Histamine and 5‐hydroxytryptamine in the Intestinal Tract of Germ‐free Animals, Animals Harbouring One Microbial Species and Conventional Animals

Abstract

Histamine and 5-hydroxytryptamine were determined in the intestinal tract of germfree and conventional rats and mice. Comparable histamine data were collected in Clostridium perfringens mono-associated rats, while 5-hydroxytryptamine determinations were extended to include the chicken. In rats and mice harbouring an intestinal microflora, bacterial formation of histamine occurs mainly in the caecum. Compared to values found in germ-free animals, histamine levels in the wall of the small intestine of the conventional animal tend to be higher, though in the rat the data are not consistent. Mono-association (harbouring of one microbial species) of germ-free rats with a histamine-producing strain of Clostridium perfringens resulted in high histamine concentrations in the caecal contents, but failed to increase the histamine levels in the wall of the small intestine. 5-Hydroxytryptamine levels in the intestinal wall in the presence of an intestinal flora were generally lower than those in germ-free animals. Modification of the flora by dietary administration of penicillin to mice partly abolished its depressing effect.Comparison of -the intestinal tract of the germ-free animal with that of its conventional counterpart shows a lower relative weight, partially caused by a lower tissue hydration (Gordon & Wostmann, 1960). The absence of a microbial flora strikingly reduces the various reticulo-endothelial elements, notably the plasma cells and the lymphocytes (Gordon & Bruckner-Kardoss, 1961). Apparently the presence of the flora imparts elements of a mild (physiological) inflammation to the gut as an essential part of the mechanism with which the host animal adapts itself to its environment. Results obtained by Gilbert (1959) and by Des Prez, Fallon & Hook (1960) seem to indicate that, depending on the species, histamine and/or 5-hydroxytryptamine are released upon contact with bacterial endotoxins. Histamine formation is accelerated under the influence of Escherichia coli endotoxin (Hinshaw, Jordan & Vick, 1961), evidently through adaptive stimulation of histidine decarboxylase (Schayer, 1962). As both amines are known to induce vasodilatation, increase permeability and produce oedema, they could be important factors in regulating the " adaptive " inflammation. Both histamine and 5-hydroxytryptamine are known to be relatively abundant in the intestinal mucosa of many species, the mucosa being the site of the most intimate contact between the microbial flora and the host.In this paper we present histamine and 5-hydroxytryptamine values in the intestinal tract of animals reared with and without a "normal" microbial flora. Rats and mice were killed by cardiac exsanguination under pentobarbitone anaesthesia. Chickens were exsanguinated after electro-shock. Germ-free animals were taken out of the germ-free environment and sacrificed within 1 hr. Tissues were collected in ice-cold acid saline (0.1 N hydrochloric acid) and stored at -25°C. Homogenization was in acid saline. Aliquots of the total homogenates were used in the...

Histamine and Mast Cell Distribution in the Gastrointestinal Wall of the Rat: Comparison between Germ-Free and Conventional Rats

“…Flowever, such variations have already been described by Beaver and Wostmann [3] and confirmed by Strandberg et al [14], who found the same concentrations as we did in the cecum of CV and GF rats respectively.…”

“…[3] showed that the histamine present in the intestinal contents was higher in CV than in GF rats. No consistent data could be seen on the histamine levels in the wall of the small intestine which 'tended' to be higher in CV that in GF rats.…”

“…an increase of transit and epithelium renewal times, in germ-free (GF) compared to con ventional (CV) rats [1][2][3]. Furthermore, acute inflam matory disorders in some immunopathological states, e.g.…”

The Effect of Hydrocortisone, Thyroxine, and Phenobarbital on Diamine Oxidase Activity in Newborn Rat Intestine

“…Administration of the histamine-receptor antagonists, dimethylpyridine or cimetidine, reverses the shortening of survival time (2). Another factor that may account for increased intestinal histamine levels is the synthesis and release of histamine into the intestinal lumen by intestinal bacteria, specifically Clostridium perfringens (16). This is interesting because this organism is associated with an outbreak of necrotizing enterocolitis.…”

Histamine distribution in the gastrointestinal wall of germ free and conventional chicken: Evidence of the role of the digestive microflora

“…Mild chronic inflammation due to the presence of the microbial intestinal flora has been evoked to explain physiological differences in the digestive processes in germ-free (GF) compared to conventional (CV) animals [1,2]. Wal et al [3] have observed that wall histamine concentration increased in the small intestine and decreased in the colon of CV rats compared to GF rats, and that the highest mucosal histamine levels were found in the stomach both for GF and CV rats.…”