IMMUNOCYTOCHEMICAL STUDY OF INTESTINAL ENDOCRINE-CELLS IN GERM-FREE MICE

Morphological and functional modifications have been described in the gastrointestinal tract of germ-free rodents in comparison to their con ventional counterparts. These differences have been related to the abs ence of normal flora, but peptides and biogenic amines may also be inv olved. Enteroglucagon-, peptide YY-, somatostatin-, serotonin-, neurot ensin-, chole-cystokinin-, and secretin- producing cells were studied by immunocytochemistry in the ileum, cecum and colon of 10 germ-free, 10 conventional and 5 conventionalized CFW adult male mice. In the cec um and colon of germfree mice, enteroglucagon- and peptide YY-positive cells appeared enlarged, were globular in shape and strongly immunost ained. Enlarged and strongly immunostained serotonin- and neurotensin- positive cells were also seen in some germ-free mice. Somatostatin-pos itive cells and all the endocrine cells of the ileum were similar in t he 3 groups, and no cholecystokinin- or secretin-positive cells were o bserved. Our results are consistent with higher enteroglucagon and pep tide YY production in germ-free mice that may be related to the lower cellular renewal rates and slower gastrointestinal transit reported in these animals. Locally produced biogenic amines and peptides may be i mportant factors in the mediation of the effect of the intestinal flor a on gastrointestinal structure and function and germ-free mice seem t o be a good model for the study of the mechanisms involved.