Enhancement of neurite outgrowth and aspartate-glutamate uptake systems in retinal explants cultured with chick gizzard extract

Critical role of p38 MAPK for regeneration of the sciatic nerve following crush injury in vivo

Background

The physiological function of p38α, which is an isoform of p38 MAPK, has been investigated previously in several studies using pharmacological inhibitors. However, the results regarding whether p38α promotes or inhibits nerve regeneration in vivo have been controversial.

Methods

We generated novel p38α mutant mice (sem mice) with a point mutation in the region encoding the p38α substrate-docking-site, which serves as a limited loss-of-function model of p38α. In the present study, we utilized sem mice and wild-type littermates (wt mice) to investigate the physiological role of p38α in nerve regeneration following crush injuries.

Results

At four weeks after crush injury, the average axon diameter and the average axon area in sem mice were significantly smaller than those in wt mice. The average myelin sheath thickness in sem mice was reduced compared to wt mice, but no significant difference was observed in the G-ratio between the two groups. The sciatic functional index value demonstrated that functional nerve recovery in sem mice following crush injury was delayed, which is consistent with the histological findings. To investigate the underlying mechanisms of these findings, we examined inflammatory responses of the sciatic nerve by immunohistochemistry and western blotting. At an early phase following crush injury, sem mice showed remarkably lower expression of inflammatory cytokines, such as TNF-α and IL-1β, than wt mice. The expression of Caspase-3 and Tenascin-C were also lower in sem mice. Conversely, at a late phase of the response, sem mice showed considerably higher expression of TNF-α and of IL-1β with lower expression of S-100 than wt mice.

Conclusions

This is the first study of the physiological role of p38 MAPK in nerve regeneration that does not rely on the use of pharmacological inhibitors. Our results indicate that p38α insufficiency may cause an inflammatory disorder, resulting in a delay of histological and functional nerve recovery following crush injury. We conclude that p38 MAPK has an important physiological role in nerve regeneration and may be important for controlling both initiation of inflammation and recovery from nerve injury.

Long-term morphometric and immunohistochemical findings in human free microvascular muscle flaps

Reinnervation, muscle regeneration, density of microvessels, and muscle-type specific atrophy were studied 3-4 years after surgery in surgically nonreinnervated free microvascular muscle flaps to 13 patients transplanted to the upper or lower extremities. Routine histology and immunohistochemistry for PGP 9.5 and S-100 (neuronal markers), Ki-67 (cell proliferation), myosin (muscle fiber types), and CD-31 (endothelium) were carried out, and results were analyzed morphometrically. Three to 4 years after surgery, severe atrophy of predominantly slow-type fibers was seen in 9 cases. In 4 cases, muscle-fiber diameter and fiber-type distribution were close to normal. Long intraoperative muscle ischemia and postoperative immobilization were associated with poor muscle bulk in flaps. The density of microvessels in flaps did not differ from control muscles. PGP 9.5 and S-100 immunopositive nerve fibers were detected in 7 patients. Reinnervation was associated with good muscle bulk. In 4 patients, activation of satellite cells was evident. The results suggest that in some cases, spontaneous reinnervation may occur in free muscle flaps, and that several years after microvascular free flap transfer, the muscle still attempts to regenerate.

HSP27 is markedly induced in Schwann cell columns and associated regenerating axons

It is well known that regenerating axons enter Schwann cell (SC) columns, within which they grow to reinnervate the appropriate targets. The current study detected a marked induction of a 27-kDa heat shock protein (HSP27) in the SC columns of crush-injured rat sciatic nerves. Immunohistochemical studies showed the first appearance of strong HSP27-immunoreactive linear structures in the proximal stump near an injury site 7 h after an operation. The HSP27-immunoreactive linear structures crossed the injury site to the distal stump 2 days after the operation. They then extended in a more proximal and more distal direction and were found to have propagated through the entire length of the nerve 1 week after the operation. This pattern of expression was maintained until 3 weeks after the operation. Double-immunofluorescent labeling and confocal laser microscopy confirmed that the linear structures consisted of SC columns and associated multiple axons. The HSP27-immunoreactive SC columns expressed glial fibrillary acidic protein, but not S-100 protein. Electron microscopy and immunoelectron microscopy demonstrated that reactive Schwann cells (SCs) and the associated axons with an outgrowing profile exhibited a strong immunoreactivity to HSP27, with the former containing a greater number of bundles of intermediate filaments. It is suggested that HSP27 may play an essential role in axonal outgrowth, especially by contributing to cytoskeletal dynamics in SCs.

