Degenerative Changes in the Claustrum and Endopiriform Nucleus after Early-Life Status Epilepticus in Rats.

The aim of the present study was to analyze the location of degenerating neurons in the dorsal (insular) claustrum (DCL, VCL) and the dorsal, intermediate and ventral endopiriform nucleus (DEn, IEn, VEn) in rat pups following lithium-pilocarpine status epilepticus (SE) induced at postnatal days [P]12, 15, 18, 21 and 25. The presence of Fluoro-Jade B-positive neurons was evaluated at 4, 12, 24, 48 h and 1 week later. A small number of degenerated neurons was observed in the CL, as well as in the DEn at P12 and P15. The number of degenerated neurons was increased in the CL as well as in the DEn at P18 and above and was highest at longer survival intervals. The CL at P15 and 18 contained a small or moderate number of degenerated neurons mainly close to the medial and dorsal margins also designated as DCl ("shell") while isolated degenerated neurons were distributed in the VCl ("core"). In P21 and 25, a larger number of degenerated neurons occurred in both subdivisions of the dorsal claustrum. The majority of degenerated neurons in the endopiriform nucleus were found in the intermediate and caudal third of the DEn. A small number of degenerated neurons was dispersed in the whole extent of the DEn with prevalence to its medial margin. Our results indicate that degenerated neurons in the claustrum CL and endopiriform nucleus are distributed mainly in subdivisions originating from the ventral pallium; their distribution correlates with chemoarchitectonics of both nuclei and with their intrinsic and extrinsic connections.

Infantile status epilepticus disrupts myelin development.

Temporal lobe epilepsy (TLE) is the most prevalent type of epilepsy in adults; it often starts in infancy or early childhood. Although TLE is primarily considered to be a grey matter pathology, a growing body of evidence links this disease with white matter abnormalities. In this study, we explore the impact of TLE onset and progression in the immature brain on white matter integrity and development utilising the rat model of Li-pilocarpine-induced TLE at the 12th postnatal day (P). Diffusion tensor imaging (DTI) and Black-Gold II histology uncovered disruptions in major white matter tracks (corpus callosum, internal and external capsules, and deep cerebral white matter) spreading through the whole brain at P28. These abnormalities were mostly not present any longer at three months after TLE induction, with only limited abnormalities detectable in the external capsule and deep cerebral white matter. Relaxation Along a Fictitious Field in the rotating frame of rank 4 indicated that white matter changes observed at both timepoints, P28 and P72, are consistent with decreased myelin content. The animals affected by TLE-induced white matter abnormalities exhibited increased functional connectivity between the thalamus and medial prefrontal and somatosensory cortex in adulthood. Furthermore, histological analyses of additional animal groups at P15 and P18 showed only mild changes in white matter integrity, suggesting a gradual age-dependent impact of TLE progression. Taken together, TLE progression in the immature brain distorts white matter development with a peak around postnatal day 28, followed by substantial recovery in adulthood. This developmental delay might give rise to cognitive and behavioural comorbidities typical for early-onset TLE.

Adenosine Kinase Isoforms in the Developing Rat Hippocampus after LiCl/Pilocarpine Status Epilepticus.

LiCl/pilocarpine status epilepticus (SE) induced in immature rats leads, after a latent period, to hippocampal hyperexcitability. The excitability may be influenced by adenosine, which exhibits anticonvulsant activity. The concentration of adenosine is regulated by adenosine kinase (ADK) present in two isoforms-ADK-L and ADK-S. The main goal of the study is to elucidate the changes in ADK isoform expression after LiCl/pilocarpine SE and whether potential changes, as well as inhibition of ADK by 5-iodotubercidin (5-ITU), may contribute to changes in hippocampal excitability during brain development. LiCl/pilocarpine SE was elicited in 12-day-old rats. Hippocampal excitability in immature rats was studied by the model of hippocampal afterdischarges (ADs), in which we demonstrated the potential inhibitory effect of 5-ITU. ADs demonstrated significantly decreased hippocampal excitability 3 days after SE induction, whereas significant hyperexcitability after 20 days compared to controls was shown. 5-ITU administration showed its inhibitory effect on the ADs in 32-day-old SE rats compared to SE rats without 5-ITU. Moreover, both ADK isoforms were examined in the immature rat hippocampus. The ADK-L isoform demonstrated significantly decreased expression in 12-day-old SE rats compared to the appropriate naïve rats, whereas increased ADK-S isoform expression was revealed. A decreasing ADK-L/-S ratio showed the declining dominance of ADK-L isoform during early brain development. LiCl/pilocarpine SE increased the excitability of the hippocampus 20 days after SE induction. The ADK inhibitor 5-ITU exhibited anticonvulsant activity at the same age. Age-related differences in hippocampal excitability after SE might correspond to the development of ADK isoform levels in the hippocampus.

