Introduction: The gut microbiota-brain axis is a bidirectional communication between the resident microbes, the gut, and the brain; it plays a pivotal role in aging and age-related diseases, particularly neurodegenerative conditions. Probiotics have emerged as a promising avenue for interventions targeting age-related diseases by modulating this axis. In this study, we explore the effects of the commensal bacteria and probiotic Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) on the gut-brain axis in the fruit fly Drosophila melanogaster by using an untargeted metabolomics approach. Flies are a genetically amenable model, display age-related phenotypes, and have a simpler microbiota than mammals that is easy to manipulate. These traits allow discoveries made in flies translatable to mammals.

Method: To understand how L. plantarum can provide a benefit to the health of animals we supplemented young and old flies with or without L. plantarum. These flies were flash-frozen and separated by heads (brain) and bodies (intestine and other organs) and collected separately. This approach allowed us to identify changes in metabolites that are age-, tissue- and treatment-specific.

Results: Our results show a total of 855 biochemicals: 798 known biochemicals and 57 unknown biochemicals. Our findings revealed substantial metabolomic disparities linked to age and body section, emphasizing the dynamic nature of the gut-brain axis in the context of aging. Notably, the influence of L. plantarum supplementation on the metabolome appeared relatively modest. However, there were significant differences in neurotransmitters of interest, specifically acetylcholine which is increased in the bodies of old flies treated with L. plantarum. Preliminary data from our lab shows that L. plantarum can alter sleep latency and locomotion.

Conclusions: Our ongoing work aims to characterize the link between L. plantarum-mediated changes in neurotransmitters and distinct behaviors. Data obtained from this project will help us characterize the molecular mechanisms used by L. plantarum to influence the gut-brain axis.

Acknowledgements: We thank the funding provided by UPRRP Start-up funds, NIH-NIGMS COBRE (5P20GM103642-10) and the Catalyzer Research Grant (#2023-00056) Puerto Rico Science, Technology & Research Trust (PRST). Funding from LSAMP, RISE UPRRP and NSF IQBIOREU. Thanks to W. Ludington (Carnegie Science) for proving LpWF strain and N. Fuenzalida (UPRRP) for technical help in setting up sleep experiments.

Authors:

Melanie Reinoso Arnaldi

Caroline Casiano

Charles Pfeiffer

Josue Rodriguez-Cordero

Alfredo Ghezzi

Jose Agosto

Imilce A. Rodriguez-Fernandez

College of Natural Sciences, Department of Biology, University of Puerto Rico Rio Piedras