The neuroprotective properties of stem cells have been described for various pathophysiological states. Here, we determined the effects of exogenous perinatal estrogen treatment on endogenous neural stem cell activity in the third ventricle stem cell niche (3VSCN) and the caudal third ventricle (C3V). Pregnant Sprague–Dawley rats were gavaged with ethinyl estradiol (EE2, 10 μg/kg/day) or vehicle on gestational days 6–21, and their offspring were similarly treated from birth to weaning on postnatal day 21. At weaning, neural stem cell activity was investigated using the stem cell markers nestin, Ki-67, phosphohistone H3 (PHH3), and doublecortin (DCX). The 3VSCN was characterized by nestin labeling, but little DCX labeling, while both the subventricular (SVZ) and subgranular zones (SGZ) displayed robust DCX expression. Ki-67 cell counts in the 3VSCN were 2.2 to 6.4 times those of the C3V. In the 3VSCN, EE2 treatment significantly increased Ki-67, PHH3, and co-labeled cell counts by 135–207 %, effects which appeared stronger in females. EE2 treatment had only marginally significant effects in the C3V, mildly increasing PHH3 and co-labeled cell counts. Perinatal estrogen treatment selectively increased and mobilized proliferative cells in the 3VSCN at weaning, potentially providing increased neuroprotection. Because PHH3 cells are thought to be in the mitotic phase of the cell cycle and Ki-67 cells can be found in most phases of the cycle, the effect of estrogen treatment on 3VSCN cells appears to involve enhancement of mitosis.
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This work was supported by the National Center for Toxicological Research/Food and Drug Administration [Protocol # P00706 to S.A.F. and Protocol # P00710 to Z.H.]. L.C. was supported by the University of Arkansas for Medical Sciences institutional in-house Hornick Awards. The authors are grateful for the technical expertise provided by the animal care staff of the Priority One Corporation and the careful reviews of this manuscript by Dr. Amy Inselman and Tucker Patterson.
This document has been reviewed in accordance with the United States Food and Drug Administration (FDA) policy and approved for publication. Approval does not signify that the contents necessarily reflect the position or opinions of the FDA nor does mention of trade names or commercial products constitute endorsement or recommendation for use. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the FDA.
Z.H. planned and conducted the triple immunofluorescent study and wrote the manuscript. L.C. reorganized and optimized images and performed the statistical analyses. M.G.P. contributed to the conceptual design and significantly edited the manuscript. S.A.F. designed the project, verified the statistical analyses, and significantly edited the manuscript.
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