Intermittent hypercapnic hypoxia effects on the nicotinic acetylcholine receptors in the developing piglet hippocampus and brainstem

This study investigated the effects of acute (1 day) vs repeated (4 days) exposure to intermittent hypercapnic hypoxia (IHH) on the immunohistochemical expression of α2, α3, α5, α7, α9 and β2 nicotinic acetylcholine receptor (nAChR) subunits in the developing piglet hippocampus and brainstem medulla, and how prior nicotine exposure alters the response to acute IHH. Five piglet groups included: 1 day IHH (1D IHH, n = 9), 4 days IHH (4D IHH, n = 8), controls exposed only to air cycles for 1 day (1D Air, n = 6) or 4 days (4D Air, n = 5), and pre-exposed to nicotine for 13 days prior to 1 day IHH (Nic + 1D IHH, n = 7). The exposure period alternated 6 min of HH (8%O₂, 7%CO₂, balance N₂) and 6 min of air over 48 min, while controls were switched from air-to-air. Results showed that: 1. repeated IHH induces more changes in nAChR subunit expression than acute IHH in both the hippocampus and brainstem medulla, 2. In the hippocampus, α2 and β2 changed the most (increased) following IHH and the CA3, CA2 and DG were mostly affected. In the brainstem medulla, α2, α5, α9 and β2 were changed (decreased) in most nuclei with the hypoglossal and nucleus of the solitary tract being mostly affected. 3. Pre-exposure to nicotine enhanced the changes in the hippocampus but dampened those in the brainstem medulla. These findings indicate that the nAChRs (predominantly with the α2/β2 complex) are affected by IHH in critical hippocampal and brainstem nuclei during early brain development, and that pre-exposure to nicotine alters the pattern of susceptibility to IHH.     

Calcium pathways such as cAMP modulate clothianidin action through activation of α-bungarotoxin-sensitive and -insensitive nicotinic acetylcholine receptors

Clothianidin is a neonicotinoid insecticide developed in the early 2000s. We have recently demonstrated that it was a full agonist of α-bungarotoxin-sensitive and -insensitive nicotinic acetylcholine receptors expressed in the cockroach dorsal unpaired median neurons. Clothianidin was able to act as an agonist of imidacloprid-insensitive nAChR2 receptor and internal regulation of cAMP concentration modulated nAChR2 sensitivity to clothianidin. In the present study, we demonstrated that cAMP modulated the agonist action of clothianidin via α-bungarotoxin-sensitive and insensitive receptors. Clothianidin-induced current–voltage curves were dependent to clothianidin concentrations. At 10 μM clothianidin, increasing cAMP concentration induced a linear current–voltage curve. Clothianidin effects were blocked by 0.5 μM α-bungarotoxin suggesting that cAMP modulation occurred through α-bungarotoxin-sensitive receptors. At 1 mM clothianidin, cAMP effects were associated to α-bungarotoxin-insensitive receptors because clothianidin-induced currents were blocked by 5 μM mecamylamine and 20 μM d-tubocurarine. In addition, we found that application of 1 mM clothianidin induced a strong increase of intracellular calcium concentration. These data reinforced the finding that calcium pathways including cAMP modulated clothianidin action on insect nicotinic acetylcholine receptors. We proposed that intracellular calcium pathways such as cAMP could be a target to modulate the mode of action of neonicotinoid insecticides.     

Inhibition of sodium glucose cotransporters following status epilepticus induced by intrahippocampal pilocarpine affects neurodegeneration process in hippocampus

