Antiglutamatergic Agents Research Articles

Neuroprotection effects of kynurenic acid-loaded micelles for the Parkinson’s disease models

Anti-glutamatergic agents may have neuroprotective effects against excitotoxicity that is known to be involved in the pathogenesis of Parkinson’s disease (PD). One of these agents is kynurenic acid (KYNA), a tryptophan metabolite, which is an endogenous N-methyl-D-aspartic acid (NMDA) receptor antagonist. However, its pharmacological properties of poor water solubility and limited blood–brain barrier (BBB) permeability rules out its systemic administration in disorders affecting the central nervous system. Our aim in the present study was to investigate the neuroprotective effects of KYNA-loaded micelles (KYNA-MICs) against PD in vitro and in vivo. Lipid-based micelles (MICs) in conjunction with KYNA drug delivery have the potential to enhance the penetration of therapeutic drugs into a diseased brain without BBB obstacles. KYNA-MICs were characterized by particle size (105.8 ± 12.1 nm), loading efficiency (78.3 ± 4.23%), and in vitro drug release (approximately 30% at 24 h). The in vitro experiments showed that KYNA-MICs effectively reduced 2-fold protein aggregation. The in vivo studies revealed that KYNA was successfully delivered by 5-fold increase in neurotoxin-induced PD brains. The results showed significant enhancement of KYNA delivery into brain. We also found that the KYNA-MICs exhibited several therapeutic effects. The KYNA-MICs reduced protein aggregation of an in vitro PD model, ameliorated motor functions, and prevented loss of the striatal neurons in a PD animal model. The beneficial effects of KYNA-MICs are probably explained by the anti-excitotoxic activity of the treatment’s complex. As the KYNA-MICs did not induce any appreciable side-effects at the protective dose applied to a chronic PD mouse model, our results demonstrate that KYNA provides neuroprotection and attenuates PD pathology.

Targeting Striatal Glutamate and Phosphodiesterases to Control L-DOPA-Induced Dyskinesia.

A large body of work during the past several decades has been focused on therapeutic strategies to control L-DOPA-induced dyskinesias (LIDs), common motor complications of long-term L-DOPA therapy in Parkinson's disease (PD). Yet, LIDs remain a clinical challenge for the management of patients with advanced disease. Glutamatergic dysregulation of striatal projection neurons (SPNs) appears to be a key contributor to altered motor responses to L-DOPA. Targeting striatal hyperactivity at the glutamatergic neurotransmission level led to significant preclinical and clinical trials of a variety of antiglutamatergic agents. In fact, the only FDA-approved treatment for LIDs is amantadine, a drug with NMDAR antagonistic actions. Still, novel agents with improved pharmacological profiles are needed for LID therapy. Recently other therapeutic targets to reduce dysregulated SPN activity at the signal transduction level have emerged. In particular, mechanisms regulating the levels of cyclic nucleotides play a major role in the transduction of dopamine signals in SPNs. The phosphodiesterases (PDEs), a large family of enzymes that degrade cyclic nucleotides in a specific manner, are of special interest. We will review the research for antiglutamatergic and PDE inhibition strategies in view of the future development of novel LID therapies.

Neurotoxicity evoked by organophosphates and available countermeasures.

Organophosphorus compounds (OP) are a constant problem, both in the military and in the civilian field, not only in the form of acute poisoning but also for their long-lasting consequences. No antidote has been found that satisfactorily protects against the toxic effects of organophosphates. Likewise, there is no universal cure to avert damage after poisoning. The key mechanism of organophosphate toxicity is the inhibition of acetylcholinesterase. The overstimulation of nicotinic or muscarinic receptors by accumulated acetylcholine on a synaptic cleft leads to activation of the glutamatergic system and the development of seizures. Further consequences include generation of reactive oxygen species (ROS), neuroinflammation, and the formation of various other neuropathologists. In this review, we present neuroprotection strategies which can slow down the secondary nerve cell damage and alleviate neurological and neuropsychiatric disturbance. In our opinion, there is no unequivocal approach to ensure neuroprotection, however, sooner the neurotoxicity pathway is targeted, the better the results which can be expected. It seems crucial to target the key propagation pathways, i.e., to block cholinergic and, foremostly, glutamatergic cascades. Currently, the privileged approach oriented to stimulating GABAAR by benzodiazepines is of limited efficacy, so that antagonizing the hyperactivity of the glutamatergic system could provide an even more efficacious approach for terminating OP-induced seizures and protecting the brain from permanent damage. Encouraging results have been reported for tezampanel, an antagonist of GluK1 kainate and AMPA receptors, especially in combination with caramiphen, an anticholinergic and anti-glutamatergic agent. On the other hand, targeting ROS by antioxidants cannot or already developed neuroinflammation does not seem to be very productive as other processes are also involved.

