The values of the De Ritis ratio in DAT-KO knockout rats (ADHD model) did not change, in comparison with Zucker rats (obesity model) and Wistar, which may be evidence of the activation and maintenance of a high level of catabolic reactions under the influence of a high level of extracellular dopamine in the striatum of these animals. The gene discussed is SLC6A3; the disease is attention deficit-hyperactivity disorder.