The effect of quercetin on absence epilepsy in WAG/Rij rats.

AIM: In the present study, the effect of quercetin, a powerful antioxidant flavonoid, on genetic absence epilepsy was studied in WAG/Rij rats. MATERIAL AND METHOD: Tripolar electrodes were implanted into WAG/Rij rats. Basal electrocorticography (ECoG) was recorded following a recovery period. After basal ECoG recording, different doses of quercetin (QRC) (25, 50 and 100 mg/kg) were injected intraperitoneally (i.p.) for 30 days. ECoG recording was continued for 31 days, three hours a day. After recording, the rats were anesthetized and euthanized through cervical dislocation and their brains were excised. Biochemically, TNF-alpha, IL-6 and NO were studied in whole rat brains. RESULTS: In WAG/Rij rats, low-dose quercetin (25 mg/kg) reduced the number and duration of spike-wave discharges (SWDs) compared to the control group. However, 50 and 100 mg/kg quercetin doses increased SWDs. Duration of SWDs was prolonged only with 100 mg/kg dose. None of the quercetin doses had any effect on average amplitude of SWDs. In addition, it was observed in biochemical analyses that 25 mg/kg quercetin reduced TNF-alpha, IL-6 and NO levels compared to the control group. While TNF-alpha and IL-6 levels in rat brains were not affected by 50 or 100 mg/kg doses, both doses were found to increase NO levels in rat brains. CONCLUSION: Based on the results of the present study, 25 mg/kg low-dose quercetin may have reduced absence seizures by reducing proinflammatory cytokines and NO, but high-dose quercetin may have increased absence seizures through increasing the NO level. This contrasting effect of quercetin on absence seizures needs to be investigated by advanced mechanisms.

N-acetylcysteine aggravates seizures while improving depressive-like and cognitive impairment comorbidities in the WAG/Rij rat model of absence epilepsy.

N-acetylcysteine (NAC) is an antioxidant with some demonstrated efficacy in a range of neuropsychiatric disorders. NAC has shown anticonvulsant effects in animal models. NAC effects on absence seizures are still not uncovered, and considering its clinical use as a mucolytic in patients with lung diseases, people with epilepsy are also likely to be exposed to the drug. Therefore, we aimed to study the effects of NAC on absence seizures in the WAG/Rij rat model of absence epilepsy with neuropsychiatric comorbidities. The effects of NAC chronic treatment in WAG/Rij rats were evaluated on: absence seizures at 15 and 30 days by EEG recordings and animal behaviour at 30 days on neuropsychiatric comorbidities. Furthermore, the mechanism of action of NAC was evaluated by analysing brain expression levels of some possible key targets: the excitatory amino acid transporter 2, cystine-glutamate antiporter, metabotropic glutamate receptor 2, the mechanistic target of rapamycin and p70S6K as well as levels of total glutathione. Our results demonstrate that in WAG/Rij rats, NAC treatment significantly increased the number and duration of SWDs, aggravating absence epilepsy while ameliorating neuropsychiatric comorbidities. NAC treatment was linked to an increase in brain mGlu2 receptor expression with this being likely responsible for the observed absence seizure-promoting effects. In conclusion, while confirming the positive effects on animal behaviour induced by NAC also in epileptic animals, we report the aggravating effects of NAC on absence seizures which could have some serious consequences for epilepsy patients with the possible wider use of NAC in clinical therapeutics.

Enhancement of Ketone Supplements-Evoked Effect on Absence Epileptic Activity by Co-Administration of Uridine in Wistar Albino Glaxo Rijswijk Rats.