Temporal lobe epilepsy (TLE) is characterized by spontaneous recurrent seizures, starting from secondary functional disorders due to several insults, including self-sustaining continuous seizures identified as status epilepticus (SE). Although hypoglycemia has been associated with SE, the effect of inhibition of the Na⁺/glucose cotransporters (SGLTs) on hippocampus during SE is still unknown. Here we evaluated the functional role of SGLT in the pattern of limbic seizures and neurodegeneration process after pilocarpine (PILO)-induced SE. Vehicle (VEH, 1 μL) or phlorizin, a specific SGLT inhibitor (PZN, 1 μL, 50 μg/μL), was administered in the hippocampus of rats 30 min before PILO (VEH + PILO or PZN + PILO, respectively). The limbic seizures were classified using the Racine's scale, and the amount of wet dog shakes (WDS) was quantified before and during SE. Neurodegeneration process was evaluated by Fluoro-Jade C (FJ-C), and FJ-C-positive neurons (FJ-C +) were counted 24 h and 15 days after SE. The PZN-treated rats showed higher (p < 0.05) number of WDS when compared with VEH + PILO. There was no difference in seizure severity between PZN + PILO and VEH + PILO groups. However, the pattern of limbic seizures significantly changed in PZN + PILO. Indeed, the class 5 seizures repeated themselves more times (p < 0.05) than the other classes in the PZN group at 50 min after SE induction. The PZN + PILO animals had a higher (p < 0.05) number of FJ-C + cells in the dentate gyrus (DG), hilus, and CA3 and CA1 of hippocampus, when compared with VEH + PILO. The PZN + PILO animals had a decreased number (p < 0.05) of FJ-C + cells in CA1 compared with VEH + PILO 15 days after SE induction. Taken together, our data suggest that SGLT inhibition with PZN increased the severity of limbic seizures during SE and increased neurodegeneration in hippocampus 24 h after SE, suggesting that SGLT1 and SGLT2 could participate in the modulation of earlier stages of epileptogenic processes.     

Paclitaxel inhibits the activity and membrane localization of PKCα and PKCβI/II to elicit a decrease in stimulated calcitonin gene-related peptide release from cultured sensory neurons

Peripheral neuropathy is a dose-limiting and debilitating side effect of the chemotherapeutic drug, paclitaxel. Consequently, elucidating the mechanisms by which this drug alters sensory neuronal function is essential for the development of successful therapeutics for peripheral neuropathy. We previously demonstrated that chronic treatment with paclitaxel (3–5 days) reduces neuropeptide release stimulated by agonists of TRPV1. Because the activity of TRPV1 channels is modulated by conventional and novel PKC isozymes (c/nPKC), we investigated whether c/nPKC mediate the loss of neuropeptide release following chronic treatment with paclitaxel (300 nM; 3 and 5 days). Release of the neuropeptide, calcitonin gene-related peptide (CGRP), was measured as an index of neuronal sensitivity. Following paclitaxel treatment, cultured dorsal root ganglia sensory neurons were stimulated with a c/nPKC activator, phorbol 12,13-dibutyrate (PDBu), or a TRPV1 agonist, capsaicin, in the absence and presence of selective inhibitors of conventional PKCα and PKCβI/II isozymes (cPKC). Paclitaxel (300 nM; 3 days and 5 days) attenuated both PDBu- and capsaicin-stimulated release in a cPKC-dependent manner. Under basal conditions, there were no changes in the protein expression, phosphorylation or membrane localization of PKC α, βI or βII, however, paclitaxel decreased cPKC activity as indicated by a reduction in the phosphorylation of cPKC substrates. Under stimulatory conditions, paclitaxel attenuated the membrane translocation of phosphorylated PKC α, βI and βII, providing a rationale for the attenuation in PDBu- and capsaicin-stimulated release. Our findings suggest that a decrease in cPKC activity and membrane localization are responsible for the reduction in stimulated peptide release following chronic treatment with paclitaxel in sensory neurons.     

Hypoxia and nicotine effects on Pituitary adenylate cyclase activating polypeptide (PACAP) and its receptor 1 (PAC1) in the developing piglet brainstem

