메뉴 건너뛰기




Volumn 96, Issue 2, 2011, Pages 156-165

Ursolic acid attenuates lipopolysaccharide-induced cognitive deficits in mouse brain through suppressing p38/NF-κB mediated inflammatory pathways

Author keywords

Cognitive deficits; Inflammatory response; LPS; P38 NF B pathways; Ursolic acid

Indexed keywords

CYCLOOXYGENASE 2; ESCHERICHIA COLI LIPOPOLYSACCHARIDE; I KAPPA B ALPHA; INDUCIBLE NITRIC OXIDE SYNTHASE; INTERLEUKIN 1BETA; INTERLEUKIN 2; INTERLEUKIN 6; MITOGEN ACTIVATED PROTEIN KINASE; MYELOID DIFFERENTIATION FACTOR 88; PROTEIN KINASE B; STRESS ACTIVATED PROTEIN KINASE; SYNAPTOPHYSIN; TOLL LIKE RECEPTOR 4; TRANSCRIPTION FACTOR RELA; TUMOR NECROSIS FACTOR ALPHA; URSOLIC ACID;

EID: 79960840149     PISSN: 10747427     EISSN: 10959564     Source Type: Journal    
DOI: 10.1016/j.nlm.2011.03.010     Document Type: Article
Times cited : (62)

References (43)
  • 1
    • 0036235478 scopus 로고    scopus 로고
    • Involvement of ERK, p38 and NF-κB signal transduction in regulation of TLR2, TLR4 and TLR9 gene expression induced by lipopolysaccharide in mouse dendritic cells
    • An H., Yu Y., Zhang M., Xu H., Qi R., Yan X., et al. Involvement of ERK, p38 and NF-κB signal transduction in regulation of TLR2, TLR4 and TLR9 gene expression induced by lipopolysaccharide in mouse dendritic cells. Immunology 2002, 106:38-45.
    • (2002) Immunology , vol.106 , pp. 38-45
    • An, H.1    Yu, Y.2    Zhang, M.3    Xu, H.4    Qi, R.5    Yan, X.6
  • 3
    • 14044279966 scopus 로고    scopus 로고
    • Toll-like receptor 4 on nonhematopoietic cells sustains CNS inflammation during endotoxemia, independent of systemic cytokines
    • Chakravarty S., Herkenham M. Toll-like receptor 4 on nonhematopoietic cells sustains CNS inflammation during endotoxemia, independent of systemic cytokines. The Journal of Neuroscience 2005, 25:1788-1796.
    • (2005) The Journal of Neuroscience , vol.25 , pp. 1788-1796
    • Chakravarty, S.1    Herkenham, M.2
  • 4
    • 45549098626 scopus 로고    scopus 로고
    • Tomatidine inhibits iNOS and COX-2 through suppression of NF-κB and JNK pathways in LPS-stimulated mouse macrophages
    • Chiu F.L., Lin J.K. Tomatidine inhibits iNOS and COX-2 through suppression of NF-κB and JNK pathways in LPS-stimulated mouse macrophages. FEBS Letters 2008, 582:2407-2412.
    • (2008) FEBS Letters , vol.582 , pp. 2407-2412
    • Chiu, F.L.1    Lin, J.K.2
  • 5
    • 0035708551 scopus 로고    scopus 로고
    • LPS induction of I[kappa]B-[alpha] degradation and iNOS expression in a skin dendritic cell line is prevented by the Janus kinase 2 inhibitor, Tyrphostin B42
    • Cruz M.T., Duarte C.B., Gonçalo M., Carvalho A.P., Lopes M.C. LPS induction of I[kappa]B-[alpha] degradation and iNOS expression in a skin dendritic cell line is prevented by the Janus kinase 2 inhibitor, Tyrphostin B42. Nitric Oxide 2001, 5:53-61.
    • (2001) Nitric Oxide , vol.5 , pp. 53-61
    • Cruz, M.T.1    Duarte, C.B.2    Gonçalo, M.3    Carvalho, A.P.4    Lopes, M.C.5
  • 6
    • 27144470284 scopus 로고    scopus 로고
    • Central and systemic endotoxin challenges exacerbate the local inflammatory response and increase neuronal death during chronic neurodegeneration
    • Cunningham C., Wilcockson D.C., Campion S., Lunnon K., Perry V.H. Central and systemic endotoxin challenges exacerbate the local inflammatory response and increase neuronal death during chronic neurodegeneration. The Journal of Neuroscience 2005, 25:9275-9284.
