Neuroprotection Effect of Female Sex Steroids after Traumatic Brain Injury in Rats: the Role of Inflammatory Cytokines

Previous studies have demonstrated estrogen and progesterone decrease brain edema induced by TBI. The aim of the present study was to determine whether ovarian hormones decrease brain edema by change in concentrations of proinflammatory cytokines. In this experimental study, 98 ovariectomized female rats (except groups 1 and 2) were divided into groups of control, sham, vehicle, low does of estrogen (E1), high dose of estrogen (E2), low dose of progesterone (P1) and high dose of progesterone (P2). Vehicle and sexual steroid hormones were injected intraperitoneally at 0.5 h after Moderate and diffuse TBI induced by Marmarou method. Brain level of cytokines and ovarian hormones were measured 6 h after TBI by ELISA method. Both E2 and P1 caused significant increase of 52.8% and 79.2% in brain level of IL-1β. P2 significantly decreased the levels of IL-6 and TNF-α by 45.9% and 72% respectively. TGF-β level seem to be decreased by E1 up to 3.37 times significantly. Level of β-Estradiol increased 4.58 times in E2 group and progesterone increased 1.56 times in P2 group significantly. This results suggested that ovarian hormones increased brain IL-1β and TGF-β and decreased IL-6 and TNF-α, this may be one mechanism by which hormones reduce cerebral edema.