For example, dopamine transporter (DAT) KO mice are often considered an ADHD model given their hyperactivity and response to psychostimulants, but such factors may be mediated by the activity of the 5-HT1b receptor, since application of 5-HT1b antagonists reduced hyperactivity, potentially via a regulatory mechanism [60]. This evidence concerns the gene SLC6A3 and attention deficit-hyperactivity disorder.