Pituitary adenylate cyclase activating polypeptide (PACAP) and its cognate receptor 1 (PAC1), have been implicated in the pathophysiology of the Sudden Infant Death Syndrome (SIDS). Two main risk factors for SIDS are prone sleeping and cigarette smoke exposure. Using piglet models of these risk factors, intermittent hypercapnic hypoxia (IHH-mimicking rebreathing in prone position) and nicotine (main reinforcing element of cigarettes), this study aimed to determine their effects on PACAP and PAC1 protein expression in the medulla. IHH was delivered for 1 (n = 7), 2 (n = 6), 3 (n = 6) and 4 (n = 7) days prior to euthanasia at 13–14 days of age, while nicotine (n = 7) was continuous for the first 14 days of life. An additional group of combined nicotine and 1 day IHH (1DIHH) was studied to determine the combined effects of the risk factors. Changes in expression were seen after the acute 1DIHH exposure (none after repeated daily exposures) and included a decrease in PACAP in the dorsal motor nucleus of vagus (DMNV; p = 0.024), nucleus of the solitary tract (NTS; p = 0.024) and the gracile nucleus (GRAC; p = 0.001), and a decrease in PAC1 in the NTS (p = 0.01). No PACAP change was noted in the nicotine-exposed piglets, however, a decrease in PAC1 was found in the DMNV (p = 0.02). IHH exposure in piglets with pre-exposure to nicotine led to a significant decrease in PACAP in the Grac (p = 0.04) but had no effect on PAC1. These findings show for the first time, the vulnerability of PACAP in the brainstem during early development to an acute hypercapnic hypoxic exposure and that those effects are greater than from nicotine exposure.     

Xenograft of human umbilical mesenchymal stem cells from Wharton’s jelly as a potential therapy for rat pilocarpine-induced epilepsy

We evaluated the effects of intra-hippocampal transplantation of human umbilical mesenchymal stem cells (HUMSCs) on pilocarpine-treated rats. Sprague–Dawley rats were divided into the following three groups: (1) a normal group of rats receiving only PBS, (2) a status epilepticus (SE) group of rats with pilocarpine-induced SE and PBS injected into the hippocampi, and (3) a SE + HUMSC group of SE rats with HUMSC transplantation. Spontaneous recurrent motor seizures (SRMS) were monitored using simultaneous video and electroencephalographic recordings at two to four weeks after SE induction. The results showed that the number of SRMS within two to four weeks after SE was significantly decreased in SE + HUMSCs rats compared with SE rats. All of the rats were sacrificed on Day 29 after SE. Hippocampal morphology and volume were evaluated using Nissl staining and magnetic resonance imaging. The results showed that the volume of the dorsal hippocampus was smaller in SE rats compared with normal and SE + HUMSCs rats. The pyramidal neuron loss in CA1 and CA3 regions was more severe in the SE rats than in normal and SE + HUMSCs rats. No significant differences were found in the hippocampal neuronal loss or in the number of dentate GABAergic neurons between normal and SE + HUMSCs rats. Compared with the SE rats, the SE + HUMSCs rats exhibited a suppression of astrocyte activity and aberrant mossy fiber sprouting. Implanted HUMSCs survived in the hippocampus and released cytokines, including FGF-6, amphiregulin, glucocorticoid-induced tumor necrosis factors receptor (GITR), MIP-3β, and osteoprotegerin. In an in vitro study, exposure of cortical neurons to glutamate showed a significant decrease in cell viability, which was preventable by co-culturing with HUMSCs. Above all, the expression of human osteoprotegerin and amphiregulin were significantly increased in the media of the co-culture of neurons and HUMSCs. Our results demonstrate the therapeutic benefits of HUMSC transplantation for the development of epilepsy, which are likely due to the ability of the cells to produce neuroprotective and anti-inflammatory cytokines. Thus, HUMSC transplantation may be an effective therapy in the future.     

Comparison of pediatric patients with status epilepticus lasting 5–29 min versus ≥ 30 min

The most common thresholds for considering prolonged seizures as status epilepticus (SE) are 5 and 30 min. It is unknown whether these different thresholds (5 or 30 min) identify patient populations with different electroclinical characteristics. We compared the characteristics of patients with SE lasting 5–29 min (SE_5–29) with those with SE lasting ≥ 30 min (SE_≥ 30). Inclusion criteria were the following: 1) 1 month to 21 years of age at the time of SE, 2) convulsive seizures, and 3) seizure duration ≥ 5 min. Exclusion criteria were the following: 1) exclusively neonatal seizures, 2) psychogenic nonepileptic seizures, or 3) incomplete information about seizure duration. Four hundred forty-five patients (50.1% male) with a median (p₂₅–p₇₅) age at SE of 5.5 (2.8–10.5) years were enrolled. Status epilepticus lasted for 5–29 min in 296 (66.5%) of subjects and for ≥ 30 min in 149 (33.5%). Patients with SE_≥ 30 were younger than the patients with SE_5–29 at the time of seizure onset (median: 1 versus 2.1 years, p = 0.0007). Status epilepticus as the first seizure presentation was more frequent in patients with SE_≥ 30 (24.2% versus 12.2%, p = 0.002). There was a tendency towards a higher rate of abnormalities in the magnetic resonance imaging at baseline in patients with SE_≥ 30 (70.5% versus 57.1%, p = 0.061). Differences were not detected in seizure frequency, seizure types, presence of developmental delay, and electroencephalogram abnormalities at baseline. In the pediatric population, SE thresholds of either 5 or 30 min identify groups of patients with very similar electroclinical characteristics, which may influence future definitions of pediatric SE.     