Antiglutamatergic agents for obsessive-compulsive disorder: Where are we now and what are possible future prospects?

Recent data suggest that obsessive-compulsive disorder (OCD) is driven by an imbalance among the habit learning system and the goal-directed system. The frontostriatal loop termed cortico-striatal-thalamo-cortical (CSTC) circuitry loop is involved in habits and their dysfunction plays an important role in OCD. Glutamatergic neurotransmission is the principal neurotransmitter implicated in the CSTC model of OCD. Hyperactivity in the CSTC loop implies a high level of glutamate in the cortical-striatal pathways as well as a dysregulation of GABAergic transmission, and could represent the pathophysiology of OCD. Moreover, the dysregulation of glutamate levels can lead to neurotoxicity, acting as a neuronal excitotoxin. The hypothesis of a role of neurotoxicity in the pathophysiology of OCD clinically correlates to the importance of an early intervention for patients. Indeed, some studies have shown that a reduction of duration of untreated illness is related to an earlier onset of remission. Although robust data supporting a progression of such brain changes are not available so far, an early intervention could help interrupt damage from neurotoxicity. Moreover, agents targeting glutamate neurotransmission may represent promising therapeutical option in OCD patients.

T165. ANTI-GLUTAMATERGIC PROPERTY OF N-ACETYLCYSTEINE DOCUMENTED IN VIVO WITH 1H MRS

BackgroundDeficits of brain glutathione (GSH), the primary antioxidant in living tissue, and associated redox imbalance are postulated to be implicated in schizophrenia. However, due to poor blood-brain barrier permeability of GSH, direct supplementation is ineffective in restoring its brain levels. Therefore, there has been great interest in investigating N-acetylcysteine (NAC), as a prodrug that can be deacetylated to supply cysteine (Cys), which crosses the BBB and is the rate-limiting substrate in brain GSH synthesis and restoration. Once inside the cell, Cys combines with glutamate (Glu) to initiate GSH synthesis in a reaction that is catalyzed by gamma-glutamyl cysteine ligase (GCL), the rate-limiting enzyme. Likely due to the in situ reaction of NAC-supplied Cys with Glu to spur GSH synthesis, NAC is believed to have anti-glutamatergic properties. However, direct in vivo evidence of NAC as an anti-glutamatergic agent is currently lacking. In this study, we used 1H MRS to monitor changes in brain levels of both GSH and Glu in response to 4 weeks of daily supplementation with NAC in healthy volunteer subjects. We postulated that 4 weeks of NAC treatment would elevate GSH and decrease Glu levels.MethodsSubjects: Participants recruited for this study consisted of 12 mentally and physically healthy human volunteer (HV) subjects.NAC Supplementation: To investigate the effects of dietary NAC supplementation on cortical GSH and Glu levels, each HV subject underwent 1H MRS scans at baseline. Then a 4-week supplement of 900mg NAC tablets was provided, to be taken 2 per day for a daily NAC dose of 1800mg. Finally, each subject was brought back after 4 weeks for the post-NAC 1H MRS scans to assess the effect of the treatment on cortical GSH and Glu levels.Brain 1H MRS: In vivo cortical GSH spectra were recorded in 15 min on a 3.0 T GE MRI system from a 3cmx3cmx2cm occipital cortex voxel, using the standard J-editing technique, with TE/TR 68/1500ms and 290 interleaved excitations (580 total). Levels of Glu, uncontaminated with glutamine, were obtained from the same occipital cortex voxel in 6 min using the CT-PRESS method, with TE/TR 139ms/1500ms, and 129 chemical shift encoding steps in increments of 0.8ms in t1 dimension. Peak areas for both GSH and Glu were derived by frequency-domain fitting of the recorded spectra. The resulting peak areas were then expressed as ratios relative to the area of the unsuppressed tissue water signal in the voxel.ResultsGSH Levels: The effect of 4 weeks of NAC supplementation on GSH levels was a numerical increase that did not reach statistical significance relative to baseline (p=0.33).Glu LevelsFollowing 4 weeks of NAC supplementation cortical Glu levels decreased significantly compared to baseline (p=0.04).DiscussionThis study has shown that following 4 weeks of taking NAC, brain Glu levels in HV decreased significantly, even though a numerical increase in GSH levels did not reach statistical significance. The observed Glu decrease at 4 weeks suggests a net increase in the consumption of intracellular Glu reserves in the GCL-catalyzed reaction that combines NAC-supplied Cys with Glu in GSH synthesis. The failure of GSH levels to increase significantly after NAC likely reflected the established “feedback inhibition” mechanism whereby GSH synthesis is shut off in a tissue with normal levels, with de novo synthesis due to NAC occurring only in a subset of subjects with “low” GSH levels (i.e., below the sample mean) at baseline. In summary, the results of this study support the role of NAC as an anti-glutamatergic agent, which seems to modulate Glu levels by increasing the availability of intracellular Cys that then combines with Glu to initiate GSH synthesis, leading to a lowering of total Glu levels as measured with MRS

