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1.
Epilepsia Open ; 2024 Jun 17.
Article En | MEDLINE | ID: mdl-38884148

OBJECTIVE: This study investigates the prevalent issues of healthcare access and the impact of antiseizure treatments among people with epilepsy (PWE) in rural Limpopo and Mpumalanga, South Africa, where healthcare facilities and affordable treatments are often inadequate. METHODS: Using a cross-sectional survey, 162 PWE were selected using multistage sampling across the provinces. Data were collected via a structured questionnaire and analyzed descriptively using SPSS v27. RESULTS: Most of the participants experienced seizures intermittently, with 70.6% in Limpopo and 53.3% in Mpumalanga reporting occasional episodes, whereas a significant minority in both regions-20.6% and 40%, respectively-suffered from frequent seizures. A notable portion of PWE also reported recurring side effects from antiseizure drugs, which led to consequential life disruptions, including educational dropout and unemployment. SIGNIFICANCE: The findings underscore an urgent need for enhanced educational programs and increased awareness to improve the understanding and management of epilepsy in these underserved areas. Optimizing care for PWE requires a multifaceted approach, including evaluating healthcare accessibility, affordability, and societal beliefs influencing treatment adherence. The study advocates for government and policy interventions to mitigate the quality of life deterioration caused by epilepsy and its treatment in rural communities. PLAIN LANGUAGE SUMMARY: In Limpopo and Mpumalanga, many individuals with epilepsy experience seizures occasionally, while a significant minority have them frequently. Numerous people also suffer recurring side effects from antiseizure medications, impacting their lives severely by causing school dropouts and job losses. This underscores the urgent need for improved education and awareness programs to manage epilepsy in these provinces effectively. The study urges government action and policy reforms to enhance care and support for people with epilepsy in rural areas, aiming to improve their quality of life.

2.
Cells ; 12(13)2023 06 30.
Article En | MEDLINE | ID: mdl-37443795

Sleep is an essential innate but complex behaviour which is ubiquitous in the animal kingdom. Our knowledge of the distinct neural circuit mechanisms that regulate sleep and wake states in the brain are, however, still limited. It is therefore important to understand how these circuits operate during health and disease. This review will highlight the function of mGlu5 receptors within the thalamocortical circuitry in physiological and pathological sleep states. We will also evaluate the potential of targeting mGlu5 receptors as a therapeutic strategy for sleep disorders that often co-occur with epileptic seizures.


Receptor, Metabotropic Glutamate 5 , Wakefulness , Animals , Receptor, Metabotropic Glutamate 5/metabolism , Sleep/physiology , Brain/metabolism , Glutamates
3.
Neuropharmacology ; 216: 109172, 2022 09 15.
Article En | MEDLINE | ID: mdl-35780977

Physiological oscillations in the cortico-thalamo-cortical loop occur during processes such as sleep, but these can become dysfunctional in pathological conditions such as absence epilepsy. The purine neuromodulator adenosine can act as an endogenous anticonvulsant: it is released into the extracellular space during convulsive seizures to activate A1 receptors suppressing on-going activity and delaying the occurrence of the next seizure. However, the role of adenosine in thalamic physiological and epileptiform oscillations is less clear. Here we have combined immunohistochemistry, electrophysiology, and fixed potential amperometry (FPA) biosensor measurements to characterise the release and actions of adenosine in thalamic oscillations measured in rodent slices. In the thalamus, A1 receptors are highly expressed particularly in the ventral basal (VB) thalamus and reticular thalamic nucleus (nRT) supporting a role for adenosine signalling in controlling oscillations. In agreement with previous studies, both adenosine and adenosine A1 receptor agonists inhibited thalamic oscillations in control (spindle-like) and in epileptic conditions. Here we have shown for the first time that both control and epileptiform oscillations are enhanced (i.e., increased number of oscillatory cycles) by blocking A1 receptors consistent with adenosine release occurring during oscillations. Although increases in extracellular adenosine could not be directly detected during control oscillations, clear increases in adenosine concentration could be detected with a biosensor during epileptiform oscillation activity. Thus, adenosine is released during thalamic oscillations and acts via A1 receptors to feedback and reduce thalamic oscillatory activity.


