shimizu, Hiroetsu Suzuki
    JOURNAL OF VETERINARY MEDICAL SCIENCE 79(3) 593-601 2017年3月  査読有り
    Recent studies have shown that phloridzin, an inhibitor of sodium glucose cotransporter (SGLT), strongly decreases high K+-induced contraction in phasic muscle, such as tenia coil, but slightly affects tonic muscle, such as trachea. In this study, we examined the inhibitory mechanism of phloridzin on high K+-induced muscle contraction in rat ileum, a phasic muscle. Phloridzin inhibited the high K+-induced contraction in the ileum and the aorta, and the relaxing effect of phloridzin at 1 mM in the ileum was approximately five-fold more potent than that in the aorta. The expression of SGLT1 mRNA in the ileum was higher than that of the aorta. Phloridzin significantly inhibited NADH/NAD ratio and phosphocreatine (PCr) content in the ileum; I however, application of pyruvate recovered the inhibition of contraction and PCr content, but had no effect on ratio of NADH/NAD. High K+ increased 2-(N (7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino)-2-deoxyglucose (2-NBDG) uptake in ileal smooth muscle cells, and phloridzin inhibited the increase in a concentration-dependent manner. These results suggest that phloridzin inhibits high K+-induced contraction because of the inhibition of energy metabolism via the inhibition of SGLT1.
  • Takeharu Kaneda, Noriyasu Sasaki, Norimoto Urakawa, Kazumasa Shimizu
    PHARMACOLOGY 97(3-4) 171-176 2016年  査読有り
    This study examined the mechanism of vasorelaxation induced by dimethyl sulfoxide (DMSO) in endothelium-intact and -denuded rat aorta. DMSO (0.1-3%) inhibited phenylephrine (PE, 1 mu mol/l)-induced contraction in a dose-dependent manner. However, this relaxation was lower in the absence of the endothelium. Increase in DMSO-induced relaxation in the presence of the endothelium was attenuated by preincubation in L-N-G-nitroarginine methyl ester (L-NAME, 100 mu mol/l) and by the removal of the endothelium. In the aorta with endothelium, DMSO (3%) and CCh (3 mu mol/l) increased cGMP contents, significantly and L-NAME (100 mu mol/l) inhibited the DMSO-induced increases of cGMP. In fura 2-loaded endothelium-denuded aorta, cumulative application of DMSO (1-3%) inhibited PE-induced muscle tension; however, this application did not affect the [Ca2+](i) level. In PE-precontracted endothelium-denuded aorta, relaxation responses to fasudil were significantly less in the presence of DMSO compared to the control. These results suggest that DMSO causes relaxation by increasing the cGMP content in correlation with the release of NO from endothelial cells and by decreasing the Ca2+ sensitivity of contractile elements partly via inhibiting Rho-kinase in rat aorta. (C) 2016 S. Karger AG, Basel
  • N. Sasaki, M. Nakamura, S. Soeta
    GENETICS AND MOLECULAR RESEARCH 13(3) 6855-6864 2014年  査読有り
    Malate dehydrogenase (MDH) plays crucial roles in energy and cellular metabolism. In this study, we describe the identification and characterization of cytosolic MDH (MDH1) and mitochondrial MDH (MDH2) in liver of domestic cat (Felis catus). To clone the feline full-length MDH genes, we performed rapid amplification of cDNA ends. The MDH1 gene encoded a protein of 334 amino acids and the MDH2 gene encoded a protein of 338 amino acids, containing a 24-amino acid mitochondrial target sequence. The feline MDH1 and MDH2 proteins shared, respectively, 98.8-93.7 and 96.7-94.4% homology with dog, giant panda, horse, cow, pig, human, mouse, and rat. The feline MDHs had a highly conserved active motif, which contained important residues for catalysis and coenzyme binding. The putatively acetylated lysine residues that regulate MDH activity were also conserved at K118, K121, and K298 in MDH1, and K185, K301, K307, and K314 in MDH2. Both MDH1 and MDH2 mRNAs were ubiquitously expressed, but these expression levels varied in a tissue-specific manner. Both MDH genes were expressed at considerably high levels in heart and skeletal muscle, but at low levels in lung and spleen.
