[Effects of different phases of estrous cycle on brain edema and neurological outcomes after severe traumatic brain injury in female rats]

ABSTRACT

Sex is one of the main recovery parameters after traumatic brain injury [TBI]. During estrus cycle phase, plasma estrogen and progesterone levels are very different. So in this study, we have assessed different effects of these phases in brain edema and neurological outcomes. Adult female Albino-N-MARI rats were divided into 6 groups [14 per group] including metestrus, diestrus, proestrus, estrus, ovarictomized [OVX] rats, and sham group [without TBI and ovary]. In all groups, brain water content for the measurement of brain edema, evans blue content for the measurement of brain vascular permeability, neurological scores, plasma estrogen and progesterone levels were assessed after severe TBI. Brain water content in diestrus, proestrus and estrus groups showed a significant decrease as compared with OVX group [P<0.001] but it was not significant in metestrus group. Evans blue content in proestrus group was lower than estrus and OVX groups [P<0.001]. Also, in diestrus group it was lower than OVX group [P<0.01].Neurological scores showed significant increases in proestrus group 4 hours after severe TBI as compared with metestrus, diestrus and OVX groups [P<0.01]. 24 hours after severe TBI, neurological scores in all groups were higher than OVX [P<0.001]. Brain water content and brain vascular permeability in sham group was lower than OVX, besides neurological scores in sham group were higher than OVX [P<0.001]. This study showed that brain edema, evans blue content and neurological scores after severe TBI are related to estrus cycle different phases. This could be related to differences in female sex hormones in different phases of estrus cycle