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.

Background: Hepatic ischemia-reperfusion injury (HIRI) is known to affect cognitive functions, with particular concern for its impact on brain metabolic dynamics. Circadian rhythms, as a crucial mechanism for internal time regulation within organisms, significantly influence metabolic processes in the brain. This study aims to explore how HIRI affects hippocampal metabolism and its circadian rhythm differences in mice, and to analyze how these changes are associated with cognitive impairments. Methods: A C57BL/6 male mouse model was used, simulating HIRI through hepatic ischemia-reperfusion surgery, with a sham operation conducted for the control group. Cognitive functions were evaluated using open field tests, Y-maze tests, and novel object recognition tests. Magnetic resonance spectroscopic imaging (MRSI) technology, combined with intravenous injection of [2-¹³C]-acetate and [1-¹³C]-glucose, was utilized to analyze metabolic changes in the hippocampus of HIRI mice at different circadian time points (Zeitgeber Time ZT0, 8:00 and ZT12, 20:00). Circadian rhythms regulate behavioral, physiological, and metabolic rhythms through transcriptional feedback loops, with ZT0 at dawn (lights on) and ZT12 at dusk (lights off). Results: HIRI mice exhibited significant cognitive impairments in behavioral tests, particularly in spatial memory and learning abilities. MRSI analysis revealed significant circadian rhythm differences in the concentration of metabolites in the hippocampus, with the enrichment concentrations of lactate, alanine, glutamate, and taurine showing different trends at ZT0 compared to ZT12, highlighting the important influence of circadian rhythms on metabolic dysregulation induced by HIRI. Conclusions: This study highlights the significant impact of HIRI on brain metabolic dynamics in mice, especially in the hippocampal area, and for the first time reveals the differences in these effects within circadian rhythms. These findings not only emphasize the association between HIRI-induced cognitive impairments and changes in brain metabolism but also point out the crucial role of circadian rhythms in this process, offering new metabolic targets and timing considerations for therapeutic strategies against HIRI-related cognitive disorders.