Adenosine , Epilepsy, Absence , Adenosine/pharmacology , Feedback , Humans , Seizures , Thalamus
4.
Essays Biochem ; 66(1): 83-88, 2022 04 29.
Article En | MEDLINE | ID: mdl-35441223

Sound knowledge of the learning process and connectedness of assessment in higher education is imperative. Assessment is essential for both learners and teachers to ensure, and to provide evidence, that learning outcomes/objectives against set competency levels have been achieved for the chosen programme of the study. However, many coming into higher education are often unaware of the rules of the game. In this perspective, we will highlight the reasons why assessment is important, how assessment and feedback affect students' learning process and why the process of assessment can often affect students' mental well-being. We will appraise the different methods of assessment with a specific example (Objective Structured Clinical Examination, OSCE) and highlight why it is important that we adopt a holistic approach towards fostering assessment know-how and student well-being.


Learning , Students , Feedback , Humans
5.
Curr Opin Pharmacol ; 38: 43-50, 2018 02.
Article En | MEDLINE | ID: mdl-29547778

Metabotropic glutamate (mGlu) receptors are expressed in key regions of the cortex and the thalamus and are known to regulate spike and wave discharges (SWDs), the electroclinical hallmarks of absence seizures. Recent preclinical studies have highlighted the therapeutic potential of selective group I and III mGlu receptor subtype allosteric modulators, which can suppress pathological SWDs. Of particular interest are positive allosteric modulators (PAMs) for mGlu5 receptors, as they currently show the most promise as novel anti-absence epilepsy drugs. The rational design of novel selective positive and negative allosteric mGlu modulators, especially for the mGlu5 receptor, has been made possible following the recent crystallographic structure determination of group I mGlu receptors. Our current knowledge of the role of different mGlu receptor subtypes in absence epilepsy is outlined in this article.


Epilepsy, Absence/metabolism , Receptors, Metabotropic Glutamate/metabolism , Animals , Anticonvulsants/therapeutic use , Brain/metabolism , Epilepsy, Absence/drug therapy , Humans
6.
Epilepsia ; 58(11): 1993-2001, 2017 11.
Article En | MEDLINE | ID: mdl-28913875

OBJECTIVES: Thrombospondins, which are known to interact with the α2 δ subunit of voltage-sensitive calcium channels to stimulate the formation of excitatory synapses, have recently been implicated in the process of epileptogenesis. No studies have been so far performed on thrombospondins in models of absence epilepsy. We examined whether expression of the gene encoding for thrombospondin-1 was altered in the brain of WAG/Rij rats, which model absence epilepsy in humans. In addition, we examined the frequency of genetic variants of THBS1 in a large cohort of children affected by idiopathic/genetic generalized epilepsies (IGE/GGEs). METHODS: We measured the transcripts of thrombospondin-1 and α2 δ subunit, and protein levels of α2 δ, Rab3A, and the vesicular glutamate transporter, VGLUT1, in the somatosensory cortex and ventrobasal thalamus of presymptomatic and symptomatic WAG/Rij rats and in two control strains by real-time polymerase chain reaction (PCR) and immunoblotting. We examined the genetic variants of THBS1 and CACNA2D1 in two independent cohorts of patients affected by IGE/GGE recruited through the Genetic Commission of the Italian League Against Epilepsy (LICE) and the EuroEPINOMICS-CoGIE Consortium. RESULTS: Thrombospondin-1 messenger RNA (mRNA) levels were largely reduced in the ventrobasal thalamus of both presymptomatic and symptomatic WAG/Rij rats, whereas levels in the somatosensory cortex were unchanged. VGLUT1 protein levels were also reduced in the ventrobasal thalamus of WAG/Rij rats. Genetic variants of THBS1 were significantly more frequent in patients affected by IGE/GGE than in nonepileptic controls, whereas the frequency of CACNA2D1 was unchanged. SIGNIFICANCE: These findings suggest that thrombospondin-1 may have a role in the pathogenesis of IGE/GGEs.


Calcium Channels/genetics , Disease Models, Animal , Epilepsy, Absence/genetics , Epilepsy, Generalized/genetics , Thrombospondin 1/genetics , Animals , Calcium Channels/biosynthesis , Cohort Studies , Epilepsy, Absence/metabolism , Epilepsy, Generalized/metabolism , Humans , Male , Rats , Rats, Wistar , Thrombospondin 1/biosynthesis
7.
Synapse ; 71(5)2017 05.
Article En | MEDLINE | ID: mdl-28187508

In the last two decades adiponectin, member of the adipokines family, gained attention because of its unique antidiabetic effects. However, the presence in the brain of adiponectin receptors and adiponectin itself raised interest because of the possible association with neuropsychiatric diseases. Indeed, clinical studies found altered concentration of adiponectin both in plasma and cerebrospinal fluid in several pathologies including depression, multiple sclerosis, Alzheimer's disease and stroke. Moreover, recent preclinical studies also suggest its involvement in different physiological functions. Despite this evidence very few studies attempted to elucidate the functional role of adiponectin at the synapse. To address this question, here we investigated the effect of Adiporon, an agonist of both adiponectin receptors on synaptic transmission and LTP at Schaffer-collateral CA1 pathway. Surprisingly, increasing concentration of Adiporon correlated with lower CA1-LTP levels and paired-pulse ratio, whereas basal transmission was always preserved. Collectively, our data show that the adiponectin system, beyond its involvement in metabolic diseases, plays also a critical role in synaptic activity thereby representing a putative target for the treatment of synaptic pathologies.


CA1 Region, Hippocampal/metabolism , Receptors, Adiponectin/metabolism , Synaptic Transmission , Animals , CA1 Region, Hippocampal/drug effects , CA1 Region, Hippocampal/physiology , Long-Term Potentiation , Male , Mice , Mice, Inbred C57BL , Piperidines/pharmacology , Receptors, Adiponectin/agonists
8.
Pharmacol Biochem Behav ; 146-147: 50-9, 2016.
Article En | MEDLINE | ID: mdl-27178815

PURPOSE: Ethosuximide (ETX) is the drug of choice for the treatment of patients with absence seizures - taking into account both its efficacy, tolerability and antiepileptogenic properties. However, 47% of subjects failed in ETX-therapy, and most antiepileptic drugs have cognitive side effects. VU0360172, a positive allosteric modulator (PAM) of mGluR5, has been proposed as a new anti-absence drug. Here it is investigated whether anti-epileptogenesis induced by ETX alters the sensitivity of VU0360172, and whether cognition is affected during and after chronic ETX treatment. METHOD: EEG's were recorded before and after a challenge with VU0360172 in chronic ETX and in control WAG/Rij rats during and after treatment. Rats were also exposed to a cue discrimination learning task in a Y-maze both during and after treatment. At the end of the experiment, mGlu5 receptors were quantified by Western Blot analysis. RESULTS: Antiepileptogenesis was successfully induced by ETX and VU0360172 showed a time and dose dependent anti-absence action in the control group. VU0360172 kept its anti-absence action in chronic ETX treated rats both during and after treatment, without time and dose dependency. This anti-absence effect of VU0360172 in both groups matched the lack of differences in mGluR5 expression. Chronic ETX enhanced the number of completed trials, the number of correct choices in the Y-maze and the number of consumed sucrose pallets. SIGNIFICANCE: VU0360172 maintains its anti-absence effects after chronic treatment; as such, VU0360172 can also be used as a adjunctive therapy in patients with absence epilepsy. The enhanced motivation and cognitive performance by ETX might be mediated by the antidepressant action of ETX as expressed by an increase in the rewarding properties of sucrose pallets.


Anticonvulsants/pharmacology , Epilepsy, Absence/prevention & control , Ethosuximide/pharmacology , Niacinamide/analogs & derivatives , Receptor, Metabotropic Glutamate 5/biosynthesis , Animals , Cerebral Cortex/metabolism , Cognition/drug effects , Dose-Response Relationship, Drug , Drug Synergism , Electroencephalography/drug effects , Food Preferences/drug effects , Male , Maze Learning/drug effects , Motor Activity/drug effects , Niacinamide/pharmacology , Rats , Thalamus/metabolism , Time Factors
9.
Brain Res Bull ; 119(Pt A): 80-92, 2015 Oct.
Article En | MEDLINE | ID: mdl-26321393

There is emerging evidence of the beneficial role of the melatonin system in a wide range of psychiatric and neurologic disorders, including anxiety, depression, and epilepsy. Although melatoninergic drugs have chronobiotic and antioxidant properties that positively influence circadian rhythm desynchronization and neuroprotection in neurodegenerative disorders, studies examining the use of melatonin for epilepsy's comorbid psychiatric and neurological symptomatology are still limited. Preclinical and clinical findings on the beneficial effects of the melatonin system on anxiety, depression, and epilepsy suggest that melatoninergic compounds might be effective in treating comorbid behavioral complications in epilepsy beyond regulation of a disturbed sleep-wake cycle.


