Effect of crush and axotomy of phrenic nerves on oxidative stress in diaphragm muscle of rats

Introduction: In this study we investigated the effect of crush and axotomy of phrenic nerves on oxidative stress and antioxidant enzyme activities in rat diaphragm muscle. Methods: The animals in the first group were not crushed or axotomized and served as controls. Phrenic nerves of the rats in the second and third groups were crushed or axotomized in the diaphragm muscle. Results: The malondialdehyde level increased in diaphragm muscles after both crush and axotomy. The antioxidant enzymes, such as superoxide dismutase, glutathione peroxidase, carbonic anhydrase, and catalase, decreased in diaphragm muscles after both crush and axotomy. Conclusions: Crushing or axotomizing the phrenic nerves may produce oxidative stress in the diaphragm muscle of the rat by increasing lipid peroxidation and decreasing antioxidant enzyme activities. Muscle Nerve, 2012     

Effects of extracorporeal shock-wave lithotripsy directed at the parotid gland on oxidative stress parameters and some trace element levels in facial nerve of rats

Introduction: This study was designed to assess the effect of extracorporeal shock‐wave lithotripsy (ESWL) exposure of the parotid gland on oxidative stress and some trace element levels in the facial nerves of rats. Methods: Twelve male Wistar albino rats were divided into two groups, each consisting of 6 animals. The rats in the first group served as controls. The left parotid glands of animals in the second group were treated with 1000 18‐kV shock waves while anesthetized with ketamine. The animals in both groups were euthanized 72 h after the ESWL treatment, and the right facial nerve was harvested for determination of oxidant/antioxidant status and trace element levels. Results: Lipid peroxidation product malondialdehyde (MDA) and antioxidant glutathione (GSH) levels increased, and the activities of antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH‐Px), decreased in the facial nerves of ESWL‐treated rats. The levels of iron, lead, manganese, and cobalt increased, and magnesium, cadmium, and copper levels decreased. Conclusions: ESWL treatment of the parotid gland may increase lipid peroxidation and decrease antioxidant enzyme activity in adjacent tissues such as the facial nerve. It also causes a decrease or increase in many mineral levels of the facial nerve, which is an undesirable condition for normal physiological function. Muscle Nerve, 2012     

Gamma-interferon-like immunoreactivity in axotomized rat motor neurons

Major histocompatibility complex (MHC) encoded antigens, absent or present at only low levels in normal brain tissue, are induced locally around axotomized motor neurons. We here report that immunoreactivity for the potent MHC-inducing factor, gamma-interferon (IFN-gamma), appears in the cytoplasm of such neurons. Rat facial nerves were interrupted (crushed or cut), and later, at various intervals, cryosections from the facial nuclei were subjected to immunohistochemistry with monoclonal antibodies reacting with IFN-gamma and MHC antigens. IFN-gamma-like immunoreactivity appeared briskly in the cytoplasm of the axotomized motor neurons. The immunoreactivity subsided after a nerve crush as the target muscles were reinnervated, but persisted when nerve regeneration was prevented after a nerve cut. These results point to a role for nerve cell-derived IFN-gamma-like molecules in eliciting the neural cell responses to axotomy.     

Synthesis of myelin proteins and ultrastructural investigations in regenerating rat sciatic nerve

Myelin protein synthesis, as well as ultrastructural and morphometric changes in regenerating peripheral nerve, was studied. Sciatic nerves of rats were crushed unilaterally; sham-operated nerves of the contralateral side served as controls. For the in vivo experiments, rats were killed at selected periods after the nerves were crushed (30, 60, 90, and 120 days); seven days prior to killing, the animals were injected intravenously with L-[4,5-3H]leucine. For the in vitro experiments, proximal and distal segments of sciatic nerve and equivalent sham-operated nerves were labeled with 3H-amino acid mixture 90 days after axotomy. Purified myelin was isolated from nerve segments; specific radioactivity and gel electrophoretic patterns of proteins were analyzed. Cross-sectional electron microscope (EM) preparations of proximal, distal, and contralateral segments of nerves also were examined. Results showed that the incorporation of labeled amino acids into total myelin proteins was enhanced significantly in the distal segment of sciatic nerves at all of the periods of regeneration studied. The yield of myelin protein per mm distal nerve segment increased as regeneration proceeded. The remyelination of fibers early after nerve crush was weak, whereas it gradually attained the normal range 90-120 days after axotomy. Morphometric analysis of myelin sheath thickness of regenerating axons was consistent with the data obtained for myelin protein synthesis.     

