Kisspeptin1 modulates odorant-evoked fear response via two serotonin receptor subtypes (5-HT1A and 5-HT2) in zebrafish

Kiss1, a neuropeptide predominantly expressed in the habenula, modulates the serotonin (5-HT) system to decrease odorant cue [alarm substance (AS)]-evoked fear behaviour in the zebrafish. The purpose of this study was to assess the interaction of Kiss1 with the 5-HT system as well as to determine the involvement of the 5-HT receptor subtypes in AS-evoked fear. We utilized 0. 28mg/kg WAY 100635 (WAY), a selective 5-HT1A receptor antagonist, to observe the effects of Kiss1 administration on AS-evoked fear. We found WAY significantly inhibited the anxiolytic effects of Kiss1 (p<0.001) with an exception of freezing behaviour. Based on this, we utilized 92.79mg/kg methysergide, a 5-HT1 and 5-HT2 receptor antagonist, and found that methysergide significantly blocked the anxiolytic effects of Kiss1 in the presence of the AS (p<0.001). From this, we conclude that Kiss1 modulates AS-evoked fear responses mediated by the 5-HT1A and 5-HT2 receptors.