No effect of riluzole and memantine on learning deficit following quinpirole sensitization - An animal model of obsessive-compulsive disorder

RationaleChronic quinpirole (QNP) sensitization is an established animal model relevant to obsessive-compulsive disorder (OCD) that has been previously shown to induce several OCD-like behavioral patterns, such as compulsive-like checking and increased locomotion. ObjectivesIn current study we explored the effect of antiglutamatergic drugs, memantine and riluzole, on cognitive and behavioral performance of QNP sensitized rats. MethodsDuring habituation phase, the rats (N = 56) were injected with QNP (0.25 mg/kg) or saline solution (every other day up to 10 injections) and placed into rotating arena without foot shocks for 50-min exploration. Active place avoidance task in rotating arena with unmarked to-be-avoided shock sector was used during acquisition phase. Rats were injected with memantine (1 mg/kg or 5 mg/kg), riluzole (1 mg/kg or 5 mg/kg) or saline solution 30 min before the trial and with QNP (0.25 mg/kg) or saline right before they were placed inside the rotating arena with 60° unmarked shock sector. Locomotion and number of entrances into the shock sector were recorded. ResultsQNP sensitization led to a robust deficit in place learning. However, neither memantine nor riluzole did reverse or alleviate the deficit induced by QNP. Contrarily, memantine significantly aggravated QNP induced deficit. ConclusionsThe exacerbation of cognitive deficit following antiglutamatergic agents could be mediated by decreased glutamate concentration in nucleus accumbens and decreased hippocampal activation in the QNP sensitization model.

Amantadine in parkinson’s disease: modern possibilities of long-term therapy

The long-term therapy of Parkinson’s disease (PD) with dopaminergic drugs is naturally accompanied by the fluctuations in symptoms and dyskinesia, and these complications are an extremely important factor that adversely affects the quality of life. The hyperactivity of glutamate NMDA receptors of the striatum plays an important role in the pathophysiology of medicinal dyskinesia, so the use of anti-glutamatergic agents, primarily amantadine, is currently the common method of combating dyskinesia. This article summarizes the current understanding of the mechanisms of action and the clinical effects of amantadine derivatives in patients with different stages of PD, with an emphasis on the antidiskinetic effect of this group of antiparkinsonian agents. It also presents the advantages of amantadine sulphate (PK-Merz) over other dosage forms (pharmacokinetics, duration of effect, tolerability, possibility of intravenous infusion administration), including those in the treatment of acute decompensation of PD.