Role of oxidative stress in surgical cavernous nerve injury in a rat model

This study investigates the role of oxidative stress in surgical cavernous nerve (CN) injury in a rat model. Eighty‐four male Sprague‐Dawley rats were randomly divided into three groups: group 1, sham‐operated rats; group 2, bilateral CN‐crushed rats; and group 3, bilateral CN‐transection‐and‐sutured‐immediately rats. Oxidative stress was evaluated by malondialdehyde levels, super oxide dismutase (SOD) activities, and glutathione peroxidase (GPX) activities in serum. Erectile function was assessed by CN electrostimulation at 3 months with mean maximal intracavernous pressure (ICP) and maximal ICP per mean arterial pressure. Nerve injury was assessed by toluidine blue staining of CNs and nicotinamide adenine dinucleotide phosphate (NADPH)‐diaphorase staining of penile tissue. GPX protein expression and nitrotyrosine‐3 (NT‐3) levels in penile tissue were measured. Erectile function and the number of myelinated axons of CNs and NADPH‐diaphorase‐positive nerve fibers were statistically decreased between groups, from sham to crush to transection. For markers, both nerve‐injury groups showed increased oxidative stress markers at early time points, with the transection group showing greater oxidative stress than the crushed group and values normalizing to sham levels by week 12. GPX expression and NT‐3 levels in penile tissue were in concordance with the results of SOD and GPX. These results show that oxidative stress plays an important role in injured CNs, and different methods of CN injury can lead to different degrees of oxidative stress in a rat model. © 2015 Wiley Periodicals, Inc.     

d-Serine administration provokes lipid oxidation and decreases the antioxidant defenses in rat striatum

The present work investigated the effects of intrastriatal administration of d-serine on relevant parameters of oxidative stress in striatum of young rats. d-Serine significantly induced lipid peroxidation, reflected by the significant increase of thiobarbituric acid-reactive substances, and significantly diminished the striatum antioxidant defenses, as verified by a decrease of the levels of reduced glutathione and total antioxidant status. Finally, d-serine inhibited superoxide dismutase activity, without altering the activities of glutathione peroxidase and catalase. In contrast, this d-amino acid did not alter sulfhydryl oxidation, a measure of protein oxidative damage. The present data indicate that d-serine in vivo administration induces lipid oxidative damage and decreases the antioxidant defenses in the striatum of young rats. Therefore, it is presumed that this oxidative stress may be a pathomechanism involved at least in part in the neurological damage found in patients affected by disorders in which d-serine metabolism is compromised, leading to altered concentrations of this d-amino acid.     

Changes in expression of peptides in rat facial motoneurons after facial nerve crushing and resection.

In situ hybridization histochemistry was used to study changes in mRNAs coding neuropeptides such as alpha-calcitonin gene-related peptide (CGRP), beta-CGRP, cholecystokinin (CCK) and galanin, in rat facial motoneurons following axotomy of the facial nerve. In control rats, 38%, 55% and 7% of the facial motoneurons expressed alpha-CGRP, beta-CGRP and CCK mRNAs, respectively. No galanin mRNA-containing motoneurons were observed in these animals. The levels of mRNA for alpha-CGRP, CCK and galanin were increased while the beta-CGRP mRNA level was decreased after axotomy. The levels of mRNAs for these peptides returned to the control values by 2-4 weeks after nerve crush, whereas nerve resection had more prolonged effects. Within 3-4 weeks after injury, nerve resection had greater effects on beta-CGRP, CCK and galanin mRNAs than did nerve crush. Thus, there appear to be differences in the regulation of mRNA expression of these peptides in axotomized motoneurons.     

