DAT Knockout Rat Models: Dopamine Dysfunction, Epigenetic Mechanisms, and Approaches to Gene Therapy: A Literature Review

Introduction. Dopamine transporter gene knockout (DAT-KO) animal model is a valuable experimental tool for studying the pathophysiology of diseases associated with dopamine dysfunction, such as attention-deficit/hyperactivity disorder, schizophrenia, and Parkinson’s disease. The aim of the present review is to systematize the scientific data on using the DAT-KO rat models for studying dopaminergic dysfunction, epigenetic mechanisms, and gene therapy approaches.
Materials and Methods. Literary sources were searched for in PubMed, Scopus, Web of Science, and Google Scholar scientific citation databases. The original studies (n=49) on the structure and function of DAT, knockout models, epigenetic mechanisms, and gene therapy published from 1991 to 2025 in English language only were included into the review. The results have been presented in a PRISMA flow chart and in the illustrations.
Results. DAT knockout rat models exhibit a 5–7-fold increase of extracellular dopamine level, hyperactivity and structural changes in the basal ganglia, which indicates dopamine dysfunction. Homozygous knockout animals are found to completely lack functional DAT protein, whereas animals with heterozygous knockout retain approximately half of its function and exhibit intermediate phenotypes. Epigenetic regulation of SLC6A3 gene expression is mediated by DNA methylation, histone modifications (including H3K9/K14 acetylation and H3K27 methylation) and microRNA modifications. Moreover, the DAT promoter remains hypomethylated during postnatal ontogenesis in rats, resulting in its age-related expression increase. Gene therapy using viral vectors has demonstrated the potential to restore DAT function.
Discussion and Conclusion. The DAT-KO rat models reliably reproduce the key neurochemical and morphological features of dopaminergic dysfunction. However, the picture seems much incomplete due to the fragmentary character of data on the dynamics of epigenetic regulation of dopamine transporter expression during disease progression and insufficient evidence base on dose-dependent effects and long-term safety of gene therapy. The epigenetic mechanisms open the new tracks for biomarker search and personalization of therapy. Gene therapy using adeno-associated viral and lentiviral vectors demonstrates the potential to restore DAT function in the preclinical models, however, further clarification on dosedependent effects and minimization of the immune response is required. The integration of epigenetic markers into the clinical protocols, development of combinatory strategies, and validation of the DAT-KO models for comorbid conditions continue to be the promising tracks for further research.

1. Savchenko A, Targa G, Fesenko Z, Leo D, Gainetdinov RR, Sukhanov I. Dopamine Transporter Deficient Rodents: Perspectives and Limitations for Neuroscience. Biomolecules. 2023;13(5):806. https://doi.org/10.3390/biom13050806

2. Puzzo C, Festucci F, Curcio G, Gigantesco A, Adriani W. Exploring Transgenerational Inheritance in Epigenotypes of DAT Heterozygous Rats: Circadian Anomalies and Attentional Vulnerability. Behavioural Brain Research. 2024;464:114921. https://doi.org/10.1016/j.bbr.2024.114921

3. Petrelli F, Dallérac G, Pucci L, Calì C, Zehnder T, Sultan S, et al. Dysfunction of Homeostatic Control of Dopamine by Astrocytes in the Developing Prefrontal Cortex Leads to Cognitive Impairments. Molecular Psychiatry. 2020;25(4):732–749. https://doi.org/10.1038/s41380-018-0226-y

4. Adinolfi A, Zelli S, Leo D, Carbone C, Mus L, Illiano P, et al. Behavioral Characterization of DAT-KO Rats and Evidence of Asocial-Like Phenotypes in DAT-HET Rats: The Potential Involvement of Norepinephrine System. Behav-ioural Brain Research. 2019;359:516–527. https://doi.org/10.1016/j.bbr.2018.11.028

5. Leo D, Sukhanov I, Zoratto F, Illiano P, Caffino L, Sanna F, et al. Pronounced Hyperactivity, Cognitive Dysfunc-tions, and BDNF Dysregulation in Dopamine Transporter Knock-out Rats. Journal of Neuroscience. 2018;38(8):1959–1972. https://doi.org/10.1523/JNEUROSCI.1931-17.2018

6. Cinque S, Zoratto F, Poleggi A, Leo D, Cerniglia L, Cimino S, et al. Behavioral Phenotyping of Dopamine Trans-porter Knockout Rats: Compulsive Traits, Motor Stereotypies, and Anhedonia. Frontiers in Psychiatry. 2018;9:43. https://doi.org/10.3389/fpsyt.2018.00043

