A rat model for an in vivo assay of enterotoxic diarrhea

The heat-labile enterotoxins from Vibrio cholerae (CT) or Escherichia coli (LT) cause diarrheal disease by increasing the intracellular level of 3'5'-adenosine monophosphate (cAMP) in the intestinal epithelium [1]. A similar hypersecretion is induced by dibutyryl-cyclic AMP (DB-cAMP) and prostaglandin E I (PGE 1), and these agents are therefore used for elucidating the mechanisms underlying enterotoxic diarrhea. Diarrhea in response to intestinal CT challenge has been registered in several animal species including mouse [2,3], rat [4], hamster, guinea pig, cat [5], chinchilla [6], rabbit [7], dog [8], and miniature pig [9]. These reports have, however, mostly been focused on immunological or bacteriological aspects, and detailed information about the test animal and the operation procedure has been lacking. In the present study the rats are used as test animals for several reasons; (1) various genetically homogeneous inbred strains are available; (2) the animal size is suitable for untroubled abdominal surgery; (3) short-time anesthesia with ether can be used during operation, which eliminates the influence of anesthetic drugs on the secretory process [10]. 2.1. Chemicals