Handedness,eyedness, and hand–eye crossed dominance in patients with different addictions

ObjectiveSome neurologic and psychiatric disorders such as schizophrenia, depression, autism and migraine are referred to as cerebral lateralization abnormalities. In this study the possible relationships among handedness, eye dominance, and crossed hand–eye dominance in patients with different addictions mentioned above are investigated.MethodsThirty three patients with cigarette, 35 patients with alcohol, 133 patients with heroin, 117 patients with hashish, 13 patients with drug addictions and 102 age matched controls were included in the study. Six of 13 patients with drug addictions were addicted to diazepam, 5 to pethidine and 2 to clonazepam. The patient group included 307 men and 24 women who ranged in age from 15 to 70 years. Handedness was ascertained by using the Edinburgh Handedness Inventory. Eye dominance was measured only by the near-far alignment test. Diagnoses were made on the basis of information provided from clinical interviews and Structured Clinical Interview for DSM-IV.ResultsPatients with heroin and hashish had a significantly increased frequency of left-handedness in comparison with the other patients and controls (chi square = 29.36, p < 0.001). Patients with cigarette, alcohol, heroin and hashish addictions had a significantly increased frequency of left-eyedness in comparison with controls (chi square = 25.24, p < 0.01). Also, patients with cigarette, alcohol, heroin and hashish addictions had a significantly increased frequency of the crossed hand–eye dominance in comparison with controls (chi square = 19.11, p < 0.01).ConclusionsDifferent addictions such as cigarette, alcohol, heroin and hashish may be associated with abnormal handedness distribution and accepted as cerebral lateralization abnormalities.     

Status epilepticus in pregnancy: Etiology,management, and clinical outcomes

BackgroundStatus epilepticus (SE) in pregnancy carries significant risk to both mother and fetus. There is limited literature available on SE occurring in pregnancy world-over, with majority being from obstetric centers.MethodsAll women who developed SE related to pregnancy (gestation, labor, or puerperium) between January 2000 and December 2016 were included in the study. Data were collected from our SE registry, maintained, and archived in the institute. The variables influencing the maternal and fetal outcome were compared using Student's t-test for continuous variables and Fisher's exact test for discrete variables.ResultsDuring the 16-year study period, a total of 348 SE events were recorded in 294 patients. Among these, there were 138 women, of which 17 had SE related to pregnancy. The etiology of SE was remote symptomatic in two and acute symptomatic in 15 patients. The various causes detected after initial evaluation for acute symptomatic SE were eclampsia (n = 4), posterior reversible encephalopathy syndrome due to various causes other than eclampsia (n = 6), cortical venous thrombosis (n = 3), subarachnoid hemorrhage (n = 1), and NMDA receptor antibody-mediated encephalitis (n = 1).13 of 17 women with SE (76%) had good outcome. Majority of the fetuses had good outcomes, i.e., Category 1 (n = 9, 57%). Duration of intensive care unit stay (p = 0.029) and Status Epilepticus Severity Score (p = 0.0324) at admission, were found to be significantly associated with poor outcomes.ConclusionIn any patient presenting with SE occurring in pregnancy, though eclampsia is presumed to be the most common overall cause; it is relevant to consider other etiologies such as posterior reversible encephalopathy syndrome, cortical venous thrombosis, and autoimmune encephalitis especially in cases presenting with refractory SE. Posterior reversible encephalopathy may occur in pregnancy due to diverse etiologies other than eclampsia.     

