Figure 4.

Melatonin alleviates IR-induced ER stress signaling (sXBP1 and p-IRE1) in the SH-SY5Y neuronal cells. (A) The mRNA levels of sXBP1 were measured by quantitative real time PCR; (B) The mRNA levels of activation of IRE1 (p-IRE1) were measured by reverse transcription PCR. Data are expressed as mean ± standard error and each experiment included three repeats per conditions. * p < 0.05, ** p < 0.01 compared with non-stimulated control; ^φ p < 0.05, ^φφ p < 0.001 compared with insulin stimulated cells; (C) p-IRE1 was visualized by immunofluorescence staining using confocal microscopy analysis. p-IRE1 is represented by green staining, nuclear DNA is indicated by 4′,6-diamidino-2-phenylindole (DAPI) staining (blue color), and the combined images are presented. Mel: melatonin pretreatment for 24 h before insulin stimulation; ASK1 inhibitor: NQDI-1 600 nM treatment for 2 h before sampling.