Gastrointestinal glutathione peroxidase prevents transport of lipid hydroperoxides in CaCo-2 cells

K Wingler ¹, C Müller , K Schmehl

⁰German Institute of Human Nutrition, Institute for Nutritional Science, Potsdam-Rehbrücke, Germany.

Gastroenterology +

|

August 10, 2000

View abstract on PubMed

Summary

Low gastrointestinal glutathione peroxidase (GI-GPx) levels prevent dietary hydroperoxide absorption. Even with selenium deficiency, GI-GPx acts as a crucial barrier, while cytosolic GPx (cGPx) manages oxidative stress.

Area Of Science

Gastroenterology
Nutritional Biochemistry
Cell Biology

Background

Gastrointestinal glutathione peroxidase (GI-GPx) is a selenium-dependent enzyme unique to the GI tract.
It is hypothesized to prevent dietary hydroperoxide absorption.
Selenium status influences GI-GPx and cytosolic GPx (cGPx) expression.

Purpose Of The Study

To investigate the role of GI-GPx in hydroperoxide transport across the intestinal barrier.
To analyze the impact of selenium levels on GI-GPx and cGPx expression and function.
To determine the localization and activity of GI-GPx in the gastrointestinal system.

Main Methods

Western blotting to assess GI-GPx and cGPx protein levels.
CaCo-2 cell monolayers used to study 13-hydroperoxy octadecadienoic acid (13-HPODE) transport.
Selenium restriction and repletion modulated enzyme expression.
Immunohistochemistry visualized GI-GPx in rat intestines.

Main Results

Low GI-GPx levels were present in selenium-deficient cells and rats; cGPx was absent.
Selenium supplementation significantly increased GI-GPx protein and total GPx activity.
13-HPODE transport was blocked in intact CaCo-2 monolayers regardless of selenium status.
Hydroperoxide damage to the monolayer correlated with 13-HPODE detection on the basolateral side.

Conclusions

Sufficient GI-GPx levels, even when low (as in selenium deficiency), prevent 13-HPODE transport.
GI-GPx functions as an effective barrier against hydroperoxide absorption.
cGPx plays a role in managing significant oxidative challenges.

Related Concept Videos