Morphine and gastroduodenal motility.

Area of Science:

• Gastroenterology
• Pharmacology
• Neurogastroenterology

Background:

• Opioid analgesics like morphine can affect gastrointestinal function.
• Understanding morphine's impact on duodenal motility is crucial for clinical practice.

Purpose of the Study:

• To investigate the effects of intravenous morphine on gastric antral and duodenal motility.
• To characterize the nature of morphine-induced duodenal contractions and their underlying mechanisms.

Main Methods:

• Healthy volunteers received intravenous morphine via infusion or bolus injection.
• Duodenal motility was monitored, and the effects of naloxone and atropine were assessed.
• Morphine's action was studied following spontaneous phase III activity and after a liquid meal.

Main Results:

• Intravenous morphine significantly increased duodenal motility, inducing phase III-like contractions.
• Naloxone, an opioid receptor antagonist, blocked morphine's effect.
• Atropine, an antimuscarinic agent, prevented morphine-induced duodenal activity.

Conclusions:

• Low-dose intravenous morphine potently stimulates duodenal contractility in a phase III-like manner.
• Morphine initiates this response via opioid receptors.
• The effect is mediated through a pathway sensitive to antimuscarinic drugs.