Sex influences in behavior and brain inflammatory and oxidative alterations in mice submitted to lipopolysaccharide-induced inflammatory model of depression

Peripheral inflammation induced by lipopolysaccharide (LPS) causes a behavioral syndrome with translational relevance for depression. This mental disorder is twice more frequent among women. Despite this, the majority of experimental studies investigating the neurobiological effects of inflammatory models of depression have been performed in males. Here, we sought to determine sex influences in behavioral and oxidative changes in brain regions implicated in the pathophysiology of mood disorders (hypothalamus, hippocampus and prefrontal cortex - PFC) in adult mice 24 h post LPS challenge. Myeloperoxidase (MPO) activity and interleukin (IL)-1 beta levels were measured as parameters of active inflammation, while reduced glutathione (GSH) and lipid peroxidation as parameters of oxidative imbalance. We observed that male mice presented behavioral despair, while females anxiety-like alterations. Both sexes were vulnerable to LPS-induced anhedonia. Both sexes presented increased MPO activity in the PFC, while male only in the hippocampus. IL-1 beta increased in the PFC and hypothalamus of animals of both sexes, while in the hippocampus a relative increase of this cytokine in males compared to females was detected. GSH levels were decreased in all brain areas investigated in animals of both sexes, while increased lipid peroxidation was observed in the hypothalamus of females and in the hippocampus of males after LPS exposure. Therefore, the present study gives additional evidence of sex influence in LPS-induced behavioral alterations and, for the first time, in the oxidative changes in brain areas relevant for mood regulation.