MTT assay

To study the protective effect of Cur/SLNs-HU-211, the cells were seeded in a 96-well plate and divided into seven equal groups: CORT plus PBS, nontreated control, CORT plus Fluoxetine (1 μM), HU-211, Cur, Cur/SLNs, and Cur/SLNs-HU-211 at a Cur concentration of 0.2 μM. Treatments were performed 24 hours after the cells were seeded. All groups were treated for 2 hours prior to the addition of CORT, and then the cells were coincubated for another 24 hours. Cell viability was obtained by the MTT assay.32 At the end of treatment, the medium was replaced with 0.5 mg/mL MTT and cultured for another 4 hours at 37°C. Then, dimethyl sulfoxide (DMSO) was added to dissolve formazan crystals. After shaking for 10 minutes at room temperature, the absorbance at 492 nm was measured using a microplate reader (ELX 800 UV, BIO-TEK, USA). The results of cell viability were presented as a percentage of nontreated control.