Both uridine and exogenous ketone supplements decreased the number of spike-wave discharges (SWDs) in a rat model of human absence epilepsy Wistar Albino Glaxo/Rijswijk (WAG/Rij) rats. It has been suggested that alleviating influence of both uridine and ketone supplements on absence epileptic activity may be modulated by A1 type adenosine receptors (A1Rs). The first aim was to determine whether intraperitoneal (i.p.) administration of a specific A1R antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX; 0.2 mg/kg) and a selective adenosine A2A receptor antagonist (7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-[4,3-e]-1,2,4-triazolo [1,5-c]pyrimidine) (SCH 58261; 0.5 mg/kg) have a modulatory influence on i.p. 1000 mg/kg uridine-evoked effects on SWD number in WAG/Rij rats. The second aim was to assess efficacy of a sub-effective dose of uridine (i.p. 250 mg/kg) combined with beta-hydroxybutyrate salt + medium chain triglyceride (KSMCT; 2.5 g/kg, gavage) on absence epilepsy. DPCPX completely abolished the i.p. 1000 mg/kg uridine-evoked alleviating effect on SWD number whereas SCH 58261 was ineffective, confirming the A1R mechanism. Moreover, the sub-effective dose of uridine markedly enhanced the effect of KSMCT (2.5 g/kg, gavage) on absence epileptic activity. These results demonstrate the anti-epilepsy benefits of co-administrating uridine and exogenous ketone supplements as a means to treat absence epilepsy.

Etanercept rescues cognitive deficits, depression-like symptoms, and spike-wave discharge incidence in WAG/Rij rat model of absence epilepsy.

Pro-inflammatory cytokines have been shown to be associated with the development of seizures in the WAG/Rij rat model of absence epilepsy. Importantly, WAG/Rij rats also exhibit cognitive deficits and depression-like behaviors. It is possible that pro-inflammatory cytokines mediate these comorbid conditions of absence epilepsy given their well-established effects on cognition and affective responses. The current study investigated the potential therapeutic effect of etanercept (tumor necrosis factor inhibitor) on cognitive impairment, depression-like behavior, and spike-wave discharges (SWDs) typically observed in the WAG/Rij rats. Eight-month-old male WAG/Rij rats and Wistar controls were tested in Morris water maze (MWM), passive avoidance (PA), forced swimming, sucrose preference, and locomotor activity tests, and electroencephalogram (EEG) recordings were taken from a separate group of WAG/Rij rats after 8 weeks of etanercept or vehicle treatment. Consistent with earlier work, WAG/Rij rats exhibited cognitive deficits and depression-like behavior. From these, the cognitive deficits and despair-like behavior were rescued by etanercept administration, which also reduced the frequency of SWDs without affecting their duration. Our results support the hypothesis that pro-inflammatory cytokines mediate the absence seizures and comorbid symptoms of absence epilepsy.

Atipamezole, a specific α2A antagonist, suppresses spike-and-wave discharges and alters Ca2⁺ /calmodulin-dependent protein kinase II in the thalamus of genetic absence epilepsy rats.

OBJECTIVE: The role of α2A adrenergic receptors (α2A ARs) in absence epilepsy is not well characterized. Therefore, we investigated the outcomes of the specific antagonism of α2A ARs on the spike-and-wave discharges (SWDs) in genetic absence epilepsy rats from Strasbourg (GAERSs), together with its influence on the behavior and second messenger systems, which may point to the mechanisms to which a possible SWD modulation can be related. METHODS: Atipamezole, an α2A AR antagonist, was administered intracerebroventricularly to the adult GAERSs, and electroencephalography (EEG) was conducted. The cumulative duration and number of SWDs, and the mean duration of each SWD complex were counted. The relative power of the EEG frequency bands and behavioral activity after the acute application of two doses (12 and 31 µg/5 µL) of atipamezole were evaluated. The levels of cyclic adenosine monophosphate and calcium/calmodulin-dependent kinase II (CaMKII) were measured in the cortex, thalamus, and hippocampus of naive Wistar rats and GAERSs, administered with artificial cerebrospinal fluid (aCSF) as a vehicle, or either acute or chronic atipamezole (12 µg), the latter being administered for 5 consecutive days. RESULTS: Atipamezole significantly suppressed SWDs dose-dependently, without affecting the relative power values of EEG frequency spectrum. The stereotypic activity was significantly lower in both naive Wistar rats and GAERSs receiving the highest dose (31 µg) of atipamezole compared to GAERSs receiving aCSF. In GAERSs, CaMKII levels were found to be higher in the thalamus after the acute and chronic application of SWD-suppressing doses of atipamezole (12 and 31 µg) compared to aCSF. SIGNIFICANCE: This study emphasizes the α2 AR-related modulation of absence epilepsy and particularly the significance of α2 AR antagonism in suppressing SWDs. Atipamezole's SWD-suppressive actions may be through CaMKII-mediated second messenger systems in the thalamus.

