小谷 友理 / Kotani Yuri:1,2 川上 浩一 / Koichi Kawakami:1
Amygdala, a center of decision-making, memory and emotional responses, is one of key components of the anxiety circuit. We are interested in dissecting precise neural circuits and understanding the molecular mechanism of anxiety using zebrafish. From neuroanatomical and hodological studies in zebrafish, it has been proposed that the medial zone of dorsal telencephalon (Dm) is a homolog of the mammalian amygdala. The emx3 gene, encoding a homeodomain transcriptional factor, is expressed in neurons in Dm at the adult stage and in the forebrain at the larval stage. In order to test whether, emx3 is essential for functions of the Dm neurons, we generated emx3 homozygous mutants using the CRISPR/Cas9 method and analyzed them for an anxiety-related behavior, namely novel tank assay. We found the emx3 homozygous mutants showed severer phenotypes in the novelty-evoked anxiety behavior, compared to sibling controls. This indicates that the emx3 gene may be involved in reduction of anxiety. We think that these functions may possibly be correlated with anxiety disorders that show an excessive fear response and/or increased anxiety. We are investigating how the emx3 gene knockout affects the function and formation of the emx3-expressing neurons in Dm.