7. Apsley AT, Domico ER, Verbiest MA, Brogan CA, Buck ER, Burich AJ, et al. A Novel Hypervariable Variable Number Tandem Repeat in the Dopamine Transporter Gene (SLC6A3). Life Science Alliance. 2023;6(4):e202201677. https://doi.org/10.26508/lsa.202201677

8. Reith MEA, Kortagere S, Wiers CE, Sun Hui, Kurian MA, Galli A, et al. The Dopamine Transporter Gene SLC6A3: Multidisease Risks. Molecular Psychiatry. 2022;27(2):1031–1046. https://doi.org/10.1038/s41380-021-01341-5

9. Nguyen H, Cheng MH, Lee JY, Aggarwal S, Mortensen OV, Bahar I. Allosteric Modulation of Serotonin and Dopamine Transporters: New Insights from Computations and Experiments. Current Research in Physiology. 2024;7:100125. https://doi.org/10.1016/j.crphys.2024.100125

10. Donovan DM, Vandenbergh DJ, Perry MP, Bird GS, Ingersoll R, Nanthakumar E, et al. Human and Mouse Do-pamine Transporter Genes: Conservation of 5′-Flanking Sequence Elements and Gene Structures. Molecular Brain Re-search. 1995;30(2):327–335. https://doi.org/10.1016/0169-328x(95)00018-n

11. Vandenbergh DJ, Persico AM, Uhl GR. A Human Dopamine Transporter cDNA Predicts Reduced Glycosylation, Displays a Novel Repetitive Element and Provides Racially-Dimorphic TaqI RFLPs. Molecular Brain Research. 1992;15(1–2):161–166. https://doi.org/10.1016/0169-328x(92)90165-8

12. Shimada S, Kitayama S, Lin CL, Patel A, Nanthakumar E, Gregor P, et al. Cloning and Expression of a Cocaine-Sensitive Dopamine Transporter Complementary DNA. Science. 1991;254(5031):576-578. https://doi.org/10.1126/sci-ence.1948034

13. Kilty JE, Lorang D, Amara SG. Cloning and Expression of a Cocaine-Sensitive Rat Dopamine Transporter. Sci-ence. 1991;254(5031):578–579. https://doi.org/10.1126/science.1948035

14. Koijam AS, Hijam AC, Singh AS, Jaiswal P, Mukhopadhyay K, Rajamma U, et al. Association of Dopamine Transporter Gene with Heroin Dependence in an Indian Subpopulation from Manipur. Journal of Molecular Neurosci-ence. 2021;71(1):122-136. https://doi.org/10.1007/s12031-020-01633-5

15. Nepal B, Das S, Reith ME, Kortagere S. Overview of the Structure and Function of the Dopamine Transporter and Its Protein Interactions. Frontiers in Physiology. 2023;14:1150355. https://doi.org/10.3389/fphys.2023.1150355

16. Pidathala S, Mallela AK, Joseph D, Penmatsa A. Structural Basis of Norepinephrine Recognition and Transport Inhibition in Neurotransmitter Transporters. Nature Communications. 2021;12(1):2199. https://doi.org/10.1038/s41467-021-22385-9

17. Nirenberg MJ, Chan J, Pohorille A, Vaughan RA, Uhl GR, Kuhar MJ, et al. The Dopamine Transporter: Compar-ative Ultrastructure of Dopaminergic Axons in Limbic and Motor Compartments of the Nucleus Accumbens. Journal of Neuroscience. 1997;17(18):6899–6907. https://doi.org/10.1523/JNEUROSCI.17-18-06899.1997

18. Basso V, Döbrössy MD, Thompson LH, Kirik D, Fuller HR, Gates MA. State of the Art in Sub-Phenotyping Midbrain Dopamine Neurons. Biology. 2024;13(9):690. https://doi.org/10.3390/biology13090690

19. Sugimoto A, Suzuki Y, Yoshinaga K, Orime N, Hayashi T, Egawa J, et al. Influence of Atomoxetine on Relation-ship Between ADHD Symptoms and Prefrontal Cortex Activity During Task Execution in Adult Patients. Frontiers in Human Neuroscience. 2021;15:755025. https://doi.org/10.3389/fnhum.2021.755025

20. Granas C, Ferrer J, Loland CJ, Javitch JA, Gether U. N-Terminal Truncation of the Dopamine Transporter Abol-ishes Phorbol Ester- and Substance P Receptor-Stimulated Phosphorylation without Impairing Transporter Internaliza-tion. Journal of Biological Chemistry. 2003;278(7):4990–5000. https://doi.org/10.1074/jbc.M205058200

21. Zeppelin T, Pedersen KB, Berglund NA, Periole X, Schiøtt B. Effect of Palmitoylation on the Dimer Formation of the Human Dopamine Transporter. Scientific Reports. 2021;11(1):4164. https://doi.org/10.1038/s41598-021-83374-y

