Nutrients regulate diamine oxidase release from intestinal mucosa

Area of Science:

• Gastroenterology
• Biochemistry
• Physiology

Background:

• Diamine oxidase (DAO) is secreted by intestinal mucosa into lymph.
• The influence of dietary nutrients on DAO release remains unclear.

Purpose of the Study:

• To investigate how different nutrients (lipids, carbohydrates, proteins) affect DAO release into intestinal lymph.
• To determine if DAO is essential for lipid absorption.

Main Methods:

• Rats with duodenal and intestinal lymph cannulas were used.
• Infusions of lipid emulsions (triolein, oleic acid, tricaprylin), carbohydrates, and proteins were administered.
• DAO release, triglyceride transport, and lipid absorption were measured, with and without inhibitors of chylomicron formation and DAO activity.

Main Results:

• Non-lipid nutrients did not increase DAO in intestinal lymph; protein reduced distal mucosal DAO.
• Triglycerides and fatty acids significantly increased DAO in intestinal lymph, with longer-chain triglycerides being more effective.
• Inhibiting triglyceride transport or DAO activity did not affect lipid absorption.

Conclusions:

• Only lipids stimulate DAO release into the intestinal lymph.
• Non-fat nutrients may increase DAO within the intestinal lumen.
• DAO is not directly required for the absorption of lipids.