Serotonin 5-HT1A, 5-HT1B, and 5-HT2A receptor mRNA expression in subjects with major depression, bipolar disorder, and schizophrenia

Background: Alterations of serotonin neurotransmission are implicated in both mood disorders and schizophrenia. Specific serotonin-receptor-based abnormalities in these psychiatric illnesses have been intensively studied; however, it has been difficult to draw any conclusions because of a lack of consensus. These inconsistencies have most likely arisen from the unavailability of selective ligands. Methods: Our study used in situ hybridization to quantify 5-HT1A, 5-HT1B, and 5-HT2A mRNA levels in the hippocampus (HC) and 5-HT1A and 5-HT2A mRNA levels in the dorsolateral prefrontal cortex (DLPFC) of subjects with a history of major depression disorder (MDD), bipolar disorder (BPD), schizophrenia, and a normal comparison group (15 subjects per group). Results: In the DLPFC, there is a significant decrease in 5-HT1A mRNA of subjects with MDD and in 5-HT2A mRNA of subjects with BPD. Subjects with MDD have a significant decrease in 5-HT1A mRNA in the HC; subjects with BPD and schizophrenia bad increased 5-HT1B mRNA levels and a significant decrease in 5-HT2A mRNA levels in the hippocampal formation. Conclusions: Alterations in 5-HT1A, 5-HT1B, and 5-HT2A, mRNA levels in the brains of subjects with both mood disorders and schizophrenia add further support for hypothesis of dysregulation of the serotonergic system in these psychiatric disorders.