Anticonvulsive Effects and Pharmacokinetic Profile of Cannabidiol (CBD) in the Pentylenetetrazol (PTZ) or N-Methyl-D-Aspartate (NMDA) Models of Seizures in Infantile Rats.

In spite of use of cannabidiol (CBD), a non-psychoactive cannabinoid, in pediatric patients with epilepsy, preclinical studies on its effects in immature animals are very limited. In the present study we investigated anti-seizure activity of CBD (10 and 60 mg/kg administered intraperitoneally) in two models of chemically induced seizures in infantile (12-days old) rats. Seizures were induced either with pentylenetetrazol (PTZ) or N-methyl-D-aspartate (NMDA). In parallel, brain and plasma levels of CBD and possible motor adverse effects were assessed in the righting reflex and the bar holding tests. CBD was ineffective against NMDA-induced seizures, but in a dose 60 mg/kg abolished the tonic phase of PTZ-induced generalized seizures. Plasma and brain levels of CBD were determined up to 24 h after administration. Peak CBD levels in the brain (996 ± 128 and 5689 ± 150 ng/g after the 10- and 60-mg/kg doses, respectively) were reached 1-2 h after administration and were still detectable 24 h later (120 ± 12 and 904 ± 63 ng/g, respectively). None of the doses negatively affected motor performance within 1 h after administration, but CBD in both doses blocked improvement in the bar holding test with repeated exposure to this task. Taken together, anti-seizure activity of CBD in infantile animals is dose and model dependent, and at therapeutic doses CBD does not cause motor impairment. The potential risk of CBD for motor learning seen in repeated motor tests has to be further examined.

Interaction of GABAA and GABAB antagonists after status epilepticus in immature rats.

Among neurotransmitter systems affected by status epilepticus (SE) in adult rats are both GABAergic systems. To analyze possible changes of GABAA and GABAB systems in developing rats lithium-pilocarpine SE was induced at postnatal day 12 (P12). Seizures were elicited by a GABAA antagonist pentylenetetrazol (PTZ) 3, 6, 9, and 13 days after SE (i.e., in P15, P18, P21, and P25 rats), and their possible potentiation by a GABAB receptor antagonist CGP46381 was studied. Pilocarpine was replaced by saline in control animals (lithium-paraldehyde [LiPAR]). Pentylenetetrazol in a dose of 50 mg/kg s.c. elicited generalized seizures in nearly all 15-day-old naive rats and in 40% of 18-day-old ones but not in older animals. After SE, PTZ no longer elicited seizures in these two younger groups, i.e., sensitivity of GABAA system was diminished. The GABAB antagonist exhibited proconvulsant effect in P15 and P18 SE as well as LiPAR rats returning the incidence of PTZ-induced seizures to values of control animals. A decrease in the incidence of minimal clonic seizures was seen in P21 LiPAR animals; these seizures in the oldest group were not affected. Change of the effect from proconvulsant to anticonvulsant (or at least to no action) took place before postnatal day 21. Both SE and LiPAR animals exhibited similar changes but their intensity differed, effects in LiPAR controls were usually more expressed than in SE rats.

Neonatal Clonazepam Administration Induced Long-Lasting Changes in GABAA and GABAB Receptors.

