Homer1a Protein Expression in Schizophrenia, Bipolar Disorder, and Major Depression.

In recent years, there was growing interest in postsynaptic density proteins in the central nervous system. Of the most important candidates of this specialized region are proteins belonging to the Homer protein family. This family of scaffolding proteins is suspected to participate in the pathogenesis of a variety of diseases. The present study aims to compare Homer1a expression in the hippocampus and cingulate gyrus of patients with major psychiatric disorders including schizophrenia, bipolar disorder and major depression. Immunohistochemistry was used to analyze changes of Homer1a protein expression in the hippocampal formation and the cingulate gyrus from the respective disease groups. Glial cells of the cingulate gyrus gray matter showed decreased Homer1a levels in bipolar disorder when compared to controls. The same results were seen when comparing cingulate gyrus gray matter glial cells in bipolar disorder with major depression. Stratum oriens glial cells of the hippocampus showed decreased Homer1a levels in bipolar disorder when compared to controls and major depression. Stratum lacunosum glial cells showed decreased Homer1a levels in bipolar disorder when compared to major depression. In stratum oriens interneurons Homer1a levels were increased in all disease groups when compared to controls. Stratum lucidum axons showed decreased Homer1a levels in bipolar disorder when compared to controls. Our data demonstrate altered Homer1a levels in specific brain regions and cell types of patients suffering from schizophrenia, bipolar disorder and major depression. These findings support the role of Homer proteins as interesting candidates in neuropsychiatric pathophysiology and treatment.