437. EVALUATING APELIN AS A POTENTIAL BIOMARKER IN MAJOR DEPRESSIVE DISORDER: CORRELATION WITH CLINICAL SYMPTOMATOLOGY

Abstract Background To date, only a limited number of studies have investigated the potential effects of apelin on mood regulation and emotional behavior. Aims & Objectives Therefore, this study investigates apelin’s role in major depressive disorder (MDD) by comparing serum and plasma apelin concentrations between 30 patients with MDD and 30 healthy controls (HCs) and correlated serum and plasma apelin levels and the severity of depressive symptoms using Montgomery–Åsberg Depression Rating Scale (MADRS). Method Blood samples were collected following 12 hours of fasting, and apelin levels were measured using an ELISA kit. Results Serum apelin concentrations showed no significant difference between the MDD and HC groups, while plasma apelin levels were significantly lower in the MDD group (p=0.002). Within patients with MDD, a positive moderate correlation was observed between total MADRS scores and plasma apelin levels (r = 0.439), with statistical significance (p < 0.05). Additionally, significant positive correlations (p < 0.05) were found between both serum and plasma apelin levels and MADRS subscales 5 (reduced appetite) and 6 (concentration difficulties). Discussion & Conclusions To the best of our knowledge, this is the first preliminary clinical study to quantify total apelin concentrations in both serum and plasma samples from patients with MDD and to compare these levels with those observed in HCs. Our findings indicate that apelin concentrations were significantly lower in patients with MDD compared to HCs in both plasma and serum. Notably, while plasma apelin levels showed a statistically significant difference between the two groups, serum apelin concentrations did not exhibit a significant discrepancy. Additionally, a moderate positive correlation was found between plasma apelin levels and total scores on the MADRS. Furthermore, both plasma and serum apelin concentrations were positively correlated with specific subscales of the MADRS, namely item 5 (reduced appetite) and 6 (concentration difficulties), in patients with MDD.