HTR5A and Anxiety: The exposure to alarm substance also increased anxiety-like behavior in the light/dark test in zebrafish and decreased nocifensive behavior, however pretreatment with fluoxetine blocked the anxiogenic effects of alarm substance on the light/dark test and also increased extracellular brain 5-HT (Maximino et al., 2014), the same behavioral relationship between alarm substance and serotoninergic system was not observed in the relationship between neuroendocrine and serotoninergic system.