eslicarbazepine and Disease-Models--Animal

Many antiseizure drugs (ASDs) act on voltage-dependent sodium channels, and the molecular basis of these effects is well established. In contrast, how ASDs act on the level of neuronal networks is much less understood.. In the present study, we determined the effects of eslicarbazepine (S-Lic) on different types of inhibitory neurons, as well as inhibitory motifs. Experiments were performed in hippocampal slices from both sham-control and chronically epileptic pilocarpine-treated rats.. We found that S-Lic causes an unexpected reduction of feed-forward inhibition in the CA1 region at high concentrations (300 µM), but not at lower concentrations (100 µM). Concurrently, 300 but not 100 μM S-Lic significantly reduced maximal firing rates in putative feed-forward interneurons located in the CA1 stratum radiatum of sham-control and epileptic animals. In contrast, feedback inhibition was not inhibited by S-Lic. Instead, application of S-Lic, in contrast to previous data for other drugs like carbamazepine (CBZ), resulted in a lasting potentiation of feedback inhibitory post-synaptic currents (IPSCs) only in epileptic and not in sham-control animals, which persisted after washout of S-Lic. We hypothesized that this plasticity of inhibition might rely on anti-Hebbian potentiation of excitatory feedback inputs onto oriens-lacunosum moleculare (OLM) interneurons, which is dependent on Ca. These results suggest that S-Lic affects inhibitory circuits in the CA1 hippocampal region in unexpected ways. In addition, ASD actions may not be sufficiently explained by acute effects on their target channels, rather, it may be necessary to take plasticity of inhibitory circuits into account.

Topics: Adamantane; Animals; Anticonvulsants; CA1 Region, Hippocampal; Calcium; Dibenzazepines; Disease Models, Animal; Dose-Response Relationship, Drug; Epilepsy; Feedback, Physiological; Hippocampus; Inhibitory Postsynaptic Potentials; Interneurons; Long-Term Potentiation; Muscarinic Agonists; Neural Inhibition; Neuronal Plasticity; Neurons; Pilocarpine; Pyramidal Cells; Rats; Receptors, AMPA

Metabolic bone disease and fractures are a great problem for patients with epilepsy. The use of antiepileptic drugs (AEDs) is known to play an essential role in the progression of bone loss by various pathophysiological mechanisms. The aim of this study was to evaluate the effects of AEDs on bone microstructure as an additional cause of an increased fracture risk in patients with epilepsy.. Five groups of each of 12 female rats were orally dosed daily for 8 weeks with either carbamazepine (CBZ) (60 mg/kg), eslicarbazepine (ESL) (80 mg/kg), valproic acid (VPA) (300 mg/kg), levetiracetam (LEV) (50 mg/kg) or saline (control (CTL)). Following killing, dissected femurs were analyzed using X-ray micro-computed tomography (µCT), dual-energy X-ray absorptiometry (DXA) and biomechanical testing. In addition, serum bone turnover markers (BTM) were monitored throughout the experiment.. Compared to CTL treatment, VPA decreased bone volume fraction by 19%, decreased apparent density by 14% and increased structural model index by 41%. No changes were observed in bone biomechanics nor mineral density evaluated by DXA or in levels of BTM.. Our findings suggest that VPA affects the microarchitectural properties of the bone. The AEDs CBZ, ESL and LEV appear to have less adverse effects on bone biology and may be a better choice when treating patients with respect to bone health.

Topics: Animals; Anticonvulsants; Bone and Bones; Carbamazepine; Dibenzazepines; Disease Models, Animal; Epilepsy; Female; Levetiracetam; Rats; Rats, Sprague-Dawley; Valproic Acid; X-Ray Microtomography

Pharmacoresistance is a problem affecting ∼30% of chronic epilepsy patients. An understanding of the mechanisms of pharmacoresistance requires a precise understanding of how antiepileptic drugs interact with their targets in control and epileptic tissue. Although the effects of (S)-licarbazepine (S-Lic) on sodium channel fast inactivation are well understood and have revealed maintained activity in epileptic tissue, it is not known how slow inactivation processes are affected by S-Lic in epilepsy.. We have used voltage clamp recordings in isolated dentate granule cells (DGCs) and cortical pyramidal neurons of control versus chronically epileptic rats (pilocarpine model of epilepsy) and in DGCs isolated from hippocampal specimens from temporal lobe epilepsy patients to examine S-Lic effects on sodium channel slow inactivation.. S-Lic effects on entry into and recovery from slow inactivation were negligible, even at high concentrations of S-Lic (300 μmol/L). Much more pronounced S-Lic effects were observed on the voltage dependence of slow inactivation, with significant effects at 100 μmol/L S-Lic in DGCs from control and epileptic rats or temporal lobe epilepsy patients. For none of these effects of S-Lic could we observe significant differences either between sham-control and epileptic rats, or between human DGCs and the two animal groups. S-Lic was similarly effective in cortical pyramidal neurons from sham-control and epileptic rats. Finally, we show in expression systems that S-Lic effects on slow inactivation voltage dependence are only observed in Na. From these data, we conclude that a major mechanism of action of S-Lic is an effect on slow inactivation, primarily through effects on slow inactivation voltage dependence of Na

