Reduced expression of apolipoprotein E receptor type 2 in peripheral blood lymphocytes from patients with major depressive disorder

We measured the mRNA levels of apolipoprotein E receptor type 2 (ApoER2) and very low-density lipoprotein receptor (VLDLR) in peripheral blood lymphocytes from 43 patients with major depressive disorder (27 drug-free patients and 16 medicated patients) and 43 age-matched healthy controls using a quantitative real-time RT-PCR method. The correlations between mRNA levels of both receptors and clinical variables in patients were also examined. The expression of ApoER2 mRNA, but not VLDLR, was significantly lower in patients as compared to controls, irrespective of the medication status. There was no statistically significant correlation between the reduction of ApoER2 mRNA levels and any of the clinical variables measured in patients. Results from this preliminary study suggest that the expression of ApoER2 may serve as a trait marker for major depressive disorder.