Social isolation stress down-regulates cortical early growth response 1 (Egr-1) expression in mice

► Social isolation (SI) of mice has been studied as an animal model of neuropsychiatric disorders. ► The effects of SI on the expression levels of Egr were examined in the frontal cortex. ► SI suppressed the expression of Egr-1 protein and Egr-1 mRNA in cortical neurons. ► It had no effect on the expression levels of other Egr family members. ► The decrease in Egr-1 in the frontal cortex may be involved in SI-induced behavioral abnormalities.