  • Noriyasu Sasaki, Miwa Ishibashi, Satoshi Soeta
    Journal of Veterinary Medical Science 75(10) 1383-1387 2013年  査読有り
    Retinol-binding protein 4 (RBP4) is a specific transporter of retinol and was recently identified as an adipokine potentially involved in type 2 diabetes in humans and rodents. However, the function and structure of feline RBP4 have not been reported. In this study, we describe the molecular cloning and expression analysis of feline RBP4. The complete feline RBP4 cDNA encodes a precursor protein comprising an 18 amino acid signal peptide and a 183 amino acid mature protein. Feline RBP4 was mapped to chromosome D2. Mature feline RBP4 is 83-94% homologous to the RBPs of humans, cows and rodents. RT-PCR analysis revealed feline RBP4 expression in liver and adipose tissues. © 2013 The Japanese Society of Veterinary Science.
  • Takeharu Kaneda, Tomoe Fujieda, Yuta Eto, Yuta Nagai, Noriyasu Sasaki, Tsuyoshi Tajima, Norimoto Urakawa, Kazumasa Shimizu
    JOURNAL OF VETERINARY MEDICAL SCIENCE 74(10) 1277-1282 2012年10月  査読有り
    To elucidate the role of glycogen in the contraction of tracheal smooth muscle, we investigated the changes in the glycogen contents of the bovine trachea during contractions induced by high K+ and hypoxia (achieved by bubbling N-2, instead of O-2), either in a glucose-free condition or in the presence of iodoacetic acid (IAA), an inhibitor of glycolysis. Hyperosmotic addition of 65 mM KCl (H-65 K+) induced a sustained contraction. A glucose-free condition did not affect H-65 K+-induced contraction. However, hypoxia slightly inhibited the contraction, and glucose-free PSS with hypoxia or IAA remarkably inhibited the H-65 K+-induced contraction. H-65 K+-induced a sustained increase in reduced pyridine nucleotide (PNred) fluorescence, representing glycolysis activity. Hypoxia alone slightly enhanced PNred fluorescence, and when combined with a glucose-free condition, it remarkably enhanced the H-65 K+-induced PNred fluorescence. IAA inhibited PNred fluorescence. In the presence of H-65 K+ a glucose-free condition, hypoxia and the combination of glucose-free PSS and hypoxia decreased the glycogen contents. However, IAA had no effect on glycogen contents. Although hypoxia or glucose-free PSS did not affect PCr and ATP contents, the combination of hypoxia and glucose-free PSS or IAA induced a gradual decrease of PCr content. In conclusion, we suggest that endogenous glycogen was utilized to increase the activity of glycolysis for maintaining high K+-induced contraction of the bovine trachea in the glucose -free and/or hypoxic condition.
  • Tracy P. Torres, Noriyasu Sasaki, E. Patrick Donahue, Brooks Lacy, Richard L. Printz, Alan D. Cherrington, Judith L. Treadway, Masakazu Shiota
    JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS 337(3) 610-620 2011年6月  査読有り
    The effects of a glycogen phosphorylase inhibitor (GPI) and metformin (MT) on hepatic glucose fluxes (mu mol . kg(-1) . min(-1)) in the presence of basal and 4-fold basal levels of plasma glucagon were investigated in 18-h fasted conscious dogs. Compared with the vehicle treatment, GPI infusion suppressed net hepatic glucose output (NHGO) completely (-3.8 +/- 1.3 versus 9.9 +/- 2.8) despite increased glucose 6-phosphate (G-6-P) neogenesis from gluconeogenic precursors (8.1 +/- 1.1 versus 5.5 +/- 1.1). MT infusion did not alter those parameters. In response to a 4-fold rise in plasma glucagon levels, in the vehicle group, plasma glucose levels were increased 2-fold, and NHGO was increased (43.9 +/- 5.7 at 10 min and 22.7 +/- 3.4 at steady state) without altering G-6-P neogenesis (3.7 +/- 1.5 and 5.5 +/- 0.5, respectively). In the GPI group, there was no increase in NHGO due to decreased glucose-6-phosphatase flux associated with reduced G-6-P concentration. A lower G-6-P concentration was the result of increased net glycogenesis without altering G-6-P neogenesis. In the MT group, the increment in NHGO (22.2 +/- 4.4 at 10 min and 12.1 +/- 3.6 at steady state) was approximately half of that of the vehicle group. The lesser NHGO was associated with reduced glucose-6-phosphatase flux but a rise in G-6-P concentration and only a small incorporation of plasma glucose into glycogen. In conclusion, the inhibition of glycogen phosphorylase a activity decreases basal and glucagon-induced NHGO via redirecting glucose 6-phosphate flux from glucose toward glycogen, and MT decreases glucagon-induced NHGO by inhibiting glucose-6-phospatase flux and thereby reducing glycogen breakdown.
