Pakkenberg, B. | bioRxiv Science

bioRxiv2018

Striking reduction in neurons and glial cells in anterior thalamic nuclei of older patients with Down’s syndrome

The anterior thalamic nuclei are important for spatial and episodic memory; however, there is surprisingly little information about how these nuclei are affected in many conditions that present with memory impairments, including Downs syndrome. To assess the status of the anterior thalamic nuclei in Downs syndrome we quantified neurons and glial cells in the brains from four older patients with this condition. There was a striking reduction in the volume of the anterior thalamic nuclei and this appeared to reflect the loss of approximately 70% of neurons. The number of glial cells was also reduced but to a lesser degree than neurons. The anterior thalamic nuclei appear to be particularly sensitive to effects of aging in Downs syndrome and the pathology in this region likely contributes to the memory impairments observed. These findings re-affirm the importance of assessing the status of the anterior thalamic nuclei in conditions where memory impairments have been principally assigned to pathology in the medial temporal lobe.

neuroscience↗

bioRxiv2018

The behavioral and neurobiological effects of reduced Brd1 expression in mice are sex-biased and implicate gender dependent dysregulation of nuclear receptor mediated signaling in mental disorders

The schizophrenia and bipolar disorder associated gene, BRD1, encodes a scaffold protein that in complex with epigenetic modifiers regulate gene sets enriched for psychiatric disorder risk. Preclinical evidence from male Brd1+/- mice has previously implicated BRD1 with phenotypes of translational relevance to schizophrenia. Here we describe the phenotype of female Brd1+/- mice and report attenuated dendritic architecture and monoaminergic dysregulation accompanied by sex-specific changes in affective behaviors. In accordance, global gene expression profiling reveals regional dysregulation of gene sets enriched with major depressive disorder and schizophrenia risk in female and male Brd1+/- mice, respectively. Independent of sex, however, differentially expressed genes cluster in common functional pathways associated with psychiatric disorders, including mitochondrial dysfunction and oxidative phosphorylation as well as G-protein coupled-, and nuclear receptor mediated signaling. Accordingly, we provide in vitro evidence that BRD1 modulates the transcriptional drive of a subset of nuclear receptors (e.g. the vitamin D and glucocorticoid receptors). Moreover, we demonstrate enrichment of psychiatric disorder risk in the target genes of nuclear receptors, sex-biased expression of several nuclear receptor genes in the adult brain of Brd1+/- mice, and that sex-biased genes in general are enriched with nuclear receptor genes particularly at the earliest developmental stage of the human brain. Overall, our data suggests that the spatio-temporal interaction between BRD1 and subsets of nuclear receptors in the brain is sex-biased and that hampered BRD1 mediated regulation of target genes governed by certain nuclear receptors may significantly contribute to sex differences in psychopathology.

neuroscience↗