Methylone promotes neurite outgrowth and has long-lasting effects on fear extinction learning

Abstract

Post-traumatic stress disorder (PTSD) is a prevalent and debilitating disorder, and available treatments are limited. TSND-201 (methylone) is in clinical trials for PTSD, showing potential to have rapid, robust and long-lasting benefit without direct agonist/antagonist activity at 5HT2A. Alterations in structural neuroplasticity are a well-studied mechanism that may underlie both the pathophysiology and treatment of PTSD. Previous work showed that methylone rapidly induced neuroplasticity-related factors in PTSD-relevant brain areas. The current study was undertaken to determine whether methylone affected structural neuroplasticity (e.g., neurite outgrowth) and whether its effects may also be long-lasting. Methylone stimulated neurite outgrowth, specifically increasing the number of branches and the length of the longest neurite per cell in cultured cortical neurons. Methylone’s effect on neurite branching was blocked by inhibitors of monoamine transporters (reboxetine, escitalopram, JHW-007) whereas its effects on the length of the longest neurite per cell were mediated by trkB receptors or mTor signaling. RNA-seq and functional enrichment analyses suggest that methylone has long-lasting effects on factors that mediate neurite outgrowth. Rapid and long-lasting effects of methylone on fear extinction learning and memory were also observed, consistent with the rapid and long-lasting neuroplasticity effects. Reboxetine blocked methylone’s improvement of extinction recall memory, suggesting NET activity is required for methylone’s behavioral effect. Together, this work provides insight into methylone’s mechanism of action and evidence that rapid-acting pharmacotherapies that induce structural neuroplasticity may have potential to treat PTSD.