Microinjection of GABAergic agents into the anterior nucleus of the thalamus modulates pilocarpine-induced seizures and status epilepticus

The anterior nucleus of the thalamus (AN) has been suggested as a potential target for seizure modulation in animal models and patients with refractory epilepsy. We investigate whether microinjections of GABAergic agonists into the AN were protective against pilocarpine-induced generalized seizures and status epilepticus (SE). Rats were treated with bilateral AN injections of muscimol (160 or 80 nmol), bicuculline (15 nmol), or saline (controls) 20 min prior to pilocarpine administration (350 mg/kg i.p.). Electrographic recordings were used to confirm seizure activity. We found that pretreatment with AN muscimol 160 nmol increased the latency to seizures and SE by 2.5–3.0-fold. This dose however was associated with side effects, particularly hypotonia. AN bicuculline was proconvulsant, whereas no major effect was observed after muscimol 80 nmol injections. The percentage of animals that developed SE was similar across groups. Overall, microinjection of high doses of muscimol into the AN delayed the occurrence of pilocarpine-induced seizures and SE but was not able to prevent these events.     

Effect of nicotinic acetylcholine receptor alpha 1 (nAChRα1) peptides on rabies virus infection in neuronal cells

Rabies virus (RABV) is neurotropic and causes acute progressive encephalitis. Herein, we report the interaction of nAChRα1-subunit peptides with RABV and the effect of these peptides on RABV infection in cultured neuronal cells. Peptide sequences derived from torpedo, bovine, human and rats were synthesized and studied for their interactions with RABV using virus capture ELISA and peptide immunofluorescence. The results showed specific binding of the nAChRα1-subunit peptides to the RABV. In the virus adsorption assay, these peptides were found to inhibit the attachment of the RABV to the neuronal cells. The nAChRα1-subunit peptides inhibited the RABV infection and reduced viral gene expression in the cultured neuroblastoma (N2A) cells. Torpedo peptide sequence (T-32) had highest antiviral effect (IC₅₀ = 14 ± 3.01 μM) compared to the other peptides studied. The results of the study indicated that nAChRα1-subunit peptides may act as receptor decoy molecules and inhibit the binding of virus to the native host cell receptors and hence may reduce viral infection.     

Effect of enzyme therapy in juvenile patients with Pompe disease: A three-year open-label study

Pompe disease is a rare neuromuscular disorder caused by deficiency of acid α-glucosidase. Treatment with recombinant human α-glucosidase recently received marketing approval based on prolonged survival of affected infants. The current open-label study was performed to evaluate the response in older children (age 5.9–15.2 years). The five patients that we studied had limb-girdle muscle weakness and three of them also had decreased pulmonary function in upright and supine position. They received 20-mg/kg recombinant human α-glucosidase every two weeks over a 3-year period.No infusion-associated reactions were observed. Pulmonary function remained stable (n = 4) or improved slightly (n = 1). Muscle strength increased. Only one patient approached the normal range. Patients obtained higher scores on the Quick Motor Function Test. None of the patients deteriorated. Follow-up data of two unmatched historical cohorts of adults and children with Pompe disease were used for comparison. They showed an average decline in pulmonary function of 1.6% and 5% per year. Data on muscle strength and function of untreated children were not available. Further studies are required.     

Neuroprotective effects of edaravone,a free radical scavenger,on the rat hippocampus after pilocarpine-induced status epilepticus