Lysine induces lipid and protein damage and decreases reduced glutathione concentrations in brain of young rats

The present work investigated the in vitro effects of lysine on important parameters of oxidative stress in cerebral cortex of young rats. Our results show that lysine significantly induced lipid peroxidation, as determined by increase of thiobarbituric acid-reactive substances and chemiluminescence levels, as well as protein oxidative damage since carbonyl formation and sulfhydryl oxidation were enhanced by this amino acid. Furthermore, the addition of free radical scavengers significantly prevented lysine-induced lipid oxidative damage, suggesting that free radicals were involved in this effect. Lysine also significantly diminished glutathione levels in cortical supernatants, decreasing, therefore, the major brain antioxidant defense. Finally, lysine markedly oxidized a glutathione commercial solution in a medium devoid of brain supernatants, indicating that it behaved as a direct acting oxidant. The present data indicate that lysine induces oxidative stress in cerebral cortex of young rats. Therefore, it is presumed that this pathomechanism may be involved at least in part in the neurological damage found in patients affected by disorders with hyperlysinemia.     

Reversal effect of monoisoamyl dimercaptosuccinic acid (MiADMSA) for arsenic and lead induced perturbations in apoptosis and antioxidant enzymes in developing rat brain

Oxidative stress (OS) has been implicated in the pathophysiology of many neurodegenerative disorders. Several studies have shown that exposure to arsenic (As) and lead (Pb) produces oxidative stress, one of the most noted molecular mechanisms for the neurotoxicity of these metals. In the present study, we examined the effect of combined exposure to these metals (As and Pb) on the activity levels of antioxidant enzymes and apoptotic marker enzymes in brain regions (cerebral cortex, hippocampus and cerebellum) of rats at postnatal day (PND) 21, 28 and 3 months age and compared the toxicity levels with individual metals (As or Pb). Further, we also evaluated the therapeutic efficacy of a chelating agent, monoisoamyl dimercaptosuccinic acid (MiADMSA) against arsenic and lead induced developmental neurotoxicity. Pregnant rats were exposed to sodium meta-arsenite (50 ppm) and lead acetate (0.2%) individually, and in combination (As = 25 ppm + Pb = 0.1%) via drinking water throughout perinatal period (GD 6 to PND 21). MiADMSA (50 mg/kg, orally through gavage) was given for three consecutive days to the PND 18 pups (i.e., PND 18 to PND 20). Exposure to metal mixture resulted in a significant decrease in the activity levels of antioxidant enzymes such as manganese-superoxide dismutase (Mn-SOD), Cu/Zn superoxide dismutase (Cu/Zn-SOD), catalase (CAT) and glutathione peroxidase (GPx) while the malondialdehyde (MDA) levels and mRNA expression levels of caspase-3 and caspase-9 were significantly increased in all the three brain regions. The observed alterations were greater with exposure to metal mixture than individual metals (As or Pb) and the changes were more prominent at PND 28 and greater in cerebral cortex than hippocampus and cerebellum. Interestingly, chelation therapy with MiADMSA showed significant recovery in antioxidant enzymes, lipid peroxidation and gene expression levels of caspase-3 and caspase-9. From these findings, it can be concluded that combined exposure to As and Pb showed an additive effect on antioxidant enzymes than individual metal exposure and chelation therapy with MiADMSA significantly reversed the As and Pb induced apoptosis and oxidative stress, a major contributing factor to neurotoxicity.     

