Absorption of elastase through the jejunal mucosa of the rat

Abstract

In order to reveal the absorption process of elastase from the intestine, hog pancreatic elastase was injected into the ligated jejunum lumen of the rat, and the tissues were cytochemically observed at various times after injection. The peroxidase anti-peroxidase (PAP) method using anti-hog-elastase rabbit antibody was used for light microscopy, and the anti-elastase Fab'-peroxidase conjugate was used for electron microscopy. The tissues stained by the PAP method exhibited a dense deposition of reaction products on the luminal surface of epithelial cells and a moderate deposition in the blood and lymph capillaries of the intestinal villi. Immunoelectron microscopy revealed that the reaction product was deposited on the surface of the microvilli and in their pocketing; some was found in the pinocytotic vesicles in the terminal-web area and on the inner surface of the enlarged smooth endoplasmic reticulum. Round droplets which gave a positive reaction were found in the widened intercellular cleft and the thick basement membrane lining the blood capillaries and lymphatics. The jejunum retained its normal ultrastructure. The results indicate that the elastase molecules, which were introduced into the rat jejunum lumen, were absorbed without being decomposed through healthy intestinal epithelial cells by pinocytosis and translocated into blood and lymph capillaries.

Studies on the Intestinal Absorption of Pollen Proteins, Observations on Rat.

“…These facts indicate that some proteins should be absorbed through healthy intestinal mucosa without being decomposed into oligopeptides or amino acids. Actually, as clearly demonstrated elsewhere, some basic proteins like hog pancreas elastase and egg white lysozyme are absorbed through healthy intestinal mucosa without being decomposed into nonantigenic components [9,10].…”

Intestinal Absorption of Lysozyme Molecules and their Destination, an Immunohistochemical Study on Rat.

“…intestine [13]. Tight junctions between the two epithelial cells were kept in the normal state through all the observations showing no lysozyme molecules invading into intercellular spaces passing through the tight junction.…”

“…Seno and associates showed that the cationic ferric colloid particles and some basic protein molecules such as bovine pancreatic elastase and cationized ferritin molecules can be absorbed through the intestinal mucosa of rat without being decomposed into amino acids [1,2,13]. The absorption is not mediated by the specific receptors but by the non-specific adsorption of cationic macromolecules on the anionic epithelial cell surface followed by the pinocytotic intake of the materials into the cell [1,[9][10][11].…”

“…The absorption is not mediated by the specific receptors but by the non-specific adsorption of cationic macromolecules on the anionic epithelial cell surface followed by the pinocytotic intake of the materials into the cell [1,[9][10][11]. The colloid particles or protein molecules are then excreted into the intercellular spaces of epithelial cells by exocytosis to be finally transported into capillaries, as indicated clearly by the immuno-histochemical methods with the electron microscope [2,13].…”

Effects of Refeeding Subsequent to Starvation on the Plasma Cell Population in the Villous Lamina Propria of the Rat Small Intestine

“…In addition to the above-mentioned route, another means of transport seems to be available, i.e., direct transmission of antigen across the intestinal epithelium into the lamina propria. It has been reported by se\ eral authors that protein macromolecules can cross the mucosal barrier of adult animals in biological acti^ c and immunogenic quantities Tsujii et al, 1984). It seems highly probable that such transmission of protein macromolecules might be promoted to a marked extent by refeeding subsequent to starvation.…”