Diamine oxidase (DAO) is abundantly expressed in mammalian small intestine catalyzing the oxidative breakdown of polyamines and histamine. The aim of this study was to determine the relationship between stimulation of intestinal diamine oxidase secretion with intestinal fat absorption and histamine release. Conscious intestinal lymph fistula rats were used. The mesenteric lymph ducts were cannulated and intraduodenal tubes were installed for the infusion of Liposyn II 20 % (an intralipid emulsion). Lymphatic DAO activity and protein secretion were analyzed by radiometric assay and Western blot, respectively. Lymphatic histamine concentration was measured by ELISA. Infusion of Liposyn II (4.43 kcal/3 ml) resulted in a ~ 3.5 fold increase in lymphatic DAO protein secretion and DAO activity, peaking at 1 h and lasting for 3 h. Liposyn II infusion also increased the lymphatic histamine release, a substrate for DAO. To determine the relationship of DAO release with histamine release, histamine was administered intraperitoneally (i.p.) (10 mg/kg) in fasting rats resulted in a significant doubling in lymphatic DAO activity, supporting a link between histamine and DAO. In addition, i.p. administration of the histamine H4 receptor antagonist JNJ7777120 significantly reduced the Liposyn II-induced DAO output by 65.9 %, whereas H1 (pyrilamine maleate), H2 (ranitidine) nor H3 (thioperamide maleate) receptor antagonists had little effect. We conclude that DAO secretion may contribute to the catabolism of histamine released during fat absorption and this is probably mediated through the histamine H4 receptor.
- dietary lipids
- intestinal lymph
- histamine receptors
- Copyright © 2012, American Journal of Physiology- Gastrointestinal and Liver Physiology