NEGR1 can influence symptom severity in fluoxetine treated major depression disorder patients

NEGR1 (neuronal growth regulator 1) is a cell adhesion molecule of the immunoglobulin (Ig) superfamily related to IgLON subgroup. NEGR1 promotes cell-cell adhesion and stimulates neurite growth of hypothalamic neurons and inhibits synapse formation. NEGR1 is one of the genomic regions significantly associated with major depression disorder (MDD). The functional role of NEGR1 on MDD is still unknown. Fluoxetine, a selective serotonin reuptake inhibitor, is used in the treatment of MDD. Thus, we aimed to investigate the effects of fluoxetine on NEGR1 expression in MDD and to examine correlations between NEGR1 levels and symptom severity. In this study, mRNA expression of NEGR1 in fluoxetine-treated and non-treated cultured peripheral blood mononuclear cells (PBMC) were detected by qPCR in 40 patients with MDD and 40 age‑matched healthy controls. The protein levels of NEGR1 in cultured PBMCs were detected by ELISA method. Hamilton Rating-Scale for Depression (HRSD) and Beck Depression Inventory (BDI) were used to evaluate depressive symptom severity. PBMC of MDD patients exhibited elevated NEGR1 protein levels when compared with healthy controls in both fluoxetine treated and non-treated groups (p = 0.01). Besides, a positive correlation was found between NEGR1 protein levels and Beck scores in fluoxetine treated MDD group (r = 0.33, p = 0.036). However, no significant relationship was observed in NEGR1 mRNA levels between MDD patients and controls in both fluoxetine treated and non-treated group (p > 0.05). Fluoxetine had no effect on the protein levels of NEGR1 directly. On the other hand, NEGR1 protein levels may affect symptom severity in MDD patients treated with fluoxetine.