Epilepsy/complications , Epilepsy/metabolism , Melatonin/metabolism , Mental Disorders/complications , Mental Disorders/metabolism , Animals , Comorbidity , Epilepsy/drug therapy , Epilepsy/epidemiology , Humans , Mental Disorders/drug therapy , Mental Disorders/epidemiology
10.
Epilepsia ; 56(7): 1141-51, 2015 Jul.
Article En | MEDLINE | ID: mdl-26040777

OBJECTIVE: Glutamate and γ-aminobutyric acid (GABA) are the key neurotransmitter systems in the cortical-thalamocortical network, involved in normal and pathologic oscillations such as spike-wave discharges (SWDs), which characterize different forms of absence epilepsy. Metabotropic glutamate (mGlu) and GABA receptors are widely expressed within this network. Herein, we examined the effects of two selective positive allosteric modulators (PAMs) of mGlu1 and mGlu5 receptors, the GABA reuptake inhibitor, tiagabine, and their interaction in the somatosensory cortex and thalamus on SWDs in WAG/Rij rats. METHODS: Male WAG/Rij rats were equipped with bilateral cannulas in the somatosensory cortex (S1po) or the ventrobasal (VB) thalamic nuclei, and with cortical electroencephalography (EEG) electrodes. Rats received a single dose of the mGlu1 receptor PAM, RO0711401, or the mGlu5 receptor PAM, VU0360172, various doses of tiagabine, or VU0360172 combined with tiagabine. RESULTS: Both PAMs suppressed SWDs regardless of the site of injection. Tiagabine enhanced SWDs when injected into the thalamus, but, unexpectedly, suppressed SWDs in a dose-dependent manner when injected into the cortex. Intracortical co-injection of VU0360172 and tiagabine produced slightly larger effects as compared to either VU0360172 or tiagabine alone. Intrathalamic co-injections of VU0360172 and subthreshold doses of tiagabine caused an antiabsence effect similar to that exhibited by VU0360172 alone in the first 10 min. At 30 min, however, the antiabsence effect of VU0360172 was prevented by subthreshold doses of tiagabine, and the combination produced a paradoxical proabsence effect at 40 and 50 min. SIGNIFICANCE: These data (1) show that mGlu1 and mGlu5 receptor PAMs reduce absence seizures acting at both thalamic and cortical levels; (2) demonstrate for the first time that tiagabine, despite its established absence-enhancing effect, reduces SWDs when injected into the somatosensory cortex; and (3) indicate that the efficacy of VU0360172 in the thalamus may be critically affected by the availability of (extra)synaptic GABA.


Epilepsy, Absence/metabolism , GABA Uptake Inhibitors/metabolism , Receptor, Metabotropic Glutamate 5/metabolism , Receptors, Metabotropic Glutamate/metabolism , Somatosensory Cortex/metabolism , Thalamus/metabolism , Animals , Anticonvulsants/administration & dosage , Anticonvulsants/metabolism , Epilepsy, Absence/prevention & control , GABA Uptake Inhibitors/administration & dosage , Infusions, Intraventricular , Male , Rats , Rats, Transgenic , Receptor, Metabotropic Glutamate 5/agonists , Receptors, Metabotropic Glutamate/agonists , Somatosensory Cortex/drug effects , Thalamus/drug effects
11.
Curr Opin Pharmacol ; 20: 89-94, 2015 Feb.
Article En | MEDLINE | ID: mdl-25506748

The question in the title: 'what's new?' has two facets. First, are 'clinical' expectations met with success? Second, is the number of CNS disorders targeted by mGlu drugs still increasing? The answer to the first question is 'no', because development program with promising drugs in the treatment of schizophrenia, Parkinson's disease, and Fragile X syndrome have been discontinued. Nonetheless, we continue to be optimistic because there is still the concrete hope that some of these drugs are beneficial in targeted subpopulations of patients. The answer to the second question is 'yes', because mGlu ligands are promising targets for 'new' disorders such as type-1 spinocerebellar ataxia and absence epilepsy. In addition, the increasing availability of pharmacological tools may push mGlu7 and mGlu8 receptors into the clinical scenario. After almost 30 years from their discovery, mGlu receptors are still alive.


