Nuclear Fos immunoreactivity in guinea pig myenteric neurons following activation of motor activity

Robert C. Ritter, Marcello Costa, Simon H. Brookes

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    28 Citations (Scopus)


    To identify enteric neurons activated during intestinal motor activity, we examined myenteric plexus of guinea pig small intestinal segments for expression of the immediate early gene product, Fos. Fos immunoreactivity was detected immunohistochemically following in vitro manipulations, which included distension, electrical stimulation, exposure to forskolin, and peristalsis. All of these manipulations induced neuronal Fos expression, which was prevented by tetrodotoxin, indicating that expression depended on nerve activity. Distension-induced Fos expression was blocked by ω-conotoxin and significantly reduced by hexamethonium, indicating that neurons expressing Fos immunoreactivity were activated synaptically. Blocking smooth muscle contraction with nicardipine reduced expression of neuronal Fos, suggesting that muscle tone influences neuronal activity. Calbindin- immunoreactive putative sensory neurons did not express Fos during distension, peristalsis, or exposure to forskolin and expressed Fos only weakly after strong electrical stimulation. Conversely, calretinin- immunoreactive ascending excitatory interneurons and longitudinal muscle motoneurons exhibited Fos immunoreactivity after all experimental manipulations. These results indicate that Fos expression can, with some caution, be used to identify classes of enteric neurons activated by different stimuli under various experimental conditions.

    Original languageEnglish
    Pages (from-to)G498-G507
    Number of pages10
    JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
    Issue number2
    Publication statusPublished - 13 Oct 1997


    • c-fos
    • Cellular oncogenes
    • Enteric neurons
    • Immediate early genes
    • Intestinal peristalsis
    • Myenteric plexus


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