Epileptic spasms in infancy: Transferring rat prenatal betamethasone-postnatal NMDA model to mice.

Epileptic spasms during infancy represent a devastating and refractory epilepsy syndrome. To advance studies on mechanisms and treatment using available mouse mutant models, we transferred our validated rat model of epileptic spasms to mice. Initially, we determined sensitivity of C57BL/6J mice to various doses (12-20 mg/kg) of NMDA on postnatal day 11 (P11) and P15. We primed mice with different doses of betamethasone (0.4-2.0 mg/kg) prenatally on gestational day (G)14 or G12 and tested spasms on P11. We also tested 2 different ACTH treatment paradigms (0.3 or 1.0 mg/kg) in prenatally primed as well as naïve mice. Data show that spasms in P11 mice, can be induced with the highest yield after 12 mg/kg dose of NMDA. Prenatal priming on G14 did not modify response to NMDA or sensitize spasms to ACTH. The betamethasone priming on G12 resulted in an increase in the number of NMDA-triggered spasms. Data indicate that the model transfer from rats to mice is non-linear and differences in prenatal brain development, metabolic rates, as well as sensitivity to convulsant drugs have to be considered.

Astrocyte and Neuronal Panx1 Support Long-Term Reference Memory in Mice.

Pannexin 1 (Panx1) is an ubiquitously expressed protein that forms plasma membrane channels permeable to anions and moderate-sized signaling molecules (e.g., ATP, glutamate). In the nervous system, activation of Panx1 channels has been extensively shown to contribute to distinct neurological disorders (epilepsy, chronic pain, migraine, neuroAIDS, etc.), but knowledge of the extent to which these channels have a physiological role remains restricted to three studies supporting their involvement in hippocampus dependent learning. Given that Panx1 channels may provide an important mechanism for activity-dependent neuron-glia interaction, we used Panx1 transgenic mice with global and cell-type specific deletions of Panx1 to interrogate their participation in working and reference memory. Using the eight-arm radial maze, we show that long-term spatial reference memory, but not spatial working memory, is deficient in Panx1-null mice and that both astrocyte and neuronal Panx1 contribute to the consolidation of long-term spatial memory. Field potential recordings in hippocampal slices of Panx1-null mice revealed an attenuation of both long-term potentiation (LTP) of synaptic strength and long-term depression (LTD) at Schaffer collateral-CA1 synapses without alterations of basal synaptic transmission or pre-synaptic paired-pulse facilitation. Our results implicate both neuronal and astrocyte Panx1 channels as critical players for the development and maintenance of long-term spatial reference memory in mice.

Astrocyte and neuronal Panx1 support long-term reference memory in mice.

Pannexin 1 (Panx1) are ubiquitously expressed proteins that form plasma membrane channels permeable to anions and moderate sized signaling molecules (e.g., ATP, glutamate). In the nervous system, activation of Panx1 channels have been extensively shown to contribute to distinct neurological disorders (epilepsy, chronic pain, migraine, neuroAIDS, etc.) but knowledge of extent to which these channels have a physiological role remains restricted to three studies supporting their involvement in hippocampus dependent learning. Given that Panx1 channels may provide an important mechanism for activity-dependent neuron-glia interaction, we used Panx1 transgenic mice with global and cell-type specific deletions of Panx1 to interrogate their participation in working and reference memory. Using the 8-arm radial maze, we show that long-term spatial reference memory, but not spatial working memory, is deficient in Panx1-null mice and that both astrocyte and neuronal Panx1 contribute to the consolidation of long-term spatial memory. Field potential recordings in hippocampal slices of Panx1-null mice revealed an attenuation of both long-term potentiation (LTP) of synaptic strength and long-term depression (LTD) at Schaffer collateral - CA1 synapses without alterations basal synaptic transmission or pre-synaptic paired-pulse facilitation. Our results implicate both neuronal and astrocyte Panx1 channels as critical players for the development and maintenance of long-term spatial reference memory in mice.

