Neuronotrophic and neurite-promoting factors: effects on early postnatal chromaffin cells from rat adrenal medulla

Long-Term Viability of Isolated Bovine Adrenal Medullary Chromaffin Cells following Intrastriatal Transplantation

Adrenal medullary grafts generally exhibit poor viability when grafted into the striatum. Previous work in our laboratory demonstrated that chromaffin cells can survive well for up to 2 mo following grafting into the intact rat striatum after cells are isolated from the nonchromaffin supporting cells (fibroblasts and endothelial cells) of the adrenal medulla. The aim of the present study was to assess the long-term viability of isolated bovine chromaffin cells following grafting into the intact rat striatum. The viability of grafted bovine adrenal medullary chromaffin cells was compared in rats receiving either (a) perfused adrenal medulla; (b) isolated chromaffin cells; or (c) isolated chromaffin cells that were subsequently recombined with their nonchromaffin supporting cells. One year postimplantation, all graft types which included fibroblasts and endothelial cells were infiltrated with macrophages and demonstrated an abundance of cellular debris. No viable chromaffin cells were observed. In contrast, healthy tyrosine hydroxylase (TH) and dopamine beta hydroxylase (DβH) immunoreactive chromaffin cells survived for 1 yr posttransplantation when grafted in isolation from the nonchromaffin constituents of the adrenal medulla. Good xenograft survival was achieved in this group despite the fact that these rats were only immunosuppressed for 1 mo postimplantation. Grafted cells demonstrated morphological characteristics of chromaffin cells in situ and these implants were not accompanied by macrophage infiltration. These data demonstrate that long-term survival of chromaffin cells can be achieved following intrastriatal implantation and the viability of grafted chromaffin cells is dependent upon the removal of the nonchromaffin supporting cells.

Neurite outgrowth on chromaffin cells applying extremely low frequency magnetic fields by permanent magnets

BACKGROUND AND AIMS

There is an increasing interest about the effects of electromagnetic fields on health and clinical applications. Electromagnetic fields have been shown to promote differentiation and regeneration of many tissues. The purpose of the present study was to evaluate if a magnetic field (MF) varying in time is able to induce neurite outgrowth in cultured chromaffin cells. For this reason, a stimulation system was developed in order to generate a magnetic field, using permanent magnets as a supply.

METHODS

In this investigation we used a pair of permanent ferrite magnets. These were mounted in a mechanical system in which both magnets rotate around a culture Petri dish. The stimulation device was designed at Centro de Investigación y de Estudios Avanzados, Avanzados del IPN, Mexico City. Primary cultures of chromaffin cells were stimulated with a magnetic field of 6.4 mT and 4, 7, 10 or 12Hz (2h daily, during a 7-day period). After treatment, percentage of neurite outgrowth was calculated.

RESULTS

Our results show that the magnetic fields produced by rotating permanent magnets induced neurite outgrowth on chromaffin cells at 7 and 10Hz.

CONCLUSIONS

The present study provides evidence that MFs varying in time (7 and 10Hz) induce neurite outgrowth in chromaffin cells. These studies will contribute to elucidate the effect of noninvasive MF stimulus in order to apply it in future regeneration therapies. Also, the device designed could be used for different kind of cells and may work as a model for future clinical devices.

Neuronal differentiation elicited by glial cell line-derived neurotrophic factor and ciliary neurotrophic factor in adrenal chromaffin cell line tsAM5D immortalized with temperature-sensitive SV40 T-antigen

To understand the characteristics of tsAM5D cells immortalized with the temperature-sensitive simian virus 40 large T-antigen, we first examined the responsiveness of the cells to ligands of the glial cell line-derived neurotrophic factor (GDNF) family. tsAM5D cells proliferated at the permissive temperature of 33 degrees C in response to either GDNF or neurturin, but not persephin or artemin. At the nonpermissive temperature of 39 degrees C, GDNF or neurturin caused tsAM5D cells to differentiate into neuron-like cells; however, the differentiated cells died in a time-dependent manner. Interestingly, ciliary neurotrophic factor (CNTF) did not affect the GDNF-mediated cell proliferation at 33 degrees C but promoted the survival and differentiation of GDNF-treated cells at 39 degrees C. In the presence of GDNF plus CNTF, the morphological change induced by the temperature shift was associated with up-regulated expression of various neuronal marker genes, indicating that the cells had undergone neuronal differentiation. In addition, tsAM5D cells caused to differentiate by GDNF plus CNTF at 39 degrees C became dependent solely on nerve growth factor (NGF) for their survival and neurite outgrowth. Moreover, upon treatment with GDNF plus CNTF, the dopaminergic phenotype was suppressed by the temperature shift. Thus, we demonstrated that tsAM5D cells had the capacity to differentiate terminally into neuron-like cells in response to GDNF plus CNTF when the oncogene was inactivated by the temperature shift. This cell line provides a useful model system for studying the role of a variety of signaling molecules for GDNF/CNTF-induced neuronal differentiation.

[Neurotrophic factor responsiveness of adrenal medullary cell line tsAM5D immortalized with temperature-sensitive SV40 T-antigen]

We established adrenal medullary cell lines from transgenic mice expressing an oncogene, the temperature-sensitive simian virus 40 large T-antigen, under the control of the tyrosine hydroxylase promoter. A clonal cell line, named tsAM5D, conditionally grew at a permissive temperature of 33 degrees C and exhibited the dopaminergic chromaffin cell phenotype as exemplified by the expression pattern of mRNA for catecholamine synthesizing-enzymes and secretory vesicle-associated proteins. tsAM5D cells proliferated at the permissive temperature in response to glial cell line-derived neurotrophic factor (GDNF), basic fibroblast growth factor (bFGF) and ciliary neurotrophic factor (CNTF). At a nonpermissive temperature of 39 degrees C, GDNF and CNTF acted synergistically to differentiate tsAM5D cells into neuron-like cells. In addition, tsAM5D cells caused to differentiate by GDNF plus CNTF at 39 degrees C became dependent solely on nerve growth factor for their survival and showed markedly enhanced neurite outgrowth. In the presence of GDNF plus CNTF, the morphological change induced by the temperature shift was associated with up-regulated expression of neuronal marker genes including microtubule-associated protein 2, neuron-specific enolase, neurofilament, and growth-associated protein-43, indicating that the cells underwent neuronal differentiation. Thus, we demonstrated that tsAM5D cells could proliferate at permissive 33 degrees C, and also had the capacity to terminally differentiate into neuron-like cells in response to GDNF plus CNTF when the oncogene was inactivated by shifting the temperature to nonpermissive 39 degrees C. These results suggest that tsAM5D cells should be a good tool to allow a detailed study of mechanisms regulating neuronal differentiation.

