Abnormal composition of gut microbiota contributes to delirium-like behaviors after abdominal surgery in mice.

AIMS: Anesthesia and surgery can cause delirium-like symptoms postoperatively. Increasing evidence suggests that gut microbiota is a physiological regulator of the brain. Herein, we investigated whether gut microbiota plays a role in postoperative delirium (POD). METHODS: Mice were separated into non-POD and POD phenotypes after abdominal surgery by applying hierarchical clustering analysis to behavioral tests. Fecal samples were collected, and 16S ribosomal RNA gene sequencing was performed to detect differences in gut microbiota composition among sham, non-POD, and POD mice. Fecal bacteria from non-POD and POD mice were transplanted into antibiotics-induced pseudo-germ-free mice to investigate the effects on behaviors. RESULTS: α-diversity and ß-diversity indicated differences in gut microbiota composition between the non-POD and POD mice. At the phylum level, the non-POD mice had significantly higher levels of Tenericutes, which were not detected in the POD mice. At the class level, levels of Gammaproteobacteria were higher in the POD mice, whereas the non-POD mice had significantly higher levels of Mollicutes, which were not detected in the POD mice. A total of 20 gut bacteria differed significantly between the POD and non-POD mice. Interestingly, the pseudo-germ-free mice showed abnormal behaviors prior to transplant. The pseudo-germ-free mice that received fecal bacteria transplants from non-POD mice but not from POD mice showed improvements in behaviors. CONCLUSIONS: Abnormal gut microbiota composition after abdominal surgery may contribute to the development of POD. A therapeutic strategy that targets gut microbiota could provide a novel alterative for POD treatment.

Relationship between Volatile Anesthetics and Tumor Progression: Unveiling the Mystery.

A series of factors can be involved in the perioperative period to cause an increase in cancer-related mortality. Unfortunately, volatile anesthesia might aggravate the deleterious effects. In this article, we review the association of diverse volatile anesthetic agents with immune system and cancer cell biology, and examine the effects on angeogenesis and postoperative metastasis or recurrence. Isoflurane, haloflurane and enflurane enhance immunosuppression and upregulate hypoxia-inducible-factor 1 and matrix metalloproteinases, leading to the cancer malignant progression, whereas roles of desflurane and sevoflurane are still unclear. As the effects of volatile anesthetics on tumor immunity have been known, it will be beneficial for using selective drugs into anesthesia and operation in cancer patients.