    • (2005) The Journal of Neuroscience , vol.25 , pp. 9275-9284
    • Cunningham, C.1    Wilcockson, D.C.2    Campion, S.3    Lunnon, K.4    Perry, V.H.5
  • 7
    • 22044442141 scopus 로고    scopus 로고
    • Effects of interleukin-1 and endotoxin in the forced swim and tail suspension tests in mice
    • Dunn A.J., Swiergiel A.H. Effects of interleukin-1 and endotoxin in the forced swim and tail suspension tests in mice. Pharmacology Biochemistry and Behavior 2005, 81:688-693.
    • (2005) Pharmacology Biochemistry and Behavior , vol.81 , pp. 688-693
    • Dunn, A.J.1    Swiergiel, A.H.2
  • 8
    • 0037199972 scopus 로고    scopus 로고
    • The phosphatidylinositol 3-kinase-Akt pathway limits lipopolysaccharide activation of signaling pathways and expression of inflammatory mediators in human monocytic cells
    • Guha M., Mackman N. The phosphatidylinositol 3-kinase-Akt pathway limits lipopolysaccharide activation of signaling pathways and expression of inflammatory mediators in human monocytic cells. The Journal of Biological Chemistry 2002, 277:32124-32132.
    • (2002) The Journal of Biological Chemistry , vol.277 , pp. 32124-32132
    • Guha, M.1    Mackman, N.2
  • 9
    • 0027982986 scopus 로고
    • Inhibition of skin tumorigenesis by rosemary and its constituents carnosol and ursolic acid
    • Huang M.-T., Ho C.-T., Wang Z.Y., Ferraro T., Lou Y.-R., Stauber K., et al. Inhibition of skin tumorigenesis by rosemary and its constituents carnosol and ursolic acid. Cancer Research 1994, 54:701-708.
    • (1994) Cancer Research , vol.54 , pp. 701-708
    • Huang, M.-T.1    Ho, C.-T.2    Wang, Z.Y.3    Ferraro, T.4    Lou, Y.-R.5    Stauber, K.6
  • 10
    • 34247172208 scopus 로고    scopus 로고
    • Aggregated ursolic acid, a natural triterpenoid, induces IL-1beta release from murine peritoneal macrophages: Role of CD36
    • Ikeda Y., Murakami A., Fujimura Y., Tachibana H., Yamada K., Masuda D., et al. Aggregated ursolic acid, a natural triterpenoid, induces IL-1beta release from murine peritoneal macrophages: Role of CD36. The Journal of Immunology 2007, 178:4854-4864.
    • (2007) The Journal of Immunology , vol.178 , pp. 4854-4864
    • Ikeda, Y.1    Murakami, A.2    Fujimura, Y.3    Tachibana, H.4    Yamada, K.5    Masuda, D.6
  • 11
    • 0035889228 scopus 로고    scopus 로고
    • Lipopolysaccharide stimulates the MyD88-independent pathway and results in activation of IFN-regulatory factor 3 and the expression of a subset of lipopolysaccharide-inducible genes
    • Kawai T., Takeuchi O., Fujita T., Inoue J.-I., Muhlradt P.F., Sato S., et al. Lipopolysaccharide stimulates the MyD88-independent pathway and results in activation of IFN-regulatory factor 3 and the expression of a subset of lipopolysaccharide-inducible genes. The Journal of Immunology 2001, 167:5887-5894.
    • (2001) The Journal of Immunology , vol.167 , pp. 5887-5894
    • Kawai, T.1    Takeuchi, O.2    Fujita, T.3    Inoue, J.-I.4    Muhlradt, P.F.5    Sato, S.6
  • 12
    • 79960838757 scopus 로고    scopus 로고
    • The antioxidative mechanism of ursolic acid. Journal of Gastroenterology
    • Kim, J. S., H. J. I., Song, S. H., Shim, K. H., Back, B. S., Kim, K. W., et al. (1996). The antioxidative mechanism of ursolic acid. Journal of Gastroenterology, 6, 52-56.