Extracellular matrix proteins with neurite promoting activity and their receptors

Characteristic features of the nervous system converge into network formation during the development. The neurons recognize precisely their target cells and form synapses, and these steps are complex, but well organized spatially and temporally. The neurite promotion from the neurons is one of the most important events for synapse formation. It is well known that extracellular matrix proteins such as laminin and their receptors, and cell adhesion molecules such as NCAM participate in cell migration and synaptic formation. We have isolated a neurite outgrowth factor (NOF) which promotes neurite outgrowth from various neurons and belongs to laminin family, and also its receptor which is identified to be an immunoglobulin superfamily protein by cDNA cloning. This ligand-receptor system is a unique example that a receptor with immunoglobulin-like structure interacts with an extracellular matrix protein.

Glial and neuronal marker proteins in the silicone chamber model for nerve regeneration

In the present study, neuronal and Schwann cell marker proteins were used to biochemically characterize the spatiotemporal progress of degeneration/regeneration in the silicone chamber model for nerve regeneration. Rat sciatic nerves were transected and the proximal and distal stumps were inserted into a bridging silicone chamber with a 10-mm interstump gap. Using dot immunobinding assays, S-100 protein and neuronal intermediate filament polypeptides were measured in different parts of the nerve 0-30 days after transection. In the most proximal nerve segment, all the measured proteins were transiently increased. In the proximal and distal stumps adjacent to the transection, the studied proteins were decreased indicating degeneration of the nerve. Within the silicone chamber, the regenerating nerve expressed the Schwann cell S-100 protein already at 7 days, whereas the neurofilament polypeptides appeared later. These observations are corroborated by previous morphological studies. The biochemical method described provides a new and fast approach to the study of nerve regeneration.

Electron microscopic immunocytochemistry of GAP-43 within proximal and chronically denervated distal stumps of transected peripheral nerve

Growth-associated protein, GAP-43 was initially described as a neuron-specific molecule thought to play a critical role in axonal growth and regeneration. However, it is also expressed in vitro in certain CNS glia, Schwann cell precursors and non-myelinating Schwann cells. In this paper, we report the subcellular localization of GAP-43 in vivo in chronically-denervated Schwann cells in the distal stumps of previously transected rat sciatic nerve. We have used a progressive lowering of temperature method combined with the non-polar acrylic resin Lowicryl HM20 and a post-embedding labelling regime to visualize the distribution of GAP-43, S-100 (marker for Schwann cells), RT97 and NF68 (markers for different subunits of the neurofilament molecule). We report that (1) the smallest calibre regrowing axons were GAP-43-positive, sometimes NF68-positive but always RT97-negative; (2) regenerating myelinated axons and larger unmyelinated axons (> 0.7 microns diameter) were NF68-positive, RT97-positive but GAP-43-negative; (3) cytoplasmic processes within Schwann cell basal lamina tubes in the distal stumps were S-100-positive, GAP-43-positive but RT97- and NF68-negative. The similar localization of GAP-43 within regrowing axons and denervated Schwann cells suggests that GAP-43 may function similarly in both situations, and may thus be involved in motility and/or elongation of axons and Schwann cells during regeneration.

A mechanism for glutamate toxicity in the C6 glioma cells involving inhibition of cystine uptake leading to glutathione depletion

We have demonstrated that addition of L-glutamate in millimolar amounts to a culture of C6 glioma cells induced cell death within 24 h. The glutamate-induced toxicity in the C6 glioma cells was completely suppressed by adding L-cystine (0.4-1.0 mM), while the C6 cells degenerated in L-cystine-deprived culture medium. Kinetic studies of [35S]cystine and [3H]glutamate uptake showed that cystine competitively inhibited glutamate uptake, and conversely glutamate inhibited cystine uptake competitively, suggesting that C6 cells have a cystine/glutamate antiporter (system CG or Xc) similar to that already described in the periphery. Exogenous cystine (1 mM) stimulated a release of endogenous glutamate from C6 cells in a Na(+)-independent Cl(-)-dependent fashion. Thus, the antiporter normally transports glutamate out of and cystine into the cells. With the glutamate analogues tested, there was a good correlation between cytotoxicity and inhibition of cystine uptake. The de novo synthesis of glutathione was largely dependent upon the uptake of extracellular cystine. Intracellular levels of glutathione were dramatically decreased within 8-10 h by culture in glutamate-added or cystine-free medium. Vitamin E (100 microM), an antioxidant, rescued the death of C6 cells induced by glutamate exposure or by culture in cystine-deprived medium, but did not restore the apparent decrease of intracellular glutathione. Taken together, the present data strongly indicate that glutamate-induced cell death is initially due to inhibition of cystine uptake through the antiporter Xc system; such inhibition leads to glutathione depletion exposing the cells to oxidative stress. Excess of extracellular glutamate introduced from endogenous or exogenous roots might disorder this mechanism, resulting in cell death.