Central Nervous System Diseases/drug therapy , Drug Design , Receptors, Metabotropic Glutamate/drug effects , Animals , Central Nervous System Diseases/physiopathology , Epilepsy, Absence/drug therapy , Epilepsy, Absence/physiopathology , Humans , Ligands , Molecular Targeted Therapy , Receptors, Metabotropic Glutamate/metabolism , Spinocerebellar Ataxias/drug therapy , Spinocerebellar Ataxias/physiopathology
12.
J Neurosci ; 32(48): 17143-54, 2012 Nov 28.
Article En | MEDLINE | ID: mdl-23197707

Abnormalities of synaptic transmission and plasticity in the hippocampus represent an integral part of the altered programming triggered by early life stress. Prenatally restraint stressed (PRS) rats develop long-lasting biochemical and behavioral changes, which are the expression of an anxious/depressive-like phenotype. We report here that PRS rats showed a selective impairment of depolarization- or kainate-stimulated glutamate and [(3)H]d-aspartate release in the ventral hippocampus, a region encoding memories related to stress and emotions. GABA release was unaffected in PRS rats. As a consequence of reduced glutamate release, PRS rats were also highly resistant to kainate-induced seizures. Abnormalities of glutamate release were associated with large reductions in the levels of synaptic vesicle-related proteins, such as VAMP (synaptobrevin), syntaxin-1, synaptophysin, synapsin Ia/b and IIa, munc-18, and Rab3A in the ventral hippocampus of PRS rats. Anxiety-like behavior in male PRS (and control) rats was inversely related to the extent of depolarization-evoked glutamate release in the ventral hippocampus. A causal relationship between anxiety-like behavior and reduction in glutamate release was demonstrated using a mixture of the mGlu2/3 receptor antagonist, LY341495, and the GABA(B) receptor antagonist, CGP52432, which was shown to amplify depolarization-evoked [(3)H]d-aspartate release in the ventral hippocampus. Bilateral microinfusion of CGP52432 plus LY341495 in the ventral hippocampus abolished anxiety-like behavior in PRS rats. These findings indicate that an impairment of glutamate release in the ventral hippocampus is a key component of the neuroplastic program induced by PRS, and that strategies aimed at enhancing glutamate release in the ventral hippocampus correct the "anxious phenotype" caused by early life stress.


Anxiety/metabolism , Behavior, Animal/physiology , Glutamic Acid/metabolism , Hippocampus/metabolism , Prenatal Exposure Delayed Effects/metabolism , Stress, Psychological/metabolism , Amino Acids/pharmacology , Animals , Benzylamines/pharmacology , Excitatory Amino Acid Antagonists/pharmacology , Female , GABA-A Receptor Antagonists/pharmacology , Hippocampus/drug effects , Kainic Acid , Male , Munc18 Proteins/metabolism , Phosphinic Acids/pharmacology , Pregnancy , R-SNARE Proteins/metabolism , Rats , Rats, Sprague-Dawley , Seizures/chemically induced , Seizures/metabolism , Synapsins/metabolism , Synaptic Transmission/drug effects , Synaptic Transmission/physiology , Synaptophysin/metabolism , Syntaxin 1/metabolism , Xanthenes/pharmacology , rab3A GTP-Binding Protein/metabolism
13.
Epilepsia ; 52(7): 1211-22, 2011 Jul.
Article En | MEDLINE | ID: mdl-21569017

Metabotropic glutamate (mGlu) receptors are positioned at synapses of the thalamocortical network that underlie the development of spike-and-wave discharges (SWDs) associated with absence epilepsy. The modulatory role of individual mGlu receptor subtypes on excitatory and inhibitory synaptic transmission in the cortico-thalamo-cortical circuitry makes subtype-selective mGlu receptor ligands potential candidates as novel antiabsence drugs. Some of these compounds are under clinical development for the treatment of numerous neurologic and psychiatric disorders, and might be soon available for clinical studies in patients with absence seizures refractory to conventional medications. Herein we review the growing evidence that links mGlu receptors to the pathophysiology of pathologic SWDs moving from the anatomic localization and function of distinct mGlu receptor subtypes in the cortico-thalamo-cortical network to in vivo studies in mouse and rat models of absence epilepsy.