Agmatine, an endogenous ligand of imidazoline receptor protects against memory impairment and biochemical alterations in streptozotocin-induced diabetic rats

Agmatine, a polycationic amine synthesized via decarboxylation of l-arginine by arginine decarboxylase is reported to exhibit anti-hyperglycemic, antioxidant and memory enhancing effects. Therefore, we tested its influence against cognitive dysfunction in streptozotocin-induced diabetic rats using Morris water maze and object recognition paradigm. Lipid peroxidation and glutathione levels as parameters of oxidative stress and choline esterase (ChE) activity as a marker of cholinergic function were assessed in the cerebral cortex and hippocampus. Thirty days after diabetes induction rats showed a severe deficit in learning and memory associated with increased lipid peroxidation, decreased reduced glutathione, and elevated ChE activity. In contrast, chronic treatment with agmatine (5-10mg/kg, i.p. for 30 days) improved cognitive performance, lowered hyperglycemia, oxidative stress, and ChE activity in diabetic rats. Further, memory improving effects of agmatine were independent of adrenal I(2) imidazoline receptors. In a separate set, agmatine treatment for an initial 15 days after diabetes confirmation also significantly reduced memory impairment during training trials after 30 days of diabetes confirmation. Moreover, treatment during training trials (30 days after diabetes) also significantly reduced memory impairment in diabetic rats. In conclusion, the present study demonstrates that treatment with agmatine prevents changes in oxidative stress and ChE activity, and probably consequent memory impairment in diabetic rats.     

A comparison of peripheral and central axotomy effects on neurofilament and tubulin gene expression in rat dorsal root ganglion neurons

The expression of major cytoskeletal protein mRNAs was studied in adult rat dorsal root ganglion (DRG) neurons after crushing either their central or peripheral branch axons. mRNA levels in DRG neurons were examined by quantitative in situ hybridization with radiolabeled cDNA probes specific for the low-molecular-weight neurofilament protein (NF-L) and beta-tubulin. The large-sized (greater than 1000 microns 2) neurons which give rise to myelinated axons in lumbar ganglia (L4 and L5) were studied 1 d through 8 weeks after either dorsal root or sciatic nerve crush. NF-L and beta-tubulin mRNA levels in axotomized DRG neurons were compared to those in contralateral control DRG neurons, as well as to those in normal (completely untreated) DRG cells. In the case of NF-L mRNA, changes were observed after central as well as peripheral branch axotomy and the time course and magnitude of changes were similar after both types of axotomy. NF-L mRNA levels initially decreased (first 2 weeks after crush) and then began to return towards control levels at longer survival times. Similar, but less pronounced, changes in NF-L mRNA levels also occurred in contralateral DRG neurons (which were uninjured); the changes in contralateral neurons were not simply a result of surgical stress since no changes in NF-L mRNA levels were observed in sham-operated DRG neurons. In the case of tubulin mRNA, changes were observed after central as well as peripheral branch axotomy by in situ hybridization, but the time course and magnitude of changes were different after each type of axotomy.(ABSTRACT TRUNCATED AT 250 WORDS)     

PTU-induced hypothyroidism modulates antioxidant defence status in the developing cerebellum

The objective of the present study was to evaluate the effect of 6-n-propylthiouracil (PTU)-induced hypothyroidism on oxidative stress parameters, expression of antioxidant defence enzymes, cell proliferation and apoptosis in the developing cerebellum. PTU challenged neonates showed significant decrease in serum T₃ and T₄ levels and marked increase in TSH levels. Significantly elevated levels of cerebellar H₂O₂ and lipid peroxidation were observed in 7 days old hypothyroid rats, along with increased activities of superoxide dismutase and glutathione peroxidase and decline in catalase activity. In 30 days old hypothyroid rats, a significant decline in cerebellar lipid peroxidation, superoxide dismutase and glutathione peroxidase activity and expression was observed along with an up-regulation in catalase activity and expression. Expression of antioxidant enzymes was studied by Western blot and semi-quantitative rt-PCR. A distinct increase in cell proliferation as indicated by proliferating cell nuclear antigen (PCNA) immunoreactivity was observed in the internal granular layer of cerebellum of 7 days old hypothyroid rats and significant drop in PCNA positive cells in the cerebellar molecular layer and internal granular layer of 30 days old PTU treated rats as compared to controls. In situ end labeling by TUNEL assay showed increased apoptosis in cerebellum of hypothyroid rats in comparison to controls. These results suggest that the antioxidant defence system of the developing cerebellum is sensitive to thyroid hormone deficiency and consequent alterations in oxidative stress status may play a role in regulation of cell proliferation of the cerebellum during neonatal brain development.     