Excitatory-inhibitory imbalance in the brain of the wobbler mouse model of amyotrophic lateral sclerosis substantiated by riluzole and diazepam.

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease. So far, no cure exists, prompting studies in disease mechanisms to facilitate development of new treatment strategies. In this study, we employed the wobbler mouse model of ALS focusing on a symptomatic group of animals. We studied the neurophysiological changes conferred by riluzole or diazepam application, two drugs employed in ALS. Riluzole is an antiglutamatergic agent and the only drug to offer some effect on the life expectancy of ALS patients. To target the inhibitory system, we utilized diazepam as a GABAergic modulator. Acute brain slices were prepared from the wobbler mouse model and analyzed using extracellular field recordings in the hippocampus. During Schaffer collateral stimulation, riluzole caused a marked reduction in the paired-pulse ratio (p<0.0001). Importantly, this reduction was more pronounced in wobbler slices (e.g. 184.2±8.9% at 20ms interval without riluzole, and 124.3±9.8% in the presence of riluzole) compared to control slices (at 20ms: from 198.7±5.8% to 160.5±6.7%). Diazepam caused less pronounced effects at wobbler slices and reduced the paired-pulse ratio more in control animals compared to wobbler individuals (p<0.0001). Comparable results were obtained during trains of stimulations (10 pulses at 20Hz). Importantly, paired-pulse ratios as well as synaptic facilitation were overall similar in control and wobbler slices, without the drugs present, indicating that the differences were only revealed pharmacologically. In summary, the present data support excitatory-inhibitory imbalances in the brain of the wobbler mouse and further consolidate this mouse as an animal model of ALS.

Cognitive impairments in some cardiovascular and somatic diseases

The paper gives an update on the pathogenesis, clinical presentation, and pathomorphology of cognitive impairments (CIs) in different autoimmune, endocrine, and infectious diseases: systemic lupus erythematosus, Sjogren’s syndrome, Behchet’s disease, primary angiitis of the central nervous system, polyarteritis nodosa, cryoglobulinemic vasculitis, hypothyroidism, herpetic lesion, and neurosyphilis. It is noted that treatment for CIs should be individual in terms of virulence factors. In vascular CIs, therapy should be aimed primarily at modifying risk factors and eliminating or reducing chronic brain ischemia. The prevention of progressive CI encompasses antihypertensive and antithrombotic therapies and surgical correction of atherosclerotic great artery stenosis. Control of hyperlipidemia, hyperglycemia and treatment of other somatic diseases are also of great importance. Such patients are usually given cetylcholinesterase inhibitors, acetylcholine precursors, antiglutamatergic agents, and metabolic and vascular drugs. By taking into account brain ischemia/ hypoxia in the above diseases, it is shown to be advisable to use antioxidants, cerebral active agents in particular, which have a complex neurometabolic effect.

Glutamatergic Dysfunctioning in Alzheimer's Disease and Related Therapeutic Targets

The impairment of glutamatergic neurotransmission plays an important role in the development of Alzheimer's disease (AD). The pathological process, which involves the production of amyloid-β peptides and hyperphosphorylated tau proteins, spreads over well-delineated neuroanatomical circuits. The gradual deterioration of proper synaptic functioning (via GluN2A-containing N-methyl-D-aspartate receptors, NMDARs) and the development of excitotoxicity (via GluN2B-containing NMDARs) in these structures both accompany the disease pathogenesis. Although one of the most important therapeutic targets would be glutamate excitotoxicity, the application of conventional anti-glutamatergic agents could result in further deterioration of synaptic transmission and intolerable side-effects. With regard to NMDAR antagonists with tolerable side-effects, ion channel blockers with low affinity, glycine site agents, and specific antagonists of polyamine site and GluN2B subunit may come into play. However, in the mirror of experimental data, only the application of ion channel blockers with pronounced voltage dependency, low affinity, and rapid unblocking kinetics (e.g., memantine) and specific antagonists of the GluN2B subunit (e.g., ifenprodil and certain kynurenic acid amides) resulted in desirable symptom amelioration. Therefore we propose that these kinds of chemical agents may have therapeutic potential for present and future drug development.