Anticonvulsants/pharmacology , Cerebral Cortex/physiology , Epilepsy, Absence/drug therapy , Receptors, Metabotropic Glutamate/physiology , Thalamus/physiology , Animals , Anticonvulsants/therapeutic use , Cerebral Cortex/drug effects , Disease Models, Animal , Humans , Mice , Nerve Net/drug effects , Nerve Net/physiology , Neuroglia/drug effects , Neuroglia/physiology , Rats , Receptors, Metabotropic Glutamate/drug effects , Thalamus/drug effects
14.
Neurosci Lett ; 443(2): 57-60, 2008 Oct 03.
Article En | MEDLINE | ID: mdl-18675882

The present study is designed to investigate the effect of some natural prenyloxyphenylpropanoids as neuroprotective agents against NMDA-induced toxicity in mixed cortical cell cultures containing both neurons and astrocytes. Excitotoxicity was induced by exposure of cultures to NMDA (100microM) at room temperature in a HEPES-buffered salt solution followed by incubation at 37 degrees C for the following 24h in MEM-Eagle's supplemented with 15.8mM NaHCO(3) and 25mM glucose. Tested compounds were mixed with NMDA. Neuronal injury was measured in all experiments by examination of cultures with phase-contrast microscopy at 20x, 18-20h after the insult while neuronal damage was quantitatively assessed by counting dead neurons stained with trypan blue and by measuring lactate dehydrogenase (LDH) released in the medium. Results showed that only natural prenyloxyphenylpropanoids containing a coumarin nucleus, namely 7-isopentenyloxycoumarin and auraptene, both found in nature from plants belonging to the genus Citrus and other of the family of Rutaceae, including edible ones, exerted a good dose-dependent manner protective effect against NMDA-induced neurotoxicity in particular at concentrations ranging from 1 to 10microM.


Astrocytes/drug effects , Coumarins/pharmacology , Neurons/drug effects , Neuroprotective Agents/pharmacology , Vegetables/chemistry , Animals , Cells, Cultured , Excitatory Amino Acid Agonists/toxicity , Mice , N-Methylaspartate/toxicity , Nerve Degeneration/chemically induced , Nerve Degeneration/prevention & control
15.
PLoS One ; 3(5): e2155, 2008 May 14.
Article En | MEDLINE | ID: mdl-18478073

Hippocampal synaptic plasticity and learning are strongly regulated by metabotropic glutamate receptors (mGluRs) and particularly by mGluR5. Here, we investigated the mechanisms underlying mGluR5-modulation of these phenomena. Prolonged pharmacological blockade of mGluR5 with MPEP produced a profound impairment of spatial memory. Effects were associated with 1) a reduction of mGluR1a-expression in the dentate gyrus; 2) impaired dentate gyrus LTP; 3) enhanced CA1-LTP and 4) suppressed theta (5-10 Hz) and gamma (30-100 Hz) oscillations in the dentate gyrus. Allosteric potentiation of mGluR1 after mGluR5 blockade significantly ameliorated dentate gyrus LTP, as well as suppression of gamma oscillatory activity. CA3-lesioning prevented MPEP effects on CA1-LTP, suggesting that plasticity levels in CA1 are driven by mGluR5-dependent synaptic and network activity in the dentate gyrus. These data support the hypothesis that prolonged mGluR5-inactivation causes altered hippocampal LTP levels and network activity, which is mediated in part by impaired mGluR1-expression in the dentate gyrus. The consequence is impairment of long-term learning.


Learning , Long-Term Potentiation , Receptors, Metabotropic Glutamate/physiology , Allosteric Regulation , Animals , Dentate Gyrus/drug effects , Dentate Gyrus/physiology , Excitatory Amino Acid Antagonists/pharmacology , Male , Memory , Pyridines/pharmacology , Rats , Rats, Wistar , Receptor, Metabotropic Glutamate 5 , Receptors, Metabotropic Glutamate/antagonists & inhibitors
16.
Brain Res ; 1153: 58-67, 2007 Jun 11.
Article En | MEDLINE | ID: mdl-17466282

Transient focal ischemia produced by local infusion of endothelin-1 (ET1) in the territory of the middle cerebral artery has been proposed as a potentially useful model for the screening of drugs developed for the treatment of thrombo-embolic stroke. However, most of the data rely exclusively on the assessment of the infarct volume, which is only a partial predictor of the neurological outcome of stroke. Here, we have validated the model using a multimodal approach for the assessment of neuroprotection, which includes (i) determination of the infarct volume by 2,3,5-triphenyltetrazolium chloride staining; (ii) an in-depth behavioral analysis of the neurological deficit; and (iii) an EEG analysis of electrophysiological abnormalities in the peri-infarct somatosensory forelimb cortical area, S1FL. The non-competitive NMDA receptor antagonist, MK-801 (3 mg/kg, injected i.p. 20 min after ET1 infusion in conscious rats) could reduce the infarct volume, reverse the EEG changes occurring at early times post-ET1, and markedly improve the neurological deficit in ischemic animals. The latter effect, however, was visible at day 3 post-ET1, because the drug itself produced substantial behavioral abnormalities at earlier times. We conclude that a multimodal approach can be applied to the ET1 model of focal ischemia, and that MK-801 can be used as a reference compound to which the activity of safer neuroprotective drugs should be compared.


