For example, 17β-estradiol enhances TLR4 expression in macrophages (Rettew et al., 2009), while progesterone depresses its expression in the brain of mice with experimental autoimmune encephalomyelitis (Garay et al., 2012) or that of rats subjected to subarachnoid hemorrhage (Wang et al., 2011). This evidence concerns the gene TLR4 and subarachnoid hemorrhage.