    • (1996) , Issue.6 , pp. 52-56
    • Kim, J.S.H.J.I.1    Song, S.H.2    Shim, K.H.3    Back, B.S.4    Kim, K.W.5
  • 14
    • 57349132885 scopus 로고    scopus 로고
    • Eriobotrya japonica leaf and its triterpenes inhibited lipopolysaccharide-induced cytokines and inducible enzyme production via the nuclear factor-{kappa}B signaling pathway in lung epithelial cells
    • Lee C.H., Wu S.L., Chen J.C., Li C.C., Lo H.Y., Cheng W.Y., et al. Eriobotrya japonica leaf and its triterpenes inhibited lipopolysaccharide-induced cytokines and inducible enzyme production via the nuclear factor-{kappa}B signaling pathway in lung epithelial cells. The American Journal of Chinese Medicine 2008, 36:1185-1198.
    • (2008) The American Journal of Chinese Medicine , vol.36 , pp. 1185-1198
    • Lee, C.H.1    Wu, S.L.2    Chen, J.C.3    Li, C.C.4    Lo, H.Y.5    Cheng, W.Y.6
  • 17
    • 29244491684 scopus 로고
    • Pharmacology of oleanolic acid and ursolic acid
    • Liu J. Pharmacology of oleanolic acid and ursolic acid. Journal of Ethnopharmacology 1995, 49:57-68.
    • (1995) Journal of Ethnopharmacology , vol.49 , pp. 57-68
    • Liu, J.1
  • 18
    • 77957854250 scopus 로고    scopus 로고
    • Ursolic acid attenuates d-galactose-induced inflammatory response in mouse prefrontal cortex through inhibiting AGEs/RAGE/NF-κB pathway activation
    • Lu J., Wu D.M., Zheng Y.L., Hu B., Zhang Z.F., Ye Q., et al. Ursolic acid attenuates d-galactose-induced inflammatory response in mouse prefrontal cortex through inhibiting AGEs/RAGE/NF-κB pathway activation. Cerebral Cortex 2010, 20:2540-2548.
    • (2010) Cerebral Cortex , vol.20 , pp. 2540-2548
    • Lu, J.1    Wu, D.M.2    Zheng, Y.L.3    Hu, B.4    Zhang, Z.F.5    Ye, Q.6
  • 19
    • 34548011290 scopus 로고    scopus 로고
    • Ursolic acid ameliorates cognition deficits and attenuates oxidative damage in the brain of senescent mice induced by d-galactose
    • Lu J., Zheng Y.L., Wu D.M., Luo L., Sun D.X., Shan Q. Ursolic acid ameliorates cognition deficits and attenuates oxidative damage in the brain of senescent mice induced by d-galactose. Biochemical Pharmacology 2007, 74:1078-1090.
    • (2007) Biochemical Pharmacology , vol.74 , pp. 1078-1090
    • Lu, J.1    Zheng, Y.L.2    Wu, D.M.3    Luo, L.4    Sun, D.X.5    Shan, Q.6
  • 21
    • 33749055328 scopus 로고    scopus 로고
    • NF-κB functions in the nervous system: From development to disease
    • Mémet S. NF-κB functions in the nervous system: From development to disease. Biochemical Pharmacology 2006, 72:1180-1195.
    • (2006) Biochemical Pharmacology , vol.72 , pp. 1180-1195
    • Mémet, S.1
  • 22
    • 34249027009 scopus 로고    scopus 로고
    • Connecting TNF-α signaling pathways to iNOS expression in a mouse model of Alzheimer's disease: Relevance fiw the behavioral and synaptic deficits induced by amyloid β protein
    • Medeiros R., Prediger R.D., Passos G.F., Pandolfo P., Duarte F.S., Franco J.L., et al. Connecting TNF-α signaling pathways to iNOS expression in a mouse model of Alzheimer's disease: Relevance fiw the behavioral and synaptic deficits induced by amyloid β protein. The Journal of Neuroscience 2007, 27:5394-5404.
    • (2007) The Journal of Neuroscience , vol.27 , pp. 5394-5404
    • Medeiros, R.1    Prediger, R.D.2    Passos, G.F.3    Pandolfo, P.4    Duarte, F.S.5    Franco, J.L.6
  • 23
    • 63249119308 scopus 로고    scopus 로고
    • Protein kinase C-δ and phosphatidylinositol 3-kinase/Akt activate mammalian target of rapamycin to modulate NF-κB activation and intercellular adhesion molecule-1 (ICAM-1) expression in endothelial cells
    • Minhajuddin M., Bijli K.M., Fazal F., Sassano A., Nakayama K.I., Hay N., et al. Protein kinase C-δ and phosphatidylinositol 3-kinase/Akt activate mammalian target of rapamycin to modulate NF-κB activation and intercellular adhesion molecule-1 (ICAM-1) expression in endothelial cells. The Journal of Biological Chemistry 2009, 284:4052-4061.
    • (2009) The Journal of Biological Chemistry , vol.284 , pp. 4052-4061
    • Minhajuddin, M.1    Bijli, K.M.2    Fazal, F.3    Sassano, A.4    Nakayama, K.I.5    Hay, N.6
  • 24
    • 33645566358 scopus 로고    scopus 로고
    • Chronic unpredictable stress exacerbates lipopolysaccharide-induced activation of nuclear factor-κB in the frontal cortex and hippocampus via glucocorticoid secretion
    • Munhoz C.D., Lepsch L.B., Kawamoto E.M., Malta M.B., Lima L.d.S., Werneck Avellar M.C., et al. Chronic unpredictable stress exacerbates lipopolysaccharide-induced activation of nuclear factor-κB in the frontal cortex and hippocampus via glucocorticoid secretion. The Journal of Neuroscience 2006, 26:3813-3820.
    • (2006) The Journal of Neuroscience , vol.26 , pp. 3813-3820
    • Munhoz, C.D.1    Lepsch, L.B.2    Kawamoto, E.M.3    Malta, M.B.4    Lima, L.5    Werneck Avellar, M.C.6
  • 25
    • 35348886061 scopus 로고    scopus 로고
    • A novel p38α MAPK inhibitor suppresses brain proinflammatory cytokine up-regulation and attenuates synaptic dysfunction and behavioral deficits in an Alzheimer's disease mouse model
    • Munoz L., Ranaivo H., Roy S., Hu W., Craft J., McNamara L., et al. A novel p38α MAPK inhibitor suppresses brain proinflammatory cytokine up-regulation and attenuates synaptic dysfunction and behavioral deficits in an Alzheimer's disease mouse model. Journal of Neuroinflammation 2007, 4:21-34.
    • (2007) Journal of Neuroinflammation , vol.4 , pp. 21-34
    • Munoz, L.1    Ranaivo, H.2    Roy, S.3    Hu, W.4    Craft, J.5    McNamara, L.6
  • 26
    • 0034193376 scopus 로고    scopus 로고
    • Role of microglial-derived tumor necrosis factor in mediating CD14 transcription and nuclear factor κB activity in the brain during endotoxemia
    • Nadeau S., Rivest S. Role of microglial-derived tumor necrosis factor in mediating CD14 transcription and nuclear factor κB activity in the brain during endotoxemia. The Journal of Neuroscience 2000, 20:3456-3468.
    • (2000) The Journal of Neuroscience , vol.20 , pp. 3456-3468
    • Nadeau, S.1    Rivest, S.2
  • 27
    • 34247566510 scopus 로고    scopus 로고
    • The family of five: TIR-domain-containing adaptors in toll-like receptor signalling
    • O'Neill L.A.J., Bowie A.G. The family of five: TIR-domain-containing adaptors in toll-like receptor signalling. Nature Reviews Immunology 2007, 7:353-364.
    • (2007) Nature Reviews Immunology , vol.7 , pp. 353-364
    • O'Neill, L.A.J.1    Bowie, A.G.2
  • 28
    • 8444253806 scopus 로고    scopus 로고
    • Pentacyclic triterpenoic acids: New chemoprotective compounds: Minireview
    • Ovesna Z., Vachalkova A., Horvathova K., Tothova D. Pentacyclic triterpenoic acids: New chemoprotective compounds: Minireview. Neoplasma 2004, 51:327-333.
    • (2004) Neoplasma , vol.51 , pp. 327-333
    • Ovesna, Z.1    Vachalkova, A.2    Horvathova, K.3    Tothova, D.4
  • 29
    • 0347090640 scopus 로고    scopus 로고
    • Simvastatin suppresses LPS-induced Akt phosphorylation in the human monocyte cell line THP-1
    • Patel T.R., Corbett S.A. Simvastatin suppresses LPS-induced Akt phosphorylation in the human monocyte cell line THP-1. Journal of Surgical Research 2004, 116:116-120.