  • Katsumi Ishioka, Asako Omachi, Noriyasu Sasaki, Kazuhiro Kimura, Masayuki Saito
    JOURNAL OF VETERINARY MEDICAL SCIENCE 71(2) 189-194 2009年2月  査読有り
    Adiponectin is an adipokine that is specifically expressed in adipose tissues, directly sensitizes the body to insulin via specific receptors and its decreased plasma concentration is responsible for insulin resistance in obese humans. Diabetes is all important problem also in veterinary medicine. and feline diabetes is very similar to human type 2 diabetes, in which obesity is an important risk factor. In the present Study. We obtained cDNA clones corresponding to feline adiponectin and adiponectin receptor 1 (AD-R1). whose nucleotide and deduced amino acid sequences were highly identical to those of other species, especially, the extra-cellular domain of feline AD-R1 was almost identical to that of human AD-R1. Adiponectin mRNA was exclusively detected in the adipose tissue. but AD-R1 was in all tissues tested in this study. Next. plasma samples were collected from 22 cats visiting veterinary practices. They were divided to 2 groups based on a five-point scale body condition score (BCS), Such as normal group (BCS ranged from 2.5 through 3.5) and obese group (BCS ranged from 4.0 through 5.0). Plasma adiponectin in obese cats (7.2 +/- 1.5 mu g/ml) was significantly lower than that of normal cats (18.0 +/- 3.2 mu g/ml). These results suggest that adiponectin may be responsible for insulin function also in the cat, and it can be a target molecule for treatment of obesity and diabetes in cats.
  • Tracy P. Torres, ReEtta L. Catlin, Robert Chan, Yuka Fujimoto, Noriyasu Sasaki, Richard L. Printz, Christopher B. Newgard, Masakazu Shiota
    DIABETES 58(1) 78-86 2009年1月  査読有り
    OBJECTIVE-We examined in 20-week-old Zucker diabetic fatty (ZDF) rats whether restoration of hepatic glucokinase (GK) expression would alter hepatic glucose flux and improve hyper-glycemia. RESEARCH DESIGN AND METHODS-ZDF rats were treated at various doses with an adenovirus that directs the expression of rat liver GK (AdvCMV-GKL) dose dependently, and various metabolic parameters were compared with those of nondiabetic lean littermates (ZCL rats) before and during a hyperglycemic clamp. Viral infection per se did not affect hepatic GK activity, since expression of a catalytically inactive form of GK did not alter endogenous hepatic GK activity. RESULTS-ZDF rats compared with ZCL rats have lower hepatic GK activity (11.6 +/- 1.9 vs. 32.5 +/- 3.2 mU/mg protein), marked hyperglycemia (23.9 +/- 1.2 vs. 7.4 +/- 0.3 nimol/l) higher endogenous glucose production (80 +/- 3 vs. 38 +/- 3 mu mol . kg(-1) min(-1)), increased glucose-6-phosphatase flux (150 +/- 11 vs. 58 +/- 8 mu mol . kg(-1) . min(-1)), and during a hyperglycemic clamp, a failure to suppress endogenous glucose production (80 +/- 7 Vs. -7 +/- 4 mu mol . kg(-1) . min(-1)) and promote glucose incorporation into glycogen (15 +/- 5 vs. 43 +/- 3 mu mol/g liver). Treatment of ZDF rats with different doses of AdvCM-V-GKL, which restored hepatic GK activity to one to two times that of ZCL rats, normalized plasma glucose levels and endogenous glucose production. During a hyperglycemic clamp, glucose production was suppressed and glucose incorporation into glycogen was normal. CONCLUSIONS-Alteration of hepatic GK activity in ZDF rats has profound effects on plasma glucose and hepatic glucose flux. Diabetes 58:78-86, 2009