Human cortical interneurons optimized for grafting specifically integrate, abort seizures, and display prolonged efficacy without over-inhibition.

Previously, we demonstrated the efficacy of human pluripotent stem cell (hPSC)-derived GABAergic cortical interneuron (cIN) grafts in ameliorating seizures. However, a safe and reliable clinical translation requires a mechanistic understanding of graft function, as well as the assurance of long-term efficacy and safety. By employing hPSC-derived chemically matured migratory cINs in two models of epilepsy, we demonstrate lasting efficacy in treating seizures and comorbid deficits, as well as safety without uncontrolled growth. Host inhibition does not increase with increasing grafted cIN densities, assuring their safety without the risk of over-inhibition. Furthermore, their closed-loop optogenetic activation aborted seizure activity, revealing mechanisms of graft-mediated seizure control and allowing graft modulation for optimal translation. Monosynaptic tracing shows their extensive and specific synaptic connections with host neurons, resembling developmental connection specificity. These results offer confidence in stem cell-based therapy for epilepsy as a safe and reliable treatment for patients suffering from intractable epilepsy.

Novel neurosteroid pregnanolone pyroglutamate suppresses neurotoxicity syndrome induced by tetramethylenedisulfotetramine but is ineffective in a rodent model of infantile spasms.

BACKGROUND: Neurosteroids are investigated as effective antidotes for the poisoning induced by tetramethylenedisulfotetramine (TMDT) as well as treatments for epileptic spasms during infancy. Both these conditions are quite resistant to pharmacotherapy; thus, a search for new treatments is warranted. METHODS: In this study, we determined the efficacy of two novel neurosteroids, pregnanolone glutamate (PAG) and pregnanolone pyroglutamate (PPG), and tested these drugs in doses of 1-10 mg/kg (ip) against the TMDT syndrome and in our rodent model of infantile spasms. RESULTS: Only PPG in doses 5 and 10 mg/kg suppressed the severity of the TMDT syndrome and TMDT-induced lethality, while the 1 mg/kg dose was without an effect. Interestingly, the 1 mg/kg dose of PPG in combination with 1 mg/kg of diazepam was also effective against TMDT poisoning. Neither PAG nor PPG were effective against experimental spasms in the N-methyl-D-aspartate (NMDA)-triggered model of infantile spasms. CONCLUSIONS: While evidence suggests that PAG can act through multiple actions which include allosteric inhibition of NMDA-induced and glycine receptor-evoked currents as well as augmentation of É£-aminobutyric acid subtype A (GABAA) receptor-induced currents, the agent appears to neither have the appropriate mechanistic signature for activity in the infantile spasm model, nor the adequate potency, relative to PPG, for ameliorating the TMDT syndrome. The full mechanisms of action of PPG, which may become a potent TMDT antidote either alone or in combination with diazepam are yet unknown and thus require further investigation.

Early onset epilepsy and sudden unexpected death in epilepsy with cardiac arrhythmia in mice carrying the early infantile epileptic encephalopathy 47 gain-of-function FHF1(FGF12) missense mutation.

