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

Polyamines increase in sympathetic neurons and non-neuronal cells after axotomy and enhance neurite outgrowth in nerve growth factor-primed PC12 cells

Following axonal damage, sympathetic neurons are capable of regenerating and reinnervating their target tissues. Some years ago exogenous administration of polyamines was shown to enhance this regeneration. Recently, it was found that axonal injury leads to a dramatic up-regulation of the expression of arginase I in sympathetic neurons. This enzyme catalyzes the conversion of arginine to ornithine, which can subsequently be converted to the diamine putrescine and, ultimately, to the polyamines spermidine and spermine. In the present study, using an antiserum that reacts with both spermidine and spermine, we have found an increase in polyamine levels in both neurons and non-neuronal cells in the superior cervical ganglion 2 and 5 days following transection of the ganglion's postganglionic trunks. Using PC12 cells primed with nerve growth factor and then stripped off the culture dish and replated as a model system for axotomized sympathetic neurons, we found that spermidine treatment, with or without nerve growth factor, resulted in an increased percentage of cells with a neurite whose length was at least twice the diameter of the neuron's cell body. These increases could be seen within 48 h and were still evident after 8 days. Together, these data support the possibility that endogenous polyamines are involved in the normal regeneration which occurs following sympathetic axonal damage.

Activation of ornithine decarboxylase and accumulation of putrescine after traumatic brain injury

Activation of ornithine decarboxylase (ODC), the initial enzyme in polyamine synthesis, and accumulation of putrescine are thought to mediate pathological processes in the ischemic and traumatized brain. Past studies have separately investigated either ODC or polyamines after head injury. The purpose of the present study was to quantify both ODC activity and polyamines in the rat parietal cortex before and after controlled cortical impact injury. Adult, male rats underwent a right craniectomy and were subjected to a 5 m/sec, 2-mm deformation impact injury. Rats were sacrificed 1, 4, 8, and 24 h postimpact and tissues from the injured (right) and contralateral (left) hemisphere were analyzed for ODC and polyamines. ODC activity was determined by measuring the decarboxylation of [14C]ornithine to putrescine. Putrescine, spermidine, and spermine were determined by high performance liquid chromatography. Cortical impact induced a 10- to 20-fold increase in ODC activity and a 4- to 5-fold increase in putrescine in the ipsilateral cortex. Spermidine and spermine did not significantly increase in the ipsilateral (right) cortex compared to controls (right cortex). In contrast, there was a slight increase in spermidine content in the contralateral (left) cortex after injury. The delayed increase in ODC activity and accumulation of putrescine may mediate pathophysiological changes observed after head injury.

Histochemical detection of age- and injury-related changes in signal transduction in the superior cervical ganglion

The superior cervical ganglion (SCG) is thought to be a good model for correlation studies of morphology, function and metabolism of neurons. The SCG has a relatively simple organization, it can be easily manipulated in situ, and it maintains synaptic transmission and a high metabolic rate during in vitro incubations. The histology and structure of SCG neurons have been characterized in detail, and physiologic stimuli, injury and aging have all been found to induce changes in the SCG morphology. During the last decade, research in the field of signal transduction has greatly expanded. Several signal transduction pathways have been identified that participate in the regulation of neurotransmitter synthesis, gene expression, neuronal excitability and growth factor responses of sympathetic neurons. We have been interested in using the SCG to study some of the second and third messengers involved in converting external stimuli received by sympathetic neurons into cellular short- and long-term events. Using immunohistochemistry, we have investigated protein kinase C-subtypes and the immediate early gene product Fos in the SCG, and characterized some of the changes induced by injury and aging in these messenger molecules. We will review the results and discuss the advantages and disadvantages of using histological methods in the study of signal transduction in sympathetic neurons.

alpha-Difluoromethylornithine delays behavioral recovery and induces decompensation after unilateral labyrinthectomy

Biochemical and pharmacologic studies suggest a role for the ornithine decarboxylase-polyamine system as a modulator of behavioral changes during vestibular compensation. alpha-Difluoromethylornithine specifically blocks the rate-limiting step of polyamine biosynthesis. To assess the effects of alpha-difluoromethylornithine on the acute phase of postural compensation, guinea pigs were divided into groups subjected to either unilateral labyrinthectomy only (n = 7), alpha-difluoromethylornithine (500 mg/kg/day) for 4 days before labyrinthectomy (n = 10), equivalent volumes of saline for 4 days before labyrinthectomy (n = 8), and sham operations (n = 5). Yaw head tilt and roll head tilt, trunk curvature, and air-righting reflex were measured at baseline and at regular intervals up to 4 weeks. alpha-Difluoromethylornithine significantly delayed recovery of normal air-righting but had no effect on yaw head tilt, roll head tilt, and trunk curvature. We also evaluated effects of alpha-difluoromethylornithine in compensated guinea pigs. Fully compensated animals from phase 1 were randomly assigned to receive alpha-difluoromethylornithine (500 mg/kg/day) or saline once daily for 4 days. Only 33% of alpha-difluoromethylornithine animals maintained air-righting, compared with 100% of saline-treated animals (p = 0.003). Maximum trunk curvature was greater in the alpha-difluoromethylornithine group (p = 0.02). Thus alpha-difluoromethylornithine not only delayed the time course for postural recovery after unilateral labyrinthectomy, it also transiently disrupted the maintenance of the compensated state.

