Institute of Anatomy, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
Int J Mol Sci. 2022 Dec 14;23(24):15934. doi: 10.3390/ijms232415934.
Growing evidence suggests a possible involvement of the intestinal microbiota in generating new neurons, but a detailed breakdown of the microbiota composition is lacking. In this report, we systematically reviewed preclinical rodent reports addressing the connection between the composition of the intestinal microbiota and neurogenesis and neurogenesis-affecting neurotrophins in the hippocampus. Various changes in bacterial composition from low taxonomic resolution at the phylum level to high taxonomic resolution at the species level were identified. As for neurogenesis, studies predominantly used doublecortin (DCX) as a marker of newly formed neurons or bromodeoxyuridine (BrdU) as a marker of proliferation. Brain-derived neurotrophic factor (BDNF) was the only neurotrophin found researched in relation to the intestinal microbiota. Phylum Actinobacteria, genus and genus found the strongest positive. In contrast, phylum Firmicutes, phylum Bacteroidetes, and family Enterobacteriaceae, as well as germ-free status, showed the strongest negative correlation towards neurogenesis or BDNF mRNA expression. Age, short-chain fatty acids (SCFA), obesity, and chronic stress were recurring topics in all studies identified. Overall, these findings add to the existing evidence of a connection between microbiota and processes in the brain. To better understand this interaction, further investigation based on analyses of higher taxonomic resolution and clinical studies would be a gain to the matter.
越来越多的证据表明肠道微生物群在产生新神经元方面可能发挥作用，但缺乏对微生物群组成的详细分析。在本报告中，我们系统地回顾了啮齿动物的临床前研究报告，这些报告涉及肠道微生物群的组成与海马体中的神经发生和影响神经发生的神经营养因子之间的关系。从低分类分辨率（门水平）到高分类分辨率（种水平），确定了细菌组成的各种变化。就神经发生而言，研究主要使用双皮质素 (DCX) 作为新形成神经元的标志物或溴脱氧尿苷 (BrdU) 作为增殖的标志物。脑源性神经营养因子 (BDNF) 是唯一与肠道微生物群相关的研究神经营养因子。放线菌门、和 属与神经发生呈最强正相关。相比之下，厚壁菌门、拟杆菌门和肠杆菌科以及无菌状态与神经发生或 BDNF mRNA 表达呈最强负相关。在所有确定的研究中，年龄、短链脂肪酸 (SCFA)、肥胖和慢性应激都是反复出现的主题。总的来说，这些发现增加了微生物群与大脑过程之间存在联系的现有证据。为了更好地理解这种相互作用，基于更高分类分辨率的分析和临床研究的进一步调查将有助于解决这个问题。