Purification and characterization of an 82-kD membrane protein as a neurite outgrowth factor binding protein: possible involvement of NOF binding protein in axonal outgrowth in developing retina

Neurite outgrowth factor (NOF) is a glycoprotein isolated from an extract of gizzard that induces neurite outgrowth from cultured retinal or ciliary ganglionic (CG) neurons. We have reported that a glycoprotein of approximately 82 kD solubilized from gizzard muscles binds to NOF (ligand blotting) and inhibits the neurite promoting activity of NOF (inhibition assay). The 82-kD protein (NOF binding protein) was purified from gizzard muscle membranes as a doublet band on SDS-PAGE and a polyclonal antibody was raised against it. An NOF binding protein in developing retina exhibited the same physicochemical properties as that of the gizzard muscle. Quantitative decrease in NOF binding protein in embryonic retinas was observed after day 11 by the inhibition assay, ligand blotting, and immunoblotting, its decrease being parallel with reduction of NOF-induced neurite outgrowth of embryonic retinas. In an immunohistochemical study, the antibody stained only the optic fiber layers of the retinas of 8-d embryos, and this staining was no longer detectable in retinas of 18-d embryos. These results suggest that the 82-kD protein is a novel membrane protein that behaves as an NOF receptor and that the loss of neuritic response of the retinal neurons to NOF reflects a decrease in NOF receptor molecules.

Dopamine release via protein kinase C activation in the fish retina

Calcium-dependent phospholipid-sensitive protein kinase [protein kinase C (PKC)] was partially purified from the carp (Cyprinus carpio) retina through DE 52 ion exchange and Cellulofine gel filtration chromatography. The phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) activated PKC in the nanomolar range. A major 38-kDa protein in the retinal supernatants (105,000 g) was phosphorylated in vitro by PKC during a short period (3 min). Other phosphoproteins also appeared during a further prolonged period (greater than 15 min). Rod-bipolar and dopamine (DA) interplexiform cells in the fish retina were immunoreactive to a monoclonal antibody to PKC (alpha/beta-subtype). The PKC antibody recognized a 78-kDa native PKC enzyme by means of an immunoblotting method. Subsequently, the effects of two kinds of PKC activators were investigated on [3H]DA release from retinal cell fractions containing DA cells that had been preloaded with [3H]DA. A phorbol ester (TPA) induced a calcium- and dose-dependent [3H]DA release during a short period (2 min), with the minimal effective dose being approximately 1 nM. Other phorbols having no tumor-promoting activity, such as 4 beta-phorbol and 4 alpha-phorbol 12,13-didecanoate, were ineffective on [3H]DA release. A synthetic diacylglycerol [1-oleoyl-2-acetylglycerol (OAG)], which is an endogenous PKC activator, was also able to induce a significant release of [3H]DA. Furthermore, TPA was found to release endogenous DA from isolated fish retina by a highly sensitive HPLC with electrochemical detection method. The OAG- or TPA-induced [3H]DA or DA release was completely blocked by inhibitors of PKC, such as 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H7) and staurosporine.(ABSTRACT TRUNCATED AT 250 WORDS)

Possible involvement of neurite outgrowth factor (NOF) receptor in axonal outgrowth from developing chick retina

We report that an 82-kDa membrane protein from chicken gizzard muscles is a neurite outgrowth factor (NOF)-receptor interacting with a domain for neurite-promoting activity of NOF. We found that an 82-kDa membrane protein in the developing chicken retina exhibited the same properties as those of gizzard muscles. The neuritic response of the retinal neurons to NOF increased in 6- and 8-day embryos, reaching a maximum level on the 8th-day and then rapidly decreased with aging. In parallel with this, the amount of NOF receptor in the retinas was maximal in 8- and 11-day embryos and thereafter decreased with aging. The results suggest that the failure in the neuritic response of the retinal neurons to NOF with aging is due to the decrease in NOF receptor.