Blockade effect of nerve growth factor on GM1 ganglioside-induced activation of transglutaminase in superior cervical sympathetic ganglia excised from adult rat

The activity of transglutaminase (TG), a Ca(2+)-dependent enzyme indicating tissue degradation or differentiation, showed in isolated adult rat superior cervical ganglia (SCG) a rapid (within 15 to 30 min) and marked (approx. 5- to 8-fold) increase with the addition of either GM1 ganglioside (GM1, 5 nM), which is rich in synapses, or sialyl cholesterol (SC, 20 microM), a synthetic sialic acid-containing compound, to the incubation medium at 37 degrees C. Under the same incubation conditions, addition of GM1 or SC decreased protein kinase C (PKC) activity (-26% to -39%) in the cytosolic fraction of the SCG, but increased the enzymic activity (+39% to +61%) in the particulate (cell membrane) fraction, suggesting that a sialic acid-containing compound (GM1 or SC) promotes PKC translocation from the cytosol to the membrane in ganglionic neurons. By contrast, addition of a promoting factor for survival of sympathetic neurons even in adulthood, nerve growth factor, (NGF, 0.25 micrograms/ml) to the medium significantly decreased ganglionic TG activity (-43%). This inhibition was completely antagonized by the co-addition of NGF-monoclonal antibody (0.75 microgram/ml). An effective blockade of GM1- or SC-induced stimulation of ganglionic TG activity was seen by further addition of NGF to the medium. Also, NGF almost abolished the translocation of ganglionic PKC activity induced by the sialic acid-containing compounds, although either NGF or 12-O-tetradecanoylphorbol ester (TPA) alone stimulated the cytosolic PKC activity (approx. +30%) in the tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of arginine, S-adenosylmethionine and polyamines on nerve regeneration

INTRODUCTION

Axon growth and axon regeneration are complex processes requiring an adequate supply of certain metabolic precursors and nutrients.

MATERIAL AND METHODS

This article reviews the studies examining some of the processes of protein modification fundamental to both nerve regeneration and to the continuous and adequate supply of specific factors such as arginine, S-adenosylmethionine and polyamines.

RESULTS

The process of arginylation notably increases following nerve injury and during subsequent regeneration of the nerve, with the most likely function of arginine-modification of nerve proteins being the degradation of proteins damaged through injury. It appears that defective methyl group metabolism may be one of the leading causes of demyelination, as suggested by the observation of reduced cerebrospinal fluid concentrations of s-adenosylmethionine (SAMe) and 5-methyltetrahydrofolate, the key metabolites in methylation processes, in patients with a reduction in myelination of corticospinal tracts. Polyamine synthesis, which depends strongly on the availability of both SAMe and arginine, markedly increases in neurons soon after an injury. This "polyamine-response" has been found to be essential for the survival of the parent neurons after injury to their axons. Polyamines probably exert their effects through involvement in DNA, RNA and protein synthesis, or through post-translational modifications that are indicated as the most relevant events of the "axon reaction."

CONCLUSIONS

Nerve regeneration requires the presence of arginine, s-adenosylmethionine, and polyamines. Further studies are needed to explore the mechanisms involved in these processes.

Polyamines in the lateral vestibular nuclei of the squirrel monkey and their potential role in vestibular compensation

Polyamine synthesis increases in response to injurious stimuli including axotomy and denervation. Reduced eye nystagmus and head-deviation have been observed in unilateral labyrinthectomized (UL) guinea pigs treated with an inhibitor of polyamine synthesis, alpha-difluoromethylornithine (DFMO). We quantified polyamines in the lateral vestibular nuclei (LVN) of control and UL squirrel monkeys during the phase of vestibular compensation (VC) and performed an experiment to determine if DFMO reduces nystagmus previously observed in the guinea pig. Polyamines were detected in the LVN of control and UL squirrel monkeys. Putrescine and spermidine increased in the ipsilateral LVN 3 days after UL with no change in the contralateral LVN. No left-right differences were noted in the 5-day post-UL monkey. DFMO reduced nystagmus in a UL squirrel monkey. These findings suggest that polyamines are important in vestibular function and may contribute to nystagmus observed in VC.

Selective alterations in transglutaminase activity of rat superior cervical ganglia in response to neurotransmitters, high potassium and sialic acid-containing compounds

We examined the in vitro effects of neurotransmitters, high KCl as well as sialic acid-containing compounds (GM1; SC) on transglutaminase (TG) activity in isolated superior cervical ganglia (SCG) one week after denervation or axotomy. Following denervation, TG activity in SCG decreased to 83% of the unoperated control value, whereas that of axotomized ganglia was 28% of control. Thus, TG activity was relatively unaffected when sympathetic ganglionic neurons were preserved, but was markedly reduced under conditions where neurons were degenerating. Addition of ACh (0.1 mM) to the medium during aerobic incubation stimulated TG activity more than 3-fold in denervated ganglia but had no effect on TG activity in axotomized ganglia. Similarly, the NE (0.05 mM)-induced decrease of TG activity observed in intact SCG was also seen following denervation (-49%) but not following axotomy. In denervated SCG, the stimulatory effects of ACh were virtually abolished by co-addition of the cholinergic antagonists, atropine or hexamethonium, while the suppressant effects of NE were blocked by the adrenergic antagonists, propranolol, prazosin or yohimbine. These results imply that transmitter-induced rapid changes in TG activity occur predominantly in ganglionic neurons. When the ganglia were depolarized by high KCl (50 mM), a significant increase in TG activity in each intact, denervated and axotomized SCG was seen with qualitatively similar manner, suggesting that high KCl-induced depolarization affects both neuronal and glial components in the SCG. The marked increase in ganglionic TG activity in response to GM1 (5 nM) and synthetic SC (0.02 mM) were lost in denervated SCG but only partially reduced in axotomized SCG.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative alterations of S-100 protein and neuron specific enolase in the rat nervous system after chronic 2,5-hexanedione exposure

The regional changes in quantities of the glial S-100 protein and the neuron specific enolase in the rat nervous system have been studied after long-term exposure to 2,5-hexanedione. The wet weights of most of the examined nervous tissues were found to be reduced, with an extensive effect seen in the brain stem. Using dot immunobinding assays, the concentrations of S-100 were found to be increased in most of the examined tissues, but unaffected in the brain stem. The total amount of S-100 per tissue was markedly reduced in the brain stem. The content of neuron specific enolase was reduced only in the brain stem. Thus the effects of 2,5-hexanedione on the nervous system varied regionally. The brain stem was severely atrophied with a reduction of neuronal as well as of glial marker proteins. Other brain regions contained increased glial cell marker proteins as signs of progressive astroglial reactions.

