Absorption and lymphatic transport of peroxidized lipids by rat small intestine in vivo: role of mucosal GSH.

The absorption and lymphatic transport of peroxidized MaxEPA fish oil was studied using the lymph fistula rat to determine the role of mucosal glutathione (GSH) in intestinal metabolism of luminal lipid hydroperoxides. Decreasing intestinal GSH concentrations with buthionine sulfoximine (BSO, 1.15 +/- 0.20 nmol/g), diethyl maleate (DEM, 0.93 +/- 0.26 nmol/g), phorone (1.46 +/- 0.14 nmol/g), or 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU, 1.54 +/- 0.18 nmol/g) compared with control (2.60 +/- 0.38 nmol/g) resulted in higher luminal recovery of the infused lipid hydroperoxide (% of infused dose): BSO (87.8 +/- 4.8%), DEM (86.1 +/- 1.3%), phorone (78.1 +/- 2.1%), and BCNU (71.7 +/- 4.8%) compared with control (52.8 +/- 4.3%). These results suggest that decreased elimination of luminal peroxidized lipids is associated with decreased tissue GSH. Treatment of rats with BSO, DEM, phorone, or BCNU resulted in dramatic increases in appearance of peroxidized lipids in lymph over 6-h lipid infusion (54.7 +/- 3.7, 57.7 +/- 4.6, 46.4 +/- 2.7, and 42.1 +/- 3.9 nmol, respectively) compared with control (20.5 +/- 3.4 nmol). The results are consistent with decreased intracellular metabolism of absorbed hydroperoxides and enhanced transport into lymph under GSH-deficient conditions. The current findings suggest that the function of the mucosal GSH peroxidase/oxidized glutathione (GSSG) reductase system may play an important role in intestinal handling of luminal lipid hydroperoxides. A compromised function of this detoxication mechanism in GSH-deficient states can significantly alter the metabolic fate of dietary peroxidized lipids.