    • (2004) Journal of Surgical Research , vol.116 , pp. 116-120
    • Patel, T.R.1    Corbett, S.A.2
  • 30
    • 0041337005 scopus 로고    scopus 로고
    • Effect of naturally occurring triterpenoids glycyrrhizic acid, ursolic acid, oleanolic acid and nomilin on the immune system
    • Raphael T.J., Kuttan G. Effect of naturally occurring triterpenoids glycyrrhizic acid, ursolic acid, oleanolic acid and nomilin on the immune system. Phytomedicine 2003, 10:483-489.
    • (2003) Phytomedicine , vol.10 , pp. 483-489
    • Raphael, T.J.1    Kuttan, G.2
  • 33
    • 49649109586 scopus 로고    scopus 로고
    • Dual signaling of MyD88 and TRIF is critical for maximal TLR4-induced dendritic cell maturation
    • Shen H., Tesar B.M., Walker W.E., Goldstein D.R. Dual signaling of MyD88 and TRIF is critical for maximal TLR4-induced dendritic cell maturation. The Journal of Immunology 2008, 181:1849-1858.
    • (2008) The Journal of Immunology , vol.181 , pp. 1849-1858
    • Shen, H.1    Tesar, B.M.2    Walker, W.E.3    Goldstein, D.R.4
  • 34
    • 2942559154 scopus 로고    scopus 로고
    • Ursolic acid protects hippocampal neurons against kainate-induced excitotoxicity in rats
    • Shih Y.H., Chein Y.C., Wang J.Y., Fu Y.S. Ursolic acid protects hippocampal neurons against kainate-induced excitotoxicity in rats. Neuroscience Letters 2004, 362:136-140.
    • (2004) Neuroscience Letters , vol.362 , pp. 136-140
    • Shih, Y.H.1    Chein, Y.C.2    Wang, J.Y.3    Fu, Y.S.4
  • 35
    • 0042090509 scopus 로고    scopus 로고
    • Ursolic acid inhibits nuclear factor-κB activation induced by carcinogenic agents through suppression of I-κBα kinase and p65 phosphorylation
    • Shishodia S., Majumdar S., Banerjee S., Aggarwal B.B. Ursolic acid inhibits nuclear factor-κB activation induced by carcinogenic agents through suppression of I-κBα kinase and p65 phosphorylation. Cancer Research 2003, 63:4375-4383.
    • (2003) Cancer Research , vol.63 , pp. 4375-4383
    • Shishodia, S.1    Majumdar, S.2    Banerjee, S.3    Aggarwal, B.B.4
  • 36
    • 15744382068 scopus 로고    scopus 로고
    • Effects of intraperitoneal lipopolysaccharide on Morris maze performance in year-old and 2-month-old female C57BL/6J mice
    • Sparkman N.L., Martin L.A., Calvert W.S., Boehm G.W. Effects of intraperitoneal lipopolysaccharide on Morris maze performance in year-old and 2-month-old female C57BL/6J mice. Behavioural Brain Research 2005, 159:145-151.
    • (2005) Behavioural Brain Research , vol.159 , pp. 145-151
    • Sparkman, N.L.1    Martin, L.A.2    Calvert, W.S.3    Boehm, G.W.4
  • 37
    • 0034193436 scopus 로고    scopus 로고
    • Ursolic acid inhibits cyclooxygenase-2 transcription in human mammary epithelial cells
    • Subbaramaiah K., Michaluart P., Sporn M.B., Dannenberg A.J. Ursolic acid inhibits cyclooxygenase-2 transcription in human mammary epithelial cells. Cancer Research 2000, 60:2399-2404.
    • (2000) Cancer Research , vol.60 , pp. 2399-2404
    • Subbaramaiah, K.1    Michaluart, P.2    Sporn, M.B.3    Dannenberg, A.J.4
  • 38
    • 17144439794 scopus 로고    scopus 로고
    • Novel triterpenoids suppress inducible nitric oxide synthase (iNOS) and inducible cyclooxygenase (COX-2) in mouse macrophages
    • Suh N., Honda T., Finlay H.J., Barchowsky A., Williams C., Benoit N.E., et al. Novel triterpenoids suppress inducible nitric oxide synthase (iNOS) and inducible cyclooxygenase (COX-2) in mouse macrophages. Cancer Research 1998, 58:717-723.