OBJECTIVE: Fibroblast growth factor homologous factors (FHFs) are brain and cardiac sodium channel-binding proteins that modulate channel density and inactivation gating. A recurrent de novo gain-of-function missense mutation in the FHF1(FGF12) gene (p.Arg52His) is associated with early infantile epileptic encephalopathy 47 (EIEE47; Online Mendelian Inheritance in Man database 617166). To determine whether the FHF1 missense mutation is sufficient to cause EIEE and to establish an animal model for EIEE47, we sought to engineer this mutation into mice. METHODS: The Arg52His mutation was introduced into fertilized eggs by CRISPR (clustered regularly interspaced short palindromic repeats) editing to generate Fhf1R52H/F+ mice. Spontaneous epileptiform events in Fhf1R52H/+ mice were assessed by cortical electroencephalography (EEG) and video monitoring. Basal heart rhythm and seizure-induced arrhythmia were recorded by electrocardiography. Modulation of cardiac sodium channel inactivation by FHF1BR52H protein was assayed by voltage-clamp recordings of FHF-deficient mouse cardiomyocytes infected with adenoviruses expressing wild-type FHF1B or FHF1BR52H protein. RESULTS: All Fhf1R52H/+ mice experienced seizure or seizurelike episodes with lethal ending between 12 and 26 days of age. EEG recordings in 19-20-day-old mice confirmed sudden unexpected death in epilepsy (SUDEP) as severe tonic seizures immediately preceding loss of brain activity and death. Within 2-53 s after lethal seizure onset, heart rate abruptly declined from 572 ± 16 bpm to 108 ± 15 bpm, suggesting a parasympathetic surge accompanying seizures that may have contributed to SUDEP. Although ectopic overexpression of FHF1BR52H in cardiomyocytes induced a 15-mV depolarizing shift in voltage of steady-state sodium channel inactivation and slowed the rate of channel inactivation, heart rhythm was normal in Fhf1R52H/+ mice prior to seizure. SIGNIFICANCE: The Fhf1 missense mutation p.Arg52His induces epileptic encephalopathy with full penetrance in mice. Both Fhf1 (p.Arg52His) and Scn8a (p.Asn1768Asp) missense mutations enhance sodium channel Nav 1.6 currents and induce SUDEP with bradycardia in mice, suggesting an FHF1/Nav 1.6 functional axis underlying altered brain sodium channel gating in epileptic encephalopathy.

The Contribution of Astrocyte and Neuronal Panx1 to Seizures Is Model and Brain Region Dependent.

Pannexin1 (Panx1) is an ATP release channel expressed in neurons and astrocytes that plays important roles in CNS physiology and pathology. Evidence for the involvement of Panx1 in seizures includes the reduction of epileptiform activity and ictal discharges following Panx1 channel blockade or deletion. However, very little is known about the relative contribution of astrocyte and neuronal Panx1 channels to hyperexcitability. To this end, mice with global and cell type specific deletion of Panx1 were used in one in vivo and two in vitro seizure models. In the low-Mg2+in vitro model, global deletion but not cell-type specific deletion of Panx1 reduced the frequency of epileptiform discharges. This reduced frequency of discharges did not impact the overall power spectra obtained from local field potentials. In the in vitro KA model, in contrast, global or cell type specific deletion of Panx1 did not affect the frequency of discharges, but reduced the overall power spectra. EEG recordings following KA-injection in vivo revealed that although global deletion of Panx1 did not affect the onset of status epilepticus (SE), SE onset was delayed in mice lacking neuronal Panx1 and accelerated in mice lacking astrocyte Panx1. EEG power spectral analysis disclosed a Panx1-dependent cortical region effect; while in the occipital region, overall spectral power was reduced in all three Panx1 genotypes; in the frontal cortex, the overall power was not affected by deletion of Panx1. Together, our results show that the contribution of Panx1 to ictal activity is model, cell-type and brain region dependent.

Modeling epileptic spasms during infancy: Are we heading for the treatment yet?

Infantile spasms (IS or epileptic spasms during infancy) were first described by Dr. William James West (aka West syndrome) in his own son in 1841. While rare by definition (occurring in 1 per 3200-3400 live births), IS represent a major social and treatment burden. The etiology of IS varies - there are many (>200) different known pathologies resulting in IS and still in about one third of cases there is no obvious reason. With the advancement of genetic analysis, role of certain genes (such as ARX or CDKL5 and others) in IS appears to be important. Current treatment strategies with incomplete efficacy and serious potential adverse effects include adrenocorticotropin (ACTH), corticosteroids (prednisone, prednisolone) and vigabatrin, more recently also a combination of hormones and vigabatrin. Second line treatments include pyridoxine (vitamin B6) and ketogenic diet. Additional treatment approaches use rapamycin, cannabidiol, valproic acid and other anti-seizure medications. Efficacy of these second line medications is variable but usually inferior to hormonal treatments and vigabatrin. Thus, new and effective models of this devastating condition are required for the search of additional treatment options as well as for better understanding the mechanisms of IS. Currently, eight models of IS are reviewed along with the ideas and mechanisms behind these models, drugs tested using the models and their efficacy and usefulness. Etiological variety of IS is somewhat reflected in the variety of the models. However, it seems that for finding precise personalized approaches, this variety is necessary as there is no "one-size-fits-all" approach possible for both IS in particular and epilepsy in general.

