Effect of hypophysectomy on urinary oestrogen in breast cancer.

Abstract

<h3>Abstract</h3> Bipolar disorder (BD) is a severe mental disorder characterized by repeated mood swings. Although genetic factors are collectively associated with the etiology of BD, the underlying molecular mechanisms, particularly how environmental factors affect the brain, remain largely unknown. We performed promoter-wide DNA methylation analysis of neuronal and nonneuronal nuclei in the prefrontal cortex of patients with BD (N=34) and controls (N=35). We found decreased DNA methylation at promoters in both cell types in the BD patients compared to the controls. Gene Ontology (GO) analysis of differentially methylated region (DMR)-associated genes revealed enrichment of molecular motor-related genes in neurons, chemokines in both cell types, and ion channel- and transporter-related genes in nonneurons. Detailed analysis further revealed that growth cone- and dendrite-related genes, including <i>NTRK2</i> and <i>GRIN1</i>, were hypermethylated in neurons of BD patients. To assess the effect of medication, neuroblastoma cells were cultured under therapeutic concentrations of three different mood stabilizers (lithium, valproate, and carbamazepine). We observed that up to 37.9% of DMRs detected in BD overlapped with mood stabilizer-induced DMRs. Interestingly, mood stabilizer-induced DMRs showed the opposite direction of changes in DMRs in BD, suggesting the therapeutic effects of mood stabilizers on DNA methylation. Among the DMRs, 12 overlapped with loci identified by a previous genome-wide association study of BD. Finally, we performed qPCR analysis of 10 DNA methylation-related genes and found that <i>DNMT3B</i> was overexpressed in BD. The cell type-specific DMRs identified in this study will be useful for understanding the pathophysiology of BD.