Antinociceptive Effect and Enzymatic Degradation of Endomorphin-1 in Newborn Rat Spinal Cord

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Author(s)

Abstract

Recently discovered endomorphin-1 and -2 are the first endogenous agonists selective for the μ-opioid receptor. We examined the antinociceptive effect and enzymatic degradation of endomorphin-1 in the newborn rat spinal cord. Endomorphin-1 inhibited the binding of [<SUP>3</SUP>H][D-Ala<SUP>2</SUP>, <I>N</I>-Me-Phe<SUP>4</SUP>, Gly-ol<SUP>5</SUP>] enkephalin (DAMGO) to the membrane fraction of the newborn rat spinal cord as potently as DAMGO and morphine. Endomorphin-1 at 1 - 1, 000 nM reduced the slow ventral root potential, which reflects noxious transmission in the isolated newborn rat spinal cord, concentration-dependently via the μ-opioid receptor. A similar effect was observed with endomorphin-2. The newborn rat spinal cord homogenate degraded endomorphin-1 in a 120-min incubation procedure, while it degraded [Leu<SUP>5</SUP>]enkephalin even in a 30-min incubation procedure. The degradation of endomorphin-1 was inhibited by actinonin but not by thiorphan. These results showed that in the newborn rat spinal cord, endomorphins had high affinity for the μ-opioid receptor and exerted μ-opioid-receptor - mediated inhibitory effects on noxious responses. Endomorphin-1 was degraded by peptidases, but slowly compared with [Leu<SUP>5</SUP>]enkephalin degradation, and the degrading enzymes were actinonin-sensitive peptidases.

Journal

  • The Japanese Journal of Pharmacology

    The Japanese Journal of Pharmacology 81(3), 264-270, 1999-11

    The Japanese Pharmacological Society

References:  26

Codes

  • NII Article ID (NAID)
    10008197179
  • NII NACSIS-CAT ID (NCID)
    AA00691188
  • Text Lang
    ENG
  • Article Type
    ART
  • ISSN
    00215198
  • NDL Article ID
    4918250
  • NDL Source Classification
    ZS51(科学技術--薬学)
  • NDL Call No.
    Z53-D199
  • Data Source
    CJP  NDL  J-STAGE 
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