Expression of Estrogen Receptor β in Hypothalamic Stem Cells - Expression of Estrogen Receptor β in Hypothalamic Stem Cells - Open Access Pub

Neural stem cell activity at least partially accounts for the postweaning development of the sexually dimorphic nucleus of the preoptic area (SDN-POA) and estrogen selectively mobilizes neural stem cells in the 3rd ventricle stem cell niche (3VSCN). Here, we examined the expression of estrogen receptor β (ERβ) in the SDN-POA and the 3VSCN. A subset of cells within the SDN-POA--delineated with or without calbindin D28K (CB28)-immunoreactivity (ir)--exhibited ERβ-ir. The ependymal cells that expressed nestin within the 3VSCN also expressed ERβ. Interestingly, a few proliferating (Ki67 positive) cells within the 3VSCN and the hypothalamic parenchyma, including the SDN-POA, displayed ERβ-ir. In parallel, a subset of cells in the subventricular zone was double-labeled with nestin and ERβ or Ki67 and ERβ while the subgranular zone exhibited few such double-labeled cells. ERβ is expressed in hypothalamic stem cells that may regulate cell regenerative cycles. DOI10.14302/issn.2574-4372.jesr-17-1611 Developmental estrogen treatment enlarges the sexually dimorphic nucleus of the preoptic area (SDN-POA) in male and female weanling rats 1. Further, neural stem cell activity at least partially accounts for postweaning SDN-POA development 2, 3. The hypothalamic subependymal niche is likely a heretofore undescribed source of neurogenesis 4 along with the rostral end of the 3rd ventricle, termed the 3rd ventricle stem cell niche (3VSCN). The 3VSCN appears distinguishable from other sections of the 3rd ventricle 2, such as the caudal portion, by its vigorous expression of nestin, a stem cell biomarker 5, 6. Notably, estrogen selectively mobilizes neural stem cells in the 3VSCN of postnatal day (PND) 21 rats, as evidenced by an increase in proliferative cell number and also an increase in mitotic activity 7. Nevertheless, it remains unclear as to whether estrogen controls the differentiation of stem cells (stem cellàneuron-specific progenitor cellàCB28-expressing neurons) by which the size of the SDN-POA is determined 1, 2. Neural sex differences are under genetic regulation and regional sex differences are characterized by sexually dimorphic expression of neuronal proteins--such as calbindin-D28k (CB28/Calb1)--are theoretically driven by sex chromosome complement, steroid receptors or, in some instances, both 8. CB28 has been used as a biomarker to define the SDN-POA 1 and stem cell activity is associated with the expression of the proliferative marker, Ki67. Ki67-immunoreactive cells exist in the SDN-POA of both weanling and adult rats 2. The CB28 promoter is capable