Benzodiazepines (BZDs) are widely used in patients of all ages. Unlike adults, neonatal animals treated with BZDs exhibit a variety of behavioral deficits later in life; however, the mechanisms underlying these deficits are poorly understood. This study aims to examine whether administration of clonazepam (CZP; 1 mg/kg/day) in 7-11-day-old rats affects Gama aminobutyric acid (GABA)ergic receptors in both the short and long terms. Using RT-PCR and quantitative autoradiography, we examined the expression of the selected GABAA receptor subunits (α1, α2, α4, γ2, and δ) and the GABAB B2 subunit, and GABAA, benzodiazepine, and GABAB receptor binding 48 h, 1 week, and 2 months after treatment discontinuation. Within one week after CZP cessation, the expression of the α2 subunit was upregulated, whereas that of the δ subunit was downregulated in both the hippocampus and cortex. In the hippocampus, the α4 subunit was downregulated after the 2-month interval. Changes in receptor binding were highly dependent on the receptor type, the interval after treatment cessation, and the brain structure. GABAA receptor binding was increased in almost all of the brain structures after the 48-h interval. BZD-binding was decreased in many brain structures involved in the neuronal networks associated with emotional behavior, anxiety, and cognitive functions after the 2-month interval. Binding of the GABAB receptors changed depending on the interval and brain structure. Overall, the described changes may affect both synaptic development and functioning and may potentially cause behavioral impairment.

Does status epilepticus induced at early postnatal period change excitability after cortical epileptic afterdischarges?

Possible changes of cortical excitability after status epilepticus (SE) elicited in 12-day-old rats were studied by means of paired cortical afterdischarges (ADs). Consequences of lithium-pilocarpine status were studied in animals with implanted electrodes 3, 6, 9, 13, and 26 days after SE. Paired low-frequency stimulation with a 1-min interval was repeated after 10 min, and duration of ADs was measured. Control rats received saline instead of pilocarpine; other treatments were the same as in SE group. Postictal refractoriness (i.e., the testing response significantly shorter than the conditioning one) appeared at the age of 18 days in lithium-paraldehyde controls, whereas SE animals exhibited this phenomenon since postnatal day 21. The only significant difference between SE and lithium-paraldehyde controls was found in the second conditioning AD in the oldest group studied-it was longer in 38-day-old SE animals. Our results demonstrated moderate signs of higher excitability of SE rats in comparison with control ones long before appearance of spontaneous seizures.

Developmental patterns of postictal refractoriness and potentiation akin to cortical stimulation.

Postictal refractoriness checked by paired stimulations of the limbic structures was demonstrated to fail in rats<2 weeks old. Cortical epileptic afterdischarges were used in our study to examine if this phenomenon is restricted to old cortical structures or if it is a general one. Rats 12, 15, 18, 25, and 90 days old with implanted electrodes formed the experimental groups. Stimulation was performed by 15-s series of 1-msec pulses with suprathreshold intensity and frequency of 8 Hz. Paired stimulation of the cerebral cortex in 12-day-old rats elicited the second afterdischarge, even if the 30-s interval was used. Refractoriness started to appear in the third postnatal week and developed progressively so that 25-day-old rats did not differ from adult animals, that is, an interval longer than 1 min was necessary for elicitation of the second seizure.

Compartmental neuronal degeneration in the ventral striatum induced by status epilepticus in young rats' brain in comparison with adults.