Polyamine metabolism in different pathological states of the brain

Biosynthesis of the polyamines spermidine and spermine and their precursor putrescine is controlled by the activity of the two key enzymes ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC). In the adult brain, polyamine synthesis is activated by a variety of physiological and pathological stimuli, resulting most prominently in an increase in ODC activity and putrescine levels. The sharp rise in putrescine levels observed following severe cellular stress is most probably the result of an increase in ODC activity and decrease in SAMDC activity or an activation of the interconversion of spermidine into putrescine via the enzymes spermidine N-acetyltransferase and polyamine oxidase. Spermidine and spermine levels are usually less affected by stress and are reduced in severely injured areas. Changes of polyamine synthesis and metabolism are most pronounced in those pathological conditions that induce cell injury, such as severe metabolic stress, exposure to neurotoxins or seizure. Putrescine levels correlate closely with the density of cell necrosis. Because of the close relationship between the extent of post-stress changes in polyamine metabolism and density of cellular injury, it has been suggested that polyamines play a role in the manifestation of structural defects. Four different mechanisms of polyamine-dependent cell injury are plausible: (1) an overactivation of calcium fluxes and neurotransmitter release in areas with an overshoot in putrescine formation; (2) disturbances of the calcium homeostasis resulting from an impairment of the calcium buffering capacity of mitochondria in regions in which spermine levels are reduced; (3) an overactivation of the NMDA receptor complex caused by a release of polyamines into the extracellular space during ischemia or after ischemia and prolonged recirculation in the tissue surrounding severely damaged areas; (4) an overproduction of hydrogen peroxide resulting from an activation of the interconversion of spermidine into putrescine via the enzymes spermidine N-acetyltransferase and polyamine oxidase. Insofar as a sharp activation of polyamine synthesis is a common response to a variety of physiological and pathological stimuli, studying stress-induced changes in polyamine synthesis and metabolism may help to elucidate the molecular mechanisms involved in the development of cell injury induced by severe stress.

Kanamycin inhibits cochlear-renal ODC in neonatal rats

Ornithine decarboxylase (ODC), a key enzyme in polyamine biosynthesis, is important in development and regeneration. We hypothesize that aminoglycoside inhibition of ODC mediates developmental hypersensitivity to aminoglycoside ototoxicity. Kanamycin effects on ODC activity (decarboxylation of ornithine) in vitro were determined in the postmitochondrial fraction of cochlear and renal homogenates from 11-day-old rats. Kanamycin inhibited cochlear and renal ODC by an uncompetitive mechanism. For the cochlear enzyme, the inhibitor constant (Ki) for kanamycin was 99 +/- 25 mumol/L; for the renal enzyme, the Ki = 1.5 +/- 0.1 mmol/L. In vivo effects of kanamycin on cochlear, renal, brain ODC activity were determined in rats treated with kanamycin (400 mg/kg/day, intramuscularly) or saline during postnatal days 11 through 20, the hypersensitive period for ototoxicity. Rats were killed on postnatal days 12, 14, 16, and 20 and ODC was assayed. Kanamycin significantly inhibited ODC in the lateral wall-organ of Corti and kidney (ANOVA alpha = 0.05), but had no effect on cochlear nerve and no consistent inhibitory effect in the brain. These results suggest that ODC is a potential target of kanamycin in susceptible tissues and may be a contributing factor in developmental sensitivity to the drug by inhibiting repair and developmental processes mediated by ODC.

Polyamines can protect against ischemia-induced nerve cell death in gerbil forebrain

We have previously demonstrated that administration of the polyamines putrescine, spermidine, or spermine can prevent neuronal degeneration in rats during naturally occurring cell death or after injurious treatments such as nerve injury or monosodium glutamate neurotoxicity. The present study demonstrates that also in adult gerbils polyamine treatment can protect forebrain neurons from degeneration after ischemia. Neurons in the hippocampus and striatum were rescued from delayed cell death after brief (5 min) global ischemia in gerbils which were treated with daily injections (10 mg/kg) of polyamines. The evidence accrued, so far, indicates that systemic polyamines can protect a wide variety of central and peripheral neurons from natural or induced degeneration.

Histamine increases ornithine decarboxylase activity in primary cultures of cerebellar granule cells

The effect of histamine on the activity of ornithine decarboxylase (ODC) of cerebellar granule neurons was studied using primary cultures grown both in serum-containing medium and in chemically defined medium. In comparison with granule neurons grown in chemically defined medium, the activity of ODC was about twice as great in the neurons grown in serum-containing medium. Treatment of cultured cerebellar neurons with histamine caused a dose-dependent increase in ODC activity. The maximum elevation was observed at 500 nM of histamine, when the increase in ODC activity was about 50% and 120% over controls in granule cells grown in serum-containing medium and in chemically defined medium, respectively. Histamine had no significant effect on the activity of lactate dehydrogenase in these cultures. The present findings provided direct evidence for the involvement of histamine in the regulation of ODC-related non-mitotic growth of granule neurons in the cerebellum.