Developmental decrease in parvalbumin-positive neurons precedes increase in flurothyl-induced seizure susceptibility in the Brd2+/- mouse model of juvenile myoclonic epilepsy.

OBJECTIVE: BRD2 is a human gene repeatedly linked to and associated with juvenile myoclonic epilepsy (JME). Here, we define the developmental stage when increased seizure susceptibility first manifests in heterozygous Brd2+/- mice, an animal model of JME. We wanted to determine (1) whether seizure susceptibility correlates with the proven decrease of γ-aminobutyric acidergic (GABAergic) neuron numbers and (2) whether the seizure phenotype can be affected by sex hormones. METHODS: Heterozygous (Brd2+/-) and wild-type (wt) mice of both sexes were tested for flurothyl-induced seizure susceptibility at postnatal day 15 (P15; wt, n = 13; Brd2+/-, n = 20), at P30 (wt, n = 20; Brd2+/-, n = 20), and in adulthood (5-6 months of age; wt, n = 10; Brd2+/-, n = 12). We measured latency to clonic and tonic-clonic seizure onset (flurothyl threshold). We also compared relative density of parvalbumin-positive (PVA+) and GAD67+ GABA neurons in the striatum and primary motor (M1) neocortex of P15 (n = 6-13 mice per subgroup) and P30 (n = 7-10 mice per subgroup) mice. Additional neonatal Brd2+/- mice were injected with testosterone propionate (females) or formestane (males) and challenged with flurothyl at P30. RESULTS: P15 Brd2+/- mice showed no difference in seizure susceptibility compared to P15 wt mice. However, even at this early age, Brd2+/- mice showed fewer PVA+ neurons in the striatum and M1 neocortex. Compared to wt, the striatum in Brd2+/- mice showed an increased proportion of immature PVA+ neurons, with smaller cell bodies and limited dendritic arborization. P30 Brd2+/- mice displayed increased susceptibility to flurothyl-induced clonic seizures compared to wt. Both genotype and sex strongly influenced the density of PVA+ neurons in the striatum. Susceptibility to clonic seizures remained increased in adult Brd2+/- mice, and additionally there was increased susceptibility to tonic-clonic seizures. In P30 females, neonatal testosterone reduced the number of flurothyl-induced clonic seizures. SIGNIFICANCE: A decrease in striatal PVA+ GABAergic neurons developmentally precedes the onset of increased seizure susceptibility and likely contributes to the expression of the syndrome.

ACTON PROLONGATUM® suppresses spasms head to head with Acthar® Gel in the model of infantile spasms.

