Histamine against aggression ‐ facts from fish

Reichmann et al. (this issue, 2020) show that histamine H3 receptor (Hrh3) antagonism or knockout (hrh3-/-) in zebrafish (Danio rerio) reduce aggressive behavior. With their projections all over the central nervous system in vertebrates, histaminergic neurons attract increasing attention in the pharmaceutical industry, especially for their inhibitory H3 receptors, coupled to Gi/o-type proteins, autoreceptors and heteroreceptors on many other neuronal systems. The Hrh3 inverse agonist/antagonist pitolisant, recently introduced for treatment of the sleep disorder narcolepsy, reduces cataplexy and excessive day time sleepiness.