Effect of U-92032, T-Type Ca2+ Channel Blocker, on Rats with Genetic Absence Epilepsy.

INTRODUCTION: Absence epilepsy is associated with diffuse spike-and-wave discharges (SWD) on the electroencephalogram (EEG). Recent studies have demonstrated that the primary somatosensory cortex is also implicated in the generation of the SWDs. OBJECTIVE: This study investigated the effects of systemic and local administrations of U-92032 into the brain of Genetic Absence Epilepsy Rats from Strasbourg (GAERS). METHODS: GAERS animals underwent stereotaxic surgery for the placement of EEG recording electrodes and guide cannulas for U-92032 administration into the lateral ventricle (intracerebroventricular [i.c.v.]), upper lips area (S1Ulp) or barrel field area (S1B) of primary somatosensory cortex. Following 7 days of recovery, electrical activity was recorded continuously for 1 h before and 6 h after intraperitoneal (0.25; 1; 5 mg/kg i.p.) or local U-92032 or dimethyl sulfoxide (DMSO) injections. RESULTS: No changes were detected in the cumulative duration, mean duration, and number of SWDs following i.p. U-92032 injections. Local i.c.v. injections of U-92032 caused a significant decrease in the cumulative duration (i.c.v., 50 and 100 nmol/L), mean duration (i.c.v., 50, 100, and 250 nmol/L), and the number (i.c.v., 250 nmol/L) of SWDs compared to DMSO groups. Intra-cortical (S1Ulp and S1B) U-92032 injections caused a significant decrease in all 3 parameters compared to DMSO groups, as well. CONCLUSION: Intra-cortical injection of U-92032 caused almost complete removal of SWDs in GAERS and i.c.v. administration resulted in a significant reduction. However, systemic i.p. administration did not cause a significant change with the applied -doses.

Ethosuximide-induced drug reaction with eosinophilia and systemic symptoms with mediastinal lymphadenopathy.

Lymphadenopathy is a common sign for drug reaction and eosinophilia with systemic symptoms (DRESS) syndrome, but hilar and mediastinal lymphadenopathy may be underreported. We describe a 7-year-old boy who started taking ethosuximide for absence seizures and presented with diffuse rash, fever, elevated transaminases, facial swelling, and hilar and mediastinal lymphadenopathy. His mediastinal lymphadenopathy was concerning for lymphoma, which led to more invasive testing to rule out malignancy. This report highlights an unusual and likely underreported presenting sign of DRESS syndrome in children.

Ictal Source Locations and Cortico-Thalamic Connectivity in Childhood Absence Epilepsy: Associations with Treatment Response.

