Peptidergic Neurosecretory Axons Regenerate into Sciatic Nerve Autografts in the Rat Hypothalamus

Hd, Dellmann; Lf, Lue; Bellin, SI

doi:10.1159/000124659

Cited by 18 publications

(13 citation statements)

References 16 publications

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“…The degeneration is more outspoken for VP-producing neurons than for OTproducing neurons [19,21]. After these operations a func tional recovery occurred over at least 2 weeks, but may al ready have started by 7 days; this recovery is accompanied by reorganization of fibers in the median eminence and pi tuitary stalk [4,13,18,30]. However, from the available lit térature it appears that the anterolateral cut in the basal hypothalamus does not give rise to the same degeneration and regeneration as seen after (neuro)hypophysectomy and stalk transection [24,25,28], The median eminence and pi tuitary stalk are anatomically and functionally intact [24,25], However, a perivascular plexus develops and regenera tive sprouting occurs after placing cuts in the hypothalamo neurohypophyseal system [12,14,24], These may contri bute to new neurohormonal connections [24],…”

Section: Discussionmentioning

confidence: 99%

Differential Responses in Vasopressin and Oxytocin Gene Expression in Distinct Hypothalamic Nuclei after Hypothalamoneurohypophyseal Disconnection and Vasopressin Substitution

1989

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A possible feedback of circulating vasopressin (VP) on the expression of its gene in the hypothalamoneurohypophyseal system was studied in rats with depleted stores of neurohypophyseal hormones. The neural lobe of the pituitary gland was disconnected by anterolateral deafferentation of the basal hypothalamus using a Halasz knife cut. One group of lesioned animals was substituted continuously with VP using mini-osmopumps. After 1 week, the lesion had caused a complete disappearance of neurohypophyseal hormones from the neurointermediate pituitary and induced a 2-fold increase in water intake and an increase in plasma osmolality of approximately 7 mOsm/kg. VP mRNA levels of the supraoptic nucleus (SON), paraventricular nucleus (PVN) and suprachiasmatic nucleus (SCN) were measured in punched tissue by Northern blot analysis and dot-blot analysis. VP mRNA levels of the SON and PVN were reduced by 50% due to the deafferentation, which might have been caused by degeneration. VP substitution of the lesioned animals normalized water intake but not plasma osmolality. In the VP-substituted animals, VP mRNA levels of the SON were 2-fold reduced compared to the nonsubstituted lesioned animals. The VP mRNA levels of the PVN were not affected by VP substitution. The VP mRNA levels of the SCN increased 2-fold after the lesion but were not influenced by VP substitution. Concomitant determination of oxytocin (OT) mRNA showed that OT mRNA levels in the PVN and SON were not affected by the deafferentation and did not respond to VP substitution. The results indicate that VP mRNA levels of the SON in hypothalamoneurohypophyseal-disconnected rats are negatively influenced by peripheral VP independently from changes in plasma osmolality. The data demonstrate that VP neurons of different hypothalamic nuclei display differential responses in VP gene expression. Furthermore, the results point to a different mechanism of regulation for VP and OT gene expression upon VP substitution and deafferentation.

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Section: Discussionmentioning

confidence: 99%

Differential Responses in Vasopressin and Oxytocin Gene Expression in Distinct Hypothalamic Nuclei after Hypothalamoneurohypophyseal Disconnection and Vasopressin Substitution

1989

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“…The matrix of all three types of grafts includes copious redundant basal lamina, sometimes in the form of tubes, which is probably elaborated hy Schwann cells, pituicytes, endothelium, or astrocytes. There is no consistent relationship between these laminae or the perivascular basal lamina with NSA comparable to that in transplanted peripheral nerve graft, in which regenerating NSA are believed to follow a scaffold of collagen or redundant basal lamina (Dellmann et al, 1986(Dellmann et al, ,1987.…”

Section: Discuss [Onmentioning

confidence: 99%

Regrowth of damaged neurosecretory axons to fenestrated vessels of implanted peripheral tissues

Kadota

Pettgrew

Brightman

1990

Synapse

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A major target of neurosecretory axons (NSA) is the basal lamina around fenestrated blood vessels (FBV) in the neural lobe of the pituitary gland. We have posed the question of whether there is neurovascular specificity. Do mature, regenerating NSA terminate selectively on the FBV of the neural lobe compared with the FBV of other tissues that normally are not innervated by NSA? Three types of tissue were transplanted between inbred Fisher rats. Fragments, about 1 mm3, of pineal, adrenal medulla, and neural lobe were grafted bilaterally to the hypothalamic, retro-chiasmatic area, which includes bundles of NSA from supraoptic and paraventricular neurosecretory nuclei exclusively, but no FBV. Two and 4 weeks later, the grafts were prepared for the immunohistochemical localization of NSA and for electron microscopy. NSA-FBV proximity was measured, and the number of NSA, FBV, and of NSA-FBV associations was counted per surface area of each graft. Regenerating NSA can associate as closely with FBV of other tissues as they can with the FBV of the neural lobe. There does not appear to be specificity with respect to the closeness of association between neurosecretory terminals and fenestrated capillaries. However, the number of these associations is greater in neural lobe grafts than in adrenal or pineal grafts at 4 weeks. The number of FBV is also greatest in neural lobe grafts at this time, an increase that would provide a greater opportunity for NSA-FBV associations.

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“…A second characteristic shared by all areas or grafts into which neurosecretory axons regenerate are glial cells. 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).…”

Section: Neurosecretory Axon Regenerationmentioning

confidence: 99%

“…To test this hypothesis, proximal stumps of intrahypothalamically transected neurosecretory axons in rats were exposed to three different transplanted vascular and glial microenvironments: (1) autologous grafts of sciatic nerve, which are characterized by a blood-nerve barrier (BNB) and neurolemmocytes; (2) isografts of neural lobe, which lack a BBB and whose predominant glial cells are pituicytes; and (3) isografts of optic nerve, which are characterized by the presence of a BBB, oligodendrocytes, and astrocytes. Although it has been established that these grafts provide microenvironments that support varying degrees of regeneration of transected neurosecretory axons (Dellmann et al, 1986(Dellmann et al, , 1987a(Dellmann et al, , 1989, the fate of the BBB after grafting, its role in neurosecretory axon regeneration, and the comparative evaluation of the various glial microenvironments with respect to regeneration and restoration of function have not been addressed.…”

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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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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Peptidergic Neurosecretory Axons Regenerate into Sciatic Nerve Autografts in the Rat Hypothalamus

Cited by 18 publications

References 16 publications

Differential Responses in Vasopressin and Oxytocin Gene Expression in Distinct Hypothalamic Nuclei after Hypothalamoneurohypophyseal Disconnection and Vasopressin Substitution

Differential Responses in Vasopressin and Oxytocin Gene Expression in Distinct Hypothalamic Nuclei after Hypothalamoneurohypophyseal Disconnection and Vasopressin Substitution

Regrowth of damaged neurosecretory axons to fenestrated vessels of implanted peripheral tissues

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

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