According to experimental and clinical studies, status epilepticus (SE) causes neurodegenerative morphological changes not only in the hippocampus and other limbic structures, it also affects the thalamus and the neocortex. In addition, several studies reported atrophy, metabolic changes, and neuronal degeneration in the dorsal striatum. The literature lacks studies investigating potential neuronal damage in the ventral component of the striatopallidal complex (ventral striatum [VS] and ventral pallidum) in SE experimentations. To better understand the development of neuronal damage in the striatopallidal complex associated with SE, the detected neuronal degeneration in the compartments of the VS, namely, the nucleus accumbens (NAc) and the olfactory tubercle (OT), was analyzed. The experiments were performed on Wistar rats at age of 25-day-old pups and 3-month-old adult animals. Lithium-pilocarpine model of SE was used. Lithium chloride (3 mmol/kg, ip) was injected 24 h before administering pilocarpine (40 mg/kg, ip). This presented study demonstrates the variability of post SE neuronal damage in 25-day-old pups in comparison with 3-month-old adult rats. The NAc exhibited small to moderate number of Fluoro-Jade B (FJB)-positive neurons detected 4 and 8 h post SE intervals. The number of degenerated neurons in the shell subdivision of the NAc significantly increased at survival interval of 12 h after the SE. FJB-positive neurons were evidently more prominent occupying the whole anteroposterior and mediolateral extent of the nucleus at longer survival intervals of 24 and 48 h after the SE. This was also the case in the bordering vicinity between the shell and the core compartments but with clusters of degenerating cells. The severity of damage of the shell subdivision of the NAc reached its peak at an interval of 24 h post SE. Isolated FJB-positive neurons were detected in the ventral peripheral part of the core compartment. Degenerated neurons persisted in the shell subdivision of the NAc 1 week after SE. However, the quantity of cell damage had significantly reduced in comparison with the aforementioned shorter intervals. The third layer of the OT exhibited more degenerated neurons than the second layer. The FJB-positive cells in the young animals were higher than in the adult animals. The morphology of those cells was identical in the two age groups except in the OT.

The outcome of early life status epilepticus-lessons from laboratory animals.

Status epilepticus (SE) is the most common neurologic emergency in children. Both clinical and laboratory studies have demonstrated that SE in early life can cause brain damage and permanent behavioral abnormalities, trigger epileptogenesis, and interfere with normal brain development. In experimental rodent models, the consequences of seizures are dependent upon age, the model used, and seizure duration. In studies involving neonatal and infantile animals, the model used, experimental design, conditions during the experiment, and manipulation of animals can significantly affect the course of the experiments as well as the results obtained. Standardization of laboratory approaches, harmonization of scientific methodology, and improvement in data collection can improve the comparability of data among laboratories.

Adenosine A1 Receptors Participate in Excitability Changes after Cortical Epileptic Afterdischarges in Immature Rats.

Background: Postictal refractoriness, i.e., the inability to elicit a new epileptic seizure immediately after the first one, is present in mature animals. Immature rats did not exhibit this refractoriness, and it is replaced by postictal potentiation. In addition to the immediate postictal potentiation, there is a delayed potentiation present at both ages. These phenomena were studied using cortical epileptic afterdischarges as a model. Objective: We aimed to analyze participation of adenosine A1 receptors in postictal potentiation and depression. Methods: Adenosine A1 receptors were studied by means of Western blotting in the cerebral cortex with a focus on the age groups studied electrophysiologically. Stimulation and recording electrodes were implanted epidurally in 12- and 25-day-old rats. The first stimulation always induced conditioning epileptic afterdischarge (AD), and 1 min after its end, the stimulation was repeated to elicit the second, testing AD. Then, the drugs were administered and paired stimulations were repeated 10 min later. A selective agonist CCPA (0.5 and 1 mg/kg i.p.) and a selective antagonist DPCPX (0.1, 0.5 and 1 mg/kg i.p.) were used to examine the possible participation of adenosine A1 receptors. Results: Control younger animals exhibited potentiation of the testing AD and a moderate increase in both conditioning and testing ADs after an injection of saline. The A1 receptor agonist CCPA shortened both post-drug ADs, and neither potentiation was present. The administration of an antagonist DPCPX resulted in marked prolongation of the conditioning AD (delayed potentiation), and the second testing AD was shorter than the post-drug conditioning AD, i.e., there was no longer immediate potentiation of ADs. To eliminate effects of the solvent dimethylsulfoxide, we added experiments with DPCPX suspended with the help of Tween 80. The results were similar, only the prolongation of ADs was not as large, and the testing ADs were significantly depressed. The older control group exhibited a nearly complete suppression of the first testing AD. There was no significant change in the conditioning and testing ADs after CCPA (delayed potentiation was blocked). Both groups of DPCPX-treated rats (with DMSO or Tween) exhibited significant augmentation of delayed potentiation but no significant difference in the immediate depression. Adenosine A1 receptors were present in the cerebral cortex of both age groups, and their quantity was higher in 12- than in 25-day-old animals. Conclusions: An agonist of the A1 receptor CCPA suppressed both types of postictal potentiation in 12-day-old rats, whereas the A1 antagonist DPCPX suppressed immediate potentiation but markedly augmented the delayed one. Immediate postictal refractoriness in 25-day-old rats was only moderately (non-significantly) affected; meanwhile, the delayed potentiation was strongly augmented.

