Differences in Anxiety Levels of Various Murine Models in Relation to the Gut Microbiota Composition

Abstract

Psychobiotics are probiotic strains that confer mental health benefits to the host through the modulation of the gut microbial population. Mounting evidence shows that the gut microbiota play an important role in communication within the gut–brain axis. However, the relationship between the host genetics and the gut microbiota and their influence on anxiety are still not fully understood. Hence, in our research, we attempted to draw a connection between host genetics, microbiota composition, and anxiety by performing an elevated plus maze (EPM) test on four genetically different mice. Four different breeds of 5-week-old mice were used in this experiment: Balb/c, Orient C57BL/6N, Taconic C57BL/6N, and Taconic C57BL/6J. After 1 week of adaptation, their initial anxiety level was monitored using the EPM test via an EthoVision XT, a standardized software used for behavorial testing. Significant differences in the initial anxiety level and microbial composition were detected. Subsequently, the microbiota of each group was modulated by the administration of either a probiotic, fecal microbiota transplantation, or antibiotics. Changes were observed in host anxiety levels in correlation to the shift of the gut microbiota. Our results suggest that the microbiota, host genetics, and psychological symptoms are strongly related, yet the deeper mechanistic links need further exploration.

Substrains matter in phenotyping of C57BL/6 mice

“…However, given that the substrains are widely considered interchangeable, significant phenotypic differences among substrains are often overlooked. The [167,168]. Use of wild-type littermates might standardize the microbiota, thereby facilitating investigation of the phenotype or function of specific genes that could be affected by the microbial community [169,170].…”

Thermoneutral housing promotes hepatic steatosis in standard diet-fed C57BL/6N mice, with a less pronounced effect on NAFLD progression upon high-fat feeding

“…expansion of the phylum Bacteroidetes ) and augment intestinal permeability in HFD-fed B6/J mice ( 16 , 36 ). Microbiome analysis revealed some differences between B6/J and B6/N mouse substrains in cecal and fecal microbial communities ( 37 , 38 ), and there is considerable evidence that the phenotypes of mouse models can vary quite a bit between animal facilities and that these differences may be related to differences in the microbiota ( 39 ). Therefore, an attenuated response to HFD administration and/or TN conditions in terms of negative modulation of gut function could explain the lack of significant liver inflammation observed in HFD-fed B6/N mice in our study.…”

Using Mice to Model Human Disease: Understanding the Roles of Baseline Housing-Induced and Experimentally Imposed Stresses in Animal Welfare and Experimental Reproducibility

“…These examples underscore how important it is for researchers to select the strain(s), protocols for inducing stress, and tests to measure the effects of stress carefully depending on the specific questions they are addressing and to be aware of the strain differences. In fact, differences in stress responses have even been reported between sub-strains of C57BL/6 [136].…”