Regeneration in the peripheral nervous system

Mammalian peripheral nerve fibres can regenerate after injury. Repair is most likely to succeed if axons are simply crushed or have only a very short (less than 0.5 cm) interstump gap to cross and most likely to fail if the interstump gap is long (greater than 1 cm) and associated with soft tissue damage. Whereas reactive axonal sprouting appears to be an intrinsic neuronal response to injury, the subsequent organization of the axonal sprouts, in particular their orderly outgrowth in minifascicles towards a distant distal stump does not occur unless Schwann cells are present. During the injury response, Schwann cells proliferate; co-migrate with regrowing axons (when the proximal stump is separated from the distal stump); respond to axonal cues by transient upregulation or re-expression of molecules which provide a favourable substrate for axonal extension; and attract bundles of regrowing axons and their associated Schwann cells across interstump gaps up to 1 cm in length. Recruited macrophages remove myelin debris from the Schwann cell tubes; they probably interact with Schwann cells in other ways during the injury response, e.g. by presenting mitogens and cytokines.

Immunohistochemical differential distribution of S-100 alpha and S-100 beta in the peripheral nervous system of the rat

The localization of the alpha subunit of the S-100 protein (S-100 alpha) and beta subunit (S-100 beta) was studied in the peripheral nervous system of the rat. In peripheral nerves, S-100 alpha and S-100 beta were found in the cytoplasm of Schwann cells. Axons were positively stained in part by S-100 alpha and almost totally by S-100 beta. In the dorsal root ganglia, S-100 alpha was found in satellite cells and their processes and in some neurons. S-100 beta was found in more of the large neurons, but almost all of the small neurons were negative for S-100 beta. In the anterior horn cells, S-100 beta staining was stronger than that of S-100 alpha. In Schwann cells, both S-100 alpha and S-100 beta were present on the rough endoplasmic reticulum, free ribosomes, and nucleus, as seen by electron microscopy. The S-100 alpha and S-100 beta in axons were associated with microtubules and neurofilaments.

Effects of chronic n-hexane exposure on nervous system-specific and muscle-specific proteins

Two kinds of nervous system-specific and muscle-specific proteins, enolase and S-100 protein, were quantitatively determined in peripheral nerves and skeletal muscles of rats chronically exposed to a neurotoxic solvent - n-hexane. Three groups of animals were exposed to n-hexane vapor at three different solvent concentrations (500 ppm, 1200 ppm, 3000 ppm) for 12 h/day, 7 days/week for 16 weeks. The body weight gain and motor nerve conduction velocity (MCV) in exposure groups show progressively concentration-dependent decreases compared to control values. Histopathological examination also demonstrates the degeneration of peripheral nerves in 3000 ppm- and 1200 ppm-exposed rats. The significant decrease in the amount of S-100 protein in peripheral nerves was observed not only in the high level exposure groups (3000 ppm and 1200 ppm), but also in the lowest level group (500 ppm), although the MCV and morphological examination remained unchanged at this level. In addition, the muscle-specific S-100 protein in 3000 ppm exposed rats' soleus also displayed a significant reduction. In contrast to this, however, enolase isozymes were not significantly changed by either dosage level in both nervous tissue and skeletal muscle. The experiment suggests that beta- and alpha-S-100 proteins which are specifically localized in nervous system and muscles, respectively, are more vulnerable than enolase isozymes under treatment with n-hexane, and may possibly serve as a specific indicator to evaluate the neurotoxic effects. Further research would be worthwhile to elucidate the role of the specific S-100 protein in evaluating the neurologic damage induced by various industrial chemicals.