New insight on the mechanisms of epileptogenesis in the developing brain.

The incidence of epilepsy is at its highest in childhood and seizures can persist for a lifetime. As brain tissue from pediatric patients with epilepsy is rarely available, the analysis of molecular and cellular changes during epileptogenesis, which could serve as targets for treatment approaches, has to rely largely on the analysis of tissue from animal models. However, these data have to be analyzed in the context of the developmental stage when the insult occurs. Here we review the current status of the available animal models, the molecular analysis done in these models, as well as treatment attempts to prevent epileptogenesis in the immature brain. Considering that epilepsy is one of the major childhood neurological diseases, it is remarkable how little is known on epileptogenesis in the immature brain at a molecular level. It is a true challenge for the future to expand the armamentarium of clinically relevant animal models, and systematic analysis of molecular and cellular data to enhance the probability of developing syndrome specific antiepileptogenic treatments and biomarkers for acquired pediatric epileptogenesis.

A companion to the preclinical common data elements for rodent models of pediatric acquired epilepsy: A report of the TASK3-WG1B, Pediatric and Genetic Models Working Group of the ILAE/AES Joint Translational Task Force.

Epilepsy syndromes during the early years of life may be attributed to an acquired insult, such as hypoxic-ischemic injury, infection, status epilepticus, or brain trauma. These conditions are frequently modeled in experimental rodents to delineate mechanisms of epileptogenesis and investigate novel therapeutic strategies. However, heterogeneity and subsequent lack of reproducibility of such models across laboratories is an ongoing challenge to maintain scientific rigor and knowledge advancement. To address this, as part of the TASK3-WG1B Working Group of the International League Against Epilepsy/American Epilepsy Society Joint Translational Task Force, we have developed a series of case report forms (CRFs) to describe common data elements for pediatric acquired epilepsy models in rodents. The "Rodent Models of Pediatric Acquired Epilepsy" Core CRF was designed to capture cohort-general information; while two Specific CRFs encompass physical induction models and chemical induction models, respectively. This companion manuscript describes the key elements of these models and why they are important to be considered and reported consistently. Together, these CRFs provide investigators with the tools to systematically record critical information regarding their chosen model of acquired epilepsy during early life, for improved standardization and transparency across laboratories. These outcomes will support the ultimate goal of such research; that is, to understand the childhood onset-specific biology of epileptogenesis after acquired insults, and translate this knowledge into therapeutics to improve pediatric patient outcomes and minimize the lifetime burden of epilepsy.

A companion to the preclinical common data elements for rodent genetic epilepsy models. A report of the TASK3-WG1B: Paediatric and genetic models working group of the ILAE/AES joint translational TASK force.

Rodent models of epilepsy remain the cornerstone of research into the mechanisms underlying genetic epilepsy. Reproducibility of experiments using these rodent models, occurring across a diversity of laboratories and commercial vendors, remains an issue impacting the cost-effectiveness and scientific rigor of the studies performed. Here, we present two case report forms (CRFs) describing common data elements (CDE) for genetic rodent models, developed by the TASK3-WG1B Working Group of the International League Against Epilepsy (ILAE)/American Epilepsy Society (AES) Joint Translational Task Force. The first CRF relates to genetic rodent models that have been engineered based on variants described in epilepsy patients. The second CRF encompasses both spontaneous and inbred rodent models. This companion piece describes the elements and discusses the important factors to consider before documenting each required element. These CRFs provide tools that allow investigators to more uniformly describe core experimental data on different genetic models across laboratories, with the aim of improving experimental reproducibility and thus translational impact of such studies.

Five percent CO2 is a potent, fast-acting inhalation anticonvulsant.