PurposeEdaravone (MCI-186) is a newly developed antioxidative radical scavenger for the treatment of acute cerebral infarction, exerting neuroprotective effects against ischemic insult. The neuroprotective effects of edaravone on pilocarpine-induced seizures in rats were investigated.MethodsRats were treated intraperitoneally with saline or edaravone (1–30 mg/kg), applied 30 min before pilocarpine hydrochloride (330 mg/kg). The onset of status epilepticus (SE) and mortality were recorded for a period of at least 3 days. The cell loss and immunoreactivities of nitric oxide synthase (NOS) in the hippocampus from control and the day 3 rats after SE, treated with saline or edaravone, were evaluated.ResultsEdaravone (1 mg/kg) significantly prevented cell loss in the hippocampus after SE while easier inducing SE. The higher dose of drug could not induce SE significantly but tended to increase the rate of mortality. Inducible NOS (iNOS) expression was significantly decreased in the hippocampus from day 3 rats treated with 1 mg/kg edaravone, compared with saline group, while neuronal NOS (nNOS) and iNOS significantly increased in the hippocampus treated with saline, compared with control group. Significant alteration of endothelial NOS (eNOS) expression in the hippocampus among control group, saline group, and edaravone group was not shown.ConclusionsEdaravone may act as a neuroprotector for the hippocampus after SE by reducing at least iNOS although the low dose of drug easier induces SE because of preventing an endogenous antiepileptic effect of NO.     

The role of necroptosis in status epilepticus-induced brain injury in juvenile rats

PurposeTo study the role of necroptosis in status epilepticus (SE)-induced injury in the developing brain and the possible associations of necroptosis with epileptogenesis and cognitive dysfunction.MethodsThe lithium-pilocarpine epilepsy model was reproduced in male rats at postnatal day 25. Propidium iodide (PI) staining was used to detect cell death after SE. Transmission electron microscopy (TEM) was performed to observe morphological changes in injured neurons. Western blot and immunofluorescence (IF) staining were used to investigate the expression of receptor interacting protein kinase-3 (RIP3), mixed lineage kinase domain-like (MLKL), and p-MLKL after SE. EEG was monitored during the chronic epileptic period. The Morris water maze test was performed to evaluate spatial learning and memory in juvenile rats after SE.ResultsMassive PI-positive (PI⁺) neurocytes were observed mainly in the amygdala and piriform cortex 24 h to 7 days after SE, with the most prominent changes observed after 72 h. Injured neurons observed via TEM exhibited necroptotic morphological features, including loss of ribosomes, autophagosome formations, deformed nuclei with condensed and marginated chromatin, and disruptive cell membranes. The expression of RIP3 and p-MLKL increased after 24 h, peaked at 72 h, and decreased 7 days after SE. In addition, IF staining revealed that MLKL was expressed in cell plasma membranes present in the amygdala and piriform cortex. This finding was concomitant with the fact that MLKL is involved in executing necroptosis by binding and disrupting the plasma membrane. During the chronic epileptic period, spontaneous recurrent seizures were observed behaviorally and interictal spikes and sharp waves were recorded by EEG in the SE group. The Morris water maze test revealed that in the place navigation test, the escape latency of the SE group was longer than that of the control group (p < 0.05). In the spatial probe test, the number of times the rats in the SE group passed through the original platform site was lesser than that of the rats in the control group (p < 0.05).ConclusionSE-induced brain injury leads to neuronal necroptosis in juvenile rats. MLKL may play a significant role in the execution of SE-induced necroptosis. Further studies are required to determine whether inhibiting necroptosis can prevent chronic epileptogenesis and improve cognitive ability for juvenile rats.     

Ucf-101 protects in vivo and in vitro models of PD against 6-hydroxydopamine toxicity by alleviating endoplasmic reticulum stress via the Wnt/β-catenin pathway

The accumulation of α-syn which induce endoplasmic reticulum stress (ERS) and mediate various signaling pathways involved in DA neuronal degeneration, and the apoptosis of dopamine (DA) neurons are pathological markers of Parkinson’s disease (PD). High-temperature requirement protein A2 (HtrA2) is synthesized in the endoplasmic reticulum, and the expression level of HtrA2 can be upregulated by drugs or by unfolded proteins. Ucf-101 is a specific inhibitor of HtrA2, and studies have shown that Ucf-101 reduced apoptosis in PC12 cells. Our study showed that PC12 cells treated with 60 μM 6-OHDA for 24 h had significantly decreased cell viability compared to that of controls. A low concentration (2.5 μM) of Ucf-101 decreased the apoptosis rate of the PD cell model, but a high concentration (≥10 μM) increased the apoptosis rate, compared to that of controls. 6-OHDA upregulated the expression of HtrA2, α-syn, CHOP, Grp78 and active caspase-3 and reduced the levels of TH and XIAP. Ucf-101 reduced the level of ERS and apoptosis both in vivo and in vitro. The ratio of p-GSK3β (Tyr216 to Ser9) increased in PD rats. However, Ucf-101 down-regulated the activation of GSK3β and activated the Wnt/β-catenin pathway that was caused by 6-OHDA. Ucf-101 activated the Wnt/β-catenin pathway and significantly attenuated 6-OHDA-induced neurotoxicity, which was related to the inhibition of ERS and the reduction of the apoptosis rate of PC12 cells and DA neurons in the midbrain of PD rats. Ucf-101 has certain neuroprotective effects.     