Temperature-dependent, neurotrophic factor-elicited, neuronal differentiation in adrenal chromaffin cell line immortalized with temperature-sensitive SV40 T-antigen

We established adrenal medullary cell lines from transgenic mice expressing an oncogene, the temperature-sensitive simian virus 40 large T-antigen, under the control of the tyrosine hydroxylase promoter. A clonal cell line, named tsAM5D, conditionally grew at a permissive temperature of 33 degrees C and exhibited the dopaminergic chromaffin cell phenotype as exemplified by the expression pattern of mRNA for catecholamine-synthesizing enzymes and secretory vesicle-associated proteins. tsAM5D cells proliferated at the permissive temperature in response to basic fibroblast growth factor (bFGF) and ciliary neurotrophic factor (CNTF). At a non-permissive temperature of 39 degrees C, bFGF and CNTF acted synergistically to differentiate tsAM5D cells into neuron-like cells. In addition, tsAM5D cells caused to differentiate by bFGF plus CNTF at 39 degrees C became dependent solely on nerve growth factor for their survival and showed markedly enhanced neurite outgrowth. In the presence of bFGF and CNTF, the morphological change induced by the temperature shift was associated with up-regulated expression of neuronal marker genes including neuron-specific enolase, growth-associated protein-43, microtubule-associated protein 2, neurofilament, and p75 neurotrophin receptor, indicating that the cells underwent neuronal differentiation. Thus, we demonstrated that tsAM5D cells could proliferate at permissive 33 degrees C, and also had the capacity to terminally differentiate into neuron-like cells in response to bFGF and CNTF when the oncogene was inactivated by shifting the temperature to non-permissive 39 degrees C. These results suggest that tsAM5D cells should be a good tool to allow a detailed study of mechanisms regulating neuronal differentiation.

Expression and regulation of CNTF receptor-alpha in the in situ and in oculo grafted adult rat adrenal medulla

Cultured and transplanted adrenal medullary cells respond to ciliary neurotrophic factor (CNTF) with neurite formation and improved cell survival although the presence of the CNTF receptor-alpha (CNTFRalpha) has been unclear. This study show that CNTFRalpha mRNA was expressed in the postnatal day 1 as well as in the adult rat adrenal medulla. The highest CNTFRalpha mRNA signal was found in the ganglion cells of the adrenal medulla. After transplantation of adrenal medullary tissue the CNTFRalpha mRNA levels were down-regulated in the chromaffin cells. CNTF treatment of grafts did not normalize the receptor levels, but treatment with nerve growth factor (NGF) did. Thus, we demonstrate that CNTFRalpha mRNA is expressed in adrenal medulla, the levels becomes down-regulated after transplantation, but normalized after treatment with NGF.

Analysis of mice carrying targeted mutations of the glucocorticoid receptor gene argues against an essential role of glucocorticoid signalling for generating adrenal chromaffin cells

Molecular mechanisms underlying the generation of distinct cell phenotypes is a key issue in developmental biology. A major paradigm of determination of neural cell fate concerns the development of sympathetic neurones and neuroendocrine chromaffin cells from a common sympathoadrenal (SA) progenitor cell. Two decades of in vitro experiments have suggested an essential role of glucocorticoid receptor (GR)-mediated signalling in generating chromaffin cells. Targeted mutation of the GR should consequently abolish chromaffin cells. The present analysis of mice lacking GR gene product demonstrates that animals have normal numbers of adrenal chromaffin cells. Moreover, there are no differences in terms of apoptosis and proliferation or in expression of several markers (e.g. GAP43, acetylcholinesterase, adhesion molecule L1) of chromaffin cells in GR-deficient and wild-type mice. However, GR mutant mice lack the adrenaline-synthesizing enzyme PNMT and secretogranin II. Chromaffin cells of GR-deficient mice exhibit the typical ultrastructural features of this cell phenotype, including the large chromaffin granules that distinguish them from sympathetic neurones. Peripherin, an intermediate filament of sympathetic neurones, is undetectable in chromaffin cells of GR mutants. Finally, when stimulated with nerve growth factor in vitro, identical proportions of chromaffin cells from GR-deficient and wild-type mice extend neuritic processes. We conclude that important phenotypic features of chromaffin cells that distinguish them from sympathetic neurones develop normally in the absence of GR-mediated signalling. Most importantly, chromaffin cells in GR-deficient mice do not convert to a neuronal phenotype. These data strongly suggest that the dogma of an essential role of glucocorticoid signalling for the development of chromaffin cells must be abandoned.

Transplant of cultured neuron-like differentiated chromaffin cells in a Parkinson's disease patient. A preliminary report

BACKGROUND

Treatment of Parkinson's Disease (PD) has been attempted by others by transplanting either the patient's own adrenal medullary tissue or fetal substantia nigra into caudate or putamen areas. However, the difficulties inherent in using the patient's own adrenal gland, or the difficulty in obtaining human fetal tissue, has generated the need to find alternative methods.

METHODS

We report here of an alternative to both procedures by using as transplant material cultured human adrenal chromaffin cells differentiated into neuron-like cells by extremely low frequency magnetic fields (ELF MF).

RESULTS

The results of this study show that human differentiated chromaffin cells can be grafted into the caudate nucleus of a PD patient, generating substantial clinical improvement, as measured by the Unified Rating Scale for PD, which correlated with glucose metabolism and D2 DA receptor increases as seen in a PET scan, while allowing a 70% decrease in L-Dopa medication.

DISCUSSION

This is the first preliminary report showing that transplants of cultured differentiated neuron-like cells can be successfully used to treat a PD patient.

Reduced acetylcholinesterase (AChE) activity in adrenal medulla and loss of sympathetic preganglionic neurons in TrkA-deficient, but not TrkB-deficient, mice

TrkA high-affinity receptors are essential for the normal development of sympathetic paravertebral neurons and subpopulations of sensory neurons. Paravertebral sympathetic neurons and chromaffin cells of the adrenal medulla share an ontogenetic origin, responsiveness to NGF, and expression of TrkA. Which aspects of development of the adrenal medulla might be regulated via TrkA are unknown. In the present study we demonstrate that mice deficient for TrkA, but not the neurotrophin receptor TrkB, show an early postnatal progressive reduction of acetylcholinesterase (AChE) enzymatic activity in the adrenal medulla and in preganglionic sympathetic neurons within the thoracic spinal cord, which are also significantly reduced in number. Quantitative determinations of specific AChE activity revealed a massive decrease (-62%) in the adrenal gland and a lesser, but still pronounced, reduction in the thoracic spinal cord (-40%). Other markers of the adrenal medulla and its innervation, including various neuropeptides, chromogranin B, secretogranin II, amine transporters, the catecholamine-synthesizing enzymes tyrosine hydroxylase and PNMT, synaptophysin, and L1, essentially were unchanged. Interestingly, AChE immunoreactivity appeared unaltered, too. Preganglionic sympathetic neurons, in contrast to adrenal medullary cells, do not express TrkA. They must, therefore, be affected indirectly by the TrkA knock-out, possibly via a retrograde signal from chromaffin cells. Our results suggest that signaling via TrkA, but not TrkB, may be involved in the postnatal regulation of AChE activity in the adrenal medulla and its preganglionic nerves.

Delay in manifestations of aging by grafting NGF cultured chromaffin cells in adulthood

Dopamine agonists or grafts compensate impaired motor functions in aged rats. However, there is no evidence showing whether grafting in adulthood retard aging manifestations. Motor performance of 13-month-old rats was tested on 2 meter-long wooden beams which had a 15 degree inclination and whose thickness varied from 3, 6, 12, 18, to 24 mm. Rats at 14 months were randomly assigned to 3 groups: sham graft (Group 1); intrastriatal graft of chromaffin cells cultured with NGF (Group 2); intrastriatal graft of chromaffin cells (Group 3). Motor performance was tested at monthly intervals up until rats were 26 months old. Two more groups were included: 26-month-old naive rats (Group 4); and 3- to 5-month-old naive rats (Group 5) both evaluated only once. At 26 months, the basal activity of ventral mesencephalic dopaminergic neurons was recorded. Results showed in Group 2 delay of motor detriments seen in aged rats, maintenance of basal firing rates of nigral cells compared to those of younger rats, and greater survival of substantia nigra cells. It is suggested that NGF cultured chromaffin cells produce a delay of motor detriments in aged rats, as a result of inducing survival and firing rates of nigral cells comparable to those seen in young rats.

