Exploring the Impact of the Microbiome on Neuroactive Steroid Levels in Germ-Free Animals

The study investigates the impact of the microbiome on neuroactive steroid levels in germ-free (GF) animals, revealing significant alterations in these levels compared to animals with a normal microbiome. Using liquid chromatography–tandem mass spectrometry, researchers found changes in neuroactive steroids in both plasma and various brain regions of GF mice, such as increased allopregnanolone and decreased 5α-androstane-3α, 17β-diol in plasma, and alterations in dihydroprogesterone, isoallopregnanolone, dihydrotestosterone, and dehydroepiandrosterone in the hippocampus, cerebellum, cerebral cortex, and hypothalamus. The study, which included 8 male GF and conventional mice per group, suggests that gut microbiota significantly influence neuroactive steroid levels, highlighting the microbiome's critical role in modulating neuroendocrine pathways and maintaining brain function, with potential implications for psychiatric disorders.