Childhood absence epilepsy (CAE), the most common pediatric epilepsy syndrome, is usually treated with valproic acid (VPA) and lamotrigine (LTG) in China. This study aimed to investigate the ictal source locations and functional connectivity (FC) networks between the cortices and thalamus that are related to treatment response. Magnetoencephalography (MEG) data from 25 patients with CAE were recorded at 300 Hz and analyzed in 1-30 Hz frequency bands. Neuromagnetic sources were volumetrically scanned with accumulated source imaging. The FC networks between the cortices and thalamus were evaluated at the source level through a connectivity analysis. Treatment outcome was assessed after 36-66 months following MEG recording. The children with CAE were divided into LTG responder, LTG non-responder, VPA responder and VPA non-responder groups. The ictal source locations and cortico-thalamic FC networks were compared to the treatment response. The ictal source locations in the post-dorsal medial frontal cortex (post-DMFC, including the medial primary motor cortex and the supplementary sensorimotor area) were observed in all LTG non-responders but in all LTG responders. At 1-7 Hz, patients with fronto-thalamo-parietal/occipital (F-T-P/O) networks were older than those with fronto-thalamic (F-T) networks or other cortico-thalamic networks (p = 0.000). The duration of seizures in patients with F-T-P/O networks at 1-7 Hz was longer than that in patients with F-T networks or other cortico-thalamic networks (p = 0.001). The ictal post-DMFC source localizations suggest that children with CAE might experience initial LTG monotherapy failure. Moreover, the cortico-thalamo-cortical network is associated with age. Finally, the cortico-thalamo-cortical network consists of anterior and posterior cortices and might contribute to the maintenance of discharges.

Ethosuximide-induced Stevens-Johnson syndrome: Beneficial effect of early intervention with high-dose corticosteroid therapy.

We report two rare cases of childhood epilepsy patients who developed ethosuximide-induced Stevens-Johnson syndrome (SJS). Unlike typical SJS, the initial eruption of both patients presented well-demarcated, infiltrating firm papules mainly on the cheeks and the extensor aspects of the arms (case 1), and multiple vesicles on the soles and oral aphthosis (case 2), which closely mimicked viral exanthema. We diagnosed both patients with ethosuximide-induced SJS, based on the dosing period and the positive results of drug-induced lymphocyte stimulation test. Systemic corticosteroids are usually selected as a standard therapy for SJS, despite controversial results regarding their effectiveness. In case 1, an i.v. pulse therapy of methylprednisolone (30 mg/kg, 3 days consecutively) was initiated on day 7 from the onset of illness, and an i.v. immunoglobulin (400 mg/kg, 5 days consecutively) was added the following day. In case 2, an i.v. prednisone treatment (1 mg/kg, for 1 week) was initiated on day 4 from the onset. Eventually, the early therapeutic interventions resulted in good outcomes in both patients.

Modulatory effects of inosine, guanosine and uridine on lipopolysaccharide-evoked increase in spike-wave discharge activity in Wistar Albino Glaxo/Rijswijk rats.

We showed previously that the number of spike-wave discharges (SWDs) was increased after intraperitoneal (i.p.) injection of lipopolysaccharide (LPS), inosine (Ino) and muscimol alone whereas i.p. guanosine (Guo), uridine (Urd), bicuculline, theophylline and (+)-5-methyl-10,11-dihydro-5H-dibenzo(a,d)cyclohepten-5,10-imine maleate (MK-801) alone decreased the SWD number in Wistar Albino Glaxo/Rijswijk (WAG/Rij) rats. These drugs may exert their effects on absence epileptic activity mainly via proinflammatory cytokines-evoked increase in cortical excitability (such as LPS), GABAergic system (LPS, Ino, Urd, muscimol and bicuculline), glutamatergic system (LPS, Guo and MK-801) and adenosinergic system (LPS, Ino, Guo, Urd and theophylline). Both GABAergic system and glutamatergic system are involved in the pathomechanism of absence epilepsy, the LPS-evoked increase in absence epileptic activity and the pro- or antiepileptic effects of non-adenosine (non-Ado) nucleosides Ino, Guo and Urd. Moreover, Ino, Guo and Urd have modulatory effects on inflammatory processes. Thus, we investigated whether Ino, Guo and Urd have also modulatory influence on LPS-evoked increase in SWD number using two different concentrations of each nucleoside in WAG/Rij rats. We demonstrated that Ino dose-dependently aggravated whereas Guo and Urd attenuated the LPS-evoked increase in SWD number. Our results suggest that different nucleosides have diverse effects on LPS-induced changes in absence epileptic activity.