Peptidergic, catecholaminergic and morphological properties of avian chromaffin cells are modulated distinctively by growth factors

Most neurons and endocrine cells are known to co-express a 'classical neurotransmitter' with one or more neuropeptides. Although their expression has been shown to be modulated by differentiation factors, it is not known if particular combinations of neurotransmitter/neuropeptide(s) are co-regulated. We have analyzed the effect of nerve growth factor (NGF), neurotrophin-3 (NT-3), brain derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), basic fibroblast growth factor (bFGF) and transforming growth factor beta 1 (TGF-beta 1) on the modulation of neuroactive substances co-expressed by avian chromaffin cells. The content of the neuropeptides neuropeptide Y (NPY), enkephalin (ENK) and somatostatin (SS) was measured by radioimmunoanalysis, and the content of the catecholamines norepinephrine (NE) and epinephrine (E) by high pressure liquid chromatography-electrochemistry (HPLC-EC). In addition, the morphological differentiation of chromaffin cells in response to the growth factors was assessed. All of the studied factors had distinct effects on the chromaffin content of neuropeptides and catecholamines. Our results show that the modulation of CAs and neuropeptides, and among the neuropeptides themselves is completely dissociated. Moreover, the cellular responses to the different growth factors show that neurochemical properties are modulated independently of morphological ones.

Sympathoadrenal progenitors in embryonic chick sympathetic ganglia show distinct responses to glucocorticoid hormones

The sympathoadrenal cell lineage originates from the neural crest and comprises the neurons of sympathetic ganglia, adrenal and extra-adrenal chromaffin cells, and the so-called small intensely fluorescent cells. In vitro studies using mammalian immature chromaffin cells, adrenal or sympathetic ganglionic progenitors, or ganglionic small intensely fluorescent cells, have suggested that glucocorticoid hormones are essential for inhibiting neuronal differentiation of sympathoadrenal progenitors and promoting the chromaffin cell phenotype. In avian systems, however, the distinct cellular phenotypes in this lineage and the molecular cues underlying their differentiation have not been fully explored. In the chick embryo, early sympathetic ganglion anlagen are populated by granule-containing cells that morphologically resemble small intensely fluorescent cells and chromaffin cell progenitors. These cells subsequently disappear from the ganglia, by death and by transition into fully differentiated sympathetic neurons, as indicated by the appearance of cells that are ultrastructurally intermediate between granule-containing cells and fully differentiated neurons (granule-containing cells in transition). In the present study, we show that treatment of cultured sympathetic cells dissociated from embryonic day (E) 7, 9, or 11 lumbar sympathetic ganglia with the glucocorticoid hormones hydrocortisone or corticosterone has neither an inhibitory nor an inductive effect on phenotypes of granule-containing cells or granule-containing cells in transition. In cell cultures of E15 ganglia, however, glucocorticoid treatment induces a granule-containing cell resembling the granule-containing phenotype. These results suggest that the early granule-containing cells and granule-containing cells in transition in chick sympathetic ganglia are not the counterparts of glucocorticoid-responsive mammalian small intensely fluorescent or chromaffin progenitor cells, despite their morphological similarity. However, E15 sympathetic ganglia apparently contain a glucocorticoid-responsive progenitor population that can differentiate into chromaffin-like cells. These progenitors seem to require a systemic or intraganglionic developmental signal or undergo a temporal switch that renders them susceptible to glucocorticoids.

Phenotypic changes induced by replating of early post-natal rat chromaffin cells

Postnatal chromaffin cells from rat adrenal medulla in culture respond to NGF by expressing neuronal traits. The replating of chromaffin cells after trypsinization produced neurite growth in a manner similar to that of NGF. The combination of replating and NGF exposure did not induce phenotypic changes over and above those observed by NGF alone. The morphological changes are independent of the preliminary culture conditions. The results of this study demonstrate for the first time that simple replating of young chromaffin cells can induce neuronal traits indistinguishable from those observed with NGF.

Adrenal medulla in neural grafting and neural plasticity

The recent history of neural transplantation using the adrenal medulla parallels an evolution in our thinking about neural grafting as a therapeutic approach to treat neurodegenerative diseases such as Parkinson's disease. Initially, neural grafting was an approach to study development and regeneration. With the discovery that adrenal chromaffin cell grafts would ameliorate some of the motor deficits associated with the loss of striatal dopamine, adrenal grafts were used to provide dopamine to the dopamine-depleted striatum. However, subsequent studies showed poor chromaffin cell survival unless trophic factors were present at the site of transplantation. These experiments lead to the appreciation of the complex interactions between neurotrophic factors, inflammatory cytokines, the grafted tissue, and the host brain's response. Thus, we find ourselves again using neural transplantation as an approach to help us better understand central nervous system plasticity and the features this plasticity shares in common with development and regeneration.

Amelioration of sensory attention and sensorimotor deficits by chromaffin cell grafts to the cerebral cortex of nucleus basalis magnocellularis lesioned rats

Rats that have received lesions to the nucleus basalis magnocellularis display with a variety of behavioral deficits; among these are decreases in performance of maze tests as well as deficiencies on measures of general health, sensory attention and sensorimotor abilities. We have previously shown that grafts of chromaffin cells placed in the cerebral cortex of nucleus basalis magnocellularis lesioned rats can ameliorate the lesion-induced deficits in performance of a task involving spatial memory. In the present study, we find that lesion-induced deficits in the sensory attention measure of exploration of the environment (head scanning) as well as the sensorimotor behavior involving a rat righting itself when placed nose down on an inclined grid are evident at 8 weeks post-lesion in lesioned-alone rats; these deficits are significantly ameliorated by chromaffin cell grafts in the cerebral cortex placed two weeks following the lesion procedure. These findings may have relevance to the use of chromaffin cells for grafting in neurodegenerative disorders in which sensorimotor or attention deficit components are involved.

The biology and behaviour of intracerebral adrenal transplants in animals and man

The catecholamine containing chromaffin cells of the adrenal medulla have recently been employed as intracerebral grafts in man and animals with lesions of the nigrostriatal dopaminergic system. This review outlines the basic biology of the chromaffin cell with reference to its efficacy as a source of dopamine in the grafted state. This is followed by an evaluation of the use of these grafts in experimentally lesioned animals and in patients with Parkinson's disease.

Characterization of a glial cell line persistently infected with borna disease virus (BDV): influence of neurotrophic factors on BDV protein and RNA expression

Borna disease virus (BDV) infects cells of the nervous system in a wide range of species. Previous work suggests that there are differences in BDV replication in neuronal cells and glial cells. Many neurons are lysed by the immunopathologic response to BDV; lysis of dentate gyrus neurons in the absence of encephalitis is seen in rats inoculated with BDV as neonates. In contrast, persistently BDV-infected astrocytes increase over the course of BDV infection. Therefore, we compared BDV replication in neuronal (SK-N-SH and SK-N-SHEP) and astrocytic (C6) cell lines. While SK-N-SH cells produced more infectious virions per cell, the C6 cells contained more BDV proteins and RNA. BDV sequences in the supernatants of both cell types were identified, despite low titers of infectious virus, suggesting the release of incomplete virions into the medium. C6 cells secreted a factor or factors into the medium that enhanced the production of BDV proteins and RNA in other cell lines. In addition, nerve growth factor treatment produced the same enhancement. Thus, BDV replication in certain neural cells in vitro may be linked to the production of cell-specific factors which affect viral replication.