Epileptic spasms during infancy (infantile spasms, IS) are a rare epilepsy syndrome with dire prognosis. Current treatments, effective in about 55% of cases, include hormonal therapy (adrenocorticotropic hormone [ACTH] = adrenocorticotropin or corticosteroids) or vigabatrin (also in combination with hormones). In addition to their limited efficacy, these treatments may also carry serious adverse effects. Thus, the search for new effective drugs to treat this rare disease is desirable. In this study, we determined the efficacy of ACTON PROLONGATUM® (AP; Ferring Pharmaceuticals) in comparison with Acthar® Gel (Mallinckrodt) and full 39 amino-acid rat ACTH molecule (Genscript) in the rodent model of IS consisting of prenatal priming with betamethasone and repeated postnatal trigger of spasms with N-methyl-d-aspartate. Treatment with these ACTH varieties was given on postnatal days (P)12, P13, and P14 in a prospective test (treatment onset on P12 AFTER induction of spasms). Two independent arms were investigated: subcutaneous (SC) and intramuscular (IM) deliveries that were evaluated separately. In the SC arm, there was a significant suppression of the number of spasms after both Acthar® Gel and AP on P13 and P15 compared with gelatin control. In the IM arm, a significant suppression of the number of spasms was achieved only after AP on both P13 and P15 indicating that after IM delivery, Acthar® Gel was not as effective as AP. In this study, we confirmed the efficacy of two ACTH formulations (gelatin-based Acthar® Gel and carboxymethyl cellulose-based AP) in the model of IS. ACTON PROLONGATUM® may become a valuable therapy for IS. In our animal model, AP was at least as efficient as the standard of care, Acthar® Gel.

Prenatal betamethasone exposure increases corticotropin-releasing hormone expression along with increased hippocampal slice excitability in the developing hippocampus.

BACKGROUND: The objective of this study was to determine whether prenatal exposure to betamethasone alters hippocampal expression of corticotropin-releasing hormone (CRH) and resultant hippocampal circuit excitability. METHODS: Real time (RT)-PCR and western blots were used to determine CRH mRNA and protein expression levels, respectively, in hippocampal extracts of two-week old rat pups prenatally primed with betamethasone or saline on gestational day 15. The data were compared to changes in epileptiform activity induced by kainic acid (KA) or depletion of [Mg2+]0 in combined hippocampus-entorhinal cortex slices. RESULTS: RT-PCR analysis showed 3-fold increased levels of CRH mRNA in hippocampal extracts from prenatally betamethasone-primed pups compared to saline controls (p < 0.05), but no changes in mRNA expression of CRH receptors (1 and 2). Changes in CRH protein isoform ratio in hippocampal extracts suggest 30 % increase in mature CRH levels in betamethasone-primed hippocampi (p < 0.05). No changes in mRNA expression in CRH feedback loop associated genes, GR and FKBP51, were found. Compared to saline-exposed pups, slices from betamethasone-primed pups had faster onset of epileptiform-like activity (inter-ictal discharges and seizure-like-events) after bath application of 4 µM KA (p < 0.05) suggesting a "more hyperexcitable" state. The epileptiform-like activity after KA application was significantly reduced following bath application of a CRH R2 antagonist (p < 0.05) but CRH R1 antagonist had no effect (p > 0.05). Also in the low-Mg2+-induced epileptiform activity, there was increased excitability, in the form of enhanced inter-ictal discharges, in slices from betamethasone primed compared to saline exposed rat pups (p < 0.05). CONCLUSIONS: Our study suggests a possible mechanistic link to prenatal betamethasone priming-induced increase in postnatal hippocampal excitability that involves enhanced expression of CRH acting at CRH R2. This is important in regards to the links between prenatal stress/corticosteroid-exposure and syndromes, such as epilepsy, autism spectrum disorders and other psychiatric disorders associated with neuronal hyperexcitability.

Tetramethylenedisulfotetramine neurotoxicity: What have we learned in the past 70 years?