Amantadine and cognitive flexibility: decision making in Parkinson's patients with severe pathological gambling and other impulse control disorders.

IntroductionDopamine replacement therapy for Parkinson’s disease (PD) was recently linked to the development of impulse control disorders such as pathological gambling (PG), hypersexuality, compulsive shopping, and binge or compulsive eating. Antiglutamatergic agents including amantadine (Ama) reduce these behaviors in PD and non-PD patients. The aim of our study is to evaluate the changes in executive functions, emotions, and reward/loss processing during Ama treatment in PD patients.MethodsThirty-three patients affected by idiopathic PD were selected from a cohort of 1,096 PD patients and categorized in three different groups: ten affected by PG (PD-PG); nine PD patients with other impulse control disorder (PD-ICD); and 14 PD patient without any psychiatric disorder (PD-CTR-controls). For the neuropsychological evaluation, the following behavioral tasks where administered: the Stroop, the emotional Stroop, and the monetary reward/loss risk-taking tasks.ResultsDuring Ama treatment, PD-PGs showed a decrease in risky choices and an increase in non-risky choices (t(9)=−2.40, P<0.05 and t(9)=2,67, P<0.05 uncorrected, respectively). Between-group comparison showed a significant decrease in risky choices for PD-PG with respect to PD-CTR (t(22)=−4.16, P<0.01), and a decreased accuracy for positive words in comparison between PD-PG and PD-ICD (t(17)=−7,49, P<0.01) and PD-PG and PD-CTR (t(22)=−4.29, P<0.01). No within- and between-group differences were observed for Stroop task.DiscussionOur data showed that Ama add-on therapy reduces hypersensitivity to reward and sustains activation toward uncertainty in PD-PG patients. These finding might explain the behavioral mechanism underlying the effect of antiglutamatergic drugs.

Efficacy of local polymer-based and systemic delivery of the anti-glutamatergic agents riluzole and memantine in rat glioma models

The poor outcome of malignant gliomas is largely due to local invasiveness. Previous studies suggest that gliomas secrete excess glutamate and destroy surrounding normal peritumoral brain by means of excitotoxic mechanisms. In this study the authors assessed the effect on survival of 2 glutamate modulators (riluzole and memantine) in rodent glioma models. In an in vitro growth inhibition assay, F98 and 9L cells were exposed to riluzole and memantine. Mouse cerebellar organotypic cultures were implanted with F98 glioma cells and treated with radiation, radiation + riluzole, or vehicle and assessed for tumor growth. Safety and tolerability of intracranially implanted riluzole and memantine CPP:SA polymers were tested in F344 rats. The efficacy of these drugs was tested against the 9L model and riluzole was further tested with and without radiation therapy (RT). In vitro assays showed effective growth inhibition of both drugs on F98 and 9L cell lines. F98 organotypic cultures showed reduced growth of tumors treated with radiation and riluzole in comparison with untreated cultures or cultures treated with radiation or riluzole alone. Three separate efficacy experiments all showed that localized delivery of riluzole or memantine is efficacious against the 9L gliosarcoma tumor in vivo. Systemic riluzole monotherapy was ineffective; however, riluzole given with RT resulted in improved survival. Riluzole and memantine can be safely and effectively delivered intracranially via polymer in rat glioma models. Both drugs demonstrate efficacy against the 9L gliosarcoma and F98 glioma in vitro and in vivo. Although systemic riluzole proved ineffective in increasing survival, riluzole acted synergistically with radiation and increased survival compared with RT or riluzole alone.

