Diet-induced changes in membrane gangliosides in rat intestinal mucosa, plasma and brain.
OBJECTIVE
The objective of this study was to determine if dietary gangliosides induce changes in the ganglioside content of intestinal mucosa, plasma and brain and to identify where GM3 and GD3 are localized in the enterocyte membrane.


METHODS
Male 18-day-old Sprague-Dawley rats were fed a semipurified diet containing 20% (w/w) fat. The control diet contained triglyceride, reflecting the fat formulation of an existing infant formula. Two experimental diets were formulated by adding sphingomyelin (1% w/w of total fat) or a ganglioside-enriched lipid (0.1% w/w of total fat) to the control diet fat. The ganglioside fraction of ganglioside-enriched lipid diet contained more than 80% GD3. After 2 weeks of feeding, the total and individual ganglioside and cholesterol content was measured in small intestinal mucosa, plasma and brain.


RESULTS
The ganglioside-enriched lipid diet significantly increased total gangliosides in the intestinal mucosa, plasma and brain compared with the control diet. The ganglioside-enriched lipid diet significantly increased the level of GD3 (7.5% w/w) in the intestine compared with control (3.2% w/w) while decreasing the level of GM3, the major ganglioside in the intestine. The ratio of cholesterol to ganglioside in the intestinal mucosa, plasma and brain decreased significantly in rats fed the ganglioside-enriched lipid diet compared with controls. Confocal microscopy showed that GM3 is exclusively localized in the apical membrane of the enterocyte whereas GD3 is primarily localized in the basolateral membrane.


CONCLUSIONS
: The authors conclude that dietary ganglioside is absorbed in the small intestine and transported to different membrane sites, altering ganglioside levels in the intestinal mucosa, plasma and brain and thus possibly having the potential to change developing enterocyte function (and possibly that of other cell lines).
Park
Eek Joong
EJ
Nutrition and Metabolism Research Group, Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada.
Suh
Miyoung
M
Ramanujam
Kal
K
Steiner
Kurt
K
Begg
David
D
Clandinin
M Thomas
MT
D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D002784:Cholesterol / Q000097:blood / Q000378:metabolism*; D020895:Enterocytes / Q000166:cytology / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005679:G(M3) Ganglioside / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism; D005732:Gangliosides / Q000008:administration & dosage* / Q000097:blood / Q000378:metabolism*; D007408:Intestinal Absorption / Q000187:drug effects; D007413:Intestinal Mucosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008563:Membrane Lipids / Q000378:metabolism; D018613:Microscopy, Confocal; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
D005679:G(M3) Ganglioside; D005732:Gangliosides; D008563:Membrane Lipids; C026226:ganglioside, GD3; D002784:Cholesterol