Protection of cholinergic and antioxidant system contributes to the effect of berberine ameliorating memory dysfunction in rat model of streptozotocin-induced diabetes

Memory impairment induced by streptozotocin in rats is a consequence of changes in CNS that are secondary to chronic hyperglycemia, impaired oxidative stress, cholinergic dysfunction, and changes in glucagon-like peptide (GLP). Treatment with antihyperglycemics, antioxidants, and cholinergic agonists are reported to produce beneficial effect in this model. Berberine, an isoquinoline alkaloid is reported to exhibit anti-diabetic and antioxidant effect, acetylcholinesterase (AChE) inhibitor, and increases GLP release. However, no report is available on influence of berberine on streptozotocin-induced memory impairment. Therefore, we tested its influence against cognitive dysfunction in streptozotocin-induced diabetic rats using Morris water maze paradigm. Lipid peroxidation and glutathione levels as parameters of oxidative stress and choline esterase (ChE) activity as marker of cholinergic function were assessed in the cerebral cortex and hippocampus. Thirty days after diabetes induction rats showed a severe deficit in learning and memory associated with increased lipid peroxidation, decreased reduced glutathione, and elevated ChE activity. In contrast, chronic treatment with berberine (25-100mg/kg, p.o., twice daily, 30 days) improved cognitive performance, lowered hyperglycemia, oxidative stress, and ChE activity in diabetic rats. In another set of experiment, berberine (100mg/kg) treatment during training trials also improved learning and memory, lowered hyperglycemia, oxidative stress, and ChE activity. Chronic treatment (30 days) with vitamin C or metformin, and donepezil during training trials also improved diabetes-induced memory impairment and reduced oxidative stress and/or choline esterase activity. In conclusion, the present study demonstrates treatment with berberine prevents the changes in oxidative stress and ChE activity, and consequently memory impairment in diabetic rats.     

Antioxidant defence of the neonatal rat brain against acute hyperammonemia

Oxidative stress associated with the presence of elevated concentrations of ammonia in the brain has been proposed as one possible mechanism involved in ammonia toxicity. In a previous study [Brain Res.973 (2003) 31], we reported that neonatal rats are more resistant to acute ammonia toxicity than adult rats. In the present work, we studied the antioxidant status of the brain in hyperammonemic neonatal rats. Increased activities of the antioxidant enzymes and enhanced glutathione content were found in the brains of the hyperammonemic neonatal rats as compared to the controls. In addition, no changes in brain reactive oxygen species (ROS) levels and lipid peroxidation due to hyperammonemia were found. Therefore, acute ammonia intoxication does not induce oxidative stress in neonatal rats, a fact that may explain the resistance against hyperammonemia shown by neonatal rats.     

Plasma lipid peroxidation and antioxidant status of Parkinson's disease patients in the Indian population

Present study was to assess lipid peroxidation and antioxidant enzymes in the blood of the Parkinson's disease (PD) patients in the Indian population. It may be useful to develop peripheral markers, for the diagnosis and prognosis of Parkinson's disease during lifetime. Malondialdehyde content was increased in patients with PD (2 fold), with respect to the activity of superoxide-dismutase (p<0.001). The levels of glutathione (p<0.001) and blood thiols were decreased. No changes were observed in gamma-GTP, glutathione peroxidase and glutathione reductase. Increased lipid peroxidation, decreased glutathione levels and increased superoxide dismutase activity in the blood of PD patients indicate oxidative stress.     