Vitamin D as a Potential Therapy in Amyotrophic Lateral Sclerosis

Vitamin D has been demonstrated to influence multiple aspects of amyotrophic lateral sclerosis (ALS) pathology. Both human and rodent central nervous systems express the vitamin D receptor (VDR) and/or its enzymatic machinery needed to fully activate the hormone. Clinical research suggests that vitamin D treatment can improve compromised human muscular ability and increase muscle size, supported by loss of motor function and muscle mass in animals following VDR knockout, as well as increased muscle protein synthesis and ATP production following vitamin D supplementation. Vitamin D has also been shown to reduce the expression of biomarkers associated with oxidative stress and inflammation in patients with multiple sclerosis, rheumatoid arthritis, congestive heart failure, Parkinson's disease and Alzheimer's disease; diseases that share common pathophysiologies with ALS. Furthermore, vitamin D treatment greatly attenuates hypoxic brain damage in vivo and reduces neuronal lethality of glutamate insult in vitro; a hallmark trait of ALS glutamate excitotoxicity. We have recently shown that high-dose vitamin D3 supplementation improved, whereas vitamin D3 restriction worsened, functional capacity in the G93A mouse model of ALS. In sum, evidence demonstrates that vitamin D, unlike the antiglutamatergic agent Riluzole, affects multiple aspects of ALS pathophysiology and could provide a greater cumulative effect.

The pathophysiology and pharmacological treatment of Huntington disease.

Introduction: Huntington disease (HD) is a progressive neurodegenerative condition characterised by motor, cognitive and behavioural dysfunction, and has an autosomal dominant mode of inheritance. As there is currently no treatment to delay progression of the disease, pharmacological intervention is aimed at symptomatic relief. Methods: We set out to assess the current evidence on the pharmacological treatment of motor and non-motor symptoms in HD by carrying out a systematic literature review across five large scientific databases. Results: The search generated 23 original studies meeting our search criteria. Studies on the following drug classes were obtained: dopamine (DA) depleting agents, neuroleptics, anti-glutamatergic agents, acetylcholinesterase inhibitors, GABA agonists, cannabinoids, antidepressants and potential neuroprotective agents. Tetrabenazine (TBZ), a DA depleting agent, was the only pharmacotherapy shown to have a clinically meaningful, statistically significant effect on chorea. The majority of the reviewed studies focussed on the treatment of motor symptoms of HD. Discussion: Overall, the evidence base for the pharmacological management of HD is poor. There is a clear need for future high quality randomised controlled trials on the symptomatic treatment of HD, particularly on the pharmacotherapy of non-motor symptoms of HD.

Psychotherapeutische und medikamentöse Behandlung der kindlichen Zwangsstörung

Cognitive-behavioral therapy (CBT) and pharmacological treatments are often applied in cases of pediatric obsessive-compulsive disorder (OCD). Especially in combination both methods are particularly efficacious; nonetheless, 40 % of all patients treated remain symptomatic. Exposure with response prevention, based on the principle of habituation, is the intervention with the best evidence. More recent cognitive and metacognitive treatments focus on modifying expectations and may have the potential to improve treatment efficacy. Selective serotonin reuptake inhibitors (SSRIs) are the first line of treatment in severe cases of OCD. With treatment resistance, the SSRI should be changed, or alternatively clomipramine can be employed. Augmentation strategies suggest the combination of two SSRIs, SSRI und clomipramin, or SSRI and (atypical) neuroleptics. Following successful treatment, medication should be reduced very slowly. Novel treatments in children and adolescent have been reported for antiglutamatergic agents as riluzole or D-cycloserine, a partial agonist of N-methyl-D-aspartic acid (NMDA).

Recurrent catatonia treated with lithium and carbamazepine: a series of 2 cases.

Recurrent catatonia treated with lithium and carbamazepine: a series of 2 cases.

