[Antibiotic-associated diarrhoea and enterocolitis (author's transl)]

Effects of Atractylodes lancea extracts on intestinal flora and serum metabolites in mice with intestinal dysbacteriosis

OBJECTIVE

This study aims to explore the effect of an extract of Atractylodes lancea (A. lancea) on antibiotics-induced intestinal tract disorder and the probable therapeutic mechanisms employed by this extract to ameliorate these disorders.

METHODS

Three days after acclimatization, nine male and nine female specific-pathogen-free (SPF) mice were randomly assigned into three groups: Group C (normal saline), Group M (antibiotic: cefradine + gentamicin), and Group T (antibiotic + A. lancea extract). Each mouse in Groups M and T received intragastric (i.g.) gavage antibiotics containing cefradine and gentamicin sulfate (0.02 ml/g^-1/D^-1) for 7 days. A. lancea extract (0.02 ml/g^-1/D^-1) was administered by i.g. gavage to Group T mice for 7 days following the cessation of antibiotic therapy. Group M received an equivalent volume of normal saline for 7 days, while Group C received an equivalent volume of normal saline for 14 days. Afterwards, we collected mouse feces to assess changes in intestinal microbiota by 16S ribosomal ribonucleic acid (rRNA) sequencing and metabolomics. In addition, serum samples were gathered and analyzed using liquid chromatography-mass spectrometry (LS-MS). Finally, we performed a correlation analysis between intestinal microbiota and metabolites.

RESULTS

After treatment with antibiotic, the richness and diversity of the flora, numbers of wall-breaking bacteria and Bacteroidetes, and the numbers of beneficial bacteria decreased, while the numbers of harmful bacteria increased. After i.g. administration of A. lancea extract, the imbalance of microbial flora began to recover. Antibiotics primarily influence the metabolism of lipids, steroids, peptides, organic acids, and carbohydrates, with lipid compounds ranking first. Arachidonic acid (AA), arginine, and proline have relatively strong effects on the metabolisms of antibiotic-stressed mice. Our findings revealed that A. lancea extract might restore the metabolism of AA and L-methionine. The content of differential metabolites detected in the serum of Group T mice was comparable to that in the serum of Group C mice, but significantly different from that of Group M mice. Compared to putative biomarkers in the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, it was found that altered metabolites, such as amino acids, glycerol, and phospholipids, were primarily associated with the metabolism.

CONCLUSIONS

The effective mechanisms of A. lancea extract in regulating the disorder of intestinal flora in mice are related to the mechanisms of A. lancea. It could relate to lipid metabolism, bile acid metabolism, and amino acid metabolism. These results will provide a basis for further explaining the mechanism by which A. lancea regulats intestinal flora.

Acute, massive, haemorrhagic adrenal necrosis experimentally produced by the Shwartzman mechanism in rabbits

Acute and severe haemorrhagic necrosis of the adrenal was produced experimentally in rabbits by means of intravenous injection of endotoxin after pretreatment by adrenocorticotropic hormone (ACTH) administration. The change occurred mainly in the zona fasciculata of the adrenal cortex, and its pathology was quite similar to that of the Shwartzman reaction. Numerous microthrombi were found in and around the lesion, but no marked changes were seen in other parts of the body. Heparin administration was very effective in preventing the necrosis. The pathogenesis of this lesion was postulated to be a univisceral Shwartzman mechanism in the adrenal. This seems to be a good experimental model for massive haemorrhagic necrosis of the adrenal in man, for example in the Waterhouse-Friderichsen syndrome, the pathogenesis of which has been assumed to involve intravascular clotting. It is suggested that hyperfunction of the adrenal cortex caused by ACTH administration could be a preparative condition for the Shwartzman reaction.

Enterotoxins from gram-negative bacteria relevant for veterinary medicine

The chemistry, mechanism of action, assay methods, pharmacology, and prevention and treatment of diarrhoea due to toxins of gram-negative microbes are discussed. Other virulence factors are mentioned briefly. Special emphasis is placed on non-specific treatment by oral rehydration.