Tetramethylenedisulfotetramine (tetramine, TETS, TMDT) is a seizure-producing neurotoxic chemical formed by the condensation of sulfamide and formaldehyde. Serendipitously discovered through an occupational exposure in 1949, it was promoted as a rodenticide but later banned worldwide due to its danger to human health. However, exceptional activity of the agent against rodent pests resulted in its clandestine manufacture with large numbers of inadvertent, intentional, and mass poisonings, which continue to this day. Facile synthesis, extreme potency, persistence, lack of odor, color, and taste identify it as an effective food adulterant and potential chemical agent of terror. No known antidote or targeted treatment is currently available. In this review we examine the origins of tetramethylenedisulfotetramine, from its identification as a neurotoxicant 70 years ago, through early research, to the most recent findings including the risk it poses in the post-911 world. Included is the information known regarding its in vitro pharmacology as a GABAA receptor channel antagonist, the toxic syndrome it produces in vivo, and its effect upon vulnerable populations. We also summarize the available information about potential therapeutic countermeasures and treatment strategies as well as the contribution of clinical development of TMDT poisoning to our understanding of epileptogenesis. Finally we identify gaps in our knowledge and suggest potentially fruitful directions for continued research on this dangerous, yet intriguing compound.

Mouse model of human poisonings with tetramethylenedisulfotetramine: Characterization of the effect of exposure route on syndrome outcomes.

Tetramethylenedisulfotetramine (TMDT) is a synthetic neurotoxic rodenticide and potential chemical threat agent. Signs of TMDT poisoning include convulsions which can progress into status epilepticus and death. Although clinical reports clearly show that poisoning via food and drink is the main route of exposure, experimental studies have primarily utilized parenteral routes. Here we used two different modes of oral administration of TMDT and compared the toxic outcomes with two different parenteral routes. Adult male mice were given various doses of TMDT either perorally in peanut butter or cereal pellets, or injected intraperitoneally (i.p.) or subcutaneously (s.c.). All routes produced the complete TMDT syndrome including twitches, clonic and tonic-clonic seizures and death. However potencies varied with the following rank order: i.p. > s.c. > oral (cereal)>>oral (peanut butter). Our data clearly show that ingestion of TMDT with peanut butter markedly reduces the overall syndrome severity relative to oral exposure via cereals. No significant differences were observed by substituting peanut oil for water as a vehicle for i.p. administered TMDT. In conclusion, high vs low fat food can differentially affect TMDT onset of action, probably due to differences in availability from the gastrointestinal tract. These results should be considered when searching for effective treatments for TMDT poisoning.

Astrocyte and Neuronal Pannexin1 Contribute Distinctly to Seizures.

ATP- and adenosine-mediated signaling are prominent types of glia-glia and glia-neuron interaction, with an imbalance of ATP/adenosine ratio leading to altered states of excitability, as seen in epileptic seizures. Pannexin1 (Panx1), a member of the gap junction family, is an ATP release channel that is expressed in astrocytes and neurons. Previous studies provided evidence supporting a role for purinergic-mediated signaling via Panx1 channels in seizures; using mice with global deletion of Panx1, it was shown that these channels contribute in maintenance of seizures by releasing ATP. However, nothing is known about the extent to which astrocyte and neuronal Panx1 might differently contribute to seizures. We here show that targeted deletion of Panx1 in astrocytes or neurons has opposing effects on acute seizures induced by kainic acid. The absence of Panx1 in astrocytes potentiates while the absence of Panx1 in neurons attenuates seizure manifestation. Immunohistochemical analysis performed in brains of these mice, revealed that adenosine kinase (ADK), an enzyme that regulates extracellular levels of adenosine, was increased only in seized GFAP-Cre:Panx1f/f mice. Pretreating mice with the ADK inhibitor, idotubercidin, improved seizure outcome and prevented the increase in ADK immunoreactivity. Together, these data suggest that the worsening of seizures seen in mice lacking astrocyte Panx1 is likely related to low levels of extracellular adenosine due to the increased ADK levels in astrocytes. Our study not only reveals an unexpected link between Panx1 channels and ADK but also highlights the important role played by astrocyte Panx1 channels in controlling neuronal activity.

AQB-565 shows promise in preclinical testing in the model of epileptic spasms during infancy: Head-to-head comparison with ACTH.