Peripheral nerve segments promote consistent long-term survival of adrenal medulla transplants in the brain

Patients with Parkinson's disease have received intracerebral transplants of autologous adrenal medulla in the attempt to counteract their severe motor dysfunctions. Unfortunately, in the majority of cases, clinical improvement has not persisted and there has been extremely poor survival of the grafts. Based on the recent observations of long-term viability of adrenal medulla grafts in the interior of transected peripheral nerves, adrenal medulla/peripheral nerve complexes were constructed in the brain to promote extended viability of chromaffin cells. A three-step, time-dependent transplantation procedure is described that results in a 100% survival rate of the adrenal medulla graft. The grafts consist of a stable population of approximately 2.0 x 10(3) chromaffin cells that survive for at least 6 months (longest time point studied): Immunoreactivity to catecholamine-related enzymes (tyrosine hydroxylase, dopamine beta-hydroxylase) and the low-affinity NGF receptor (192-IgG) are expressed by the chromaffin cells. The ultrastructural characteristics of the cells are normal and comparable to their in vivo counterparts. Construction of these peripheral nerve/adrenal medulla complexes evidently improves local conditions in and around the grafts, enabling the chromaffin cells to remain viable. This new methodology achieves the goal of reliable and extended survival of the adrenal medulla graft after intracerebral transplantation. The enhanced longevity now provides an opportunity to reevaluate the efficacy of the adrenal medulla transplant to ameliorate the functional disorders associated with striatal dopamine depletion, especially over long time periods.

Adrenal medulla and substantia nigra co-grafts in peripheral nerve: chromaffin cells survive for long time periods and prevent degeneration of nigral neurons

A series of degenerative cytoskeletal changes characterize grafts of embryonic substantia nigra when isolated for long time periods in the peripheral nervous system. This study was designed to determine whether the adrenal medulla could modulate the cytoskeletal changes in the substantia nigra when co-grafted within peripheral nerves. The sciatic nerves of young adult rats received single transplants of embryonic day 15 substantia nigra or co-transplants of substantia nigra plus young adult adrenal medulla in close proximity. Immunocytochemistry was used to examine the expression of tyrosine hydroxylase, phosphorylated (RT97) and non-phosphorylated (SMI-32) neurofilament proteins in the grafts. Single substantia nigra grafts, examined after 1 month, consisted of numerous neurons and fibers that expressed the epitope for tyrosine hydroxylase. Normal spatial distributions of the phosphorylated and non-phosphorylated neurofilament subunits were observed. In contrast, single 1-year-old nigral transplants were shrunken, contained significantly fewer tyrosine hydroxylase positive neurons and displayed abnormal neurofilaments staining patterns including swollen axons, a reduction in the density of labeled axons and perikaryal accumulation of the phosphorylated neurofilament subunit. When co-grafted with the adrenal medulla, the nigral transplants did not show the degenerative cytoskeletal aspects evident in the single 1-year-old grafts. The loss of neurons was prevented and the neurofilament immunolabeling was indistinguishable from the young substantia nigra preparations. In addition, all the 1-year-old adrenal medulla grafts were viable within the peripheral nerves, consisting of hundreds of cells identified by immunoreactivity to tyrosine hydroxylase and the rat beta-nerve growth factor receptor (192-IgG). The experiments illustrate a strong protective effect by the adrenal medulla on neurons of the substantia nigra in the peripheral nerve environment. It is suggested that a catecholaminergic trophic source and/or neural interactions with the adrenal medulla may be important factors in the long-term survival of neurons and maintenance of normal cytoskeletal characteristics in the grafted substantia nigra neurons under these experimental circumstances.

Intracerebral adrenal medulla grafts: a review

This review summarizes basic and clinical research on intracerebral adrenal medulla grafts, emphasizing potential applications to Parkinson's disease. Properties of intraventricular and intraparenchymal grafts are described, and cell survival and functional effects are compared. It is clear that adrenal medulla allografts survive poorly in the parenchyma of the corpus striatum and better in the lateral ventricle. Nerve growth factor (NGF) may improve the survival of adrenal medulla grafts. In the absence of added NGF even adrenal medulla grafts in the ventricle survive irregularly, and the factors required for graft survival in the ventricle are not well understood. In the 6-hydroxydopamine-lesioned rat model most evidence suggests, not surprisingly, that adrenal medulla grafts produce functional effects only when they survive. These effects may be related to production of catecholamines by the transplanted cells. In addition, adrenal medulla grafts may produce trophic effects on host brain. These effects are most evident in animals with MPTP-induced damage to dopaminergic systems and may be nonspecific, possibly related in part to the brain injury that is induced by graft implantation. Trophic effects may contribute to the functional effects of adrenal medulla grafts: For intraparenchymal grafts, trophic effects that do not require cell survival may contribute small functional changes, while additional behavioral effects may require substantial chromaffin cell survival. The evidence for direct dopamine-mediated effects as compared to trophic mechanisms of action for these grafts in animal models for Parkinson's disease is presented. Clinical studies of adrenal medulla grafts in human patients are examined and compared in detail. When inspected closely, the various clinical studies are in general agreement on most points, although there are differences in the degree of improvement found, both across different studies and individual patients. It is concluded that some beneficial clinical effects occur, with small to modest changes in most patients and substantial improvement in a minority of patients. There also seem to be larger or more consistent changes in durations of "on" and "off" times in L-dihydroxyphenylalanine-treated patients. There are substantial side effects, and it is not clear that the clinical changes are sufficient to justify performing adrenal medulla transplantation in human patients as a routine procedure.(ABSTRACT TRUNCATED AT 400 WORDS)

Chromaffin cell grafts to rat cerebral cortex reverse lesion-induced memory deficits

Adrenal chromaffin cells were isolated from donor adult rats and transplanted to the cerebral cortex of bilaterally nucleus basalis magnocellularis-lesioned rats. Chromaffin cell grafts to lesioned animals completely reversed the spatial memory deficit seen in lesioned alone animals on a T-maze alternation task. Although chromaffin cell grafts have been used previously to reverse motor abnormalities arising from defective nigro-striatal aminergic transmission, the present report is the first evidence that chromaffin cell transplants can reverse deficits in memory function. Grafts also enhanced cortical acetylcholinesterase staining.

Chromaffin cells express two types of insulin-like growth factor receptors

The receptor binding, internalization and tyrosine kinase activation of insulin-like growth factors, IGF-I and IGF-II have been investigated in cultured adult bovine chromaffin cells. IGF-I receptor alpha-subunits (Mr approximately 130,000) bound IGF-I and IGF-II with identical affinity (Kd approximately 1 nM) and insulin with about 1000 times lower affinity. IGF-II receptors (Mr approximately 250,000) bound IGF-II with a Kd of 0.5 nM, IGF-I with about 10 times lower affinity and insulin with greater than 10,000 times lower affinity. The amounts of IGF-I and IGF-II receptors on the cell surface were 8 x 10(4) and 4 x 10(4) sites per cell, respectively. Insulin bound to a specific receptor with Kd approximately 2 nM and the amount of receptors was 1.5 x 10(4) sites per cell. IGF-I and IGF-II stimulated tyrosine kinase activity and autophosphorylation of the IGF-I receptor beta-subunit (Mr approximately 94,000) with equal potency (ED50 approximately 1 nM), whereas insulin was approximately 5 times less potent. Both IGF-I and IGF-II were internalized after their binding to cell surface receptors. Mannose-6-phosphate, which binds to the IGF-II receptor, did not alter the binding or internalization of IGF-II. It is concluded that IGF-I and IGF-II can exert their biological effects in chromaffin cells by activation of the IGF-I receptor tyrosine kinase or by interaction with the IGF-II receptor.