Cholinergic differentiation of clonal rat pheochromocytoma cells (PC12) induced by factors contained in glioma-conditioned medium: enhancement of high-affinity choline uptake system and reduction of norepinephrine uptake system

The effects of glioma-conditioned medium (GCM) and factors contained in GCM on the neurochemical differentiation of the PC12 clone of rat pheochromocytoma cells were investigated. The results obtained are as follows. The accumulation of choline into PC12 cells proceeded through two uptake systems with high (Km = 3.20 microM) and low (Km = 65.2 muM) affinities as revealed by least-squares iterative fitting of a substrate-velocity curve to the data. Culturing of PC12 cells in the presence of GCM led to a 5-fold increase in the Vmax value of the high-affinity uptake system without affecting the Km of the high-affinity uptake system. Both Km and Vmax of the low-affinity uptake system were unaffected by the GCM treatment. The high-affinity choline uptake system in both GCM-treated and untreated PC12 cells was devoid of Na+ dependency and showed low sensitivity to hemicholinium-3. The ratio of [3H]acetylcholine converted from [3H]choline taken up by PC12 cells at 1 muM choline for 1 h was two-fold higher than that by untreated cells. PC12 possess a high-affinity norepinephrine uptake system. Culturing of PC12 cells in the presence of GCM led to a decrease in the rate of uptake of 3 muM norepinephrine to 43% of that in control cells. The 40-K and 10-K fractions isolated by gel filtration of GCM had both abilities to enhance the high-affinity choline uptake system and to suppress the high-affinity norepinephrine uptake system. From these observations it was concluded that GCM contains factors which induce the cholinergic neuronal differentiation of PC12 cells.

S-100 protein-induced changes in the physical state of synaptosomal particulate fractions as monitored by spin labels

This report documents changes in the physical state of synaptosomal particulate fractions (SYN) upon binding of S-100 protein, as monitored by spin labels. Studies were conducted on SYN labeled with either 5-doxylstearic acid or 16-doxylstearic acid, which probe the polar region and the hydrophobic core of the lipid bilayer, respectively. S-100 perturbs to some extent both the polar surface and the hydrophobic core of SYN in a time- and temperature-dependent manner. Ca2+ is essential for S-100 to perturb the membranes. K+ almost completely inhibits the S-100 perturbing effect if present in the incubation medium, but fails to reverse the S-100-induced changes if added after S-100 has interacted with SYN. At room temperature and below, the overall S-100 effect registered after about 30 min of association of the protein with SYN is an increase in the fluidity of both the surface and the interior of the membranes. Spectra registered at intervals at room temperature indicate that the S-100 perturbing effect on the membrane surface is practically monophasic, consisting of an increase in fluidity, while that on the membrane interior is multiphasic, consisting of a decrease in fluidity during the first 10 min of association, followed by an increase in fluidity during the subsequent 20 min and a return to starting values during the second 30 min of association. Around 37 degrees C, on the contrary, a decrease in fluidity is registered in both regions. The data suggest that S-100 induces a spatial rearrangement of membrane components (proteins) involved in the specific binding and/or partially penetrates into the lipid bilayer.

Development of cholinergic projections in organotypic cultures of rat septum, hippocampus and cerebellum

ChAT and AChE activity in the hippocampus originate primarily in axons from cholinergic neurons located in the medial septum. The development of cholinergic projections in organotypic explant cultures of rat septum, hippocampus, cerebellum and habenula was studied using AChE histochemistry and biochemical ChAT and AChE determinations. Hippocampal and cerebellar explants cultured without a septum contain negligible amounts of ChAT after 6 days of culture. When the hippocampus was cultured for several days in the presence of a septal explant, a massive increase in ChAT was observed in the hippocampal explant. When co-cultures were stained for AChE, AChE-positive projections were seen to grow out from the septum to invade the hippocampal explant. To a certain extent this ingrowth of septal cholinergic fibers into the hippocampus is target-specific, since cerebellar explants cultured with septum showed neither an ingrowth of AChE-containing septal fibers, nor an increase in ChAT activity. Also, habenular AChE-positive fibers fail to grow into a co-cultivated hippocampal explant. Further, in septal explants co-cultivated with hippocampal explants an increase in ChAT activity was seen as compared to septal explants cultivated alone. The possible factors responsible for the observed specificity and the increase in ChAT activity under co-culture conditions are discussed.

