Liraglutide, a glucagon-like peptide 1 (GLP-1) receptor agonist used in diabetes and obesity, could alleviate depression through a pathway that does not depend on the GLP-1 receptor but instead on the gut microbiota, since the treatment increases the presence of the bacterium Lactobacillus delbrueckii. This symbiotic microorganism produces a lipid that modulates neuronal activity, normalizing the hyperactivation of brain regions in mice involved in emotional processing, which ultimately reduces depressive behaviors.