Differentiation of embryonic chick sympathetic neurons in vivo: ultrastructure, and quantitative determinations of catecholamines and somatostatin

The ultrastructural and transmitter development of lumbar sympathetic ganglia was studied in embryonic day-6 through -18 chick embryos. At embryonic day 6, ganglia are populated by two morphologically distinct types of neuronal cells and Schwann cell precursors. The neuronal populations basically comprise a granule-containing cell and a developing principal neuron. Granule-containing cells have an irregularly shaped or oval nucleus with small clumps of chromatin attached to the inner nuclear membrane and numerous large (up to 300 nm) membrane-limited granules. Developing principal neurons display a more rounded vesicular nucleus with evenly distributed chromatin, prominent nucleoli, more developed areas of Golgi complexes, and rough endoplasmic reticulum and large dense-core vesicles up to 120 nm in diameter. There are granule-containing cells with fewer and smaller granules which still display the nucleus typical for granule-containing cells. These granule-containing cells may develop toward developing principal neurons or the resting state of granule-containing cells found in older ganglia. Both granule-containing cells and developing principal neurons proliferate and can undergo degeneration. At embryonic day 9 there are far more developing principal neurons than granule-containing cells. Most granule-containing cells have very few granules. Mitotic figures and signs of cell degeneration are still apparent. Synapse-like terminals are found on both developing principal neurons and granule-containing cells. Ganglionic development from embryonic day 11 through 18 comprises extensive maturation of developing principal neurons and a numerical decline of granule-containing cells. Some granule-containing cells with very few and small granules still persist at embryonic day 18. The mean catecholamine content per neuron increases from 0.044 femtomol at embryonic day 7 to 0.22 femtomol at embryonic day 15. Concomitantly, there is a more than 6-fold increase in tyrosine hydroxylase activity. Adrenaline has a 14% share in total catecholamines at embryonic day 15. Somatostatin levels are relatively high at embryonic day 7 (1.82 attomol per neuron) and are 10-fold reduced by embryonic day 15. Our results suggest the presence of two morphologically distinct sympathetic neuronal precursors at embryonic day 6: one with a binary choice to become a principal neuron or to die, the other one, a granule-containing cell, which alternatively may develop into a principal neuron, acquire a resting state or die.

Development and plasticity of adrenal chromaffin cells: cues based on in vitro studies

Neural crest derived precursors of the sympathoadrenal cell lineage give rise to two major cell types that differ in a number of morphological, ultrastructural, and biochemical characteristics: principal sympathetic neurons and chromaffin cells of the adrenal medulla. The present article reviews experimental studies performed on cultured adrenal medullary cells and designed to unravel the nature of epigenetic signals governing the developmental choice between the endocrine chromaffin and the neuronal sympathetic phenotype. Emphasis is placed on the role of glucocorticoids in initiation, development, and maintenance of the endocrine chromaffin phenotype and apparently antagonistic influences exerted by nerve growth factor (NGF) in vitro, resulting in the acquisition of neuronal properties by differentiated chromaffin cells. Experimental data from in vitro studies are compatible with the following conclusions. Glucocorticoids represent the decisive signal for the initial induction of endocrine differentiation. Moreover, high steroid hormone concentrations, as present in the adrenal medulla, are a prerequisite for the maturation of chromaffin cells. Even in a differentiated state, the endocrine phenotype is unstable in the absence of glucocorticoids, and the cells seem to reenter the neuronal developmental pathway. Under these conditions, cellular survival and differentiation into sympathetic neurons become NGF-dependent, as in normal sympathetic development. Thus, the effects of NGF survival, neurite outgrowth, and transmitter synthesis of cultured chromaffin cells probably do not reflect the induction of a specific phenotype, but they may be interpreted as a general neurotrophic support observable with other responsive cell types.

Presence of nerve growth factor-like immunoreactivity in carcinoid tumour cells and induction of a neuronal phenotype in long-term culture

Mid-gut carcinoid tumour cells expressed a neuronal phenotype, observed and characterized immunocytochemically in long-term culture. Initially the culture contained a main population of spherical tumour cells with granules immunopositive for serotonin (5-HT) and tachykinins (TK). Production and secretion of these substances into media was verified biochemically. Cytoplasmic granules with 5-HT-like immunoreactivity (5-HT-LI) were markedly reduced during culture, while granules with TK-LI were unchanged in number, corresponding to the biochemical findings. After a few days in culture, tumour cells were flattened and fine neurite-like processes extended. After 2-3 weeks many endocrine tumour cells had converted to neuron-like cells with slender cell processes containing granules with TK-LI. Varicose enlargements and apparent growth cones were observed. When neurites were extended, 50-80% of the neuron-like cells were positive with antisera against the neurofilament triplet. Cells of both endocrine and neuronal phenotypes were positive with antisera against tetanustoxin, Thy 1-antigen, neuron-specific enolase, synapsin and a synaptic vesicle protein (p 38) supporting the concept of these tumour cells as para-neurons. Intermediate filaments, studied with monoclonal anti-vimentin, were found in all cells. Filaments were also observed ultrastructurally. Initially, nerve growth factor (NGF)-LI was found in granules of all spherical tumour cells. When neuritic processes were extended, the cells appeared to lose these granules. After 40 days in culture, NGF-LI was absent or very sparse. The studies indicate autocrine secretion of a growth factor, reacting with the NGF antiserum, by cultured mid-gut carcinoid tumour cells inducing a neuronal phenotype with enhanced NF and TK synthesis and suppressed 5-HT synthesis. In bioassay systems the culture media caused a delayed neurite reaction on PC12 cells, but no reaction on chick ciliary ganglion cells, indicating that the factor is not authentic NGF.

The neuro-endocrine ambiguity of sympathoadrenal cells

This introductory article presents a survey of the principle cellular constituents of the sympathoadrenal section in the peripheral autonomic nervous system, their development and plasticity and factors that govern the expression of particular morphologic and transmitter phenotypes. The article focuses on results obtained in cell culture studies with isolated chromaffin cells that have permitted the analysis of molecular signals possibly serving as environmental cues during the development of sympathoadrenal cells.

Survival and neuritic growth of sympathoadrenal (chromaffin) precursor cells in vitro

Chromaffin precursor cells from embryonic rat adrenal glands were isolated at 16.3 and 20.3 days of gestation and purified by centrifugation on density gradients. Approximately 50% of the cells of both age groups that had attached to the culture substratum by 12 hr survived during a 4-day culture period in the absence of exogenous trophic factors. Nerve growth factor (NGF) and a C6 glioma-cell-conditioned medium (C6-CM) had no or a very moderate promoting effect on survival. The glucocorticoid dexamethasone (DEX) supported the survival of 70-80% of the cells that otherwise would have died. Spontaneous neuritic growth of the sympathoadrenal precursor cells was significantly more pronounced with cells isolated at embryonic day (E) 16.3 than at E20.3. NGF had a significantly smaller promoting effect on neurite ougrowth at E16.3 than at E20.3. C6-CM induced neurite outgrowth from 25% (E16.3) and 35% (E20.3) of the surviving cells. DEX (10(-6) M) completely abolished spontaneous neuritic growth and partially suppressed C6-CM-mediated fiber outgrowth. These data underscore the importance of glucocorticoids for the maintenance and development of an endocrine morphologic phenotype of sympathoadrenal precursors. They suggest that the cells may be initially driven by growth factors other than NGF into a neuronal direction and that they lack NGF-responsiveness and -dependence during the early stages of their development.

Laminin and other basal lamina proteins with neurite promoting activity in medium conditioned by C6 glioma cells

Neurite promoting activities (NPFs) are essential factors in neuronal differentiation. Some of them are associated with proteins of the extracellular matrix (ECM). C6 cells, a rat glioma cell line, release NPF activities into the cell culture medium. We used antibodies against ECM-proteins for enrichment and partial characterization of these activities. Results show that, (1) C6 cells express and release laminin; (2) the C6-laminin consists of 260 kD chains only and is therefore different from typical basal lamina laminin (220 and 440 kD chains), but comparable to other laminins of glial origin (chains in the 200 kD range only); (3) C6-laminin partially purified by affinity chromatography shows NPF-activity; (4) laminin concentration in C6 cell-conditioned medium is not sufficient to account for the total neurite promoting activity of the medium, and (5) in addition to laminin C6 cells express and release fibronectin and possibly type IV collagen.

Growth cone migration across extracellular matrix components depends on integrin, but migration across glioma cells does not

To promote neurite elongation, nerve growth cones must adhere to other surfaces. A complex of integral membrane glycoproteins mediates cell binding to the extracellular glycoproteins fibronectin and laminin (Horwitz et al., J Cell Biol 101:2134-2144, 1985). The receptor complex, named integrin, binds to fibronectin by recognition of a specific peptide sequence, Arg-Gly-Asp-Ser (RGDS), in the fibronectin molecule (Pierschbacher and Ruoslahti, Proc Natl Acad Sci USA 81:5985-5988, 1984). We have used antibodies to integrin and an RGDS synthetic peptide to probe the functions of integrin in the migration of growth cones extended from sensory and spinal cord neurons of chick embryos. Analyses of time lapse videotapes of growth cone migration before and after adding RGDS indicated that 2 mM RGDS rapidly inhibits growth cone movement on substrata coated with fibronectin or a fragment of fibronectin containing the RGDS sequence. RGDS has no effect on growth cone movement on laminin or on a surface coated with material deposited from heart conditioned medium. However, a monclonal antibody to the integrin complex (10 micrograms/ml CSAT) completely blocks growth cone movement on substrata treated with fibronectin, laminin, or heart conditioned medium. Thus integrin may be involved in growth cone adhesion to several extracellular molecules, although the selective effects of RGDS indicate that the integrin complex may have heterogeneous sites for interaction with different components of the extracellular matrix. CSAT antibody has no discernible effect, however, on growth cone migration across the upper surfaces of C6 glioma cells. These data indicate that the surfaces of nerve growth cones contain multiple binding molecules that mediate different adhesive interactions during migration.

Survival, morphology, and catecholamine storage of chromaffin cells in serum-free culture: evidence for a survival and differentiation promoting activity in medium conditioned by purified chromaffin cells

Adult bovine and young rat chromaffin cells cultured in serum-free medium were examined for their survival and differentiation following exposure to various additives, trophic agents and conditioned media. Adrenal chromaffin cells dissociated from 8 day old rats were maintained by dexamethasone, NGF and CNTF or without any additives in an N1-supplemented medium in similar numbers as in serum-containing medium for up to 6 days. Neuritic growth elicited by NGF or CNTF was enhanced in the absence of serum. Medium conditioned by purified bovine chromaffin cells improved cell survival and caused neurite outgrowth in a dose-dependent manner. The activiti(es) was sensitive to heat and trypsin and not blocked by the addition of anti-NGF antibodies. Bovine chromaffin cell survival was reduced by 30% when cells were maintained for one week in the absence as compared to the presence of serum. Addition of insulin, the N1 supplement, dexamethasone or dbcAMP single or in combinations improved the survival to different extents. A combination of insulin (5 micrograms/ml) and dexamethasone (5 X 10(-6) M) proved to be optimal in this respect. However, these supplements failed to restore the cellular catecholamine, noradrenaline and adrenaline contents to levels seen in the presence of serum. This was also true for a chromaffin cell-conditioned medium, which improved survival without elevating the catecholamine contents. Conditioned medium, however, partly restored a more physiological adrenaline-noradrenaline-ratio.

Differential effects of nerve growth factor and ciliary neuronotrophic factor on catecholamine storage and catecholamine synthesizing enzymes of cultured rat chromaffin cells

The effects of nerve growth factor (NGF) and ciliary neuronotrophic factor (CNTF) on catecholamine content and in vitro activities of tyrosine hydroxylase (TH) and phenylethanolamine N-methyltransferase (PNMT) were studied in adrenal chromaffin cells cultured from 8-day-old rats. Both NGF and CNTF enhanced chromaffin cell survival and partially prevented losses of adrenaline during the 4-day culture period in a dose-dependent manner. CNTF was more potent, although cellular levels of adrenaline and noradrenaline were not maintained. NGF did not add to the effect of CNTF. The effect of CNTF on catecholamine storage was not accompanied by changes in the activities of TH and PNMT. In contrast, NGF induced TH but not PNMT activity. These data indicate differences between the mechanisms by which NGF and CNTF affect adrenal chromaffin cells.

Characterization and partial purification of a novel neuronotrophic factor from bovine seminal vesicle

Extracts from bovine seminal vesicles have been shown to contain high concentrations of nerve growth factor (NGF)-like biological activity and of the NGF protein with properties corresponding to that of NGF from other sources. We now demonstrate that a second neuronotrophic protein, termed seminal vesicle-derived neuronotrophic factor (SVNF), is present in seminal vesicle extracts (SVEs), which could not be distinguished from NGF on the basis of biological activity. SVNF has neuronotrophic activity on NGF target cells like embryonic chicken-sensory and sympathetic neurons, sympathetic neurons, and chromaffin cells from neonatal rats, but it is inactive on embryonic chicken ciliary or neonatal rat nodose ganglion neurons. It also stimulates fiber outgrowth from rat pheochromocytoma (PC 12) cells. In gel filtration chromatography on Biogel A 1.5 m, the activity is eluted with an apparent molecular weight of 40 kilodaltons, and by preparative isoelectric focusing, the isoelectric point was determined to be in the neutral range (6.8-7.8). The biological activity of SVNF, in contrast to that of NGF, is partially retained after preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis and can be electrophoretically eluted with an apparent molecular weight of 16-20 kilodaltons. Electrophoretically purified SVNF is not inhibited by antisera to mouse NGF, but its activity is increased greater than 10-fold in the presence of very low concentrations of NGF. For partially purified SVNF, a specific activity of 2.9-5.8 X 10(5) biological units/mg of protein was determined in the presence of subthreshold NGF concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Intrastriatal adrenal medulla grafts in rats. Long-term survival and behavioral effects

Rats with rotational behavior consequent to unilateral lesions of the substantia nigra have been proposed for an experimental model of Parkinson's disease. Adrenal medulla or embryonic substantia nigra grafts in the lateral ventricle of these animals reduce this rotational behavior. For application to primate and human subjects, it may be necessary to implant tissue directly into the parenchyma of the corpus striatum rather than into the ventricle in order to achieve a sufficient distribution of the grafted tissues and increase the efficacy of the grafts. In the present study, the properties of intraparenchymal adrenal medulla grafts were investigated. Grafts were obtained from both young (4 to 5 weeks old) and aging (22 to 24 months old) donor rats. Much of the implanted tissue did not survive, although 200 chromaffin cells per recipient rat were found to have survived for at least 6 months. All of the surviving cells developed process-like cytoplasmic extensions, although these processes did not appear to have reinnervated host brain tissue. Grafts from both young and aging donor rats prevented a slight deterioration in the performance of a sensory neglect test that was observed in a control group that received grafts of sciatic nerve. There was also a tendency that did not reach statistical significance for grafts from young (but not from aging) donors to decrease apomorphine-induced rotational behavior. It is concluded that, although the corpus striatum does not appear to provide a particularly favorable environment for the implantation of adrenal medulla grafts, striatal implants of adrenal medulla might become a promising procedure if a means of improving the survival of these tissues could be developed.

Destruction of the preganglionic nerves by beta-bungarotoxin does not interfere with normal embryonic development of the rat adrenal medulla

Using beta-bungarotoxin (beta-BTX) as a tool to eliminate the preganglionic cholinergic nerve supply to the embryonic rat adrenal gland, we have investigated whether or not these nerves affect the differentiation of embryonic chromaffin cells (pheochromoblasts). Rat fetuses received a single injection of 1 or 2 micrograms beta-BTX or an identical volume of saline at embryonic day (E) 17 and were taken for morphological and biochemical analyses at E 21. Administration of beta-BTX caused a 15 to 20% reduction in body weight, crown-rump-length and adrenal weight. Spinal cord development was reduced and acetylcholinesterase-positive cells in ventral and lateral columns were virtually absent in toxin-treated animals. In adrenal glands, a decrease of choline acetyltransferase activity to 13% of control levels and a concomitant decrease of ultrastructurally identifiable nerve fibers and axon terminals revealed that application of 2 micrograms beta-BTX effectively reduced the neuronal input to E 21 adrenal glands. Values for total adrenal catecholamines, relative amounts of adrenaline and noradrenaline, tyrosine hydroxylase and phenylethanolamine N-methyltransferase activities were unaltered. All ultrastructural features of pheochromoblasts (except the lack of synapse-like axon terminals) were inconspicuous. Corticosterone levels in adrenals and plasma were identical to controls. These data strongly suggest that normal embryonic development of adrenal chromaffin cells does not require an intact nerve supply.

Glial-like cells in sympathetic neural crest derivatives during human embryogenesis. Detection by S-100 immunohistochemistry

The present study investigates at the light and electron microscopic levels the possible presence and distribution during human development of glial-like satellite cells in sympathetic neural crest derivatives by S-100 immunohistochemistry. From the earliest stages investigated, immunostained cells were detected inside sympathetic migrating masses and at their periphery, where they constituted a continuous layer isolating sympathetic elements from mesenchymal cells. The detection and peculiar distribution of these glial-like cells in developing sympathetic tissue could open new perspectives in the study of events linked to the migration and differentiation of some neural crest derivatives.

Effects of pre- and postnatal administration of antibodies to nerve growth factor on the morphological and biochemical development of the rat adrenal medulla: a reinvestigation

Whether or not adrenal medullary (chromaffin) cells which respond to nerve growth factor (NGF) both in vitro and in vivo require NGF for their normal development is controversial. Systemic deprivation of endogenous NGF by injection of anti-NGF antibodies into rat fetuses or by transfer of anti-NGF to the offspring of autoimmunized mothers has provided conflicting results. We have reinvestigated the effects of a specific antiserum to NGF on the morphology, catecholamine (CA) and neuropeptide (Met-enkephalin, Met-ENK; substance P, SP) content, and choline acetyltransferase (ChAT) activity of the rat adrenal medulla. Fetuses were injected with anti-NGF antibodies on day 17 of gestation and postnatally at daily intervals for 7 days. The histological appearance of adrenal medullae of anti-NGF injected animals was not altered as compared to controls. Ultrastructurally, no degenerative changes or developmental retardation of chromaffin cells could be detected. However, numbers of chromaffin granules per micron 2 of cytoplasmic area were greater and the mean diameters of the cores of adrenaline storage granules were smaller in antibody-treated than in control animals. CA and SP content, ratios of adrenaline to noradrenaline and ChAT activities were identical in anti-NGF-treated and control animals. Anti-NGF antibodies caused a reduction of adrenal Met-ENK by 40% as compared to controls. Superior cervical ganglia from the same animals were used to document immunosympathectomy induced by the antiserum. They displayed the well-established structural alterations and a marked reduction of the CA content. We conclude that administration of anti-NGF antibodies to embryonic and early postnatal rats induces only subtle changes in the ultramorphology of chromaffin cells without altering the development of normal CA levels. The small, yet significant effects of anti-NGF antibodies on adrenal Met-ENK, however, may suggest a role for endogenous NGF in the regulation of opioid peptide metabolism in developing chromaffin cells.

Rat adrenal chromaffin cells become sensitive to alpha-latrotoxin when cultured in vitro: the effect of nerve growth factor

Previous studies showed that in the intact rat chromaffin cells are insensitive to the presynaptic stimulatory toxin, alpha-latrotoxin (alpha-LTx). In contrast, primary cultures of rat adrenal chromaffin cells respond to alpha-LTx by releasing stored catecholamines. The toxin-induced response was greater in cultures from young (8-10-day-old) than adult (40-50-day-old) animals, and increased when the time of culturing was prolonged from 4 to 20 days. Even greater responses were observed in cells cultured in the presence of nerve growth factor, a treatment which induces a neuronal-like phenotype. Acquisition of sensitivity to alpha-LTx appears to be an early marker of chromaffin cell commitment to differentiate towards a neuron.

Nerve growth factor and dexamethasone modulate synthesis and storage of catecholamines in cultured rat adrenal medullary cells: dependence on postnatal age

Catecholamine content and in vitro activities of tyrosine hydroxylase (TH) and noradrenaline N-methyltransferase (NMT) were measured in cultures of isolated adrenal medullary cells from newborn and young postnatal rats to study the effects of the differentiation factors glucocorticoids and nerve growth factor (NGF). During the 4-day culture period the cellular catecholamine (CA) content and TH activity remained stable, whereas NMT activity dropped to about half of the initial level. In cells from 2- and 10-day-old rats 10 microM dexamethasone specifically prevented this loss in NMT activity. Furthermore, this glucocorticoid treatment increased, in a dose-dependent manner, the total CA content by 50-100% over control levels without changes in the adrenaline (A) proportion or TH activity. In contrast, NGF did not affect NMT activities at all. In cells from 10-day-old rats 100 ng/ml NFG elevated TH activity and total CA content to about 160% of controls and did not change the proportion of A. This increase in total CA content was linear with the NGF dose and required greater than 5 ng/ml NGF. In chromaffin cells from 2-day-old rats 100 ng/ml NGF affected neither TH activity nor the total content, whereas it significantly reduced the proportion of A by about 25%.

Nerve regeneration through biodegradable polyester tubes

One approach to repair of transected nerves is to attempt extrinsic guidance of axons across the gaps. We inserted the proximal and distal stumps of severed mouse sciatic nerves into opposite ends of biodegradable polyester tubes. The nerves and ensheathing tubes were examined after postoperative survival times of as long as 2 years. Myelinated fiber number in each successfully regenerated nerve was measured and correlated with the tube's residual lumen size. In selected regenerated nerves axonal sizes and myelin sheath widths were sampled and compared with control values. Swelling and deformation of tube walls occurred in nearly all tubes. Successful regeneration was obtained through more than half of the implants, and was more probable in tubes with larger initial lumens. Myelinated fiber number in regenerated nerves ranged from 231 to 3561 (normally 3900 to 4200); larger values again were found in tubes with larger initial lumens. Mean axonal areas in regenerated nerves were roughly half of normal, though myelin sheaths became appropriately thick. We concluded that the more biodegradable a tube, the more likely it was to incur distortion and luminal narrowing. Tube composition per se seemed of importance mainly as it related to maintenance of adequate luminal size over the length of the degrading tubes; luminal adequacy, not tube composition, seemed paramount in determining the extent of nerve regeneration.

Developmental changes in the responses of rat chromaffin cells to neuronotrophic and neurite-promoting factors

This study describes the survival and neurite outgrowth behaviors of cultured adrenal medullary (chromaffin) cells obtained from postnatal rats 1 day (D1) to 100 days (D100) old in response to nerve growth factor (NGF), chick eye ciliary neuronotrophic factor (CNTF), and laminin. In the absence of trophic factors the 4-day survival of cultured chromaffin cells (relative to the number of cells attached at 2 hr) increased from one-third of the cells at D1 to 40% at D8 and 90-100% at D16 and older stages. At saturating concentrations NGF increased cell survival at D8 by 90%, but failed to support all chromaffin cells present at 2 hr. In contrast, CNTF supported the survival of all cells at D8. At D1 NGF and CNTF had only a very small effect on survival during the 4-day culture period, although both factors clearly enhanced the numbers of surviving cells after 8 days. Either NGF or CNTF also elicited neurite outgrowth from rat chromaffin cells, which amounted to approximately 15-20% at D1 and D8 and subsequently decreased to about 5-8% at D30 and virtually zero at D100. At this last age both factors applied together clearly elicited neurites. Such a potentiating effect of NGF and CNTF was also seen at earlier postnatal ages. Laminin did not affect neurite growth at D30 in the absence of trophic factors, as already described for D8 rat chromaffin cells. In the presence of NGF, however, it increased neurite length and branching during a 4-day culture period and even enhanced neurite recruitment at later culture times. These data suggest that rat chromaffin cells undergo age-related changes in their responses to NGF and CNTF and that laminin modulates their neurite outgrowth behaviors in the presence of trophic factors.

Phenotypical changes of embryonic chick adrenal medullary cells in vitro induced by nerve growth factor and ciliary neuronotrophic factor

This study investigates the survival properties and changes in the morphological phenotype of adrenal medullary (chromaffin and neuronal) cells cultured from embryonic chicks at different developmental ages (embryonic days E8 to E16) in response to nerve growth factor (NGF) and ciliary neuronotrophic factor (CNTF). The 4-day survival of medullary cells from all embryonic ages except E8 was about 80% of the seeded cells and was only slightly enhanced by the addition of saturating doses of CNTF (10 ng/ml). With no factors, after 4 days 10-30% of the surviving medullary cells extended neurites. NGF (100 ng/ml) and, even more, CNTF (10 ng/ml) and their combination substantially increased the proportions of neurite-bearing cells (up to 70%). The effect of the factors were maximal at E10 and E12 and declined at older developmental ages. Neurite growth was virtually unaffected by NGF and CNTF at E8. These results show that in vitro survival and neurite growth of chick adrenal medullary cells in response to trophic factors is developmentally regulated.

Embryonic rat adrenal glands in organ culture: effects of dexamethasone, nerve growth factor and its antibodies on pheochromoblast differentiation

In the present study we sought to determine the developmental potentialities and restrictions of adrenal medullary cells (pheochromoblasts) by investigating their morphological and biochemical response to nerve growth factor (NGF), anti-NGF antibodies and dexamethasone (DEX) after explantation into culture at different embryonic stages. With the exception of explants taken at embryonic day 15 (E 15) cultures of embryonic adrenal glands showed neurite outgrowth, which was not influenced by the addition of NGF, anti-NGF antibodies or DEX to the culture medium during the 4-day-culture period. Pheochromoblasts in E 17 + 4 explants showed spontaneous ultramorphological and biochemical maturation in terms of an increase in the number of catecholamine storage vesicles (CSVs) per micron 2 of cytoplasmic area, diameters of the cores of CSVs, percentages of electron-lucent cores of CSVs indicative of increased storage of adrenaline, overall catecholamine (CA) content and relative amount of adrenaline. NGF did not significantly affect this maturational process. Anti-NGF antibodies slightly decreased the proportion of adrenaline. The most pronounced maturation was seen in response to DEX and DEX plus NGF, although a maturational state equivalent to the E 21 stage was not achieved. E 21 + 4 explants showed neither spontaneous nor drug-induced biochemical maturation. Medullary cells in NGF-treated E 21 explants frequently retained the morphological features of pheochromoblasts. Treatment with anti-NGF antibodies significantly reduced the portion of adrenaline as compared to any other treatment. We conclude that under the culture conditions employed (1) a few pheochromoblasts spontaneously express a neuronal phenotype, (2) differentiation of pheochromoblasts towards chromaffin cells is enhanced by glucocorticoids but not by NGF, and (3) anti-NGF antibodies do not impair spontaneous neuritic growth and morphological maturation of pheochromoblasts, but cause a small reduction in the relative amount of adrenaline.

Nerve growth factor and dexamethasone specify the catecholaminergic phenotype of cultured rat chromaffin cells: dependence on developmental stage

Antibodies to epinephrine (E) and bovine phenylethanolamine N-methyltransferase (PNMT) have been used to monitor the regulation of the E- and PNMT-immunoreactive chromaffin cell phenotypes by dexamethasone (DEX) and nerve growth factor (NGF). The cells were isolated from 1-, 10- and 30-day-old (D1, D10 and D30) rat adrenal glands and grown for 4 days on a polyornithine substratum. DEX (10(-5)M) supported the survival of 90% of the cells from all postnatal ages studied. In contrast, only 45% (D1), 33% (D10) and 60% (D30) of the chromaffin cells had survived after 4 days in control cultures or when treated with NGF (100 ng/ml). Throughout this study numbers of E-immunoreactive cells were approximately 10% larger than those of cells stained by anti-PNMT antibodies irrespective of the treatments applied. 55% of the cells isolated at D1 and 79% of the cells at D10 were stained by anti-E antibodies. The proportion of E-positive cells was constant in D1 cultures carried for 4 days, while E-immunoreactive cells dropped to 63% in cultures from D10. At D1 and D10 DEX and NGF had opposite effects on the portions of E-positive cells, DEX increasing and NGF decreasing their relative numbers, 66% of the chromaffin cells isolated at D30 displayed E-specific immunoreactivity. DEX caused a significant increase (to 74%), while both NGF-treated and control cultures exhibited a decrease in the relative numbers of E-immunoreactive cells.(ABSTRACT TRUNCATED AT 250 WORDS)