IL6 and major depressive disorder: In rodents, depression-like behavior induced by the use of chronic social defeat stress, male sterility, and luteinizing hormone has been associated with higher levels of pro-inflammatory IL-1β, IL-6, and TNF-α (Grippo et al., 2005; Kubera et al., 2011; Wohleb et al., 2011; Hodes et al., 2014).