Atrial natriuretic factor constitutes an intrinsic functional unit within superior cervical ganglia of the rat

The molecular forms of atrial natriuretic factor were studied in the sympathetic ganglia of the rat. The peptide atrial natriuretic factor was also tested for its ability to induce intracellular changes in ganglionic elements. Chromatographic evaluation of extracted ganglionic atrial natriuretic factor revealed the presence of proatrial natriuretic factor together with lower molecular weight peptides. Atrial natriuretic factor induced a maximal six-fold increase of cGMP accumulation within ganglia in vitro, most probably in principal ganglionic cells. Its effect on cGMP was not mediated by acetylcholine or any other neurotransmitter because it persisted after muscarinic receptor blockade and in a calcium-free medium and was not affected by ganglia decentralization. Thus, atrial natriuretic factor appears to be produced by a structural neural component of ganglia (in preganglionic cholinergic neurons or small intensely fluorescent cells?) and has receptors at sites different from its source. It is suggested that atrial natriuretic factor may be locally involved in the process of neurotransmission and may be yet another peptide neurotransmitter and/or neuromodulator.

Effects of isolation and high helium pressure on the nucleolus of sympathetic neurons in the rat superior cervical ganglion

In prokaryotes, unicellular eukaryotes and cell-free systems, pressure is known to exert an inhibitory effect on protein synthesis and RNA metabolism, the mechanism(s) of which remain to be investigated in detail. The purpose of the present in vitro study was to compare ultrastructural and quantitative changes of the nucleolus, which is the site of ribosome biogenesis, in sympathetic neurons of rat superior cervical ganglia (SCG) maintained for 2, 3 and 5 h in NCTC 109 medium and subjected to pressure or not. In control SCG (left) the nucleolus greatly increased in volume (+ 33%) 2 h after excision, in comparison with SCG fixed immediately. This overall enlargement was found to reflect a marked increase in all nucleolar components (from 16 to 87%). After 5 h, volumes of nucleolus, fibrillar centers and vacuolar component returned to control values, whereas dense fibrillar and granular components remained affected. Such early and transient changes are regarded as reflecting basic metabolic changes associated with increased nucleolar RNA that should be of primary concern to experiments using SCG transplanted in culture media. Compression under helium up to 180 atmospheric pressure for 1 h of right SCG maintained for 2 h in culture medium, was shown to induce, on the contrary, a marked decrease in nucleolar volume (-39%) and in volumes of all nucleolar components (from -36 to -51%). When they were kept at constant high pressure for 1 and 3 h a progressive recovery of volumes of nucleoli and nucleolar components was observed. Consequently, compression was shown to exert opposite effects to those of isolation of SCG. Present data are interpreted as an inhibitory effect of pressure on ribosome biogenesis. Such observations on a vertebrate neuron might open a new field in the search for cellular mechanisms underlying the effects of pressure on living organisms and especially on the nervous system.

Effects of hemicholinium-3 and sodium ions on choline uptake system in excised superior cervical sympathetic ganglia of rats

Active choline uptake by rat superior cervical sympathetic ganglia (SCG), which contain abundant cholinergic nerve terminals, was studied with respect to sensitivity to inhibition by hemicholinium-3 (HC-3) and dependence on extracellular Na under standard conditions of assay. Choline was taken up by a single saturable process with apparent Km = 3.07 x 10(-5) M and Vmax = 286 pmoles/min/mg protein. Neither denervation followed by degeneration of cholinergic nerve terminals nor axotomy with successive neuronal degeneration significantly decreased in choline uptake by the ganglia in vitro. HC-3 dose-dependently inhibited ganglionic choline uptake more effectively at lower than at higher choline concentrations. HC-3 sensitive inhibition of ganglionic choline uptake was not seen in young rats one week after birth but appeared with maturity, attaining approximately 50% maximal inhibition in adult SCG. Extent of inhibition by HC-3 and Na dependence of ganglionic choline uptake was not altered by denervation or axotomy.

Treatment with polyamines can prevent monosodium glutamate neurotoxicity in the rat retina

It has been previously shown that treatment of newborn rats with the polyamines putrescine, spermidine and spermine can rescue sympathetic neurons from naturally occurring cell death and from induced death after axotomy or immunosympathectomy. The present study demonstrates that polyamine treatment can also prevent the neurodegenerative effects in the retina and the loss of body weight caused by monosodium glutamate. The findings indicate that polyamine treatment may have a rather general beneficial effect on neuron survival.

Atrial natriuretic factor in sympathetic ganglia of the rat: dependence on cholinergic innervation

Atrial natriuretic factor is detectable in the peripheral autonomic ganglia of the rat by radioimmunoassay and immunohistochemistry. In the present study, surgical and neurochemical methods were used to evaluate the source of this peptide in sympathetic ganglia. Decentralization of the ganglia and/or central administration of colchicine diminished the atrial natriuretic factor content in para- and prevertebral ganglia. Axotomy did not affect levels of ganglionic atrial natriuretic factor. A messenger ribonucleic acid species hybridizing with rat atrial natriuretic factor complementary deoxyribonucleic acid was not found within the total ribonucleic acid extracted from superior cervical ganglia. These results indicate a direct dependence of ganglionic atrial natriuretic factor on cholinergic innervation.

