Role of estradiol in the dynamic control of tanycyte plasticity mediated by vascular endothelial cells in the median eminence.
In the ever-changing physiological context of the neuroendocrine brain, the mechanisms by which cellular events involving neurons, astroglia, and vascular cells are coordinated to bring forth the appropriate neuronal signaling is not yet known but is amenable to examination. In the median eminence of the hypothalamus, endothelial cells are key players in the plasticity of tanycytes (specialized astroglia) and neuroendocrine synapse efficacy. Here we report that estradiol acts on both purified endothelial cells and isolated tanycytes to trigger endothelial-to-glial communication that leads to a sudden and massive retraction of tanycyte processes. The blockade of endothelial nitric oxide synthase by in vitro adenoviral-mediated gene transfer of a dominant-negative form of endothelial nitric oxide synthase abrogates the estradiol-induced tanycyte plasticity mediated by endothelial cells. In parallel, increases in prostaglandin-E(2) (PGE(2)) due to changes in cyclooxygenase (COX)-1 and COX-2 expression induced by the exposure of tanycytes to estradiol promote acute tanycyte plasticity. We also demonstrate by electron microscopy that the administration of PGE(2) to median eminence explants induces rapid neuroglial plasticity at the neurovascular junction of neurons that release GnRH (the neuropeptide controlling reproduction). Conversely, preventing local PGE(2) synthesis in the median eminence of adult female rats with the COX inhibitor indomethacin impairs the ovarian cycle, a process that requires a pulsatile, coordinated delivery of GnRH into the hypothalamo-hypophyseal portal system. Taken together, our findings show that estradiol controls the dialog between endothelial cells and astroglia to regulate neuroglial plasticity in the neuroendocrine brain.
Institut National de la Santé et de la Recherche Médicale Unité 837, Bâtiment, Biserte, Place de Verdun, 59045 Lille Cedex, France.
Sandrine
S
de Seranno
Xavier
X
d'Anglemont de Tassigny
Cecilia
C
Estrella
Anne
A
Loyens
Sergey
S
Kasparov
Danièle
D
Leroy
Sergio R
SR
Ojeda
Jean-Claude
JC
Beauvillain
Vincent
V
Prevot
D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western; D002450:Cell Communication / Q000187:drug effects / Q000502:physiology; D018929:Cell Culture Techniques; D048430:Cell Shape / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D015232:Dinoprostone / Q000494:pharmacology; D042783:Endothelial Cells / Q000187:drug effects / Q000502:physiology*; D004805:Ependyma / Q000187:drug effects / Q000502:physiology*; D004958:Estradiol / Q000494:pharmacology / Q000502:physiology*; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology; D008473:Median Eminence / Q000502:physiology*; D009457:Neuroglia / Q000187:drug effects / Q000502:physiology*; D052250:Nitric Oxide Synthase Type III / Q000502:physiology; D011451:Prostaglandin-Endoperoxide Synthases / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
D004958:Estradiol; D052250:Nitric Oxide Synthase Type III; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone