Key chemical is potent stimulator of esophageal and upper stomach muscle movement

 A research group has discovered that a natural substance in the body, known as platelet-activating factor (PAF), can strongly stimulate muscle movements in parts of the digestive system, especially the esophagus and the upper part of the stomach.

The findings are published in the journal Biological and Pharmaceutical Bulletin. The team was led by Dr. Kento Yoshioka, Dr. Keisuke Obara, and Professor Yoshio Tanaka from the Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Toho University.

PAF is a chemical produced in the body during allergic reactions and inflammation. While it was already known to affect muscles in some parts of the digestive tract, its effects on the esophagus had not been clearly studied until now.

In this study, the research group investigated how PAF affects different sections of the digestive tract in rats. They found that PAF caused strong contractions—especially in the muscles of the esophagus and the stomach's upper region (called the gastric fundus). These two regions share a common origin in early development, which may explain their similar reactions to PAF.

Interestingly, in other parts of the intestine, such as the small intestine and colon, PAF had weaker effects. However, it still caused unusual, rhythmic muscle movements in the colon (ascending colon), which may be linked to chronic digestive diseases like inflammatory bowel disease.

This figure shows how a substance called PAF (platelet-activating factor) affects the muscles in different parts of the digestive tract in rats. Credit: Keisuke Obara

These findings suggest that PAF could play a key role in both normal and abnormal digestive reactions, such as those triggered by food allergies or acid reflux. Since PAF is also involved in severe allergic reactions (like anaphylaxis), the study helps explain why people with these conditions sometimes experience stomach or esophageal discomfort.

This research could lead to new treatments using drugs that block PAF's effects, potentially easing symptoms in digestive and allergic disorders.

More information: Keisuke Obara et al, Platelet-Activating Factor (PAF) Induces Strong Mechanical Activities Accompanied by Basal Tension Increases in Esophageal and Gastric Fundus Smooth Muscles from Rat, Biological and Pharmaceutical Bulletin (2025). DOI: 10.1248/bpb.b25-00125

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