Herpes simplex virus latent infection: reactivation and elimination of latency after neurectomy

Section of the sciatic nerve during the period of herpes simplex virus (HSV) latent infection was performed to evaluate residual latency in mouse dorsal root ganglion. In control mice without sciatic neurectomy, latency was present in 90-100%, while in those which underwent a neurectomy procedure, latent infection was surprisingly decreased to 28-50%. To investigate the hypothesis that the decrease of latency resulted from HSV reactivation and replication (with subsequent neuron destruction), groups of mice were treated with acyclovir to inhibit HSV reactivation, after having undergone a neurectomy procedure. Acyclovir treatment largely prevented the neurectomy-related elimination of latency and supported the hypothesized mechanism.

Retrograde changes in transglutaminase activity after peripheral nerve injuries

It has been previously demonstrated that transglutaminase activity in rat superior cervical ganglion is rapidly and transiently increased minutes after nerve injury. The present series of experiments sought to determine: (1) whether or not similar changes are expressed by other peripheral neuronal systems, and (2) if injury-induced changes in the enzyme activity can be detected along the injured nerve, and if so do they occur in axons or in non-neuronal cells. In the nodose ganglion transglutaminase activity increased (approximately 40%) 48 h after the vagus nerve was crushed 25 mm from the ganglion. In the vagus nerve the activity was transiently increased (approximately 100%) within 1 h, followed by a second increase (approximately 140%) after 3 h. This occurred only in the proximal nerve stump close to the injury site and not in the section of nerve closer to the ganglion. Comparable enzyme activity was found in unoperated vagus nerve and in distal stumps of previously ligated vagus nerves. In dorsal root ganglia no changes were found for up to 24 h after the sciatic nerve was crushed 40 mm from the ganglion. In the facial nucleus a transient increase was observed after the facial nerve was crushed about 14 mm distally with a peak (approximately 300) at 3 days and a decline within 14 days. A second lesion of the facial nerve made 12 days following a conditioning lesion led to a rebound of enzyme activity in the facial nucleus.(ABSTRACT TRUNCATED AT 250 WORDS)

Early polyamine treatment enhances survival of sympathetic neurons after postnatal axonal injury or immunosympathectomy

We have recently demonstrated that following injury of their axon, sympathetic neurons of the rat superior cervical ganglion become dependent on polyamine synthesis for their survival. In addition we have observed that the treatment of newborn rats with biogenic polyamines can prevent the naturally occurring reduction in the number of neurons in the ganglion. In the present study groups of newborn rats were subjected to either postganglionic nerve crush (axotomy) or to treatment with antiserum to nerve growth factor (immunosympathectomy), two treatments which result in a massive loss of neurons in the ganglion. Daily injections of the polyamines putrescine, spermidine and spermine (10 mg/kg each), for 7 days after the operation to the axotomized group, and for 9 days starting with the first antiserum injection to the immunosympathectomized group, attenuated the nerve cell loss. The polyamine treatment also attenuated the reduction in the activity of the neurotransmitter-synthesizing enzyme tyrosine hydroxylase observed after both axotomy and immunosympathectomy in the ganglion. These results further indicate that polyamines are important for the survival of sympathetic neurons and, while their mechanism of action is unknown, an interaction with nerve growth factor regulation cannot be excluded. In the iris, the reduction observed in [3H]norepinephrine uptake after the two noxious treatments was unproportionately small when compared to the large drop in the number of parent neurons in the ganglion. This suggests that compensatory mechanisms exist which act to adjust the number of functional axon terminals per neuron so that the number of terminals innervating the target remains relatively constant.

Inhibition of inner ear ornithine decarboxylase by neomycin in-vitro

We quantitated the activity of ornithine decarboxylase (ODC) in homogenates and subcellular fractions of inner ear tissues from the rat and guinea pig and demonstrate inhibition of cochlear ODC by the aminoglycoside neomycin. Subcellular fractionation showed the enzyme associated with the post-mitochondrial supernatant fraction in each of the tissues: Specific activities of ODC, defined as alpha-difluoromethylornithine (DFMO)-sensitive decarboxylation of ornithine, in the supernatant fractions of combined inner ear tissues were: guinea pig = 44 +/- 4 pmoles CO2 produced/hour/mg protein, and rat = 133 +/- 30. In the guinea pig, supernatant fractions of the lateral wall tissues (stria vascularis and spiral ligament) had specific activities of 62 +/- 25, those of the organ of Corti (plus VIIIth nerve) 64 +/- 41. The ototoxic aminoglycoside neomycin produced a dose-dependent inhibition of ODC with half-maximal inhibition observed at 50 microM drug and almost complete inhibition at 100 microM. This is the first report of the presence of ODC in the inner ear and its inhibition by neomycin. Since both the ODC-inhibitors, DFMO and neomycin, can cause hearing loss in patients and experimental animals it is suggested that inhibition of ODC may be an important factor in the ototoxicity of these drugs.

Early changes in degenerating mouse sciatic nerve are associated with endothelial cells

This study determines the earliest reproducible biochemical change in nerves undergoing Wallerian degeneration by assessing the timing, magnitude, and specificity of changes in markers of cellular function in distal stumps of transected mouse sciatic nerves. Analysis of temporal changes in synthesis of DNA, RNA, protein, and in activity of ornithine decarboxylase in transected and sham-operated nerves 0-5 days postoperatively indicated that incorporation of [3H]thymidine, a marker of premitotic activity, was the earliest and only specific marker of early Wallerian degeneration. Although the 3-4 day peak in [3H]thymidine incorporation in distal stumps at the onset of the [3H]thymidine response (1 day post-transection) revealed preferential labeling of endothelial cells lining intrafascicular capillaries.