Absence epileptic activity changing effects of non-adenosine nucleoside inosine, guanosine and uridine in Wistar Albino Glaxo Rijswijk rats.

Adenosine (Ado) and non-adenosine (non-Ado) nucleosides such as inosine (Ino), guanosine (Guo) and uridine (Urd) may have regionally different roles in the regulation of physiological and pathophysiological processes in the central nervous system (CNS) such as epilepsy. It was demonstrated previously that Ino and Guo decreased quinolinic acid (QA)-induced seizures and Urd reduced penicillin-, bicuculline- and pentylenetetrazole (PTZ)-induced seizures. It has also been demonstrated that Ino and Urd may exert their effects through GABAergic system by altering the function of GABA(A) type of gamma-aminobutyric acid receptors (GABAA receptors) whereas Guo decreases glutamate-induced excitability through glutamatergic system, which systems (GABAergic and glutamatergic) are involved in pathomechanisms of absence epilepsy. Thus, we hypothesized that Ino and Guo, similarly to the previously described effect of Urd, might also decrease absence epileptic activity. We investigated in the present study whether intraperitoneal (i.p.) application of Ino (500 and 1000mg/kg), Guo (20 and 50mg/kg), Urd (500 and 1000mg/kg), GABA(A) receptor agonist muscimol (1 and 3mg/kg), GABA(A) receptor antagonist bicuculline (2 and 4mg/kg), non-selective Ado receptor antagonist theophylline (5 and 10mg/kg) and non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist (+)-5-methyl-10,11-dihydro-5H-dibenzo (a,d) cyclohepten-5,10-imine maleate (MK-801, 0.0625 and 0.1250mg/kg) alone and in combination have modulatory effects on absence epileptic activity in Wistar Albino Glaxo Rijswijk (WAG/Rij) rats. We found that Guo decreased the number of spike-wave discharges (SWDs) whereas Ino increased it dose-dependently. We strengthened that Urd can decrease absence epileptic activity. Our results suggest that Guo, Urd and their analogs could be potentially effective drugs for treatment of human absence epilepsy.

TSC1 R509X Mutation in a Chinese Family with Tuberous Sclerosis Complex.

Tuberous sclerosis complex is a rare autosomal dominant disorder caused by mutations in either of TSC1 and TSC2 genes. Tuberous sclerosis complex presents diverse clinical characteristics, and either of TSC1 and TSC2 genes shows a wide range of mutations in their coding regions. However, the correlation between genotype and phenotype is yet unknown. We describe the clinical characteristics of a Chinese family with TSC1 gene mutation and present a literature review of Chinese patients with tuberous sclerosis complex gene mutation reported since 2004. This is the first report of TSC1 R509X mutation in a Chinese family, which might deepen our insight into the clinical and molecular pathogenesis of tuberous sclerosis complex.

Effect of caffeine and adenosine receptor ligands on the expression of spike-and-wave discharges in Genetic Absence Epilepsy Rats from Strasbourg (GAERS).

The influence of caffeine on epileptic seizures remains a matter of debate. Here we tested on Genetic Absence Epilepsy Rats from Strasbourg (GAERS) the consequences of acute and chronic exposure to caffeine on the expression of spike-and-wave discharges (SWDs). Since caffeine is a mixed nonspecific A(1) and A(2A) adenosine receptor antagonist, we measured also the influence of antagonists and agonists of these receptors on SWD expression. GAERS were equipped with four cortical electrodes over the frontoparietal cortex and the cumulated duration and number of SWDs were recorded for 120 min after the injection of increasing doses of caffeine, specific antagonists and agonists of A(1) and A(2A) adenosine receptors. The effects of chronic caffeine were also studied. In GAERS, caffeine dose-dependently reduced the cumulated number and duration of SWDs which almost disappeared after the injection of the two highest doses of caffeine, 5 and 10 mg/kg. Likewise, the A(1) and A(2A) adenosine receptor antagonists led to a dose-dependent reduction of SWD expression while the agonists dose-dependently increased SWD expression. Conversely, the chronic exposure to caffeine via drinking water for 15 days did not influence SWD expression. With the exception of the two highest doses of caffeine that largely enhanced activity, all compounds including low doses of caffeine had no effect on locomotor activity of GAERS. These data show that the acute exposure to low doses of caffeine, or A(1) and A(2A) adenosine receptor antagonists reduces SWD expression in GAERS, independently from any effect on motor activity. The chronic exposure of GAERS to caffeine does not affect the expression of epilepsy.