22. Daniels GM, Amara SG. Regulated Trafficking of the Human Dopamine Transporter: Clathrin-Mediated Inter-nalization and Lysosomal Degradation in Response to Phorbol Esters. Journal of Biological Chemistry. 1999;274(50):35794-35801. https://doi.org/10.1074/jbc.274.50.35794

23. Afonso-Oramas D, Cruz-Muros I, de la Rosa DA, Abreu P, Giráldez T, Castro-Hernández J, et al. Dopamine Transporter Glycosylation Correlates with the Vulnerability of Midbrain Dopaminergic Cells in Parkinson’s Disease. Neurobiology of Disease. 2009;36(3):494–508. https://doi.org/10.1016/j.nbd.2009.09.002

24. Olasore HS, Osuntoki AA, Magbagbeola OA, Awesu AB, Olashore AA. Association of Dopamine Transporter Gene (DAT1) 40 bp 3' UTR VNTR Polymorphism (rs28363170) and Cannabis Use Disorder. Substance Use: Research and Treatment. 2023;17:1–7. https://doi.org/10.1177/11782218231163696

25. Zeng Q, Ning F, Gu S, Zeng Q, Chen R, Peng L, et al. The 10-Repeat 3'-UTR VNTR Polymorphism in the SLC6A3 Gene May Confer Protection against Parkinson’s Disease: A Meta-Analysis. Frontiers in Genetics. 2021;12:789112. https://doi.org/10.3389/fgene.2021.789112

26. Ng J, Barral S, Waddington SN, Kurian MA. Dopamine Transporter Deficiency Syndrome (DTDS): Expanding the Clinical Phenotype and Precision Medicine Approaches. Cells. 2023;12(13):1737. https://doi.org/10.3390/cells12131737

27. Madduluri B, Garapati D, Yareeda S. Dopamine Transporter Deficiency Syndrome: A Rare Case of Infantile-Onset Dystonia-Parkinsonism. Journal of Movement Disorders. 2025;18(3):280–282. https://doi.org/10.14802/jmd.25057

28. Itan Yuval, Shang Lei, Boisson B, Patin E, Bolze A, Moncada-Vélez M, et al. The Human Gene Damage Index as a Gene-Level Approach to Prioritizing Exome Variants. Proceedings of the National Academy of Sciences of the United States of America. 2015;112(44):13615-13620. https://doi.org/10.1073/pnas.1518646112

29. Torres GE, Yao WD, Mohn AR, Quan H, Kim KM, Levey AI, et al. Functional Interaction between Monoamine Plasma Membrane Transporters and the Synaptic PDZ Domain-Containing Protein PICK1. Neuron. 2001;30(1):121–34. https://doi.org/10.1016/s0896-6273(01)00267-7

30. Egaña LA, Cuevas RA, Baust TB, Parra LA, Leak RK, Hochendoner S, et al. Physical and Functional Interaction between the Dopamine Transporter and the Synaptic Vesicle Protein Synaptogyrin-3. Journal of Neuroscience. 2009;29(14):4592-4604. https://doi.org/10.1523/JNEUROSCI.4559-08.2009

31. Torres GE, Sweeney AL, Beaulieu JM, Shashidharan P, Caron MG. Effect of TorsinA on Membrane Proteins Reveals a Loss of Function and a Dominant-Negative Phenotype of the Dystonia-Associated DeltaE-TorsinA Mutant. Proceedings of the National Academy of Sciences of the United States of America. 2004;101(44):15650–15655. https://doi.org/10.1073/pnas.0308088101

32. Giros B, el Mestikawy S, Godinot N, Zheng K, Han H, Yang-Feng T, et al. Cloning, Pharmacological Character-ization, and Chromosome Assignment of the Human Dopamine Transporter. Molecular Pharmacology. 1992;42(3):383–390. https://doi.org/10.1016/S0026-895X(25)08925-4

33. Kurzina NP, Volnova AB, Aristova IY, Gainetdinov RR. A New Paradigm for Training Hyperactive Dopamine Transporter Knockout Rats: Influence of Novel Stimuli on Object Recognition. Frontier in Behavioral Neuroscience. 2021;15:654469. https://doi.org/10.3389/fnbeh.2021.654469

34. Lloyd JT, Yee AG, Kalligappa PK, Jabed A, Cheung PY, Todd KL, et al. Dopamine Dysregulation and Altered Responses to Drugs Affecting Dopaminergic Transmission in a New Dopamine Transporter Knockout (DAT-KO) Rat Model. Neuroscience. 2022;491:43–64. https://doi.org/10.1016/j.neuroscience.2022.03.019

