Moreover, decreased IL-10 levels have been observed in patients with major depressive disorder (44), and antidepressant treatments have been shown to increase IL-10 levels (43, 45).In this study, LPS treatment significantly decreased serum IL-4 and IL-10 levels in rats, whereas taVNS intervention markedly increased IL-4 and IL-10 levels. Here, IL4 is linked to major depressive disorder.