Regional peptide uptake study in the rat intestinal mucosa: glatiramer acetate as a model drug.
OBJECTIVE
To identify regions of the rat intestine that are able to internalize from the lumen oligopeptides, using the model drug glatiramer acetate (GA).


METHODS
GA was introduced into rat intestinal sacs and the integrity of GA during uptake was monitored using antibody detection. Sodium docecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting of intestinal homogenates that had been exposed to GA were performed to identify GA presence. An enzyme-linked immunosorbent assay (ELISA) protocol was adapted for GA quantification. Immunohistochemistry was undertaken to examine the rat colonic wall for GA uptake, and confocal microscopy was used to differentiate adsorbed and internalized peptide in cultured colorectal adenocarcinoma cells.


RESULTS
The colon and the ileum, respectively, were identified to be the intestinal regions in which GA was maximally preserved during uptake from the lumen. GA was identified to cross the colonic wall from the epithelium to the serosa. Internalization of GA into cultured colonic epithelial cells was demonstrated.


CONCLUSIONS
The rat colonic wall was identified to be less proteolytically active toward GA compared to the wall of the more proximal regions of the small intestine. GA has the capacity to penetrate from the lumen into the colonic wall. The maintenance of GA integrity within the wall of the colon offers the potential for local biological activity of the drug.
Haupt
Susan
S
The Hebrew University of Jerusalem, Faculty of Medicine, School of Pharmacy, Israel.
Gil
Efrat
E
Tirosh
Regin
R
Klinger
Ety
E
Gad
Alexander
A
Rubinstein
Abraham
A
D000818:Animals; D015153:Blotting, Western; D002461:Cell Line, Transformed; D003106:Colon / Q000378:metabolism; D015194:Diffusion Chambers, Culture; D000068717:Glatiramer Acetate; D006801:Humans; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000201:enzymology / Q000378:metabolism*; D007457:Iodine Radioisotopes / Q000378:metabolism; D008297:Male; D010455:Peptides / Q000378:metabolism* / Q000493:pharmacokinetics*; D051381:Rats; D014407:Tumor Cells, Cultured
D007457:Iodine Radioisotopes; D010455:Peptides; D000068717:Glatiramer Acetate