Social defeat promotes specific cytokine variations within the prefrontal cortex upon subsequent aggressive or endotoxin challenges

► Social defeat and LPS elicit plasma corticosterone and brain cytokine variations. ► Repeated social defeat sensitized PFC IL-1b and TNF-a expression upon a later defeat challenge. ► In contrast, corticosterone and IL-6 were desensitized after subsequent defeat or LPS challenge. ► Social defeat may proactively influence corticosterone and cytokine responses to later insults.