Hormonal regulation of adipose S-100 protein release

The release of S-100 protein from epididymal fat pads was enhanced by epinephrine in vitro, and about 50% of S-100 protein in the tissue was released into the medium after 2-h incubation at 37 degrees C with 10 microM epinephrine. Similar results were obtained with the incubation of isolated adipocytes. The S-100 protein release was also enhanced by isoproterenol, norepinephrine, ACTH, and dibutyryl cyclic AMP, which all increase the lipolysis by increasing cyclic AMP levels in the tissue. Propranolol, a beta-adrenergic blocker, could block the increase of S-100 protein release by catecholamines, indicating that the release was mediated by the beta-adrenergic effect of catecholamines. However propranolol had no suppressive effect on the enhancement of S-100 protein release by ACTH or dibutyryl cyclic AMP. Insulin had an inhibitory effect on the epinephrine-enhanced S-100 protein release. Epinephrine or ACTH could not stimulate the S-100 protein release in the absence of Ca2+, whereas the epinephrine-enhanced glycerol release was not affected under the same conditions. The increase in S-100 protein release was induced by only a pretreatment of the tissue with epinephrine. However, the lipolysis in the tissue was not enhanced by the pretreatment alone. These results indicate that the release of S-100 protein from adipocytes is regulated by the hormones that have been known to control the lipolysis with a manner slightly different from that of lipolysis.

Effects of various forms of stimulation on the content of enolase isozymes and S-100 protein in superior cervical sympathetic ganglia excised from rats

Contents of the three forms (alpha alpha, alpha gamma, and gamma gamma) of enolase isozymes and S-100 protein in superior cervical sympathetic ganglia (SCG) excised from rats were determined by the sensitive method of enzyme immunoassay, after application of various forms of stimulation, during incubation for 3 h at 37 degrees C in vitro. The amounts of the three forms of enolase isozymes and of S-100 protein in the SCG were not altered by preganglionic or postganglionic stimulation (10 Hz) or by the addition of acetylcholine (1 mM) or a high concentration of K+ (70 mM) to the incubation medium. Norepinephrine (NE; 50 microM), as well as isoproterenol (200 microM) or 3,4-dihydroxy phenylethylamine (dopamine; 200 microM), increased the ganglionic alpha alpha and alpha gamma enolase content to 1.5 to 2.0 times the control level, whereas NE tended to slightly decrease the gamma gamma enolase content. The increase in the alpha isozymes did not appear until after 2 to 3 h of incubation with this agent as a result of an increase in protein synthesis. Propranolol, an adrenergic antagonist, partly inhibited the NE-induced increase in both alpha alpha and alpha gamma enolases. NE and its agonists also considerably increased the S-100 protein level in the SCG; however, the effect developed within half an hour of incubation as a result of the conversion of the bound S-100 protein to the water-soluble form, and did not greatly increase thereafter. Cyclic AMP (1 mM) produced the same kind of increase in the ganglionic S-100 protein content as NE did.(ABSTRACT TRUNCATED AT 250 WORDS)

Embryonic development of monoaminergic neurons in the chick retina

By means of a histofluorescence technique, embryonic and postnatal development of monoaminergic neurons was followed in the chicken retina with or without intravitreal injection of monoamines 30-60 minutes before eye removal. Fluorescent cells were tentatively classified into five subsets with respect to the soma shape, localization, migration of somata during retinal development, uptake capacity (color and intensity in fluorescence), and sensitivity to neurotoxins. The five subsets of cells were endogenous dopaminergic (DA), catecholamine-accumulating (CA), indoleamine-accumulating (IA), CA-bipolarlike, and IA-bipolarlike cells. Greenish endogenous DA-cells first appeared at the 14-15th embryonic day. The cell body of DA-cells was initially fusiform and located slightly distal to the innermost level of the inner nuclear layer (INL). They became round or oval and migrated to the innermost level of the INL by day 20. Both large and small bottle-shaped CA-cells were visualized at an intermediate portion of INL by intravitreal injection of exogenously applied dopamine or noradrenaline (1-2 micrograms/eye) at day 10. Large bottle-shaped cells, like the DA cells, changed to round or oval and migrated to the innermost level of the INL by day 20. On the other hand, small bottle-shaped CA-cells retained their cell shape and location in the INL as retinal development progressed. Therefore, the large bottle-shaped CA-cells seen in an early developmental stage correspond to the DA-cells. IA-cells were visualized one or two cell rows outward in the INL first at day 13-14 by intravitreal injection of 5,6-dihydroxytryptamine or 5-hydroxytryptamine (1-5 micrograms).(ABSTRACT TRUNCATED AT 250 WORDS)

Antiserum against neurite outgrowth factor in chick gizzard extract and its inhibitory effect on neuritic response in cultured ciliary neurons

