General paper
Evidence for serotonergic system involvement in the effect of morphine on gastrointestinal motility in the rat

https://doi.org/10.1016/0306-3623(94)00238-IGet rights and content

Abstract

  • 1.

    1. Intestinal motility was measured by the transit of charcoal meal through the small intestine of the rat.

  • 2.

    2. Morphine given subcutaneously induced a reduction in the gastrointestinal transit (GIT), and the response was dose-dependent (0.1–2.5 mg/kg).

  • 3.

    3. The inhibitory effect of morphine was antagonized by prior subcutaneous administration of naloxone (1 mg/kg).

  • 4.

    4. Depletion of serotonergic neurons by para-chlorophenylalanine (100 mg/kg, ip, 3 days) completely abolished the inhibitory action of morphine.

  • 5.

    5. Methysergide (5 mg/kg, sc) and ketanserin (5 mg/kg, sc) also reduced the morphine effect.

  • 6.

    6. Destruction of serotonergic neurones by intracerebronventricular injection of 5,7-dihydroxytryptamine (20μ/kg) abolished the effect of morphine.

  • 7.

    7. These observations provide some evidence for the involvement of a central serotonergic system in the effect of morphine on gastrointestinal motility.

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