Topics: Adult; Analysis of Variance; Animals; Anticonvulsants; Biophysics; Cells, Cultured; Dentate Gyrus; Dibenzazepines; Disease Models, Animal; Dose-Response Relationship, Drug; Electric Stimulation; Epilepsy; Female; Humans; In Vitro Techniques; Male; Membrane Potentials; Middle Aged; Neurons; Patch-Clamp Techniques; Pilocarpine; Rats; Rats, Wistar; Sodium Channels

Oxcarbazepine (OXC), widely used to treat focal epilepsy, is reported to exacerbate seizures in patients with generalized epilepsy. OXC is metabolized to monohydroxy derivatives in two enantiomeric forms: (R)-licarbazepine and (S)-licarbazepine. Eslicarbazepine acetate is a recently approved antiepileptic drug that is rapidly metabolized to (S)-licarbazepine. It is not known whether (S)-licarbazepine exacerbates seizures. Here, we test whether OXC or either of its enantiomers exacerbates the number of spike-and-wave discharges (SWDs) in mice harboring the human γ-aminobutyric acid A receptor (GABAA)γ2(R43Q) mutation. OXC (20 mg/kg), (S)-licarbazepine (20 mg/kg), and (R)-licarbazepine (20 mg/kg) all significantly increased the number of SWDs, while their duration was unaffected. The potential for (S)-licarbazepine to exacerbate SWDs suggests that eslicarbazepine acetate should be used with caution in generalized epilepsy. Furthermore, generalized seizure exacerbation for first-, second-, and third-generation carbamazepine-based compounds is likely to occur through a common mechanism.

Topics: Animals; Anticonvulsants; Brain; Brain Waves; Carbamazepine; Dibenzazepines; Disease Models, Animal; Epilepsy, Generalized; Humans; Mice; Mice, Transgenic; Mutation; Oxcarbazepine; Receptors, GABA-A; Valproic Acid

Latrunculin A microperfusion of the hippocampus induces acute epileptic seizures and long-term biochemical changes leading to spontaneous seizures. This study tested the effect of eslicarbazepine acetate (ESL), a novel antiepileptic drug, on latrunculin A-induced acute and chronic seizures, and changes in brain amino acid extracellular levels. Hippocampi of Swiss mice were continuously perfused with a latrunculin A solution (4 μM, 1 μl/min, 7 h/day) with continuous EEG and videotape recording for 3 consecutive days. Microdialysate samples were analyzed by HPLC and fluorescence detection of taurine, glycine, aspartate, glutamate and GABA. Thereafter, mice were continuously video monitored for two months to identify chronic spontaneous seizures or behavioral changes. Control EEG recordings (8 h) were performed in all animals at least once a week for a minimum of one month.. Oral administration of ESL (100 mg/kg), previous to latrunculin A microperfusion, completely prevented acute latrunculin A-induced seizures as well as chronic seizures and all EEG chronic signs of paroxysmal activity. Hippocampal extracellular levels of taurine, glycine and aspartate were significantly increased during latrunculin A microperfusion, while GABA and glutamate levels remained unchanged. ESL reversed the increases in extracellular taurine, glycine and aspartate concentrations to basal levels and significantly reduced glutamate levels. Plasma and brain bioanalysis showed that ESL was completely metabolized within 1 h after administration to mainly eslicarbazepine, its major active metabolite.. ESL treatment prevented acute latrunculin A-induced seizures as well as chronic seizures and all EEG chronic signs of paroxysmal activity, supporting a possible anti-epileptogenic effect of ESL in mice.

Topics: Acute Disease; Amino Acids; Animals; Anticonvulsants; Aspartic Acid; Bridged Bicyclo Compounds, Heterocyclic; Chronic Disease; Dibenzazepines; Disease Models, Animal; Extracellular Space; gamma-Aminobutyric Acid; Glutamic Acid; Glycine; Hippocampus; Male; Mice; Seizures; Taurine; Thiazolidines