Epileptic spasms during infancy (infantile spasms) represent a serious treatment and social problem despite their rare occurrence. Current treatments include hormonal therapy (adrenocorticotropin-ACTH or corticosteroids) or vigabatrin (per se or in the combination). These treatments are partially effective and with potentially significant adverse effects. Thus, the search for new effective drugs is warranted. We tested efficacy of a novel fusion peptide AQB-565 developed by Aequus Biopharma in a model of infantile spasms consisting of prenatal exposure to betamethasone and repeated postnatal trigger of spasms with N-methyl-d-aspartic acid (NMDA). AQB-565 molecule includes the first 24 amino acids of ACTH, a ten amino acid linker and a modified melanocyte-stimulating hormone molecule. In contrast to ACTH with almost uniform activity over all peripheral and central melanocortin receptor isoforms, AQB is preferentially active on central melanocortin receptors MC3 and MC4. Here, we used equivalent doses of rat ACTH (full molecule) and AQB-565 and compared their efficacy in a prospective randomized test against of repeated bouts of spasms on postnatal days (P)12, P13 and P15 in the rat model. All doses of ACTH (range 0.02-1.0 mg/kg s.c.) and all doses but one of AQB-565 in the same range suppressed spasms in P15 rats (treatment stopped on P14). There was no dose-dependent effect and both compounds had all-or-none effect that is similar to clinical outcome of hormonal treatment of infantile spasms in children. Thus, AQB-565 may represent a novel treatment of infantile spasms similarly effective as ACTH but with potentially limited side effects.

Reduced Hippocampal Dendrite Branching, Spine Density and Neurocognitive Function in Premature Rabbits, and Reversal with Estrogen or TrkB Agonist Treatment.

Preterm-born children suffer from neurological and behavioral disorders. Herein, we hypothesized that premature birth and non-maternal care of preterm newborns might disrupt neurobehavioral function, hippocampal dendritic arborization, and dendritic spine density. Additionally, we assessed whether 17ß-estradiol (E2) replacement or the TrkB receptor agonist, 7,8-dihydroxyflavone (DHF), would reverse compromised dendritic development and cognitive function in preterm newborns. These hypotheses were tested by comparing preterm (E28.5) rabbit kits cared and gavage-fed by laboratory personnel and term-kits reared and breast-fed by their mother doe at an equivalent postconceptional age. Neurobehavioral tests showed that both premature-birth and formula-feeding with non-maternal care led to increased anxiety behavior, poor social interaction, and lack of novelty preference compared with term-kits. Dendritic branching and number of total or mushroom dendritic spines were reduced in the CA1 field of preterm-kits compared with term controls. While CDC42 and Rac1/2/3 expression levels were lower, RhoA-activity was higher in preterm-kits compared with term controls. Both E2 and DHF treatment reversed prematurity-induced reduction in spine density, reduced total RhoA-GTPase levels, and enhanced cognitive function. Hence, prematurity and non-maternal care result in cognitive deficits, and reduced dendritic arbors and spines in CA1. E2 replacement or DHF treatment might reverse changes in dendritic spines and improve neurodevelopment in premature infants.

Exciting and not so exciting roles of pannexins.

It is the current view that purinergic signaling regulates many physiological functions. Pannexin1 (Panx1), a member of the gap junction family of proteins is an ATP releasing channel that plays important physio-pathological roles in various tissues, including the CNS. Upon binding to purinergic receptors expressed in neural cells, ATP triggers cellular responses including increased cell proliferation, cell morphology changes, release of cytokines, and regulation of neuronal excitability via release of glutamate, GABA and ATP itself. Under pathological conditions such as ischemia, trauma, inflammation, and epilepsy, extracellular ATP concentrations increases drastically but the consequences of this surge is still difficult to characterize due to its rapid metabolism in ADP and adenosine, the latter having inhibitory action on neuronal activity. For seizures, for instance, the excitatory effect of ATP on neuronal activity is mainly related to its action of P2X receptors, while the inhibitory effects are related to activation of P1, adenosine receptors. Here we provide a mini review on the properties of pannexins with a main focus on Panx1 and its involvement in seizure activity. Although there are only few studies implicating Panx1 in seizures, they are illustrative of the dual role that Panx1 has on neuronal excitability.

