Location: Livestock Behavior ResearchTitle: The microbiota-gut-brain axis: Gut microbiota modulates conspecific aggression in diversely selected laying hens
Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2022
Publication Date: 5/24/2022
Citation: Hu, J., Johnson, T., Zhang, H., Cheng, H. 2022. The microbiota-gut-brain axis: Gut microbiota modulates conspecific aggression in diversely selected laying hens. Frontiers in Microbiology.2022; 10(6):1081. https://doi.org/10.3390/microorganisms10061081.
Interpretive Summary: Gut microbiota plays an important role in the bidirectional interactions between the gut and brain. Disturbance of the commensal gut microbiota leads to both intestinal and neuropsychiatric disorders. The goal of this project was to examine if injurious behavior in laying hens can be prevented or reduced by modification of gut bacteria. The project objectives were to profile the gut microbiota of two diversely selected inbred chicken lines and to evaluate the line’s unique correlations between aggression, gut microbiota composition and diversity, and physiological attribute. The results show there was a functional linkage between the line differences in serotonergic activity, stress response, innate immunity, and gut microbial community. The data suggests gut microbiota has the potential to directly regulate aggressiveness through the gut-brain axis. This information can be used by scientists and egg producers to develop new management strategies to prevent or reduce injurious behavior in laying hens.
Technical Abstract: Commensal gut microbiota plays an important role in regulating brain function, consequently influencing mental and emotional stability. Modification of gut microbiota composition has been identified as a biotherapy in neuropsychiatric disorders. But the precise mechanism underlying the gut microbiota effects on neuropsychiatric pathophysiology has not been well investigated. The aim of this study was to reveal the unique correlations between conspecific aggression, gut microbiota composition and diversity, and physiological attribute of two unique inbred chicken lines. The lines, 63 and 72, were diversely selected for resistance and susceptibility to Marek’s disease and lymphoid leukosis, and they are also known to behave differently in aggression as well as egg production. Ten 60-week-old hens from each line were sampled for blood, brain and cecal content (n=10). Serotonin, tryptophan, epinephrine, norepinephrine, cytokines, corticosterone, and heterophil/lymphocyte ratio were determined. In addition, bacterial microbiota in the cecal samples were determined by sequencing of the V4 region of the 16s rRNA genes and related functional prediction was performed. The results showed that the central serotonin and tryptophan levels were higher in line 63 compared to line 72 (P < 0.05). In addition, stress indicators, including the levels of plasma corticosterone, heterophil/lymphocyte ratio, and central norepinephrine, were lower in line 63 (P < 0.05). The level of tumor necrosis factor (TNF)-a tended to be higher in line 63. In the cecum, several major genera, including Eubacterium, Bacteroides, Faecalibacterium, Fournierella, and Lachnospiraceae were enriched in line 63, while Clostridiales vadin BB60 and Romboutsia were dominated in line 72. Multiple metabolic pathways were also differentially regulated between the lines; particularly, the kynurenine pathway of tryptophan metabolism was predicted to be more active in line 72. These results suggest there is a functional linkage between the line differences in serotonergic activity, stress response, innate immunity, and gut microbial community. The gut microbial ecology interacting with the line genotype or phenotype affects hens’ aggression through the gut-brain axis. It provides a new sight for preventing or reducing injurious behavior through modifying the gut microbiota (microbiome).