Development of neural lobe-like neurovascular contact regions after intrahypothalamic transection of the hypothalamo-neurohypophysial tract

Dellmann, H. D.; Carithers, Jeanine

doi:10.1016/0006-8993(92)91186-i

Cited by 11 publications

(9 citation statements)

References 32 publications

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“…Regenerating neurosecretory axons are almost invariably associated with glial cells, and naked regenerating neurosecretory axons are extremely scarce (Dellmann et al, 1986(Dellmann et al, , 1987a(Dellmann et al, ,b, 1988Ouassat and Dellmann, unpublished observations). When glial cells are killed prior to transplantation in grafts of sciatic and optic nerves and explanted neural lobes, neurosecretory axon regeneration fails to occur (Dellmann and Carithers, 1993). If thus appears that viable glial cells are an indispensable element in that regeneration.…”

Section: Neurosecretory Axon Regenerationmentioning

confidence: 99%

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Regeneration of neurosecretory axons into various types of intrahypothalamic graft is promoted by the absence of the blood-brain barrier: A neurophysin-immunohistochemical and horseradish peroxidase-histochemical study

Ouassat

Dellmann

1997

J. Neurosci. Res.

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In order to test the hypothesis that neurosecretory axon regeneration occurs only in the presence of specific vascular, perivascular, and glial microenvironments, isografts of neural lobe and optic nerve and autografts of sciatic nerve were transplanted into the hypothalamo‐neurohypophysial tract at the lateral retrochiasmatic area of adult male rats. The integrity of the blood‐brain barrier (BBB) to intravenously administered horseradish peroxidase (HRP), the regenerative process of neurosecretory axons, and functional recovery from lesion‐induced diabetes insipidus were analyzed at 18 hr, 36 hr, 10 days, 30 days, and 80 days postsurgery. Neurophysin‐positive axons invaded all grafts, as well as perivascular spaces of the adjacent hypothalamus. Wherever neurosecretory axon regeneration occurred, the BBB was breached. Reestablishment of the BBB was paralleled by a decrease in both density and staining intensity of regenerated neurophysin‐positive axons. These observations illustrate that neurosecretory axon regeneration is tributary of the absence of BBB. It is speculated that blood‐borne factors, provided when the BBB is breached, initiate and sustain neurosecretory axon regeneration. In addition, products of glial elements may enhance or complement the above stimulatory processes. J. Neurosci. Res. 47:173–185, 1997. © 1997 Wiley‐Liss, Inc.

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Section: Neurosecretory Axon Regenerationmentioning

confidence: 99%

“…Thus, blood-derived substances are present wherever regeneration of neurosecretory axons has been observed. Additionally, there is always a close association between regenerating neurosecretory axons and glial cells (Dellmann et al, 1987a(Dellmann et al, , 1988(Dellmann et al, , 1989Dellmann and Carithers, 1993).…”

Section: Introductionmentioning

confidence: 99%

Regeneration of neurosecretory axons into various types of intrahypothalamic graft is promoted by the absence of the blood-brain barrier: A neurophysin-immunohistochemical and horseradish peroxidase-histochemical study

Ouassat

Dellmann

1997

J. Neurosci. Res.

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“…Damage to the HNT stimulates neurosecretory axon regeneration into hypothalamic perivascular spaces in the vicinity of the lesion or grafts (Dellmann et al, 1987b, present study). In addition, neurosecretory axon regeneration occurs in perivascular spaces of neural lobe and optic nerve grafts (Dellmann et al, 1987a(Dellmann et al, , 1989, present study), of leptomeninges (Dellmann et al, 1988b), and in hypothalamic neurovascular contact zones (Dellmann and Carithers, 1992b). Within these connective tissue spaces, regenerating neurosecretory axons are associated with cells whose fine structural characteristics and relationships are similar to peripheral neurolemmocytes (Peters et al, 1991).…”

Section: Neurolemmocyte-like Cellsmentioning

confidence: 63%

“…This degeneration of neurites in the absence of serum may suggest that blood-derived proteins are needed for the maintenance of axonal regenerative growth in the mammalian CNS. With respect to this proposal, it seems that all tissues that can support neurosecretory axon regeneration lack a BBB (Kiernan, 1971;Dellmann et al, 1987b;Dellmann and Carithers, 1992b (Snider and Johnson, 1989).…”

