Rat gastric motor response to food protein-induced anaphylaxis.

OBJECTIVE

Antigen challenge of sensitized rats leads to delayed gastric emptying, but the mechanism (gastroparesis or prolonged trituration) and mediators are unknown.

METHODS

Hooded Lister rats were sensitized by intraperitoneal injection of egg albumin as antigen, and control rats were sham-sensitized. On day 14, antral manometric and antroduodenal myoelectric activities in sensitized and sham-sensitized rats were recorded in response to antigen challenge, and the contractility of gastric antral circular muscle strips (mucosa intact) in standard tissue baths was measured in response to antigen or other agents.

RESULTS

In vivo, the intragastric antigen challenge of sensitized (but not sham-sensitized) rats provoked diarrhea, reduction in the antral motility index, and disruption of the duodenal migrating motor complex. In vitro, antigen induced a tonic contraction of antral circular muscle segments from sensitized animals. Doxantrazole, but not disodium cromoglycate, inhibited antigen-induced contraction. Whereas histamine, 5-hydroxytryptamine, prostaglandins, leukotrienes, and platelet-activating factor contracted gastric muscle strips, neither specific antagonists, prostaglandin synthase, or 5-lipoxygenase inhibitors inhibited antigen-induced contraction. Tetrodotoxin increased antigen-induced contraction; however, the antigen-induced contraction was unaffected by atropine, guanethidine, or NG-nitro-L-arginine methyl ester.

CONCLUSIONS

Food protein-induced, immunoglobulin E-mediated delayed gastric emptying in sensitized rats is associated with a transient reduction in gastric antral contractions. Antigen-induced contraction appears to be under nonadrenergic, noncholinergic, nonnitroxinergic inhibitory neural control.