Retrograde transport of endogenous nerve growth factor in superior cervical ganglion of adult rats

The concentration of naturally synthesized nerve growth factor (NGF) was measured in various tissues of adult rats, using a highly sensitive two-site enzyme immunoassay. The highest concentration was found in the superior cervical sympathetic ganglion (SCG). Transection of the postganglionic external carotid nerve (ECN) reduced the ganglionic level of NGF more than did section of the internal carotid nerve (ICN). When both the preganglionic nerve and the ECN were cut, the ganglionic NGF level decreased even more. On the other hand, when the preganglionic nerve and the ICN were both sectioned, leaving the ECN intact, endogenous NGF content in the SCG was significantly enhanced 3-9 h after operation. Bilateral extirpation of submaxillary gland produced a rapid decrease in ganglionic NGF 3-6 h after operation, and even unilateral removal of one salivary gland caused a decrease in both ganglia, which was however much greater in the ipsi- than in the contralateral ganglion. Removal of the eyeballs caused a much smaller reduction in ganglionic NGF than did removal of the glands. These results suggest that the endogenous NGF that accumulates in the SCG is mostly synthesized in the submaxillary gland rather than in the iris, and that it is transported to the SCG, mostly via the ipsilateral ECN.

The effect of axotomy and denervation on calmodulin content in the superior cervical sympathetic ganglion of the rat

Calmodulin (CaM) in the superior cervical sympathetic ganglion (SCG) of the rat and its changes after transection of the pre- or postganglionic nerves were studied biochemically and immunohistochemically. The concentration of CaM in the SCG was assayed using the extent of activation of CaM-dependent adenylate cyclase from bovine neural retina. In the SCG, CaM concentration was 4.5 micrograms/mg protein, a level similar to that in another peripheral ganglion, the nodose ganglion (4.9 micrograms/mg protein). Following denervation of the SCG, the total amount of ganglionic CaM did not change significantly within a week. On the other hand, CaM content per ganglion increased gradually 3 days after axotomy. Immunohistochemical examination revealed that CaM in unoperated SCG is present both in the neuronal fibers and in the cell soma of sympathetic neurons. But the intensity of the staining with CaM-antibody in the cytoplasmic soma varied among cells. The gross profile of the CaM immunostaining seemed to be unchanged one week after either denervation or axotomy, but the immunoelectron microscopic study showed heavy staining of the innercellular membranes of irregular shape in the axotomized SCG.

Changes of ornithine decarboxylase activity in dorsal root ganglion cells after axon injury: possible relationship to alterations in neuronal chromatin

An autoradiographic technique was used to detect changes in ornithine decarboxylase in rat dorsal root ganglion neurons after sciatic nerve lesions. Binding of [3H]difluoromethylornithine ([3H]DFMO) to tissue sections of L5 ganglia was compared between axotomized and unoperated ganglia at 0.5, 1, 2, 3, 4, 5, 7, 8, 9, 11, 14, and 30 days after a crush lesion of the sciatic nerve. The [3H]DFMO binding to axotomized ganglion neurons was elevated compared with the unoperated side at 0.5, 1, 5, 7, 8, and 11 days postoperation. Enzymatic measurements of ornithine decarboxylase on ganglia at 1, 4, 8, and 9 days after sciatic nerve crush confirmed basic patterns of enzyme activity comparisons derived from autoradiography. Compared with patterns of [3H]actinomycin D binding to nuclei during the same periods after axotomy, [3H]DFMO binding increased prior to increases in [3H]actinomycin D binding within the first week. After that time, changes in both variables occurred in parallel. The data suggest that increased activities of ornithine decarboxylase or concentrations of polyamines may be linked to the induction of increased RNA synthesis in the early phases of the axon reaction.

Effects of fimbria-fornix transection and ganglioside treatments on histochemical staining for glucose-6-phosphate dehydrogenase in the lateral septum

The present study examined whether ganglioside treatments would affect an enzyme marker (glucose-6-phosphate dehydrogenase; G6PDH) of neural metabolism in an established model system (the hippocamposeptal projection) of deafferentation and sprouting. Rats were subjected to unilateral transections of the fimbria-fornix (FF) in order to (1) interrupt the hippocamposeptal projection, (2) deafferent the lateral septal nucleus (LSN) ipsilaterally, and (3) induce sprouting by the contralateral FF. In untreated rats which were killed at 2-4 days postlesion, histochemical staining for G6PDH was reduced by 35-40% in the deafferented LSN relative to the contralateral side. However, at 6-8 days (i.e., when sprouting begins), staining intensity returned toward contralateral values (i.e., recovered). This pattern of changes in G6PDH staining was not observed in the caudate nucleus adjacent to the LSN. In ganglioside-treated rats which were killed at 4 days, there was a significantly smaller reduction of G6PDH staining in the deafferented LSN (23%; P = .05). This effect was not observed in the LSN of treated rats killed at 2 days, nor in the caudate nucleus at either time point. The present data indicate that (1) FF transection results in a reduction and subsequent recovery of G6PDH staining in the deafferented LSN; and (2) ganglioside treatments may accelerate the onset of the recovery of G6PDH activity. We suggest that gangliosides' effect on G6PDH reflects an acute enhancement of biosynthetic events in deafferented neurons.

