NR3C1 and major depressive disorder: The time zone view can be analyzed from two periods: before 2005, there was little research in this field, which did not attract wide attention of researchers, so there were only a few hot keywords; since 2006, glucocorticoid receptor, DNA methylation, gene expression, brain development, epigenetic regulation, hypothalamic pituitary adrenal axis, depression, and posttraumatic stress disorder gradually emerged and achieved rapid development.