    • (1998) Cancer Research , vol.58 , pp. 717-723
    • Suh, N.1    Honda, T.2    Finlay, H.J.3    Barchowsky, A.4    Williams, C.5    Benoit, N.E.6
  • 39
    • 0028978032 scopus 로고
    • Phosphorylation of human I kappa B-alpha on serines 32 and 36 controls I kappa B-alpha proteolysis and NF-kappa B activation in response to diverse stimuli
    • Traenckner E.B., Pahl H.L., Henkel T., Schmidt K.N., Wilk S., Baeuerle P.A. Phosphorylation of human I kappa B-alpha on serines 32 and 36 controls I kappa B-alpha proteolysis and NF-kappa B activation in response to diverse stimuli. The EMBO Journal 1995, 14:2876-2883.
    • (1995) The EMBO Journal , vol.14 , pp. 2876-2883
    • Traenckner, E.B.1    Pahl, H.L.2    Henkel, T.3    Schmidt, K.N.4    Wilk, S.5    Baeuerle, P.A.6
  • 40
    • 77049116249 scopus 로고    scopus 로고
    • Purple sweet potato color suppresses lipopolysaccharide-induced acute inflammatory response in mouse brain
    • Wang Y.J., Zheng Y.L., Lu J., Chen G.Q., Wang X.H., Feng J., et al. Purple sweet potato color suppresses lipopolysaccharide-induced acute inflammatory response in mouse brain. Neurochemistry International 2010, 56:424-430.
    • (2010) Neurochemistry International , vol.56 , pp. 424-430
    • Wang, Y.J.1    Zheng, Y.L.2    Lu, J.3    Chen, G.Q.4    Wang, X.H.5    Feng, J.6
  • 41
    • 0030911732 scopus 로고    scopus 로고
    • Activation of transcription factor NF-κB and p38 mitogen-activated protein kinase is mediated by distinct and separate stress effector pathways
    • Wesselborg S., Bauer M.K.A., Vogt M., Schmitz M.L., Schulze-Osthoff K. Activation of transcription factor NF-κB and p38 mitogen-activated protein kinase is mediated by distinct and separate stress effector pathways. The Journal of Biological Chemistry 1997, 272:12422-12429.
    • (1997) The Journal of Biological Chemistry , vol.272 , pp. 12422-12429
    • Wesselborg, S.1    Bauer, M.K.A.2    Vogt, M.3    Schmitz, M.L.4    Schulze-Osthoff, K.5
  • 42
    • 44649203399 scopus 로고    scopus 로고
    • Purple sweet potato color repairs d-galactose-induced spatial learning and memory impairment by regulating the expression of synaptic proteins
    • Wu D.M., Lu J., Zheng Y.L., Zhou Z., Shan Q., Ma D.F. Purple sweet potato color repairs d-galactose-induced spatial learning and memory impairment by regulating the expression of synaptic proteins. Neurobiology of Learning and Memory 2008, 90:19-27.
    • (2008) Neurobiology of Learning and Memory , vol.90 , pp. 19-27
    • Wu, D.M.1    Lu, J.2    Zheng, Y.L.3    Zhou, Z.4    Shan, Q.5    Ma, D.F.6
  • 43
    • 0033775754 scopus 로고    scopus 로고
    • NF-[kappa]B regulates the LPS-induced expression of interleukin 12 p40 in murine peritoneal macrophages: Roles of PKC, PKA, ERK, p38 MAPK, and proteasome
    • Zhang J.S., Feng W.G., Li C.L., Wang X.Y., Chang Z.L. NF-[kappa]B regulates the LPS-induced expression of interleukin 12 p40 in murine peritoneal macrophages: Roles of PKC, PKA, ERK, p38 MAPK, and proteasome. Cellular Immunology 2000, 204:38-45.
    • (2000) Cellular Immunology , vol.204 , pp. 38-45
    • Zhang, J.S.1    Feng, W.G.2    Li, C.L.3    Wang, X.Y.4    Chang, Z.L.5


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.