Viscum Album in the Treatment of a Girl With Refractory Childhood Absence Epilepsy.

Viscum album (European mistletoe) extracts have known immunomodulatory effects but little data exist on anticonvulsant activity despite its usefulness having been reported for centuries. A 4½-year-old girl with childhood absence epilepsy and global developmental delay was treated with different antiepileptic drugs and ketogenic diet but failed to become seizure free over a 2-year period. She also received different herbal remedies as part of an integrative medicine approach. Initial improvement occurred on valproate-ethosuximide, a further improvement was seen after adding clobazam to valproate. Final cessation of absence activity occurred after a dose increase of V album. She was still seizure free at the 12-month follow-up. V album appears to have been a necessary adjunct treatment for this child to become seizure free. We call on physicians to report their experiences of V album in epilepsy and suggest further study.

Animal models of absence epilepsies: what do they model and do sex and sex hormones matter?

While epidemiological data suggest a female prevalence in human childhood- and adolescence-onset typical absence epilepsy syndromes, the sex difference is less clear in adult-onset syndromes. In addition, although there are more females than males diagnosed with typical absence epilepsy syndromes, there is a paucity of studies on sex differences in seizure frequency and semiology in patients diagnosed with any absence epilepsy syndrome. Moreover, it is unknown if there are sex differences in the prevalence or expression of atypical absence epilepsy syndromes. Surprisingly, most studies of animal models of absence epilepsy either did not investigate sex differences, or failed to find sex-dependent effects. However, various rodent models for atypical syndromes such as the AY9944 model (prepubertal females show a higher incidence than prepubertal males), BN model (also with a higher prevalence in males) and the Gabra1 deletion mouse in the C57BL/6J strain offer unique possibilities for the investigation of the mechanisms involved in sex differences. Although the mechanistic bases for the sex differences in humans or these three models are not yet known, studies of the effects of sex hormones on seizures have offered some possibilities. The sex hormones progesterone, estradiol and testosterone exert diametrically opposite effects in genetic absence epilepsy and pharmacologically-evoked convulsive types of epilepsy models. In addition, acute pharmacological effects of progesterone on absence seizures during proestrus are opposite to those seen during pregnancy. 17ß-Estradiol has anti-absence seizure effects, but it is only active in atypical absence models. It is speculated that the pro-absence action of progesterone, and perhaps also the delayed pro-absence action of testosterone, are mediated through the neurosteroid allopregnanolone and its structural and functional homolog, androstanediol. These two steroids increase extrasynaptic thalamic tonic GABAergic inhibition by selectively targeting neurosteroid-selective subunits of GABAA receptors (GABAARs). Neurosteroids also modulate the expression of GABAAR containing the γ2, α4, and δ subunits. It is hypothesized that differences in subunit expression during pregnancy and ovarian cycle contribute to the opposite effects of progesterone in these two hormonal states.

Validation of a screening tool for attention and executive functions (EpiTrack Junior) in children and adolescents with absence epilepsy.

