Characterization of heterogeneous glial cell populations involved in dehydration-induced proliferation in the adult rat neurohypophysis

Virard, Isabelle; Gubkina, Olena; Alfonsi, Fabienne; Durbec, Pascale

doi:10.1016/j.neuroscience.2007.10.035

Cited by 16 publications

(23 citation statements)

References 40 publications

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“…Earlier studies in the rat reported a mitotic NL activity [40] after stimulations inducing a neurohormonal demand, like a two week NaCl imbibition [41,42] or dehydration [43]. Virard et al [44] suggested that the rat NL contains glial progenitors. The pituicyte is also considered an osmotic sensor involved in the neurohypophysis hormone output [45].…”

Section: Discussionmentioning

confidence: 99%

Adaptation of <i>Camelus dromedarius</i> pars nervosa of the hypophysis to winter and summer living conditions

Alim

Rodrı́guez

Andrade

et al. 2012

Folia Histochem Cytobiol.

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Abstract:The aim of this work is to study the characteristics of the dromedary nervous lobe and determine how the seasons condition its organization. To this end, electron microscopy was performed and examined quantitatively on animals from winter and summer periods. The results show a higher number of cells in the nervous lobe in summer than in winter. The most abundant glial elements in winter are light pituicytes engulfing neurosecretory nerve fibers making neuroglial contact, and dark pituicytes containing numerous heterogeneous light bodies. In summer, the most distinctive glial cells may be pituicytes in a phagocytic state making contact with characteristic large light bodies that could represent a degenerative process of large neuropeptide storage. Granular pituicytes were also observed in contact with glial and neuronal components. However, lipid droplets, described in pituicytes of other mammals, were not observed in our samples. Quantitative analysis of neurovascular contacts revealed that the number of nerve terminals contacting the basal lamina did not differ between summer and winter, but the mean number of glial processes increased in winter. Our data provides evidence that the storage of neuropeptides is very marked in summer and that, associated with an autophagic and phagocytic phenomenon, this suggests an adaptation to anticipate any situation that would cause dehydration of the dromedary. Thus, in its tough environment, the animal remains permanently prepared to avoid any large water loss.

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Section: Discussionmentioning

confidence: 99%

Adaptation of <i>Camelus dromedarius</i> pars nervosa of the hypophysis to winter and summer living conditions

Alim

Rodrı́guez

Andrade

et al. 2012

Folia Histochem Cytobiol.

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“…3E). It has been demonstrated that PDGFRA-positive OPCs differentiate into pituicytes in the NH (Virard et al 2008). Double-labeling immunohistochemistry of PDGFRA and a pituicyte marker GFAP revealed that the expression of PDGFRA in pituicytes was at an undetectable level (Fig.…”

Section: Expression Of Pdgfb and Pdgfrsmentioning

confidence: 91%

“…The number of BrdUlabeled endothelial cells (mean number of BrdU-labeled cellsGS.E.M./mm 2 ) was 131.66G19.84 in the NH after administration of BrdU for 6 days. It has been shown that proliferating parenchyma cells are OPCs that differentiate into pituicytes in the NH of adult rats (Virard et al 2008). Analysis of the 3D image revealed the presence of a BrdU-labeled nucleus within an endothelial cell (Fig.…”

Section: Proliferation Of Endothelial Cellsmentioning

confidence: 94%

“…The present immunohistochemistry revealed that PDGFB and PDGFRB were highly expressed in OXTcontaining axonal terminals and pericytes respectively. It has been demonstrated that PDGFRA is expressed specifically in OPCs in the NH of adult rats (Virard et al 2008). The present pharmacological experiment using the selective PDGFR inhibitor STI571 largely diminished proliferation of endothelial cells in the NH of adult mice.…”

Section: Significance Of Vegf Signalingmentioning

confidence: 99%

“…It has been demonstrated that PDGFRA-expressing OPCs are shown to proliferate and differentiate into pituicytes and the chronic salt loading significantly increased proliferation of OPCs in the NH of adult rats (Virard et al 2008). It has been reported that proliferation of OPCs is mediated through PDGF and neurotropin 3 (Robinson & Miller 1996).…”

