Rise of Prostanoids in Rat Small Intestinal Mucosa following Intestinal Protein Hypersensitivity

Abstract

ABSTRACI'. The purpose of the present study was to establish whether there is an elevated prostaglandin concentration in the intestinal mucosa in rats suffering from an immediate type hypersensitivity reaction. Rats of the Hooded-Lister strain were sensitized and challenged with ovalbumin. Control rats were given adjuvant only. Prostanoid content of scraped mucosa was determined by radioimmunoassay. It was found that the prostaglandin Ez content in the sensitized intestine was significantly elevated as compared to the controls. There was no significant rise of 6-keto prostaglandin F, or thromboxane E2 in the sensi- The gastrointestinal manifestations of food hypersensitivity are similar to the effects elicited by administration of exogenous prostanoids (I). The possibility exists therefore, that prostanoids are involved in the symptomatology of immediate type hypersensitivity reactions in the intestine. In order to test this hypothesis, we used rats sensitized with ovalbumin, and subsequently challenged with this protein. We have previously shown that in these sensitized animals an immediate allergic type reaction in the small intestine can be developed upon challenge with ovalbumin (2). Herein we were able to show that the prostanoid content of such a challenged mucosa is raised. MATERIALS AND METHODSSensitization and challenge. Rats of Hooded-Lister strain were used. Their weight ranged between 150 and 180 g. Nineteen rats were sensitized by an intraperitoneal injection of ovalbumin 250 lg/0.5 ml with adjuvant consisting of killed Bordetella pertussis (1.6 x 1070.5 ml). On the 14th day a booster injection of ovalbumin (2.5 pg10.5 ml) was given intraperitoneally. In our experience this method of sensitization has always resulted in a positive passive cutaneous anaphylactic reaction (2). The challenge procedure was based on that described by Byars and Ferraresi (3). On the 19th day the rats were challenged with 25 mg ovalbumin intragastrically (Sigma Chemical Co.) after an overnight fast. Forty-five min after the ovalbumin challenge, the rats were anesthetized with ether and then sacrificed. The first 5 cm of intestine immediately distal to the pylorus were removed, rinsed with ice-cold saline, and the mucosa was scraped and stored at 70" C for PGs determination. The control group consisted of 17 rats which were injected only with the adjuvant 19 days before challenge. They were challenged as the sensitized group.Prostanoid determination, The tissue was sonicated in 1.0 ml of ice-cold 50 mM Tris-HC1 buffer, pH 7.0, containing 0.02 M EDTA. The homogenate was centrifuged and the supernatant was extracted twice with 2 vol of ether. The aqueous phases were assayed for their PG content.PGE2 was determined by radioimmunoassay as described byBauminger et al. (4). TXB,, the stable metabolite of TXA,, and 6-keto PGFI,, the stable metabolite of prostacyclin, were determined by radioimmunoassay as previously described in detail (5). The protein concentration was determined by the method of Lowry d al. (6). Statistical eva...

Eicosanoids Content in Small Intestinal Mucosa of Children with Celiac Disease

“…The authors suggested that LTB 4 may be involved in the pathogenesis of the inflammatory process in IBD. In a rat model of ovalbumin protein hypersensitivity, we have demonstrated significantly elevated content of PGE z (20) and LTB 4 (21) in the small intestinal mucosa of ovalbumin-sensitized and challenged rats compared to controls.…”

Eicosanoids in Hypoxic Insult to Neonatal Rabbit Bowel

“…, bowel hypoxia. Changes reaction , that there is an increase in the bowel content of PGE z and LTB 4 (23,24). In a study by Hyman et al (5) the levels of thromboxane B z were measured in the urine of infants with NEC, and found to be higher than in term healthy infants ; moreover, a gradual decrease in those levels paralleled clinical improvement.…”

Intestinal anaphylaxis in the rat: Mediators responsible for the ion transport abnormalities

“…Stimulation of mucosal mast cells leads to release of a number of preformed and newly synthesized pharmacologically active mediators [5]. These include 5-hydroxytryptamine (5-HT), histamine and the arachidonic acid metabolites prostaglandin D 2 (PGD2) and prostaglandin E 2 (PGE2) which are capable of inducing active C1-secretion [6][7][8] and are known to be released during antigen stimulation of sensitized epithelial tissue [9,10]. In addition, it is known that stimulation of submucosal neurones results in C1-secretion and that 5-HT will activate enteric cholinergic neurones within the submucosal plexus [11].…”