35. Vaganova AN, Fesenko ZS, Volnova AB, Gainetdinov RR. Stable Dopamine-Signaling mRNA Co-Expression in the Substantia Nigra is Deregulated in Pathological Conditions, but Not in Dopamine Transporter Knockout Rats. Bio-molecules. 2025;15(8):1117. https://doi.org/10.3390/biom15081117

36. Liang Z, Liu W, Cao M, Cui J, Lan J, Ding Y, et al. Epigenetic Regulation-Mediated Disorders in Dopamine Transporter Endocytosis: A Novel Mechanism for the Pathogenesis of Parkinson’s Disease. Theranostics. 2025;15(6):2250–2278. https://doi.org/10.7150/thno.107436

37. Moore LD, Le T, Fan G. DNA Methylation and Its Basic Function. Neuropsychopharmacology. 2013;38(1):23–38. https://doi.org/10.1038/npp.2012.112

38. Green AL, Eid A, Zhan L, Zarbl H, Guo GL, Richardson JR. Epigenetic Regulation of the Ontogenic Expression of the Dopamine Transporter. Frontiers in Genetics. 2019;10:1099. https://doi.org/10.3389/fgene.2019.01099

39. Song H, Chen J, Huang J, Sun P, Liu Y, Xu L, et al. Epigenetic Modification in Parkinson’s Disease. Frontiers in Cell and Developmental Biology. 2023;11:1123621. https://doi.org/10.3389/fcell.2023.1123621

40. Jiang X, Liu B, Nie Z, Duan L, Xiong Q, Jin Z, et al. The Role of M6a Modification in the Biological Functions and Diseases. Signal Transduction and Targeted Therapy. 2021;6(1):74. https://doi.org/10.1038/s41392-020-00450-x

41. Yankova E, Blackaby W, Albertella M, Rak J, De Braekeleer E, Tsagkogeorga G, et al. Small-Molecule Inhibition of METTL3 as a Strategy against Myeloid Leukaemia. Nature. 2021;593:597–601. https://doi.org/10.1038/s41586-021-03536-w

42. Li Y, Gan Y, Liu J, Li J, Zhou Z, Tian R, et al. Downregulation of MEIS1 Mediated by ELFN1-AS1/EZH2/DNMT3a Axis Promotes Tumorigenesis and Oxaliplatin Resistance in Colorectal Cancer. Signal Transduction and Targeted Therapy. 2022;7(1):87. https://doi.org/10.1038/s41392-022-00902-6

43. Ng J, Barral S, De La Fuente Barrigon C, Lignani G, Erdem FA, Wallings R, et al. Gene Therapy Restores Dopa-mine Transporter Expression and Ameliorates Pathology in iPSC and Mouse Models of Infantile Parkinsonism. Science Translational Medicine. 2021;13(594):eaaw1564. https://doi.org/10.1126/scitranslmed.aaw1564

44. Illiano P, Bass CE, Fichera L, Mus L, Budygin EA, Sotnikova TD, et al. Recombinant Adeno-Associated Virus-Mediated Rescue of Function in a Mouse Model of Dopamine Transporter Deficiency Syndrome. Scientific Reports. 2017;7:46280. https://doi.org/10.1038/srep46280

45. Ng J, Barral S, Waddington SN, Kurian MA. Gene Therapy for Dopamine Dyshomeostasis: From Parkinson’s to Primary Neurotransmitter Diseases. Movement Disorders. 2023;38(6):924–936. https://doi.org/10.1002/mds.29416

46. Escors D, Breckpot K. Lentiviral Vectors in Gene Therapy: Their Current Status and Future Potential. Archivum Immunologiae et Therapiae Experimentalis. 2010;58(2):107–119. https://doi.org/10.1007/s00005-010-0063-4

47. Xu L, Yao S, Ding YE, Xie M, Feng D, Sha P. Designing and Optimizing AAV-Mediated Gene Therapy for Neurodegenerative Diseases: From Bench to Bedside. Journal of Translational Medicine. 2024;22(1):866. https://doi.org/10.1186/s12967-024-05661-2

48. Wang Y, Mu S, Liu F. Viral Vectors in Neurodegenerative Diseases: Immune Responses and Therapeutic Appli-cations. Frontiers in Neurology. 2025;16:1603125. https://doi.org/10.3389/fneur.2025.1603125

49. Belskaya A, Kurzina N, Savchenko A, Sukhanov I, Gromova A, Gainetdinov RR. Rats Lacking the Dopamine Transporter Display Inflexibility in Innate and Learned Behavior. Biomedicines. 2024;12(6):1270. https://doi.org/10.3390/biomedicines12061270