Overview
- The peer-reviewed animal study published May 15 in Molecular Psychiatry used spatial transcriptomics to compare short-term and long-term fluoxetine exposure and mapped gene changes across the dorsal raphe serotonin field.
- Researchers identified two distinct serotonin neuron subpopulations: one shows a short-term rise in prodynorphin (Pdyn) that fades with prolonged treatment, and another shows a delayed increase in thyrotropin-releasing hormone (TRH) after weeks.
- Authors suggest the opposing molecular timelines may explain a common clinical pattern where some patients feel worse soon after starting an SSRI but improve only after several weeks.
- The findings are preclinical and do not prove causation in humans; the team and press releases emphasize the need for functional experiments, cross-species checks, and clinical validation before any change to treatment.
- The study also shows how spatial transcriptomics can reveal cell-type and location-specific drug effects and it points to Pdyn and TRH pathways as targets for research aimed at faster or safer antidepressant therapies.