Comparison of risk factors for pediatric convulsive status epilepticus when defined as seizures ≥5 min versus seizures ≥30 min

PurposeTo identify risk factors (RF) of pediatric convulsive status epilepticus (SE) and to determine whether defining SE as seizures ≥5 min (SE₅) or seizures ≥30 min (SE₃₀) would modify the risk factors identified.MethodsRetrospective case–control study. We included patients 1 month to 21 years of age at the time of convulsive SE. We compared the characteristics of patients with SE (cases) versus those without SE (controls) using two different seizure duration thresholds: 5 min and 30 min.Results1062 patients (54% males) were enrolled. The median (p₂₅–p₇₅) age at the episode was 6.4 (2.8–11.8) years. 444 (41.8%) patients had SE₅ and 149 (14%) patients had SE₃₀. On univariate analysis, risk factors for SE were not markedly different when considering a 5 or 30 min threshold. Compared to their respective controls patients with both SE₅ and SE₃₀ were younger at the age of seizure onset and at the age of SE, were on more antiepileptic drugs (AEDs) at baseline, had a higher rate of changes in AEDs in the three months prior to the episode, were more likely to have developmental delay at baseline, and a higher mortality rate. A higher baseline seizure frequency, and a higher increase in seizure frequency prior to the index episode were seen only in SE₅.ConclusionThis series identifies RF which predict convulsive SE in pediatric patients. These RF are similar when considering a 5 min or a 30 min threshold for the definition of SE.     

Oxidative stress mediates hippocampal neuron death in rats after lithium–pilocarpine-induced status epilepticus

Oxidative stress, which is defined as the over-production of free radicals, can dramatically alter neuronal function and has been linked to status epilepticus (SE). The pathological process and underlying mechanisms involved in the oxidative stress during SE are still not fully clear. In the current study, SE was induced in rats by lithium–pilocarpine administration. Our data show that hippocampal neuron death occurs at 6 h and is sustained for 7 days after SE. The production of nitric oxide (NO) started to increase at 30 min and was evident at 6 h and 7 days after SE, which coincided with increased expression of neuronal nitric oxide synthase (nNOS), inducible nitric oxide synthase (iNOS) and malondialdehyde (MDA) after SE, whereas, activated caspase-3 prominently appeared at 7 days after SE. Further, FK506, an immunosuppressant, partially rescued the neuron death and attenuated the expression of NO, nNOS, iNOS, MDA and activated caspase-3. Taken together, our study indicates that oxidative stress mediated hippocampal neuron death occurs prior to caspase-3 activation and that FK506 plays an important role in protecting hippocampal neurons during status epilepticus.     

Chronic glucocorticoids exposure enhances neurodegeneration in the frontal cortex and hippocampus via NLRP-1 inflammasome activation in male mice

