Fecal microbiota transplantation improves spatial learning disability caused by developmental anesthetic neurotoxicity in neonatal rats

Abstract

Abstract Background: Anesthetic exposure induces neurodegeneration in children. Although this problem has been elucidated in decades, the prophylaxis for developmental anesthetic neurotoxicity (DAN) has not been established. It has been reported that gut microbiota produces various metabolites and influences brain function of host, which has been called as Gut microbiota-Brain axis. We report the effect of fecal microbiota transplantation (FMT) on spatial learning disability caused by DAN in neonatal rats. Methods: In experiment 1, neonatal rats were divided into C (Control) and S (Sevoflurane) groups to elucidate the effect of sevoflurane exposure on gut microbiota composition. In S group, rats were exposed by 2.1% sevoflurane for 2 hours in postnatal day (PND) 7-13. In experiment 2, neonatal rats were divided into S and SF groups. In SF group, neonatal rats were received FMT just after sevoflurane exposure in PND 7-13. The sample of FMT was obtained from non-anesthetized mother rat. Behavioral tests were performed to evaluate spatial learning ability from PND 26-39. Results: Sevoflurane exposure significantly altered the gut microbiota composition. Especially, the relative abundance of Bacteroidetesphylum was significantly increased and that of Firmicutes phylum was significantly decreased by sevoflurane exposure. The FMT improved spatial learning ability. The microbiota analysis revealed that the α-diversity of gut microbiota was increased by FMT. Particularly, FMT decreased the relative abundances of Bacteroidetes phylum, Bacteroidia class, Bacteroidales order, Bacteroidaceae family, Bacteroides genus. Meanwhile, the relative abundances of Firmicutes phylum, Clostridia order, Clostridiales class, Ruminococcaceae family, Ruminococcus genus, and butyric acid-producing bacteria increased by FMT. Moreover, the FMT increased the fecal concentration of butyrate, and exerted the histone acetylation and the mRNA expression of brain derived neurotrophic factor in hippocampus. Immunofluorescence staining with Iba-1 antibody revealed that microglia infiltration in hippocampus was significantly suppressed by FMT. The mRNA expressions of apoptosis-inducing proteins were significantly suppressed and those of anti-apoptotic proteins were significantly promoted by FMT. The TUNEL staining indicated that neuronal apoptosis in hippocampus was significantly suppressed by FMT. Conclusions: FMT improved spatial learning ability in rats with DAN. The modulation of gut microbiota might be an effective prophylaxis for DAN in children.