Decoding the contributions of gut microbiota and cerebral metabolism in acute liver injury mice with and without cognitive dysfunction

Gut Microbiota-Mediated Alterations of Hippocampal CB1R Regulating the Diurnal Variation of Cognitive Impairment Induced by Hepatic Ischemia-Reperfusion Injury in Mice

Patients suffering from hepatic ischemia-reperfusion injury (HIRI) frequently exhibit postoperative cognitive deficits. Our previous observations have emphasized the diurnal variation in hepatic ischemia-reperfusion injury-induced cognitive impairment, in which gut microbiota-associated hippocampal lipid metabolism plays an important role. Herein, we further investigated the molecular mechanisms involved in the process. Hepatic ischemia-reperfusion surgery was performed under morning (ZT0, 08:00) and evening (ZT12, 20:00). Fecal microbiota transplantation was used to associate HIRI model with pseudo-germ-free mice. The novel object recognition test and Y-maze test were used to assess cognitive function. 16S rRNA gene sequencing and analysis were used for microbial analysis. Western blotting was used for hippocampal protein analysis. Compared with the ZT0-HIRI group, ZT12-HIRI mice showed learning and short term memory impairment, accompanied by down-regulated expression of hippocampal CB1R, but not CB2R. Both gut microbiota composition and microbiota metabolites were significantly different in ZT12-HIRI mice compared with ZT0-HIRI. Fecal microbiota transplantation from the ZT12-HIRI was demonstrated to induce cognitive impairment behavior and down-regulated hippocampal CB1R and β-arrestin1. Intraperitoneal administration of CB1R inhibitor AM251 (1 mg/kg) down-regulated hippocampal CB1R and caused cognitive impairment in ZT0-HIRI mice. And intraperitoneal administration of CB1R agonist WIN 55,212-2 (1 mg/kg) up-regulated hippocampal CB1R and improved cognitive impairment in ZT12-HIRI mice. In summary, the results suggest that gut microbiota may regulate the diurnal variation of HIRI-induced cognitive function by interfering with hippocampal CB1R.

The Role of Gut Microbiota and Circadian Rhythm Oscillation of Hepatic Ischemia-Reperfusion Injury in Diabetic Mice

Circadian rhythm oscillation and the gut microbiota play important roles in several physiological functions and pathology regulations. In this study, we aimed to elucidate the characteristics of diabetic hepatic ischemia-reperfusion injury (HIRI) and the role of the intestinal microbiota in diabetic mice with HIRI. Hepatic ischemia-reperfusion injury surgery was performed at ZT0 or ZT12. The liver pathological score and the serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were analyzed to evaluate liver injury. We conducted an FMT experiment to examine the role of intestinal microbiota in diabetic mice with HIRI. The 16S rRNA gene sequencing of fecal samples was performed for microbial analysis. Our results showed that hyperglycemia aggravated HIRI in diabetic mice, but there was no diurnal variation seen in diabetic HIRI. We also demonstrated that there were significant alterations in the gut microbiota composition between the diabetic and control mice and that gut microbiota transplantation from diabetic mice had obvious harmful effects on HIRI. These findings provide some useful information for the future research of diabetic mice with HIRI.

Improvements of Age-Related Cognitive Decline in Mice by Lactobacillus helveticus WHH1889, a Novel Strain with Psychobiotic Properties

A gradual decline in cognitive function occurs with age. Accumulating evidence suggests that certain probiotic strains exert beneficial effects on age-related cognitive decline. Our previous study revealed that Lactobacillus helveticus WHH1889 attenuated symptoms of anxiety and depression in depressed mice via shaping the 5-hydroxytryptamine (5-HT) and 5-hydroxytryptophan (5-HTP) metabolism and gut microbial community, indicating the psychobiotic potential of WHH1889. In the present study, the effects of WHH1889 on age-related cognitive decline were investigated. WHH1889 was orally administrated (1 × 109 CFU/day) for twelve weeks in aged mice, and their cognitive behaviors, neurochemical factors, cognitive-related gene expressions, neuroinflammation, and serum tryptophan pathway-targeted metabolic profiling, as well as gut microbiome composition were assessed. WHH1889 demonstrated improvement of the cognitive behaviors via the novel object recognition test (NORT), the active shuttle avoidance test (ASAT), the Y-maze test, and the passive avoidance test (PAT). The hippocampal neuronal loss; the declined concentrations of BDNF, 5-HT, and 5-HTP; the decreased gene expressions of neurodegeneration biomarkers; and the increased production of hippocampal inflammatory cytokines in aged mice were restored by WHH1889. In addition, WHH1889 increased the 5-HT/5HTP levels and decreased the serum levels of tryptophan-derived metabolites (e.g., kynurenine, xanthurenic acid, 3-hydroxykynurenine, and 3-hydroxyanthranilic acid). Furthermore, WHH1889 was revealed to shape the gut microbiota community by reversing the relative abundances of Bacteroidota and Firmicutes. The present findings suggest that L. helveticus WHH1889 exerted cognitive improving effects on aged mice, which was associated with the modulation of 5-HT and 5-HTP metabolism and gut microbial composition. The supplementation of WHH1889 may therefore be a promising therapeutic agent for age-related cognitive deficits.

Regulation of mild cognitive impairment associated with liver disease by humoral factors derived from the gastrointestinal tract and MRI research progress: a literature review

Patients with liver disease are prone to various cognitive impairments. It is undeniable that cognitive impairment is often regulated by both the nervous system and the immune system. In this review our research focused on the regulation of mild cognitive impairment associated with liver disease by humoral factors derived from the gastrointestinal tract, and revealed that its mechanisms may be involved with hyperammonemia, neuroinflammation, brain energy and neurotransmitter metabolic disorders, and liver-derived factors. In addition, we share the emerging research progress in magnetic resonance imaging techniques of the brain during mild cognitive impairment associated with liver disease, in order to provide ideas for the prevention and treatment of mild cognitive impairment in liver disease.

The role of gut microbiota in diabetic peripheral neuropathy rats with cognitive dysfunction

Introduction

Owing to advancements in non-invasive magnetic resonance imaging, many studies have repeatedly showed that diabetes affects the central nervous system in the presence of peripheral neuropathy, suggesting a common or interacting pathological mechanism for both complications.

Methods

We aimed to investigate the role of abnormal gut microbiota in rats with diabetic peripheral neuropathy (DPN) combined with cognitive dysfunction. Glucose-compliant rats with nerve conduction deficits were screened as a successful group of DPN rats. The DPN group was then divided into rats with combined cognitive impairment (CD) and rats with normal cognitive function (NCD) based on the results of the Novel object recognition test. Rat feces were then collected for 16S rRNA gene sequencing of the intestinal flora.

Results and Discussion

The results revealed that abnormalities in Firmicutes, Ruminococcaceae, Bacteroidia, and Actinobacteria-like microorganisms may induce DPN complicated by cognitive dysfunction.