Mucus thickness in the gastrointestinal tract of laboratory animals.
OBJECTIVE
The objective of this study was to systematically assess the mucus thickness in the gastrointestinal tract of laboratory animals commonly used in preclinical studies.


METHODS
Mucus thickness was studied post-mortem in the rat, rabbit and pig, using cryosections stained by the modified periodic acid Schiff/Alcian blue method.


RESULTS
The mucus thickness in the fundus region of the stomach was higher in the pig (190.7 ± 80.7 µm) than in the rabbit (155.1 ± 85.8 µm) and the rat (31.3 ± 11.4 µm). However, along the small intestine (ileum), mucus was thicker in the rabbit (147.8 ± 115.6 µm), followed by the pig (53.8 ± 22.1 µm) and the rat (34.1 ± 14.9 µm). This rank order was also observed in the ascending colon.


CONCLUSIONS
Inter-species variability in mucus thickness along the gut was demonstrated and suggests that the pig resembles more closely the mucus pattern of humans. This may be highly relevant when preclinical animal models are used in drug absorption studies or in the development of oral mucoadhesive drug delivery systems.
Center for Pharmaceutical Studies, Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal             The School of Pharmacy, University of London, London, UK.
Felipe J O
FJ
Varum
Francisco
F
Veiga
João S
JS
Sousa
Abdul W
AW
Basit
D000268:Adhesiveness; D000818:Animals; D000830:Animals, Laboratory; D004396:Coloring Agents / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism*; D023421:Models, Animal; D009093:Mucus / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D013194:Staining and Labeling / Q000379:methods; D013552:Swine
D004396:Coloring Agents