5-hydroxytryptamine type-3A receptor in the process of fear extinction

The 5-hydroxytryptamine type-3 (5-HT3) receptor is the only ligand-gated ion channel in the 5-HT receptor subfamilies. Although it is known that the 5-HT3 receptor is expressed in the hippocampus, amygdala and prefrontal cortex, it is not well studied whether it has roles in fear memory processes. We performed behavioral analyses of 5HT3A receptor knockout mice in fear conditioning tests and found that the 5-HT3 receptor is indispensable for the fear extinction, but not for the acquisition or retention of fear memory. Furthermore, we found the 5-HT3A receptor contributes to the specificity of context in fear extinction processes. Our results indicate the 5-HT3A receptor is one of the key molecules for regulation of fear extinction. Moreover, it could be an important treatment target for the fearrelated disorders, such as post-traumatic stress-disorder (PTSD).