PURPOSE: CO2 has been long recognized for its anticonvulsant properties. We aimed to determine whether inhaling 5% CO2 can be used to suppress seizures in epilepsy patients. The effect of CO2 on cortical epileptic activity accompanying behavioral seizures was studied in rats and nonhuman primates, and based on these data, preliminary tests were carried out in humans. METHODS: In freely moving rats, cortical afterdischarges paralleled by myoclonic convulsions were evoked by sensorimotor cortex stimulation. Five percent CO2 was applied for 5 min, 3 min before stimulation. In macaque monkeys, hypercarbia was induced by hypoventilation while seizure activity was electrically or chemically evoked in the sensorimotor cortex. Seven patients with drug-resistant partial epilepsy were examined with video-EEG (electroencephalography) and received 5% CO2 in medical carbogen shortly after electrographic seizure onset. RESULTS: In rats, 5% CO2 strongly suppressed cortical afterdischarges, by approximately 75%, whereas responses to single-pulse stimulation were reduced by about 15% only. In macaques, increasing pCO2) from 37 to 44-45 mm Hg (corresponding to inhalation of 5% CO2 or less) suppressed stimulation-induced cortical afterdischarges by about 70% and single, bicuculline-induced epileptiform spikes by approximately 25%. In a pilot trial carried out in seven patients, a rapid termination of electrographic seizures was seen despite the fact that the application of 5% CO2 was started after seizure generalization. CONCLUSIONS: Five percent CO2 has a fast and potent anticonvulsant action. The present data suggest that medical carbogen with 5% CO2 can be used for acute treatment to suppress seizures in epilepsy patients.

Perampanel exhibits anticonvulsant action against pentylentetrazol-induced seizures in immature rats.

Perampanel is a new antiepileptic drug with unique mechanism of action - antagonism of AMPA receptors. Its action in immature animals is not yet sufficiently known therefore we started to study anticonvulsant action of perampanel pretreatment (1-20 mg/kg i.p.) against seizures elicited by pentylenetetrazol. Three age groups of rats were examined - 12, 18 and 25 days old. Perampanel selectively suppressed the tonic phase of generalized seizures in the two younger groups and whole tonic-clonic seizures in the 25-day-old group. It exhibited also an anticonvulsant action against minimal clonic seizures present in control 18- and 25-day-old rats. Perampanel is an effective anticonvulsant drug even at very early stages of brain development.

The GluN2B-Selective Antagonist Ro 25-6981 Is Effective against PTZ-Induced Seizures and Safe for Further Development in Infantile Rats.

The GluN2B subunit of NMDA receptors represents a perspective therapeutic target in various CNS pathologies, including epilepsy. Because of its predominant expression in the immature brain, selective GluN2B antagonists are expected to be more effective early in postnatal development. The aim of this study was to identify age-dependent differences in the anticonvulsant activity of the GluN2B-selective antagonist Ro 25-6981 and assess the safety of this drug for the developing brain. Anticonvulsant activity of Ro 25-6981 (1, 3, and 10 mg/kg) was tested in a pentylenetetrazol (PTZ) model in infantile (12-day-old, P12) and juvenile (25-day-old, P25) rats. Ro 25-6981 (1 or 3 mg/kg/day) was administered from P7 till P11 to assess safety for the developing brain. Animals were then tested repeatedly in a battery of behavioral tests focusing on sensorimotor development, cognition, and emotionality till adulthood. Effects of early exposure to Ro 25-6981 on later seizure susceptibility were tested in the PTZ model. Ro 25-6981 was effective against PTZ-induced seizures in infantile rats, specifically suppressing the tonic phase of the generalized tonic-clonic seizures, but it failed in juveniles. Neither sensorimotor development nor cognitive abilities and emotionality were affected by early-life exposure to Ro 25-6981. Treatment cessation did not affect later seizure susceptibility. Our data are in line with the maturational gradient of the GluN2B-subunit of NMDA receptors and demonstrate developmental differences in the anti-seizure activity of the GluN2B-selective antagonist and its safety for the developing brain.

Anticonvulsant Action of GluN2A-Preferring Antagonist PEAQX in Developing Rats.

