3F-phenetrazine, and amphetamine-type substance, has recently emerged as a novel psychoactive compound. However, there is currently no scientific evidence regarding its neuropharmacological properties or abuse liability. To investigate its psychostimulant, rewarding, and reinforcing, we examined locomotor activity and behavioral sensitization using the open field test, conditioned place preference (CPP), and self-administration paradigms in male rodents. Additionally, serotonin levels and c-Fos expression were measured in the dorsal striatum (DS) of mice acutely treated with 3F-phenetrazine. Furthermore, changes of dendritic spine density and c-Fos and Arc mRNA levels were measured in the DS of mice after repeated exposure to 3F-phenetrazine. Acute injection of 3F-phenetrazine significantly increased locomotor activity, whereas repeated injection of 3F-phenetrazine produced behavioral sensitization in mice. 3F-phenetrazine also induced rewarding, and reinforcing effects in rodents. In terms of neurochemical changes, acute exposure to 3F-phenetrazine significantly increased serotonin levels and c-Fos expression in the DS of mice. Repeated exposure to 3F-phenetrazine increased dendritic spine density and mRNA levles of c-Fos and Arc in the DS of mice. Taken together, these findings demonstrate that 3F-phenetrazine induces addiction-related behaviors through neuronal changes in the DS and possesses abuse potential.

Acknowledgements: This research was supported by grants from the Ministry of Food and Drug Safety (22214MFD251) in 2023, National Research Foundation of Korea grant funded by the Korea government (MSIT) (RS-2025-00520266), and the Korea Institute of Toxicology (271008923)