Probiotic Bacterial Produced Serotonin (5-HT) in the Microbiome of Caenorhabditis Elegans Alters Behavior

Name: Jillian Murray
Major: Neuroscience (Biology)
Minor: Psychology

Research about the neural connections between the gut and brain, called the gut-brain-axis, have emerged as an exciting field of neuroscience and psychology as a possible treatment for mood disorders caused by neurotransmitter imbalance. Scientists have found that bacteria within the microbiome of the gut influence properties of inflammation, immunity, and the production of neurotransmitters. Over-the-counter probiotic supplements have recently been marketed with the idea that the beneficial strains of bacteria can be colonized in microbiome of humans to produce serotonin (5-HT) and dopamine, two neurotransmitters reduced in depression. In the literature however, the success of probiotics in altering mood and behavior has been highly debated, and ultimately deemed unsuccessful. Our study analyzes the behavioral effect of probiotic bacterium that secrete 5-HT (Lactobacillus gasseri, Lactobacillus helveticus and Bifidobacterium bifidum) in the organism Caenorhabditis elegans. We colonized the microbiome of WT and 5-HT deficient nematodes (cat-4) with these bacterial strains, and measured changes in male tail curling and locomotive food motivation, both 5-HT dependent behaviors. We hypothesized that probiotic bacteria would rescue 5-HT dependent behaviors in the cat-4 mutant and cause an increase in tail curling and locomotive behavior. Our hypothesis was proven partially correct, showing that microbiome produced 5-HT increased tail curling behavior, however reduced locomotive behavior in both WT and cat-4 nematodes. These findings demonstrate that over the counter probiotic supplements can transport through the gut-brain-axis and may be a beneficial component to supplement mood disorder treatment.

Posted in Comments Enabled, Independent Study, Symposium 2023 on April 13, 2023.

2 responses to “Probiotic Bacterial Produced Serotonin (5-HT) in the Microbiome of Caenorhabditis Elegans Alters Behavior”

1. Katie Fleig says:

   April 20, 2023 at 8:19 pm

   Congratulations, Jillian!!

2. Ann Agurkis says:

   April 21, 2023 at 8:29 am

   Is the probiotic bacterium which you studied the common types found in OTC probiotics? Also are there specific foods that seem to have the same benefit or perhaps just a well rounded diet? Do you think there has been a change in general re: people’s or more specifically, teens/young adults’, micro biomes that could be related to the rise in depression and anxiety over the last several years?
   So many questions! How long did it take to change the micro biome of the nematodes and does this translate to human time line? Ie how long could it possible take to start feeling better if one takes OTC probiotics for depression, for instance?