Antiserum against a neurite outgrowth factor (NOF) of gizzard extract that promotes neurite outgrowth from dissociated ciliary ganglionic neurons (CG neurons) of 8-day-old chick embryo was prepared to determine whether or not the antiserum inhibits neurite outgrowth from cultured neurons or explants of chick and murine tissues. When CG neurons were cultured on a polyornithine-coated well exposed to NOF (NOF-bound POR well), marked neurite outgrowth was observed. When NOF-bound POR wells were exposed to antiserum, neurite outgrowth from CG neurons was gradually inhibited with increasing amounts of antiserum, while exposure to preimmune serum did not prevent neurite outgrowth. Antiserum had no effect on neuronal survival during a 48-h incubation. The diluted antiserum, which produced nearly 100% inhibition of the NOF activity, was almost equally active in suppressing the activity of NOFs in conditioned media (CM) of various chick embryo tissues, but showed much less inhibitory effects on NOFs in CM of murine tissues. The appearance of neurites from explants of spinal cord, dorsal root ganglion, or retina of chick embryo was also inhibited by the antiserum. These results indicate that antiserum against NOF from gizzard extract suppressed the activity of NOFs from various sources, and that there are species differences in NOFs, at least between chick and murine.

Regulation of nervous system-specific S-100 protein and enolase levels in adipose tissue by catecholamines

The effect of catecholamines on the levels of S-100 protein and nervous system-specific enolase (NSE) in epididymal adipose tissue of Wistar rats in vivo was examined by sensitive enzyme immunoassay methods. Soluble S-100 protein levels in the adipose tissue of 9-12-week-old rats (1.46 +/- 0.19 microgram/mg protein) were decreased to less than 50% of those of controls by serial injection (for 4-7 days) of epinephrine (0.1 mg/day) or norepinephrine (0.15 mg) with, however, little effect on the levels of membrane-bound (pentanol-extractable) S-100 protein. A significant decrease in the soluble S-100 protein levels was observed at 2 h after a single injection of epinephrine (1.04 +/- 0.13 microgram/mg protein). On the other hand, levels of NSE subunit (gamma subunit or 14-3-2 protein) in adipose tissue (0.51 +/- 0.03 gamma gamma-equivalent pmol/mg protein) were increased to 170% of control by serial injection (for 7 days) of epinephrine or norepinephrine with little change of the level of enolase alpha subunit on a mg protein basis. Isoproterenol had no apparent effect on the levels of soluble S-100 protein and NSE subunit. These results suggest that the levels of S-100 protein and NSE in adipose tissue are regulated by catecholamines.

Effects of denervation and axotomy on nervous system-specific protein, ornithine decarboxylase, and other enzyme activities in the superior cervical sympathetic ganglion of the rat

The time courses of changes of three enolase isozymes (alpha alpha, alpha gamma, and gamma gamma), S-100 protein, 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase), ornithine decarboxylase (ODC), beta-galactosidase, and glucose-6-phosphate dehydrogenase (G6PDH) were examined from 1 to 14 days after cutting of the preganglionic nerve (denervation) or the postganglionic nerve (axotomy) of the superior cervical sympathetic ganglion (SCG) of the rat. The wet weight and protein content in the axotomized SCG increased continuously, to nearly twice those of the denervated SCG for 1-2 weeks after the operations. Among enolase isozymes in the SCG, neuron-specific gamma gamma-enolase decreased rapidly after denervation and stayed at a low level for 2 weeks, whereas the isozyme remained almost unchanged after axotomy. On the contrary, ganglionic alpha alpha-enolase and the alpha gamma-hybrid form increased remarkably to reach a maximum at the second day after axotomy, and remained above control for 1 to 2 weeks; these two enolase isozymes showed little change after denervation. Denervation caused a much larger increase than did axotomy in the ganglionic S-100 protein, an astrocyte-specific protein, during the first week after the operation, while the protein content decreased after 2 weeks of either denervation or axotomy. CNPase, a myelin-associated enzyme, rose suddenly 2 days after axotomy, and remained at a rather high level compared with the denervated ganglion, which showed little variation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of sodium fluorescein on neurite outgrowth from the retinal explant culture: an in vitro model for retinal toxicity

Effect of sodium fluorescein was examined on neurite outgrowth from the retinal explants of chick embryos cultured with chicken gizzard extract, containing macromolecules which promote neurite outgrowth. A dose more than 0.5 mg/ml of fluorescein completely prevented the neurite outgrowth from the retinal explants. The minimum dose of toxic effect of fluorescein on the neurite outgrowth was about 0.2 mg/ml. The fluorescein also caused lysis of pre-existing neurites which had been fully extended by gizzard extract.