Microinjection of opioid antagonist into periaqueductal gray blocks formalin-induced alterations of substance P in spinal dorsal horn

J. H. Du, L. F. He

    Research output: Contribution to journalArticle


    Using formalin injected into the rat's hind paw as nociceptive stimulation, the effect of naloxone and β-endorphin (β-EP) antiserum microinjected into the periaqueductal gray (PAG) on the level of substance P like immunorcactivity (SPLI) of the spinal dorsal horn was observed. After formalin injection, a significant increase in SPLI was found as compared with the control (P < 0.01). After naloxone or β-EP antiserum microinjection, SPLI level in the dorsal horn was decreased (P < 0.05). It is thus suggested that nociceptive stimulation induce the release of β-EP in the PAG, which, in turn, modulate SP release in the spinal dorsal horn.

    Original languageEnglish (US)
    Pages (from-to)390-393
    Number of pages4
    JournalActa Physiologica Sinica
    Issue number4
    StatePublished - Jan 1 1994



    • formalin test
    • image processing
    • immunohistochemistry
    • naloxone
    • periaqueductal gray
    • spinal dorsal horn
    • substance P
    • β-endorphin

    ASJC Scopus subject areas

    • Medicine(all)

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