Section: Presence Of Bbbmentioning

confidence: 99%

“…It is obvious from this study and other investigations (Dellmann et al, 1986(Dellmann et al, , 1987a(Dellmann et al, , 1987b(Dellmann et al, , 1988(Dellmann et al, , 1989 Dellmann et al (1985Dellmann et al ( , 1987a (Wittkowski, 1986;Hatton, 1990), they may serve as bridge-like template to guide regenerating neurosecretory axons. They may also release substances that promote survival of hypothalamic neurons in the regeneration process (Dellmann et al, 1987a;Dellmann and Carithers, 1992b). Based on studies on the development of the magnocellular neurosecretory neuronal system, a secretory role has been proposed for pituicytes, which would provide trophic and tropic factors to the growing neurosecretory neurons (Galabov and Schiebler, 1978;Dellmann and Sikora, 1981;Wittkowski, 1986).…”

Section: Role Of Glial Cellsmentioning

confidence: 99%

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Regeneration of neurosecretory axons into intrahypothalamic grafts of neural lobe, sciatic nerve, and optic nerve: a neurophysin-immunohistochemical, HRP-histochemical, and fine structural study

Ouassat

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Transected axons of adult hypothalamo‐neurohypophysial neurons regenerate along tanycytic processes

Chauvet

Parmentier

Alonso

1995

J of Neuroscience Research

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In the intact hypothalamo-neurohypophysial system, oxytocinergic or vasopressinergic neurons project their axons throughout the internal layer of the median eminence towards the blood vessels of the hypophysial neural lobe. When transected at the level of the median eminence, these axons undergo massive sprouting towards the external layer of the organ and the underlying perivascular region containing hypophysial portal vessels. The present study was designed to explore the possible roles of median eminence glial cells in such a reorganization of transected neurohypophysial axons. The relationships between regenerating axons and glial cells were studied by laser scanning confocal microscopy and electron microscopy on vibratome sections immunostained with specific antibodies against neurohypophysial peptides and/or against glial markers. All along the intact median eminence, two main types of glial cells were identified: (1) tanycytes immunoreactive to vimentin and slightly immunoreactive to glial fibrillary acidic protein, and (2) classical astrocytes immunoreactive to glial fibrillary acidic protein but vimentin-negative. In the intact median eminence, neurohypophysial axons were associated with astrocytic processes located in the internal layer. After a lesion of the hypophysial stalk, peptidergic regenerating axonal sprouts were found to project massively towards the external layer and to penetrate the underlying perivascular region in close association with tanycytic-like processes immunoreactive to both vimentin and to glial fibrillary acidic protein. In contrast, regenerating sprouts were absent from those regions of the lesioned median eminence containing astrocytic processes immunoreactive to glial fibrillary acidic protein but vimentin-negative. When fixed lesioned median eminences were treated by placing crystals of the lipophilic dye DiI on their ventricular surface, regenerating axons were found to be closely associated with DiI-labelled tanycytic-like end feet terminating in the external layer, and with connected thin processes projecting through the external vascular region. These data indicate that in the median eminence of the adult rat, lesioned neurohypophysial axons regenerate in close association with tanycytic processes.

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Development of neural lobe-like neurovascular contact regions after intrahypothalamic transection of the hypothalamo-neurohypophysial tract

Cited by 11 publications

References 32 publications

Regeneration of neurosecretory axons into various types of intrahypothalamic graft is promoted by the absence of the blood-brain barrier: A neurophysin-immunohistochemical and horseradish peroxidase-histochemical study

Regeneration of neurosecretory axons into various types of intrahypothalamic graft is promoted by the absence of the blood-brain barrier: A neurophysin-immunohistochemical and horseradish peroxidase-histochemical study

Regeneration of neurosecretory axons into intrahypothalamic grafts of neural lobe, sciatic nerve, and optic nerve: a neurophysin-immunohistochemical, HRP-histochemical, and fine structural study

Transected axons of adult hypothalamo‐neurohypophysial neurons regenerate along tanycytic processes

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