Dizocilpine Maleate/therapeutic use , Endothelin-1 , Ischemic Attack, Transient/chemically induced , Ischemic Attack, Transient/prevention & control , Neuroprotective Agents/therapeutic use , Analysis of Variance , Animals , Behavior, Animal , Brain Infarction/drug therapy , Brain Infarction/etiology , Disease Models, Animal , Electroencephalography/drug effects , Functional Laterality , Ischemic Attack, Transient/complications , Ischemic Attack, Transient/pathology , Male , Rats , Rats, Wistar , Severity of Illness Index , Somatosensory Cortex/drug effects , Somatosensory Cortex/physiopathology , Tetrazolium Salts
17.
Neuro Oncol ; 7(3): 236-45, 2005 Jul.
Article En | MEDLINE | ID: mdl-16053698

U87MG human glioma cells in cultures expressed metabotropic glutamate (mGlu) receptors mGlu2 and mGlu3. Addition of the mGlu2/3 receptor antagonist LY341495 to the cultures reduced cell growth, expression of cyclin D1/2, and activation of the MAP kinase and phosphatidylinositol-3-kinase pathways. This is in line with the evidence that activation of mGlu2/3 receptors sustains glioma cell proliferation. U87MG cells were either implanted under the skin (1x10(6) cells/0.5 ml) or infused into the caudate nucleus (0.5x10(6) cells/5 microl) of nude mice. Animals were treated for 28 days with mGlu receptor antagonists by means of subcutaneous osmotic minipumps. Treatments with LY341495 or (2S)-alpha-ethylglutamate (both infused at a rate of 1 mg/kg per day) reduced the size of tumors growing under the skin. Infusion of LY341495 (10 mg/kg per day) also reduced the growth of brain tumors, as assessed by magnetic resonance imaging analysis carried out every seven days. The effect of drug treatment was particularly evident during the exponential phase of tumor growth, that is, between the third and the fourth week following cell implantation. Immunohistochemical analysis showed that U87MG cells retained the expression of mGlu2/3 receptors when implanted into the brain of nude mice. These data suggest that mGlu2/3 receptor antagonists are of potential use in the experimental treatment of malignant gliomas.


Amino Acids/pharmacology , Brain Neoplasms/drug therapy , Excitatory Amino Acid Antagonists/pharmacology , Glioma/drug therapy , Receptors, Metabotropic Glutamate/antagonists & inhibitors , Xanthenes/pharmacology , Animals , Blotting, Western , Cell Line, Tumor , Cell Proliferation/drug effects , Cyclin D1/biosynthesis , Cyclin D1/drug effects , Cyclin D2 , Cyclins/biosynthesis , Cyclins/drug effects , Enzyme Activation/drug effects , Humans , Immunohistochemistry , Ki-67 Antigen/drug effects , Ki-67 Antigen/metabolism , MAP Kinase Signaling System/drug effects , Magnetic Resonance Imaging , Mice , Mice, Nude , Phosphatidylinositol 3-Kinases/drug effects , Receptors, Metabotropic Glutamate/drug effects , Reverse Transcriptase Polymerase Chain Reaction
18.
J Hepatol ; 38(2): 179-87, 2003 Feb.
Article En | MEDLINE | ID: mdl-12547406

