Morphological changes of the hippocampal astrocytes at different phases of the estrous cycle in female mice

ABSTRACT

Usual fluctuations of sex hormones during the estrous cycle in female miceaffect the hippocampal neurogenesis. The hippocampus also comprises many steroidreceptors suggesting the modulatory effects of gonadal hormones on the hippocampalplasticity. Sex differences at the level of structure and function of the hippocampus aremostly due to the fluctuations of steroid hormones during the estrous cycle. The purpose ofthis study was to investigate the morphological changes in hippocampal astrocytes and alsothe expression of glial fibrillary acidic protein [GFAP] at different phases of the estrouscycle. In this study, different stages of the estrous cycle were determinedin 6-8 week NMRI female mice by methylene blue-stained vaginal smears. Themorphological changes of astrocytes in the hippocampus were investigated using GFAPimmunohistochemistry. In addition to the morphological study, the expression of astrocyticmarker was quantitatively evaluated. GFAP immunostaining showed the changes in the morphology of astrocytes andalso in the serum level of estrogen during the estrous cycle. The highest concentrations ofestrogen and GFAP reactivity were observed in the proestrus stage. Different stages of the estrous cycle in female mice were associated withmorphological changes of hippocampal astrocytes and the alternation in the serum level ofestrogen