Neuroinflammation plays an important role in the pathogenesis of neurodegenerative diseases, such as Alzheimer’s disease (AD) and depression. Chronic glucocorticoids (GCs) exposure has deleterious effects on the structure and function of neurons and is associated with development and progression of AD. However, little is known about the proinflammatory effects of chronic GCs exposure on neurodegeneration in brain. Therefore, the aim of this study was to evaluate the effects of chronic dexamethasone (DEX) treatment (5 mg/kg, s.c. for 7, 14, 21 and 28 days) on behavior, neurodegeneration and neuroinflammatory parameters of nucleotide-binding oligomerization domain-like receptor pyrin domain-containing 1 (NLRP-1) inflammasome in male mice. The results showed that DEX treatment for 21 and 28 days significantly reduced the spontaneous motor activity and exploratory behavior of the mice. In addition, these mice showed significant neurodegeneration and a decrease of microtubule-associated protein 2 (MAP2) in the frontal cortex and hippocampus CA3. DEX treatment for 7, 14, 21 and 28 days significantly decreased the mRNA and protein expression of glucocorticoid receptor (GR). Moreover, DEX treatment for 21 and 28 days significantly increased the proteins expression of NLRP-1, Caspase-1, Caspase-5, apoptosis associated speck-like protein (ASC), nuclear factor-κB (NF-κB), p-NF-κB, interleukin-1β (IL-1β), IL-18 and IL-6 in the frontal cortex and hippocampus brain tissue. DEX treatment for 28 days also significantly increased the mRNA expression levels of NLRP-1, Caspase-1, ASC and IL-1β. These results suggest that chronic GCs exposure may increase brain inflammation via NLRP-1 inflammasome activation and induce neurodegeneration.     

Positron emission tomography findings in children with infantile spasms and autism

The purpose of this study was to evaluate positron emission tomography (PET) findings in patients diagnosed with infantile spasms and autism. This study includes 90 patients who were diagnosed with infantile spasms at the Department of Pediatric Neurology in the Istanbul University Medical Faculty between 1995 and 2007. Of the 90 patients, 15 patients who were diagnosed with autism using the Autism Behaviour Checklist and Childhood Autism Rating Scale and a control group of nine patients without autism but with infantile spasms underwent PET examination. Mean patient age (± standard error, SE) varied between 3 years and 16 years (7.8 ± 4 years), while the mean follow-up time (±SE) varied between 2 years and 16 years (average: 7.1 ± 4 years). Autism was present in 11 patients with symptomatic spasms and in four patients with cryptogenic spasms (p = 0.009). On the PET scans of the 15 patients with autism, 13 (86.7%) had significantly decreased metabolic activity in the temporal lobe (p < 0.001), nine (60%) had significantly decreased activity in the frontal lobe (p = 0.004), and seven (46.7%) had significantly decreased activity in the parietal lobe (p = 0.022). In our opinion, hypometabolism in the frontal and parietal lobes, in addition to that previously reported in the temporal lobe, plays a role in the development of autism in patients with infantile spasms.     

Electrical stimulation of left anterior thalamic nucleus with high-frequency and low-intensity currents reduces the rate of pilocarpine-induced epilepsy in rats

PurposeBilateral electrical stimulation of anterior nuclei of thalamus (ANT) has shown promising effects on epileptic seizures. However, bilateral implantation increases the risk of surgical complications and side effects. This study was undertaken to access the effectiveness of a stimulation paradigm involving high frequency and low intensity currents to stimulate the left ANT in rats.MethodsMale Sprague-Dawley rats were implanted with electroencephalogram (EEG) electrodes, and an additional concentric bipolar stimulation electrode into either the left or right ANT. The stimulus was a train of pulses (90 μs duration each) delivered with a frequency of 200 Hz and a current intensity of 50 μA. Thalamic stimuli were started 1 h before the first intraperitoneal pilocarpine injection (i.p., 300 mg/kg), and were applied for 5 h.ResultsEEG documented seizure activity and status epilepticus (SE) developed in 87.5% of rats treated with no ANT stimulation after a single dose of pilocarpine. Left ANT stimulation significantly increased the tolerance threshold for pilocarpine-induced EEG seizure activity; 20% of rats developed their EEG documented seizure activity after receiving the first dose, whereas 50%, 10% and 20% of rats did not develop seizure activity until they had received the 2nd, 3rd and 4th pilocarpine injection at 1-h intervals. Moreover, left thalamic stimulation reduced the occurrences of both EEG documented seizure activity and SE induced by single-dose pilocarpine to 25%. However, our result demonstrated that little effect on the occurrence rate of seizures and SE was found when rats received right ANT stimulation.ConclusionsThese results suggest that continuously 5-h left ANT stimulation with high frequency and low intensity currents, beginning from 1 h before the pilocarpine administration, may successfully reduce the occurrence rate of EEG documented seizure activity and SE development in rats.