Neurodevelopmental wiring deficits in the Ts65Dn mouse model of Down syndrome

• Published in: Neuroscience letters Vol. 714; p. 134569
• Main Authors: Jain, Shruti, Watts, Christina A., Chung, Wilson C.J., Welshhans, Kristy
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01.01.2020
• Subjects: Animals; Animals, Newborn; Anterior Commissure, Brain - pathology; Anterior Commissure, Brain - physiopathology; Axon guidance; Axon Guidance - physiology; Axons - pathology; Cell Size; Corpus Callosum - pathology; Corpus Callosum - physiopathology; Disease Models, Animal; Down syndrome; Down Syndrome - pathology; Down Syndrome - physiopathology; Fornix, Brain - pathology; Fornix, Brain - physiopathology; Hippocampus; Hippocampus - pathology; Hippocampus - physiopathology; In Vitro Techniques; Interhemispheric connectivity; Mice; Mice, Transgenic; Neural Pathways; Neurogenesis - physiology; Neuronal Outgrowth; Neurons - pathology; Organ Size; Ts65Dn; Interhemispheric connectivity; Down syndrome; Axon guidance; Ts65Dn; Hippocampus
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2019.134569

•We examined which connectivity deficits are present at birth in Ts65Dn mice.•Corpus callosum volume is not changed in early postnatal Ts65Dn mice.•Hippocampal commissure volume is reduced in early postnatal Ts65Dn mice.•Early postnatal Ts65Dn mice have an in vitro stunting of hippocampal axon length.•Hippocampal commissure deficits may arise during development in Down syndrome. Down syndrome is the most common genetic cause of intellectual disability and occurs due to the trisomy of human chromosome 21. Adolescent and adult brains from humans with Down syndrome exhibit various neurological phenotypes including a reduction in the size of the corpus callosum, hippocampal commissure and anterior commissure. However, it is unclear when and how these interhemispheric connectivity defects arise. Using the Ts65Dn mouse model of Down syndrome, we examined interhemispheric connectivity in postnatal day 0 (P0) Ts65Dn mouse brains. We find that there is no change in the volume of the corpus callosum or anterior commissure in P0 Ts65Dn mice. However, the volume of the hippocampal commissure is significantly reduced in P0 Ts65Dn mice, and this may contribute to the impaired learning and memory phenotype of this disorder. Interhemispheric connectivity defects that arise during development may be due to disrupted axon growth. In line with this, we find that developing hippocampal neurons display reduced axon length in vitro, as compared to neurons from their euploid littermates. This study is the first to report the presence of defective interhemispheric connectivity at the time of birth in Ts65Dn mice, providing evidence that early therapeutic intervention may be an effective time window for the treatment of Down syndrome.