Recovery of cholinesterases in soman-injected superior cervical ganglion of the rat in the presence and absence of innervation

We have previously described the procedure for quantitative separation of extracellular and intracellular ChEs using mild treatment of rat superior cervical ganglion with papain. Here, this procedure was used in order to investigate the recovery of ChEs in the two pools after irreversible inhibition by soman which was directly injected into the ganglion. After such treatment only ganglion ChEs were totally inhibited, whereas the activity of ChEs in preganglionic neurons and their axons remained unaffected. Comparing in innervated and decentralized ganglia the pattern of recovery rate and ultrastructural reappearance of ChEs after local inhibition, with that reported after systemic ChEs inhibition, it was possible to distinguish between the indirect effects of innervation on the recovery rate and pattern of ChEs of ganglion origin and the direct contribution to the total ganglion enzyme activity of ChEs originating in the preganglionic elements. The absence of nerve contracts affects mostly extracellular activity, particularly AChE, whereas the intracellular activity of AChE was only slightly decreased and the activity of nsChE was somewhat increased. This increase coincides with the enhanced cytochemical reaction of nsChE in some nonneuronal cells in the ganglion. Actinomycyn D decreased the rate of initial rapid phase of recovery of intracellular ChEs when injected in the ganglion daily for three days, whereas the recovery of extracellular ChEs was already decreased the first day of Actinomycyn D application. This indicates that the externalization of the enzyme is more affected than its synthesis by inhibition the translation step.(ABSTRACT TRUNCATED AT 250 WORDS)

Early polyamine treatment accelerates regeneration of rat sympathetic neurons

After injury of their axons, damaged neurons shift their metabolic activity into a reparative mode aimed at survival and regeneration or, alternatively, they undergo degeneration and die. Previous reports have shown that at the initial stages of the response to axonal injury, polyamines are essential for neuronal survival and can accelerate functional recovery. In this study we examined the ability of exogenous polyamines to accelerate regeneration following crush of the pre- or postganglionic sympathetic nerves of the superior cervical ganglion in adult rats. We found that early treatment with polyamines after pre- or postganglionic nerve crush, accelerated the reappearance of choline acetyltransferase activity in the superior cervical ganglion, and of [3H]norepinephrine uptake in the iris, respectively. Functional recovery from eyelid ptosis was also accelerated. We conclude that treatment with polyamines can enhance regeneration of peripheral sympathetic neurons.

Stimulation of amino acid uptake and Na+,K+-ATPase activity by norepinephrine in superior cervical sympathetic ganglia excised from adult rats

Active uptake of a labelled nonmetabolizable amino acid, alpha-aminoisobutyric acid (AIB), into isolated superior cervical sympathetic ganglia (SCG) excised from adult rats was considerably stimulated by the addition of either norepinephrine (NE, 50 microM) or 3,4-dihydroxyphenylethylamine (dopamine, DA, 100 microM) to the medium during aerobic incubation for 2 h at 37 degrees C. The NE-induced increase in AIB uptake was significantly antagonized by the addition of an alpha 1-adrenoceptor antagonist (prazosin, 10 microM) in SCG axotomized 1 week prior to the examination, in which most of the ganglionic neurons had degenerated and reactive proliferation of the satellite glial components was in progress. The addition of neither acetylcholine (ACh, 1 mM) plus eserine (0.1 mM) nor cyclic nucleotides (1 mM) changed the AIB uptake by the SCG. In the axotomized SCG, the NE-evoked increase in AIB uptake was much more pronounced than that of intact or denervated SCG. A kinetic study of the active AIB uptake in the SCG showed that NE produced a decrease of the Km value and an increase in the Vmax, especially in the axotomized SCG. Ganglionic Na+, K+-ATPase activity was greatly stimulated in the presence of NE, but not by ACh. These results strongly suggest that the NE-induced enhancement of active AIB uptake in the isolated SCG is occurring in glial cells rather than in neuronal cells, with a possible alteration of membrane properties for amino acid uptake and with an apparent regulation by the stimulated transport enzyme Na+, K+-ATPase.

Autoradiographic measurement of relative changes in ornithine decarboxylase in axotomized superior cervical ganglion neurons

An autoradiographic method is described for detecting changes in ornithine decarboxylase in axotomized superior cervical ganglion neurons of rats using [3H]difluoromethylornithine. An increase in binding to neurons was seen at 12 h and 1 day after crushing the postganglionic nerves. Binding returned to control values between 3 and 5 days postoperation. The patterns found using this method were in general agreement with prior reports of enzymatic changes in whole ganglia.

Tubulin synthesis in the regenerating rat superior cervical ganglion: a biphasic response

Axotomy of a major cranial post ganglionic branch of the superior cervical ganglion of an adult rat resulted in increased radiolabeling of tubulin and microtubule-associated proteins after an in vitro 5-h incubation with [14C]-methionine. The increased incorporation of the radiolabel began at day 1 postoperatively and exhibited a biphasic response, peaking at days 3 and 8.

Differences in horseradish peroxidase labeling of sensory, motor and sympathetic neurons following chronic axotomy of the rat sural nerve

In an attempt to clarify the ultimate fate of permanently axotomized adult primary neurons, horseradish peroxidase (HRP) was used as a cell marker to label the motor, sensory and postganglionic sympathetic neurons of rat sural nerves which had been sectioned at the ankle and prevented from regenerating for periods of up to 80 weeks. Axotomy did not affect sympathetic neurons, but resulted 4 weeks later in a sudden reduction in the number of labeled sensory and motor cells which persisted to the end of the study. The missing neuronal population amounted to 44.4% and 45.9% respectively of the normal sensory and motor contingent and included most of the large afferent and efferent neurons. However, examination of sural nerves at the thigh, 30 mm proximal to the neuroma, revealed marked axonal atrophy but no change in the number of myelinated and unmyelinated fibers up to 52 weeks after axotomy. Such prolonged survival of the peripheral processes is indirect evidence that axotomized neurons can endure long-term detachment from their end organs and suggests that the lack of HRP labeling in certain sensory and motor neurons does not imply their degeneration, but expresses one of many retrograde dysfunctions triggered by axotomy.