  • E. Magori, M. Nakamura, A. Inoue, A. Tanaka, N. Sasaki, H. Fukuda, H. Mizutani, T. Sako, N. Kimura, T. Arai
    Research in Veterinary Science 78(1) 39-44 2005年2月1日  査読有り
    The activities of the enzymes in the malate-aspartate shuttle were measured in peripheral leucocytes of spontaneous type 1 diabetic dogs and cats treated with insulin injections. In the diabetic dogs and cats, fasting plasma glucose concentrations were three- or fourfold greater than the control levels in spite of insulin injections and the activities of cytosolic malate dehydrogenase (MDH), one of pivotal enzymes in the malate-aspartate shuttle, were remarkably lower than the controls. Depressed expression of cytosolic MDH mRNA was confirmed by RT-PCR analysis in the diabetic animals. The cytosolic ratio of MDH/lactate dehydrogenase (LDH) activity (M/L ratio) in leucocytes of the diabetic animals was significantly lower than that of normal control animals. The smaller M/L ratio appeared to reflect depression of energy metabolism in the diabetic animals. Intrinsically lower and further decreased MDH activities may be factors that induce insulin resistance observed in diabetic cats. © 2004 Elsevier Ltd. All rights reserved.
  • H Shibata, N Sasaki, T Honjoh, Ohishi, I, M Takiguchi, K Ishioka, M Ahmed, M Soliman, K Kimura, M Saito
    JOURNAL OF VETERINARY MEDICAL SCIENCE 65(11) 1207-1211 2003年11月  査読有り
    Leptin is a protein synthesized and secreted primarily by adipose tissue. The blood leptin concentration is known to reflect body fat content in rodents, humans and dogs, and thereby is useful for quantitative assessment of obesity. In the present study, we produced recombinant feline leptin in Escherichia coli transfected with feline leptin cDNA we cloned previously. The recombinant feline leptin with a molecular weight of 16 kDa induced phosphorylation of the signal transducers and activators of transcription 3 (STAT3) protein in the cells expressing rat leptin receptor. The anti-feline leptin antibody raised in rabbits reacted well to feline and human leptin and less to rodents' leptin in Western blot analysis. Sandwich enzyme-linked immunosorbent assay (ELISA) was developed, using rabbit anti-feline leptin antibody and recombinant feline leptin as a standard. In this ELISA system, cross-reactivity to human, rat and mouse leptin was 30.7%, 69.5% and 66.6%, respectively. The plasma leptin levels of 24 healthy cats were in a range from 0.3 to 29.7 ng/ml with the mean +/- SEM of 4.5 +/- 1.3 ng/ml, being positively proportional to body fat content. These results indicate that our ELISA system may be useful for assessment of obesity in cats.
  • K Ishioka, K Kanehira, N Sasaki, H Kitamura, K Kimura, M Saito
    COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY B-BIOCHEMISTRY & MOLECULAR BIOLOGY 131(3) 483-489 2002年3月  査読有り
    Uncoupling proteins (UCPs) are members of the mitochondrial transporter family that dissipate the proton gradient as heat more than via ATP synthesis. In the present study, nucleotide and amino acid sequences of UCPs 1, 2 and 3 of a dog were determined, and their mRNA expression in various peripheral tissues was examined. The sequences were highly (76-97%) homologous to those of other species. Although lower homologies (60-74%) were found when compared among the three canine UCPs, their deduced amino acid sequences had some common domains, such as three mitochondrial carrier protein motifs, six transmembrane a-helix domains, and putative purine nucleotide binding domains. By Northern blot analyses, UCP1 mRNA was not detected in any tissues examined. UCP2 mRNA was expressed in most tissues, particularly abundantly in adipose tissue, spleen and lung. Two sizes of UCP3 mRNA were found exclusively in heart and skeletal muscle. These results suggest that canine UCPs have uncoupling activity, and are involved in the regulation of metabolic heat production and/or energy expenditure, as do those of other species. (C) 2002 Elsevier Science Inc. All rights reserved.
