Effects of Sevoflurane Anesthesia on Cerebral Lipid Metabolism in the Aged Brain of Marmosets and Mice

Boosting Microglial Lipid Metabolism via TREM2 Signaling by Biomimetic Nanoparticles to Attenuate the Sevoflurane-Induced Developmental Neurotoxicity

Lipid metabolism has been considered as a potential therapeutic target in sevoflurane-induced neurotoxicity that can potentially affect the learning and memory function in the developmental brain. Recently, triggering receptor expressed on myeloid cells 2 (TREM2) is identified as a crucial step in regulating lipid metabolism and associated with the pathogenesis of neurodegenerative diseases. Herein, it is reported that quercetin modified Cu2- x Se (abbreviated as CSPQ) nanoparticles can ameliorate sevoflurane-induced neurotoxicity by tuning the microglial lipid metabolism and promoting microglial M2-like polarization via TREM2 signaling pathway, in which the apolipoprotein E (ApoE), and adenosine triphosphate-binding cassette transporters (ABCA1 and ABCG1) levels are upregulated. Furthermore, the protective effects of CSPQ nanoparticles against sevoflurane-induced neurotoxicity via TREM2 are further demonstrated by the small interfering RNA (siRNA)-TREM2 transfected BV2 cells, which are obviously not influenced by CSPQ nanoparticles. The cell membrane coated CSPQ (referred as CSPQ@CM) nanoparticles can significantly reduce sevoflurane-induced learning and memory deficits, improve lipid metabolism dysfunction, and promote the remyelination in the hippocampus of mice. The study shows great potential of targeting microglial lipid metabolism in promoting remyelination of neurons for treatment of neurotoxicity and neurodegenerative diseases.

Comparison of differential metabolites in brain tissue of aged marmosets and serum of elderly patients after prolonged anesthesia

Objective

To compare the differential metabolites in the brain tissue of aged marmosets after long-term anesthesia (≥ 6 h) and the serum of elderly patients by metabolomics methods.

Methods

Six aged marmosets (≥ 8 years old) were divided into two groups: anesthesia and control. The aged monkeys in the anesthesia group were induced with 6-8% sevoflurane and 100% oxygen (2 l/min) for 1-2 min and maintained with 1.5-2.5% sevoflurane and 100% oxygen (2 l/min) for 6 h. In the control group (n = 3), anesthesia was only induced under the same conditions for 1-2 min. The prefrontal cortex tissues of the two groups of aged marmosets were collected for metabolomics detection. Twenty-nine elderly patients (≥ 65 years old) who had undergone surgical anesthesia for more than 6 h were enrolled. Serum samples were collected before and on the first day after surgery for metabolomics analysis. Differential metabolites were compared between human serum and marmoset brain tissue.

Results

The changes in lactate and xanthurenic acid in the serum of elderly patients were consistent with those in the brain tissue of aged marmoset monkeys, that is, lactate was up-regulated and xanthurenic acid was down-regulated. However, serum levels of 5-methylterahydrofolic acid and leucine were down-regulated in elderly patients after anesthesia. In contrast, 5-methylterahydrofolic acid and leucine levels were up-regulated in the prefrontal cortex of aged marmosets compared with control marmosets. Furthermore, glycolysis/gluconeogenesis and pentose phosphate pathway were both significantly enriched in the prefrontal cortex of aged marmosets and serum of elderly patients after surgery.

Conclusion

The changes of serum metabolites in elderly patients are not exactly the same as the metabolic changes of brain tissues in aged marmosets. The metabolic changes in serum lactate and xanthurenic acid levels can reflect brain tissue metabolism. The enrichment pathways of differential metabolites in the serum of elderly patients and the brain tissue of aged marmosets were partially the same.