Section: Significance Of Vegf Signalingmentioning

confidence: 99%

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VEGF-dependent and PDGF-dependent dynamic neurovascular reconstruction in the neurohypophysis of adult mice

Furube¹,

Mannari²,

Morita³

et al. 2014

Journal of Endocrinology

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Hypothalamo-neurohypophysial system (HNS) releases arginine vasopressin (AVP) and oxytocin (OXT) from axonal terminals of the neurohypophysis (NH) into blood circulation for controlling body fluid homeostasis and lactation. Chronic osmotic and suckling stimulations have been shown to cause neurovascular and neuroglial reconstruction in the NH of adult mammals and no study has been reported for vascular dynamics. The aim of this study was to elucidate the occurrence of continuous angiogenesis and growth factor-dependent neurovascular reconstruction in the NH of adult mice. Active proliferation of endothelial cells and oligodendrocyte progenitor cells (OPCs) was observed using the immunohistochemistry of bromodeoxyuridine and Ki-67. Vascular endothelial growth factor A (VEGFA) and VEGF receptor 2 (VEGFR2 (KDR)) were highly expressed at pituicytes and endothelial cells respectively. Moreover, prominent expression of platelet-derived growth factor B (PDGFB) and PDGF receptor beta was observed at OXT-containing axonal terminals and pericytes respectively. Administration of the selective tyrosine kinase inhibitor AZD2171 for VEGFRs and STI571 for PDGFRs significantly decreased proliferation of endothelial cells and OPCs. Moreover, AZD2171 treatment decreased vascular density by facilitating apoptosis of endothelial cells and the withdrawal of its treatment led to remarkable rebound proliferation of endothelial cells, so that vascular density rapidly returned to normal levels. AZD2171 decreased the density of both AVP-and OXT-containing axonal terminals, whereas STI571 selectively decreased the density of AVP-containing ones. Thus, this study demonstrates that the signaling pathways of VEGF and PDGF are crucial mediators for determining proliferation of endothelial cells and OPCs and the density of AVP-and OXT-containing axonal terminals in the HNS.

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Pituicyte modulation of neurohormone output

Rosso

Mienville

2008

Glia

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Pituicytes have long been suspected to play a role in the regulation of neurohypophysial hormone output. This role has been mainly ascribed to morphological changes in these cells and subsequent modifications of their tight structural relationships with surrounding nerve terminals and capillaries. These entirely reversible changes are brought about by physiological states such as parturition, lactation, or dehydration, and it was inferred that they should facilitate neurohormone output, based on concerted analyses of in vitro, in situ, and ex vivo experiments. Pituicyte stellation, the in vitro counterpart of these morphological changes, can be induced by beta-adrenergic or A1-adenosine receptor activation, and appears to result from inhibition of the small GTPase RhoA. Actin depolymerization is the key event allowing stellation. Vasopressin and oxytocin reverse stellation and return pituicytes to their basal shape by activating Cdc42, another small GTPase that reorganizes the actin cytoskeleton in a cortical position. Adenosine and neurohormones also have opposite actions on the efflux of taurine, a local messenger that is released by pituicytes in hypotonic conditions and accordingly inhibits vasopressin output from axon terminals. As adenosine is likely generated from endogenous ATP co-released with neurohormones and broken down by local ectoATPases, these data suggest a subtle balance between a positive and a negative feedback on vasopressin output operated, respectively, by adenosine and vasopressin to maintain hydromineral homeostasis. A theoretical scenario is presented to account for the putative sequence of pituicyte-related events following disturbance of the hydromineral system.

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Characterization of heterogeneous glial cell populations involved in dehydration-induced proliferation in the adult rat neurohypophysis

Cited by 16 publications

References 40 publications

Adaptation of <i>Camelus dromedarius</i> pars nervosa of the hypophysis to winter and summer living conditions

Adaptation of <i>Camelus dromedarius</i> pars nervosa of the hypophysis to winter and summer living conditions

VEGF-dependent and PDGF-dependent dynamic neurovascular reconstruction in the neurohypophysis of adult mice

Pituicyte modulation of neurohormone output

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