  • N Sasaki, H Shibata, T Honjoh, K Kimura, M Saito, Ohishi, I
    JOURNAL OF VETERINARY MEDICAL SCIENCE 63(10) 1115-1120 2001年10月  査読有り
    Leptin, the product of the obese (ob) gene. is an adipocyte-derived hormone involved in regulating food intake and energy expenditure in humans and rodents. To determine the primary structure of feline leptin, we cloned the feline leptin cDNA using reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of complementary DNA (cDNA) ends (RACE) methods. The full-length feline leptin cDNA was 2935 bp with a 501 bp open reading frame encoding the precursor peptide of 167 amino acids including 21 residues of signal peptide. The sequence of a 146-amino acid mature leptin was 81.5-91.8% homologous to those of other species. RT-PCR analysis revealed that the leptin mRNA was expressed in adipose tissues and not detected in liver, hearth kidney, lung, pancreas, brain and skeletal muscle. These data show that feline leptin is highly homologous to leptins of other species. and expressed in adipose tissues in cats.
  • Y Niizuma, A Takahashi, N Sasaki, S Hayama, N Tokita, Y Watanuki
    ECOLOGICAL RESEARCH 16(2) 197-203 2001年6月  査読有り
    When rearing chicks, Leach's storm-petrels (Oceanodroma leucorhoa) commute between foraging areas and breeding colonies with heavy food loads. At this time they should maximize the size of energy-supplying organs in response to increased energy expenditure but minimize total body mass to decrease the energetic cost of flight. Nineteen storm-petrels were killed to examine the changes in body composition and the masses of energy-supplying organs in birds that were incubating and rearing chicks. Parents lost a mean of 7.95 g in body mass between the stages of incubation and chick-rearing mainly via a loss of skin including subcutaneous adipose tissue, and a small fraction of heart and digestive organs, which are considered energy-supplying organs. This mass loss actually enables them to decrease flight cost by 14.4%. The benefits of decreasing flight costs by reducing total body mass are greater than if the energy-supplying organs of birds are enlarged only.
  • Yoshiko Nakamura, Itsuro Nagase, Atsushi Asano, Noriyasu Sasaki, Toshihide Yoshida, Tsunekazu Umekawa, Naoki Sakane, Masayuki Saito
    Journal of Veterinary Medical Science 63(3) 309-314 2001年3月  査読有り
    Chronic stimulation of the β3-adrenergic receptor (AR) in obese animals resulted in a reduced adiposity associated with an increased expression of thermogenic uncoupling protein (UCP)1 in adipose tissues. In this study, the mRNA expression of newly cloned UCP isoforms (UCP2 and UCP3) were examined in obese yellow KK and C57BL control mice. UCP2 mRNA was found in all tissues examined, with higher levels in adipose tissues and skeletal muscle of the obese mice. UCP3 mRNA was expressed in skeletal muscle, heart and brown adipose tissue similarly in the two mouse strains. Daily injection of a selective β3-adrenergic agonist, CL316,243 (0.1 mg/kg), for 10 days resulted in a marked reduction of white fat pad weight and 1.8∼4.8-fold increase in the mRNA levels of UCP2 and UCP3 in skeletal muscle of obese mice. No noticeable change in the UCP2 and 3 mRNA levels was found in brown and white adipose tissues. It was also found that CL316,243 injection produced a marked and sustained elevation of the plasma free fatty acid level. These results, together with our previous findings of the fatty acid-induced UCP expression in a myocyte cell line in vitro, suggest that the β3-AR agonist-induced UCP expression in skeletal muscle may be mediated through the elevated plasma free fatty acids. It was also suggested that anti-obesity effect of β3-AR agonists is attributable to increased thermogenesis not only by UCP1 but also by UCP2 and UCP3.
  • M Iwase, K Kimura, N Sasaki, R Komagome, K Ishioka, M Morimatsu, T Murakami, M Saito
    RESEARCH IN VETERINARY SCIENCE 68(2) 109-114 2000年4月  査読有り
    Leptin, the product of the ob gene, is one of the key molecules for the regulation of appetite and whole-body energy balance, and thereby for the pathogenesis of obesity. In an attempt to clarify the roles of leptin in obesity and/or related diseases in companion animals, canine leptin CDNA was cloned by amplifying reverse-transcriptase products of RNA extracted from the adipose tissue of the beagle. A CDNA clone of about 3 kbp contained a 501 bp open reading frame coding a 167-amino acid protein with a 21-amino acid signal peptide. The sequence of a 146-amino acid mature leptin was more than 79 per cent identical to those of other mammals. Northern blot analysis revealed abundant expression of leptin mRNA in adipose tissue, but not in other tissues, in adult beagles. When Chinese hamster ovary cells expressing the rat leptin receptor were stimulated with recombinant canine leptin produced by E. coli, some intracellular signal transduction proteins were phosphorylated, indicating that the recombinant leptin was biologically active. The data reported herein will be helpful for further studies of leptin of the dog in health and disease. (C) Harcourt Publishers Ltd.
  • M Iwase, K Kimura, R Komagome, N Sasaki, K Ishioka, T Honjoh, M Saito
    JOURNAL OF VETERINARY MEDICAL SCIENCE 62(2) 207-209 2000年2月  査読有り
    Leptin is the ob gene product secreted from adipocytes in mammals, and thereby its plasma level reflects body fat content. To establish an assay method for leptin in the dog, rabbit anti-canine leptin antibody was obtained using canine recombinant leptin as an antigen. This antibody reacted to canine leptin much stronger than mouse, rat and human leptins. Sandwich enzyme-linked immunosorbent assay (ELISA) using this antibody was developed. The serum leptin levels of 13 healthy dogs were in a range from 1.4 to 5.6 ng/ml with the mean +/- SEM of 3.0 +/- 0.3 ng/ml.
  • K. Kimura, K. Kimura, N. Sasaki, A. Asano, J. Mizukami, S. Kayahashi, T. Kawada, T. Fushiki, M. Morimatsu, T. Yoshida, M. Saito
    Hormone and Metabolic Research 32(3) 91-96 2000年  査読有り
    Wild-type or mutated human β3-adrenergic receptor (Trp64Arg) cDNAs were stably expressed in mouse 3T3-L1 cells. Saturation binding study using a β- adrenergic ligand revealed that there was no significant difference in the receptor density and the equilibrium dissociation constant between the two cell lines. However, the ability of the mutant β3-adrenergic receptor to accumulate cyclic AMP (cAMP) in response to isoproterenol was much reduced and Kact for cAMP accumulation was lowered as compared to the wild type receptor. The amount of alpha subunit of stimulatory GTP-binding protein (GSα) and adenylyl cyclase activity in response to forskolin were not different in the two cell lines. The responses of the mutant receptor to epinephrine, norepinephrine and L-755,507, a highly specific agonist for human β3-adrenergic receptor, were also reduced, but the reduction of Kact for L-755,507 was more evident than other agonists tested. The cAMP accumulation in response to some conventional β3 agonists was less than 10% of that to isoproterenol even in the cells expressing the wild type receptor. These results suggest that the Trp64Arg mutant β3-adrenergic receptor has less ability to stimulate adenylyl cyclase, and that lipolytic activity through the β3-adrenergic receptor by catecholamines in subjects carrying this mutation might be suppressed.
  • SAKANE Naoki, YOSHIDA Toshihide, UMEKAWA Tsunekazu, KOGURE Akinori, KONDO Motoharu, NAKAMURA Yoshiko, SASAKI Yasunori, ASANO Atsushi, SAITO Masayuki
    Endocrine journal 45(5) 647-651 1998年10月  査読有り
  • Noriyasu Sasaki, Eiji Uchida, Masayoshi Niiyama, Toshihide Yoshida, Masayuki Saito
    Journal of Veterinary Medical Science 60(4) 465-469 1998年4月  査読有り