The GluN2A subunit of N-methyl-D-aspartate (NMDA) receptors becomes dominant during postnatal development, overgrowing the originally dominant GluN2B subunit. The aim of our study was to show changes of anticonvulsant action of the GluN2A subunit-preferring antagonist during postnatal development of rats. Possible anticonvulsant action of GluN2A-preferring antagonist of NMDA receptors P = [[[(1S)-1-(4-bromophenyl)ethyl]amino](1,2,3,4-tetrahydro-2,3-dioxo-5-quinoxalinyl)methyl]phosphonic acid tetrasodium salt (PEAQX) (5, 10, 20 mg/kg s.c.) was tested in 12-, 18-, and 25-day-old rats in three models of convulsive seizures. Pentylenetetrazol-induced generalized seizures with a loss of righting reflexes generated in the brainstem were suppressed in all three age groups in a dose-dependent manner. Minimal clonic seizures with preserved righting ability exhibited only moderately prolonged latency after the highest dose of PEAQX. Anticonvulsant action of all three doses of PEAQX against cortical epileptic afterdischarges (generated in the forebrain) was found in the 25-day-old animals. The highest dose (20 mg/kg) was efficient also in the two younger groups, which might be due to lower specificity of PEAQX and its partial affinity to the GluN2B subunit. Our results are in agreement with the postero-anterior maturation gradient of subunit composition of NMDA receptors (i.e., an increase of GluN2A representation). In spite of the lower selectivity of PEAQX, our data demonstrate, for the first time, developmental differences in comparison with an antagonist of NMDA receptors with a dominant GluN2B subunit.

Effects of Dizocilpine, Midazolam and Their Co-Application on the Trimethyltin (TMT)-Induced Rat Model of Cognitive Deficit.

Research of treatment options addressing the cognitive deficit associated with neurodegenerative disorders is of particular importance. Application of trimethyltin (TMT) to rats represents a promising model replicating multiple relevant features of such disorders. N-methyl-D-aspartate (NMDA) receptor antagonists and gamma-aminobutyric acid type A (GABAA) receptor potentiators have been reported to alleviate the TMT-induced cognitive deficit. These compounds may provide synergistic interactions in other models. The aim of this study was to investigate, whether co-application of NMDA receptor antagonist dizocilpine (MK-801) and GABAA receptor potentiator midazolam would be associated with an improved effect on the TMT-induced model of cognitive deficit. Wistar rats injected with TMT were repeatedly (12 days) treated with MK-801, midazolam, or both. Subsequently, cognitive performance was assessed. Finally, after a 17-day drug-free period, hippocampal neurodegeneration (neuronal density in CA2/3 subfield in the dorsal hippocampus, dentate gyrus morphometry) were analyzed. All three protective treatments induced similar degree of therapeutic effect in Morris water maze. The results of histological analyses were suggestive of minor protective effect of the combined treatment (MK-801 and midazolam), while these compounds alone were largely ineffective at this time point. Therefore, in terms of mitigation of cognitive deficit, the combined treatment was not associated with improved effect.

Dynamic miRNA changes during the process of epileptogenesis in an infantile and adult-onset model.

Temporal lobe epilepsy (TLE) is the most common epilepsy type. TLE onset in infancy aggravates features like severity, drug responsiveness, or development of comorbidities. These aggravations may arise from altered micro RNA (miRNA) expression specific to the early onset of the disease. Although the miRNA involvement in TLE is widely studied, the relationship between the onset-age and miRNA expression has not been addressed. Here, we investigated the miRNA profile of infantile and adult-onset TLE in rats combining sequencing and PCR. Since miRNA expression changes with the disease progression, we scrutinized miRNA dynamics across three stages: acute, latent, and chronic. We report that infantile-onset TLE leads to changes in the expression of fewer miRNAs across these stages. Interestingly, the miRNA profile in the acute stage of infantile-onset TLE overlaps in dysregulation of miR-132-5p, -205, and -211-3p with the chronic stage of the disease starting in adulthood. The analysis of putative targets linked the majority of dysregulated miRNAs with pathways involved in epilepsy. Our profiling uncovered miRNA expression characteristic for infantile and adulthood-onset epileptogenesis, suggesting the distinct biology underlying TLE in the onset age-dependent matter. Our results indicate the necessity of addressing the onset age as an important parameter in future epilepsy research.