BACKGROUND/AIMS: mGlu5 metabotropic glutamate receptor antagonists protect rat hepatocytes against hypoxic death. Here, we have examined whether mGlu5 receptor antagonists are protective against liver damage induced by oxidative stress. METHODS: Toxicity of isolated hepatocytes was induced by tert-butylhydroperoxide (t-BuOOH) after pretreatment with the mGlu5 receptor antagonists, MPEP, SIB-1757 and SIB-1893. The effect of these drugs was also examined in mice challenged with toxic doses of acetaminophen. RESULTS: Addition of tBuOOH (0.5 mM) to isolated hepatocytes induced cell death (70+/-5% at 3 h). Addition of MPEP or SIB-1893 to hepatocytes reduced both the production of reactive oxygen species (ROS) and cell toxicity induced by t-BuOOH (tBuOOH=70+/-5%; tBuOOH+MPEP=57+/-6%; tBuOOH+SIB-1893=40+/-4%). In mice, a single injection of acetaminophen (300 mg/kg, i.p.) induced centrilobular liver necrosis, which was detectable after 24 h. MPEP (20 mg/kg, i.p.) substantially reduced liver necrosis and the production of ROS, although it did not affect the conversion of acetaminophen into the toxic metabolite, N-acetylbenzoquinoneimine. MPEP, SIB-1893 and SIB-1757 (all at 20 mg/kg, i.p.) also reduced the increased expression and activity of liver iNOS induced by acetaminophen. CONCLUSIONS: We conclude that pharmacological blockade of mGlu5 receptors might represent a novel target for the treatment of drug-induced liver damage.


Acetaminophen/toxicity , Analgesics, Non-Narcotic/toxicity , Chemical and Drug Induced Liver Injury/drug therapy , Excitatory Amino Acid Antagonists/pharmacology , Pyridines/pharmacology , Receptors, Metabotropic Glutamate/antagonists & inhibitors , Animals , Chemical and Drug Induced Liver Injury/metabolism , Hepatocytes/drug effects , Hepatocytes/metabolism , Male , Mice , Oxidative Stress/drug effects , Phenazopyridine/pharmacology , Rats , Rats, Wistar , Receptor, Metabotropic Glutamate 5 , tert-Butylhydroperoxide
19.
J Neurosci ; 22(13): 5403-11, 2002 Jul 01.
Article En | MEDLINE | ID: mdl-12097492

The chemokine RANTES is critically involved in neuroinflammation and has been implicated in the pathophysiology of multiple sclerosis. We examined the possibility that activation of G-protein-coupled metabotropic glutamate (mGlu) receptors regulates the formation of RANTES in glial cells. A 15 hr exposure of cultured astrocytes to tumor necrosis factor-alpha and interferon-gamma induced a substantial increase in both RANTES mRNA and extracellular RANTES levels. These increases were markedly reduced when astrocytes were coincubated with l-2-amino-4-phosphonobutanoate (l-AP-4), 4-phosphonophenylglycine, or l-serine-O-phosphate, which selectively activate group III mGlu receptor subtypes (i.e., mGlu4, -6, -7, and -8 receptors). Agonists of mGlu1/5 or mGlu2/3 receptors were virtually inactive. Inhibition of RANTES release produced by l-AP-4 was attenuated by the selective group III mGlu receptor antagonist (R,S)-alpha-methylserine-O-phosphate or by pretreatment of the cultures with pertussis toxin. Cultured astrocytes expressed mGlu4 receptors, and the ability of l-AP-4 to inhibit RANTES release was markedly reduced in cultures prepared from mGlu4 knock-out mice. This suggests that activation of mGlu4 receptors negatively modulates the production of RANTES in glial cells. We also examined the effect of l-AP-4 on the development of experimental allergic encephalomyelitis (EAE) in Lewis rats. l-AP-4 was subcutaneously infused for 28 d by an osmotic minipump that released 250 nl/hr of a solution of 250 mm of the drug. Detectable levels of l-AP-4 ( approximately 100 nm) were found in the brain dialysate of EAE rats. Infusion of l-AP-4 did not affect the time at onset and the severity of neurological symptoms but significantly increased the rate of recovery from EAE. In addition, lower levels of RANTES mRNA were found in the cerebellum and spinal cord of EAE rats infused with l-AP-4. These results suggest that pharmacological activation of group III mGlu receptors may be useful in the experimental treatment of neuroinflammatory CNS disorders.


Astrocytes/metabolism , Chemokine CCL5/biosynthesis , Receptors, Metabotropic Glutamate/agonists , Aminobutyrates/pharmacology , Animals , Astrocytes/chemistry , Astrocytes/drug effects , Cells, Cultured , Chemokine CCL5/genetics , Encephalomyelitis, Autoimmune, Experimental/etiology , Encephalomyelitis, Autoimmune, Experimental/genetics , Encephalomyelitis, Autoimmune, Experimental/metabolism , Kinetics , Leukocytes, Mononuclear/metabolism , Mice , RNA, Messenger/biosynthesis , Rats , Rats, Inbred Lew , Receptors, Metabotropic Glutamate/analysis
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