    The aim of this study was to evaluate the effectiveness of β3-adrenergic agonists for the treatment and prevention of obesity in the dog. When a selective β-adrenergic agonist. CL316,243 (0.1 mg/kg). was given orally to adult beagles every day for 5-7 weeks, body weight and girth were decreased compared with control placebo-treated dogs. Gross anatomical examinations revealed no noticeable abnormalities in CL316,243-treated dogs, except an apparent decrease in abdominal fat. Immunohistochemical examination of perirenal adipose tissue showed a remarkable increase in brown adipocytes expressing a thermogenic protein, uncoupling protein (UCP). The increased expression of UCP and its mRNA in CL316,243-treated dogs was also confirmed by Western blot and reverse transcription polymerase chain reaction analyses. It was concluded that treatment with a β3-adrenergic agonist stimulates UCP expression, which may lead to an increase in energy expenditure, and thereby is useful for the treatment and prevention of obesity in the dog.
  • Noriyasu Sasaki, Eiji Uchida, Masayoshi Niiyama, Toshihide Yoshida, Masayuki Saito, Masayuki Saito
    Journal of Veterinary Medical Science 60(4) 459-463 1998年4月  査読有り
    It is known that in rodents and humans the β3-adrenergic receptor (β3-AR) is present primarily in adipocytes and plays a significant role in the adrenergic stimulation of lipolysis. We examined the expression of β3-AR mRNA in the dog and the lipomobilizing effects of β3-AR-selective agonists in vivo Reverse transcription polymerase chain reaction of RNA extracted from dog adipose tissue produced a cDNA fragment, the nucleotide sequence of which was highly homologous to the corresponding regions of human (86.4%) and mouse (79.5%) β3-AR cDNA. The β3-AR mRNA was present at high levels in subcutaneous and visceral adipose tissues, but undetectable in other organs. When a selective β3-AR agonist, CL316,243, was infused intravenously into beagle dogs, the plasma level of free fatty acid increased in 30 min and persisted at higher levels for several hours. ICI D7114, another β3-AR agonist, also showed a similar lipomobilizing effect, but with lower potency. β3-AR agonist infusion also increased the plasma insulin level. These results suggested that functional β3-AR is present in adipose tissues of the dog and that it is effective for in vivo lipomobilization.
  • I. Nagase, N. Sasaki, K. Tsukazaki, T. Yoshida, M. Morimatsu, M. Saito
    Japanese Journal of Veterinary Research 42(3-4) 137-146 1994年12月  査読有り
    When mammals are exposed to a cold environment for a long time, the capacity of nonshivering thermogenesis by brown adipose tissue (BAT) increases in association with the increased expression of some specific proteins and tissue hyperplasia, which are totally dependent on sympathetic innervation to this tissue. To clarify roles of the β-adrenergic mechanism in BAT hyperplasia, the effects of chronic administration of various β-adrenergic agonists on BAT were examined in rats, especially focusing on some agonists to the β3-adrenoceptor which is present specifically in adipocytes. Chronic administration of noradrenaline or isoproterenol for 7-10 days produced a marked increase in the tissue contents of DNA, total protein, mitochondrial uncoupling protein, and insulin-regulatable glucose transporter protein. The trophic effects of noradrenaline and isoproterenol were mimicked by chronic administration of β3-adrenergic agonists, such as CL316,243, BRL 26830A, and ICI D7114. These results suggest that the β3-adrenoceptor plays important roles for hyperplasia of BAT, and thereby increasing in the capacity of thermogenesis.

MISC

 28

書籍等出版物

 4
  • 丸山マサ美, 木村利人, 足立智孝, 宮坂義浩, 吉住朋晴, 佐々木典康, 三成寿作, 瀬戸山 晃一 (担当:分担執筆, 範囲:第5章 医学・生命科学研究における動物実験の倫理)
    大学教育出版 2024年6月 (ISBN: 9784866923031)
  • 横田 博, 木村和弘, 志水泰武 (担当:分担執筆, 範囲:17 組換えDNA技術)
    朝倉書店 2016年4月 (ISBN: 9784254460353)
  • アンドリュー・ガーディナー, 多川政弘 (担当:共訳, 範囲:12章雌の生殖器,13章内分泌疾患)
    インターズー 2005年10月 (ISBN: 489995347X)
  • 斉藤 昌之, 鈴木 嘉彦, 横田 博 (担当:分担執筆, 範囲:19 組換えDNA技術)
    朝倉書店 2005年 (ISBN: 9784254460254)

講演・口頭発表等

 48

担当経験のある科目(授業)

 9

共同研究・競争的資金等の研究課題

 10

産業財産権

 1

社会貢献活動

 7

メディア報道

 2