Effect of N-acetylcysteine, allopurinol and vitamin E on jaundice-induced brain oxidative stress in rats

We examined the possible protective effect of certain antioxidants (N-acetylcysteine, allopurinol and vitamin E) against the oxidative stress of brain tissue induced by experimental obstructive jaundice in rats. Thirty-six male Wistar rats were randomly divided into six groups; group I control, group II sham operated, group III bile duct ligated and groups IV, V, and VI in which the rats, after bile duct ligation, were given every day an intraperitoneal injection with N-acetylcysteine, allopurinol and Vit-E respectively. All rats were sacrificed on the tenth day by exsanguination and the oxidative state in samples from cortex, midbrain and cerebellum was assessed by measuring the thiol redox state and lipid peroxidation quantified by MDA measurements. The main finding was that all three antioxidants decrease lipid peroxidation in the three brain areas. Cysteine levels increased and protein thiol levels were reserved only in the group treated with N-acetylcysteine, whereas oxidized glutathione increased dramatically in the group treated with allopurinol, suggesting that each antioxidant agent had a certain influence profile on the different antioxidant defense systems. The observed effects of the antioxidants in this experimental model could also provide insight into some aspects of jaundice-induced hepatic encephalopathy in humans.     

Oxidative stress in brain and antioxidant activity of Ocimum sanctum in noise exposure

Noise is a pervasive aspect of many modern communities, work environments and its damaging effects, particularly the production of free radicals are not limited to the auditory organ. The oxidative stress in three discrete brain regions, in wistar strain male albino rats subjected to three different durations of noise exposures (acute, sub-acute and chronic noise stress) and the in vivo as well as the in vitro antioxidant activity of Ocimum sanctum has been analyzed. Broadband white noise (100dB) exposure significantly increased the levels of superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6), glutathione peroxidase (EC 1.11.1.9), lipid peroxidation, oxidized glutathione (GSSG) and decreased the levels of reduced glutathione (GSH), GSH/GSSG ratio. However, administration of ethanolic extract of O. sanctum attenuates the alterations induced by noise exposure. The antioxidant activity of O. sanctum is also evident from its effectiveness in scavenging the free radicals in a dose dependent manner in the herbal antioxidant assays. The results indicate that adaptation to noise does not occur in the brain regions even after 30 days of noise exposure. The abundance of phytochemicals such as phenolics and flavanoids in O. sanctum may be held responsible for its attenuating activity. Therefore, this study indicates that O. sanctum has the potential for further evaluation as an ideal antioxidant for the noise induced oxidative stress.     

Oxidative damage is ameliorated by curcumin treatment in brain and sciatic nerve of diabetic rats

To date, there have not been enough studies about the effects of curcumin against oxidative stress on sciatic nerves caused by streptozotocin (STZ) in diabetic rats. Therefore, this study was undertaken to determine whether curcumin, by virtue of its antioxidant properties, could affect the oxidant/antioxidant balance in the sciatic nerve and brain tissues of streptozotocin (STZ)-induced diabetic rats. A total of 28 rats were randomly divided into four groups of seven rats each: normal controls, only curcumin treated, diabetic controls, and diabetics treated with curcumin. Biomarkers-malondialdehyde (MDA), total oxidant status (TOS), total antioxidant status (TAS), oxidative stress index (OSI), and NO levels-for oxidative stress in the brain and sciatic nerve tissues of the rats were measured. We found a significant increase in MDA, NO, TOS, and OSI, along with a reduction in TAS levels in the brains and sciatic nerves of the STZ-induced diabetic rats (for both parameters p < 0.05). The MDA, TOS, OSI, and NO levels in these tissues were significantly reduced in the curcumin-treated diabetic group compared to the untreated diabetic group. In conclusion, the results of this study suggested that curcumin exhibits neuroprotective effects against oxidative damage in the brain and sciatic tissues of diabetic rats.     

NGF rescues substance P expression but not neurofilament or tubulin gene expression in axotomized sensory neurons.

