Analysis of the Gut Microbiota and Inflammatory Factors in mGluR5-Knockout Mice.

INTRODUCTION

Accumulating evidence indicates that the glutamatergic system plays an important role in the development of depression. Notably, the antidepressant effect of metabotropic glutamate receptor 5 (mGluR5) modulation is inconsistent across studies. Here, we attempted to identify the involvement of the gut microbiota and inflammation in mGluR5 mice.

METHODS

mGluR5 mice and their wild-type littermates were used in our study. We used the open field (OF) and elevated plus maze (EPM) tests to assess anxiety-like behaviors, and we used the two-day forced swim test (FST) and tail suspension test (TST) to test despair-like behaviors. 16S rDNA was used to analyze the gut microbiota. Enzyme-linked immunosorbent assays (ELISAs) were used to measure the levels of inflammatory factors. Western blotting was used to detect the levels of various proteins.

RESULTS

mGluR5 mice had no significant increase or decrease of despair-like behavior in the absence of stress exposure. However, mGluR5 mice exhibited despair-like behaviors following stress exposure. No significant changes in other glutamate receptors or representative synaptic proteins were detected in the prefrontal cortex (PFC) or hippocampus of mGluR5 mice. Very similar bacterial groups were observed in mGluR5 mice and wild-type controls. In addition, there was no significant difference in the -diversity of the microbiota between mGluR5 mice and wild-type controls. The levels of all measured cytokines (IL-1, IL-2, IL-4, IL-6, IL-10, and TNF-) did not change significantly in the PFCs or colons of mGluR5 mice.

CONCLUSION

In conclusion, we deduced that mGluR5 mice are susceptible to despair-like behavior. The systemic knockout of mGluR5 did not affect the gut microbiota or inflammatory factors in mice.