Neuroprotective effects of a novel kynurenic acid analogue in a transgenic mouse model of Huntington’s disease

Huntington's disease (HD) is a progressive neurodegenerative disorder, the pathomechanism of which is not yet fully understood. Excitotoxicity is known to be involved in the development of HD and antiglutamatergic agents may, therefore, have beneficial neuroprotective effects. One of these agents is the tryptophan metabolite kynurenic acid (KYNA), which is an endogenous NMDA receptor antagonist. However, its pharmacological properties rule out its systemic administration in CNS disorders. We have tested a novel KYNA analogue, N-(2-N,N-dimethylaminoethyl)-4-oxo-1H-quinoline-2-carboxamide hydrochloride, in the N171-82Q transgenic mouse model of HD. The analogue exhibited several significant effects: it prolonged the survival of the transgenic mice, ameliorated their hypolocomotion, prevented the loss of weight and completely prevented the atrophy of the striatal neurons. The beneficial effects of this KYNA analogue are probably explained by its complex anti-excitotoxic activity. As it did not induce any appreciable side-effect at the protective dose applied in a chronic dosing regime in this mouse model, it appears worthy of further thorough investigations with a view to eventual clinical trials.

Pathological gambling in Parkinson disease is reduced by amantadine

To investigate the possible efficacy of amantadine in the control of pathological gambling (PG) associated with Parkinson disease (PD), 17 PD patients with PG were randomly selected for a double-blind crossover study with amantadine 200mg/day versus placebo and an open follow-up. Assessments included PG-specific scales (Yale-Brown Obsessive-Compulsive Scale for PG, Gambling-Symptom Assessment Scale, South Oaks Gambling Screen) and assessment of expenditures and time spent gambling. Amantadine abolished or reduced PG in all treated patients, as confirmed by scale score and daily expenditure reduction. Amantadine might be useful to treat PG. The effect of amantadine, acting as an antiglutamatergic agent, also opens new insights into the pathogenesis of PG.

Current and emerging treatments for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a relatively rare neurodegenerative disorder of both upper and lower motoneurons. Currently, the management of ALS is essentially symptoms-based, and riluzole, an antiglutamatergic agent, is the only drug for the treatment of ALS approved by the food and drug administration. We reviewed current literature concerning emerging treatments for amyotrophic lateral sclerosis. A Medline literature search was performed to identify all studies on ALS treatment published from January 1st, 1986 through August 31st, 2009. We selected papers concerning only disease-modifying therapy. Forty-eight compounds were identified and reviewed in this study. Riluzole is the only compound that demonstrated a beneficial effect on ALS patients, but with only modest increase in survival. Although several drugs showed effective results in the animal models for ALS, none of them significantly prolonged survival or improved quality of life of ALS patients. Several factors have been implicated in explaining the predominantly negative results of numerous randomized clinical trials in ALS, including methodological problems in the use of animal-drug screening, the lack of assessment of pharmacokinetic profile of the drugs, and methodological pitfalls of clinical trials in ALS patients.

Pathophysiology of Neurodegeneration in Familial Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder of the motor neurons in the spinal cord, brainstem, and motor cortex. Ten percent of ALS cases are familial, with both autosomal dominant and recessive modes of inheritance reported. Mutations in the copper/zinc superoxide-dismutase-1 (SOD-1) gene, the first gene linked with ALS, result in the classical ALS phenotype. To date, 135 mutations have been identified in the SOD-1 gene, accounting for approximately 20% of familial ALS cases. Mutations are widely distributed throughout the gene with preponderance for exon 4 and 5. Although mutations result in a toxic gain of function of the SOD-1 enzyme, which normally functions as a free radical scavenger, the mechanisms underlying motor neuron degeneration have not been clearly elucidated. Evidence is emerging of a complex interaction between genetic and molecular factors, with resultant damage of critical target proteins and organelles within the motor neuron. The clinical effectiveness afforded by anti-glutamatergic agents such as riluzole, suggests that glutamate excitotoxicity contributes to neurodegeneration in ALS, with glutamate excitotoxicity mediated via corticomotoneurons that provide a direct link between the motor cortex and the spinal motor neuron. This review provides an overview of the genetics of ALS, and describes recent advances in the understanding of the pathophysiological mechanisms underlying neurodegeneration.