A reduction in the supply of retrogradely transported NGF has been proposed as a possible signal for the axotomy response in dorsal root ganglion (DRG) neurons. Components of the axotomy response that have previously been well characterized in axotomized DRG cells include changes in cytoskeletal gene expression and changes in the expression of neurotransmitters/neuromodulators such as substance P. In this study, we examined the role of NGF in the axotomy response by examining protein synthesis and mRNA levels of the low-MW neurofilament protein (NF-L) and beta-tubulin in DRG cells at 1, 7, and 12 d after axotomy with and without continuous administration of exogenous NGF. We also examined substance P levels in the DRG by immunocytochemistry under the same experimental conditions. Sciatic nerves of adult male rats were unilaterally transected at the midthigh level, and the proximal nerve stumps were placed into Silastic tubes connected to osmotic minipumps that were filled with biologically active NGF. NGF (0.5 mg/ml in saline) was continuously infused (0.5 microliter/hr) onto the proximal stumps of transected sciatic nerves for 1-12 d. Control animals were prepared in an identical fashion except that the nerves were treated with saline alone. At death, DRGs were removed from the animals; the L4 experimental DRGs (axotomized) and contralateral L4 DRGs (uninjured) were used immediately for protein synthesis experiments, while the experimental and contralateral L5 DRGs were fixed in 4% paraformaldehyde and subsequently used for in situ hybridization and immunocytochemistry. From another set of experimental animals, the L4 and L5 DRGs were harvested and used for total RNA isolation and RNA blotting experiments. Immunocytochemical studies using a polyclonal antibody to substance P showed that the immunodetectable levels of this peptide decreased to undetectable levels in DRG neurons after axotomy and saline administration. However, in axotomized neurons treated with NGF, the level of immunodetectable substance P did not decrease, but instead, increased over even that present in normal DRG neurons. Pulse labeling of DRGs with 35S-methionine:cysteine followed by 2-dimensional (2D) gel electrophoresis and fluorography revealed that the synthesis of neurofilament (NF) proteins was decreased, while that of tubulin was increased, 12 d after sciatic nerve transection. NGF administration to axotomized neurons did not alter this pattern. Quantitative analysis of in situ hybridizations of DRG neurons and RNA blot analysis with cDNA probes specific for NF-L and beta-tubulin mRNAs showed that NGF treatment of axotomized DRGs did not significantly affect cytoskeletal gene expression at the mRNA level.(ABSTRACT TRUNCATED AT 400 WORDS)     

Evidence that the major metabolites accumulating in hyperornithinemia–hyperammonemia–homocitrullinuria syndrome induce oxidative stress in brain of young rats

Ornithine and homocitrulline are the major metabolites accumulating in hyperornithinemia–hyperammonemia–homocitrullinuria syndrome, a genetic disorder characterized by neurological regression whose pathogenesis is still not understood. The present work investigated the in vitro effects of ornithine and homocitrulline on important parameters of oxidative stress in cerebral cortex from young rats. Ornithine significantly increased chemiluminescence and thiobarbituric acid-reactive substances levels, indicators of lipid peroxidation, while homocitrulline only augmented chemiluminescence values. Furthermore, ornithine-induced increase of thiobarbituric acid-reactive substances levels was attenuated (melatonin and reduced glutathione) or totally prevented (α-tocopherol) by free radical scavengers, suggesting that reactive species were involved in the lipid oxidative damage. We also observed that ornithine and homocitrulline significantly decreased the tissue antioxidant defenses, determined by reduced glutathione concentrations, the major non-enzymatic antioxidant defense found in the brain. Homocitrulline reduction of glutathione levels was completely prevented by melatonin and α-tocopherol, whereas ornithine-induced decrease of glutathione levels was only attenuated by these free radical scavengers. Ornithine and homocitrulline also induced protein oxidative damage, increasing carbonyl formation and sulfhydryl oxidation. In contrast, these amino acids did not affect nitric oxide production, indicating that nitrogen reactive species were not implicated in the lipid and oxidative damage provoked by ornithine and homocitrulline. Therefore, it is presumed that the major metabolites accumulating in hyperornithinemia–hyperammonemia–homocitrullinuria syndrome elicit oxidative stress and that this pathomechanism may possibly be involved in the brain damage found in patients affected by this disorder.