Measuring 5-HT and NE in Depression

Blood samples were collected both at RW and after SD, which were performed after the HAMD assessment and MRI scan. Because the procedure of blood sample collection was invasive, only 17 paired samples were finally obtained. Blood was collected into ethylenediaminetetraacetic acid tubes (5 ml, for measurement of 5-HT and NE). Samples were left standing at room temperature for at least 30 min. The supernatant serum was removed after centrifuging at 3,000 × g for 10 min in a 4°C centrifuge. Then, a 600-μl liquid component was immediately transferred in Eppendorf tubes, which were stored at a −80°C refrigerator until further use. Enzyme-linked immunosorbent assay was performed to measure the concentrations of 5-HT (Elabscience, E-EL-0033c, China) and NE (Elabscience, E-EL-0047c, China) following the manufacturer's instruction (27 (link)).