A companion to the preclinical common data elements on neurobehavioral comorbidities of epilepsy: a report of the TASK3 behavior working group of the ILAE/AES Joint Translational Task Force.

The provided companion has been developed by the Behavioral Working Group of the Joint Translational Task Force of the International League Against Epilepsy (ILAE) and the American Epilepsy Society (AES) with the purpose of assisting the implementation of Preclinical Common Data Elements (CDE) for studying and for reporting neurobehavioral comorbidities in rodent models of epilepsy. Case Report Forms (CRFs) are provided, which should be completed on a per animal/per test basis, whereas the CDEs are a compiled list of the elements that should be reported. This companion is not designed as a list of recommendations, or guidelines for how the tests should be run-rather, it describes the different types of assessments, and highlights the importance of rigorous data collection and transparency in this regard. The tests are divided into 7 categories for examining behavioral dysfunction on the syndrome level: deficits in learning and memory; depression; anxiety; autism; attention deficit/hyperactivity disorder; psychosis; and aggression. Correspondence and integration of these categories into the National Institute of Mental Health (NIMH) Research Domain Criteria (RDoC) is introduced. Developmental aspects are addressed through the introduction of developmental milestones. Discussion includes complexities, limitations, and biases associated with neurobehavioral testing, especially when performed in animals with epilepsy, as well as the importance of rigorous data collection and of transparent reporting. This represents, to our knowledge, the first such resource dedicated to preclinical CDEs for behavioral testing of rodents.

Estrogen Protects Neurotransmission Transcriptome During Status Epilepticus.

Women with epilepsy commonly have premature onset of menopause. The decrease in estrogen levels is associated with increased occurrence of neurodegenerative processes and cognitive decline. Previously, we found that estradiol (E2) replacement in ovariectomized (OVX) female rats significantly reduced the seizure-related damage in the sensitive hilar region of hippocampal dentate gyrus (DG). However, the complex mechanisms by which E2 empowers the genomic fabrics of neurotransmission to resist damaging effects of status epilepticus (SE) are still unclear. We determined the protective effects of the estradiol replacement against kainic acid-induced SE-associated transcriptomic alterations in the DG of OVX rats. Without E2 replacement, SE altered expression of 44% of the DG genes. SE affected all major functional pathways, including apoptosis (61%), Alzheimer's disease (47%), cell cycle (59%), long-term potentiation (62%), and depression (55%), as well as synaptic vesicle cycle (62%), glutamatergic (53%), GABAergic (49%), cholinergic (52%), dopaminergic (55%), and serotonergic (49%) neurotransmission. However, in rats with E2 replacement the percentage of significantly affected genes after SE was reduced to the average 11% (from 8% for apoptosis to 32% for GABAergic synapse). Interestingly, while SE down-regulated most of the synaptic receptor genes in oil-injected females it had little effect on these receptors after E2-replacement. Our novel Pathway Protection analysis indicated that the E2-replacement prevented SE-related damage from 50% for GABA to 75% for dopaminergic transmission. The 15% synergistic expression between genes involved in estrogen signaling (ESG) and neurotransmission explains why low E2 levels result in down-regulation of neurotransmission. Interestingly, in animals with E2-replacement, SE switched 131 synergistically expressed ESG-neurotransmission gene pairs into antagonistically expressed gene pairs. Thus, the ESG pathway acts like a buffer against SE-induced alteration of neurotransmission that may contribute to the E2-mediated maintenance of brain function after the SE injury in postmenopausal women. We also show that the long-term potentiation is lost in OVX rats following SE but not in those with E2 replacement. The electrophysiological findings in OVX female rats with SE are corroborated by the high percentage of long-term potentiation regulated genes (62%) in oil-injected while only 13% of genes were regulated following SE in E2-replaced rats.