Phagocytotic Activation of Muscularis Resident Macrophages Inhibits Smooth Muscle Contraction in Rat Ileum Phagocytotic Activation of Muscularis Resident Macrophages Inhibits Smooth Muscle Contraction in Rat Ileum

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Author(s)

    • SATO Koichi
    • Laboratory of Veterinary Pharmacology, Faculty of Agriculture, Yamaguchi University
    • HORI Masatoshi
    • Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo
    • NASU Tetsuyuki
    • Laboratory of Veterinary Pharmacology, Faculty of Agriculture, Yamaguchi University
    • OZAKI Hiroshi
    • Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo

Abstract

Intestinal muscularis resident macrophages distributed in myenteric region may play an important role in the immunological host defense against infection. In this study, we investigated the phagocytic stimulation of resident macrophages on cyclooxygenase-2 (COX-2) expression and smooth muscle contraction in the small intestine of rat. After the injection of FITC-dextran to rat, phagocytosed macrophages could be detected in the myenteric plexus. FITC-positive macrophages were also immunostained with COX-2 antibody. The number of COX-2 immunopositive cells increased in a time-dependent manner reaching its maximum at 4 hr after the injection, which then decreased gradually but considerable number of cells were still remained on 7 days. The injection of FITC-dextran, however, did not change the population of ED2-positive resident macrophages even on 7 days. Production of PGE<sub>2</sub> was significantly higher in the dextran treated tissue as compared to control tissue. In the smooth muscle tissue phagocytosed dextran, carbachol-induced contraction was significantly decreased. The suppression of the carbachol-induced contraction was completely restored by COX inhibitor, indomethacin. Finally we demonstrated that, in freshly isolated macrophage cells, addition of dextran induced a slow and sustained increase in intracellular Ca<sup>2+</sup> concentration. These results indicate that phagocytotic activation of muscularis resident macrophages induces COX-2 gene expression and then results in production of PGE<sub>2</sub> to suppress the smooth muscle contractile activity.<br>

Journal

  • Journal of Veterinary Medical Science

    Journal of Veterinary Medical Science 69(10), 1053-1060, 2007

    JAPANESE SOCIETY OF VETERINARY SCIENCE

Codes

  • NII Article ID (NAID)
    130000447588
  • Text Lang
    ENG
  • Article Type
    journal article
  • ISSN
    0916-7250
  • Data Source
    IR  J-STAGE 
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