Ornithine decarboxylase in motoneurons during regeneration

The activity of ornithine decarboxylase, the rate-limiting enzyme in polyamine synthesis, was assayed in the isolated facial nucleus of the rat at various times after axotomy of the facial nerve. In addition, it was measured 24 h after the second of a series of two lesions (conditioning lesion design) with various times between the first and second operations. Ornithine decarboxylase activity was found to increase 8 h after nerve transection and was maximum after 24 h (300% of control). Thereafter the activity declined to subnormal levels where it remained for several weeks. Ornithine decarboxylase activity did not increase again when a second axotomy was made 2 weeks after the first lesion. However, ornithine decarboxylase did respond to the second axotomy if it was carried out 3 weeks after the first lesion. Histochemical localization of ornithine decarboxylase demonstrated that the increase in enzyme activity was mainly confined to the perikarya of the motoneurons. These data suggest that this enzyme is somehow involved in triggering the "regeneration program" and clearly indicate that at least some aspects of the neuronal response to axotomy are not further stimulated by a conditioning lesion.

Stimulative effect of nerve growth factor on alpha-aminoisobutyric acid uptake and Na,K-ATPase activity in superior cervical sympathetic ganglia excised from adult rats

Effects of nerve growth factor (NGF) on the uptake of non-metabolizable alpha-aminoisobutyric acid (AIB) and on Na,K-ATPase activity in superior cervical sympathetic ganglia (SCG) excised from adult rats were examined during aerobic incubation in vitro. Active uptake of labelled AIB into isolated SCG during 1 to 5 hours incubation at 37 degrees C was significantly accelerated by the addition of NGF to the incubation medium in a dose-dependent manner. Although the Km value of the AIB uptake by the SCG did not change with the addition of NGF, Vmax was nearly doubled. The NGF-evoked increase in AIB uptake was antagonized by the further addition of its specific antiserum in a dose-dependent fashion, and was largely suppressed in a medium containing ouabain. In SCG, axotomized one week prior to the examination, from which most of the neurons had disappeared and reactive proliferation of satellite glial components was in progress, the NGF-induced acceleration of AIB uptake was completely absent. The ganglionic Na,K-ATPase activity was greatly stimulated in the presence of NGF, and the effect was completely eliminated in the axotomized SCG. These results strongly suggest that the NGF-induced acceleration of active AIB uptake by the isolated SCG occurs not in glial cells but exclusively in the neuronal components with the apparent coupling of an Na ion extrusion process.

Alkaline ribonuclease activity is increased in rat sympathetic ganglia after nerve injury

Ribonuclease activity at pH 7.1 ("alkaline" ribonuclease) was determined in homogenates of rat superior cervical ganglion up to 5 days after postganglionic nerve injury under optimal conditions of assay. Measurements were performed in the presence and absence of the sulfhydryl blocking agent, N-ethylmaleimide, to assess the proportion of "alkaline" ribonuclease apparently bound to endogenous inhibitor. Total ribonuclease activity per ganglion was stimulated 1.3 fold by 1 day after injury and remained elevated over the 5 day period. Free ribonuclease activity accounted for about 60% of the observed increase in total activity at day 1, but had returned to control level by day 3. At day 3 the entire 90% increase in total activity was attributable to ribonuclease bound to endogenous inhibitor (i.e. latent activity). These changes are occurring at times after nerve injury when marked alterations in RNA turnover have been observed, implicating "alkaline" ribonucleases in the control of RNA metabolism during nerve regeneration.

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)

Effects of various kinds of stimulation on ornithine decarboxylase activity in superior cervical sympathetic and nodose ganglia of rats

Levels of cyclic nucleotides and ornithine decarboxylase (ODC) activity were examined following the application of various kinds of stimuli to superior cervical sympathetic ganglia (SCG), nodose ganglia, and vagus nerve fibers excised from the rat. The level of cyclic GMP in the SCG rose rapidly to about 4.5- to 7.5-fold the unstimulated control with 10 min of incubation after applications of preganglionic electrical stimulation (10 Hz), acetylcholine (ACh; 1 mM), or high extracellular K+ ( [K+]0, 70 mM). The cyclic GMP level in nodose ganglia was increased less than in the SCG by either ACh or high [K+]0 but was not affected by ACh in vagus fibers. Cyclic AMP in the SCG was also increased about 4- to 5.5-fold over the control within 10 min with the addition of ACh, norepinephrine (NE; 0.05 mM), or high [K+]0. Although NE caused a small increase in cyclic AMP, neither ACh nor high [K+]0 produced any appreciable change in nodose ganglia or vagus fibers. The ODC activity in the SCG was increased by preganglionic stimulation of 3- to 4-hr duration but not by a shorter period. A similar change in ODC activity was caused by the addition of oxotremorine (1 mM), isoproterenol (0.1 mM), NE, cyclic AMP (1 mM), or dibutyryl cyclic GMP (1 mM). The effect was exaggerated by the further addition of 3-isobutyl-1-methylxanthine (IBMX), a phosphodiesterase inhibitor. The increase in ODC activity caused by ACh was abolished by a muscarinic cholinergic antagonist, atropine (0.01 mM), and following axotomy for a week, but not by a nicotinic antagonist or by denervation in the SCG. A similar increase in ganglionic ODC activity by NE was inhibited by an adrenergic blocker, propranolol (0.01 mM), and following axtotomy for a week, but not by denervation. Cholinergic or adrenergic stimulation did not cause an increase in ODC activity in nodose ganglia or vagus fibers. These results suggest that the stimulation-induced increase in ODC activity occurs in postganglionic neurons rather than in satellite glial cells and is mediated by muscarinic cholinergic or adrenergic receptors. The process appears to involve cyclic nucleotide-mediated protein biosynthesis in the SCG.