The current study aims to analyze gene expression related to MDD and suicidality. Postmortem brain samples (N=6/group) from age and gender-matched MDD, MDD with suicidality (MDD-S) and control will be compared.

Suicidality is strongly associated with the psychopathologies of MDD. Myelin-associated oligodendrocyte basic protein (MOBP) and oligodendrocytic myelin paranodal and inner loop protein (OPALIN), and chemokine ligand 2 (CCL2) genes encode structural component of myelin and immune regulation. In this study, we are trying to understand the role of these genes with MDD and suicidality.

Quantitative PCR reactions were performed from the dorsolateral prefrontal cortex (DLPFC), Brodmann area 9 in MDD, MDD-S and control. Student t-test and ANOVA were performed and the expression of CCL2, MOBP and OPALIN was calculated via fold changes across the three groups.

Gene expression analysis of CCL2 was significantly increased in MDD and MDD-S compared to the control. Expression of MOBP and OPALIN was significantly decreased in both MDD patients and MDD with suicidality patients. However, there is no significant difference in MOBP and OPALIN expression between MDD and MDD with suicidality groups.

MOBP and OPALIN play a critical role in myelin formation and emotional, motivational, and social behaviors. Decreased MOBP and OPLAIN expression result in decreased myelin protein formation. Therefore, current study demonstrated that the myelin dysregulation might be a crucial event in MDD and suicidality. Increased CCL2 may be due to other concurrent injuries in the central nervous system. We will try to conduct additional analysis with a greater number of samples to differentiate MDD from MDD with suicidality group to elucidate the biochemical basis of suicidality in patients with MDD.