OBJECTIVE: Our prospective study aimed at the validation of EpiTrack Junior, a neuropsychological screening tool for attention and executive functions in children with epilepsy. METHODS: Twenty-two children with absence epilepsy aged 8-17 years underwent comprehensive neuropsychological evaluation including EpiTrack Junior and measures of intelligence, verbal and nonverbal memory, word fluency and visuoconstructive organization. Concurrent and discriminant validity of EpiTrack Junior subtests and total score as well as sensitivity and specificity of the total score were analyzed. RESULTS: EpiTrack Junior total score was impaired in 59% of participants. Concurrent validity was demonstrated in 4/6 subtests and for the total score. Discriminant validity was shown with respect to verbal and nonverbal long-term memory. Sensitivity was higher than specificity and highest for the "working memory index". CONCLUSION: EpiTrack Junior is recommended as a sensitive and time-efficient screening tool for attention and executive functions in children with epilepsy. Impaired results should be followed up with detailed evaluation including information from the parents and school as well as counseling where indicated.

Estimulador de nervo vago em paciente com síndrome de Lennox-Gastaut: relato de caso / Vagus nerve stimulator in a patient with Lennox-Gastaut syndrome: case report

A Síndrome de Lennox-Gastaut (SLG) é uma encefalopatia epiléptica grave da infância caracterizada por múltiplos tipos de crises intratáveis, anormalidades cognitivas e comportamentais e alterações eletroencefalográficas características. Na grande maioria dos casos as crises se tornam refratárias mesmo com politerapia, sendo indicado tratamentos alternativos. O uso de calosotomia é descrito para ajudar no controle das crises, entretanto novas terapias como o estimulador de nervo vago (ENV) começaram a ser utilizadas. Neste caso, relatamos um paciente com SLG, que apesar das drogas antiepilépticas apresentava crises diárias, que foi submetido a ENV, com redução das crises. Discutimos o tratamento não farmacológico da SLG, comparando a calosotomia com ENV...

The Lennox-Gastaut Syndrome (LGS) is a severe childhood epileptic encephalopathy characterized by multiple types of intractable seizures, cognitive and behavioral abnormalities and specific electroencephalographic features. Most patients are refractory even with polytherapy, so alternative treatment is indicated. Callosotomy is indicated in these cases, however vagus nerve stimulator (VNS) is a less invasive option. This is a case report of a patient with LGS, which despite antiepileptic drugs had daily seizures, who underwent VNS, with reduction of seizures. We discuss the nonpharmacological treatment of LGS, comparing the callosotomy with VNS...

Potentiation of mGlu5 receptors with the novel enhancer, VU0360172, reduces spontaneous absence seizures in WAG/Rij rats.

Absence epilepsy is generated by the cortico-thalamo-cortical network, which undergoes a finely tuned regulation by metabotropic glutamate (mGlu) receptors. We have shown previously that potentiation of mGlu1 receptors reduces spontaneous occurring spike and wave discharges (SWDs) in the WAG/Rij rat model of absence epilepsy, whereas activation of mGlu2/3 and mGlu4 receptors produces the opposite effect. Here, we have extended the study to mGlu5 receptors, which are known to be highly expressed within the cortico-thalamo-cortical network. We used presymptomatic and symptomatic WAG/Rij rats and aged-matched ACI rats. WAG/Rij rats showed a reduction in the mGlu5 receptor protein levels and in the mGlu5-receptor mediated stimulation of polyphosphoinositide hydrolysis in the ventrobasal thalamus, whereas the expression of mGlu5 receptors was increased in the somatosensory cortex. Interestingly, these changes preceded the onset of the epileptic phenotype, being already visible in pre-symptomatic WAG/Rij rats. SWDs in symptomatic WAG/Rij rats were not influenced by pharmacological blockade of mGlu5 receptors with MTEP (10 or 30 mg/kg, i.p.), but were significantly decreased by mGlu5 receptor potentiation with the novel enhancer, VU0360172 (3 or 10 mg/kg, s.c.), without affecting motor behaviour. The effect of VU0360172 was prevented by co-treatment with MTEP. These findings suggest that changes in mGlu5 receptors might lie at the core of the absence-seizure prone phenotype of WAG/Rij rats, and that mGlu5 receptor enhancers are potential candidates to the treatment of absence epilepsy. This article is part of a Special Issue entitled 'Metabotropic Glutamate Receptors'.