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Eero Castrén

Neuroscience Center, HiLIFE and Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki 00014, Finland.

5 papers in the library · 144 citations · publishing 2023-2025

Papers

Beyond the 5-HT2A Receptor: Classic and Nonclassic Targets in Psychedelic Drug Action.

The Journal of neuroscience : the official journal of the Society for Neuroscience November 8, 2023 Lindsay P Cameron, Joseph Benetatos, Vern Lewis et al. 88 citations

Serotonergic psychedelics like psilocybin and LSD activate serotonin 5-HT2A receptors in cortical brain regions, altering perception, cognition, and emotions. Their ability to promote neuroplasticity—forming new neural connections and rewiring networks—is thought to underlie therapeutic potential for depression, anxiety, and substance use disorders. These compounds also interact with other serotonin receptor subtypes (5-HT1A, 5-HT2C) and neurotrophin receptors, adding complexity to their effects. Research is exploring nonhallucinogenic derivatives that retain therapeutic benefits without intense psychedelic experiences, potentially reducing adverse reactions. The review also discusses psychedelics as substrates for post-translational protein modification as part of their mechanism.

Rethinking the role of TRKB in the action of antidepressants and psychedelics.

Trends in neurosciences November 1, 2024 Cecilia Anna Brunello, Cecilia Cannarozzo, Eero Castrén 29 citations

Antidepressant drugs, including slow-acting types, fast-acting ketamine, and psychedelics, all promote neuronal plasticity through activation of BDNF signaling via its receptor TRKB, though each drug targets different cells. The authors propose that some antidepressants may directly bind to TRKB and allosterically enhance BDNF signaling. Activating TRKB in parvalbumin-containing interneurons disinhibits cortical networks and reopens a juvenile-like window of plasticity. This rewiring of faulty neural circuits, combined with environmental input, may explain clinical antidepressant effects. This hypothesis could guide development of new treatments.

Fluoxetine and Ketamine Enhance Extinction Memory and Brain Plasticity by Triggering the p75 Neurotrophin Receptor Proteolytic Pathway.

Biological psychiatry February 1, 2025 Cassiano Ricardo Alves Faria Diniz, Ana Paula Crestani, Plinio Cabrera Casarotto et al. 15 citations

Antidepressants such as fluoxetine and ketamine bind to the p75 neurotrophin receptor (p75NTR) and trigger its proteolysis by α- and γ-secretase, leading to p75NTR nuclear localization. These drugs also enhance brain plasticity and extinction memory in mice and rats, and these effects depend on p75NTR signaling. The authors propose that antidepressants co-opt both the BDNF/TrkB and proBDNF/p75NTR systems to promote activity-dependent synaptic competition and brain remodeling.

Antidepressants enter cells, organelles, and membranes.

Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology January 1, 2024 Zack Blumenfeld, Kallol Bera, Eero Castrén et al. 10 citations

Many antidepressants work by entering cells and binding to targets inside the cytoplasm or organelles, contrary to the traditional view that they act only at extracellular sites on cell surface proteins. The ability of a drug to cross membranes depends on its charge and lipid solubility, described by parameters LogP, pKa, and LogD at pH 7.4. Some antidepressants have an unusually large volume of distribution, reflecting both binding to membranes and trapping inside acidic organelles. For SSRIs and SNRIs, the exact cellular compartment where they engage their target transporters remains unknown. Rapidly acting antidepressants like ketamine and psychedelics also rely on these intracellular mechanisms, an area termed location-biased or inside-out pharmacology.

Knowledge gaps in psychedelic medicalisation: Preclinical and neuroimaging mechanisms.

Neuroscience applied January 1, 2024 Drummond E-Wen Mcculloch, Juan Pablo Lopez, Christina Dalla et al. 2 citations

Classical psychedelic drugs like psilocybin and LSD stimulate the serotonin 2A receptor and are being investigated for clinical effects in brain disorders. Experts at the ECNP 'New Frontiers meeting' in March 2023 identified key knowledge gaps in psychedelic mechanisms, including the need for appropriate behavioral models, dose optimization, molecular mechanisms, sex differences, and effects on neurotransmitter release and brain activity. The meeting highlighted the importance of preclinical and neuroimaging research to address these gaps.