| Popis |
Introduction: Epilepsy is a neurological disorder characterized by hypersynchronous neuronal activity and caused by many factors. A potential relationship between accumulation of neurodegeneration-associated proteins (NAPs) and hyperexcitability have been suggested. In this study, we focused on analyzing ex vivo electrical activity of hippocampal slices from patients with drug-resistant temporal lobe epilepsy (TLE), the content of NAPs, and their potential correlation. Methods: Hippocampal tissue obtained during the surgical procedure was transferred into a special solution (0–4?°C, 95% O2/5% CO2 during the whole experiment) and quickly transported to the laboratory, where 400-µm hippocampal slices were prepared using Leica VT1200S vibratome. The slices were then stabilized for at least 3 hours (23?°C). Spontaneous electrical activity was recorded using a multi-electrode array (MEA) technique (MEA2100-Lite-System, 60MEA200/30iR-Ti-gr; sampling rate 25 kHz; 32 °C). After filtering (300–3000 Hz), the spike frequency (?0.01?Hz), spike amplitude (?±6SD of the noise), interspike interval coefficient of variation (ISIcv), and number of active electrodes were evaluated. The ROUT test (Q = 1%) was applied to remove outliers. Regarding NAPs, the content of tau protein, ß-amyloid, ?-synuclein, and TDP-43 were examined using immunohistochemistry. Results: In total, 28 consecutive patients have been recruited so far; in 17 patients (~61 %; 11 females, F/ 6 males, M), electrical activity from hippocampal slices was successfully recorded (73 active slices in total).The spike frequency during spontaneous activity was 0.066?Hz in F and 0.055 Hz in M and it increased to 0.136?Hz in F (P < 0.05) and 0.141 Hz in M after stimulation with 100?µM 4-aminopyridine (4AP). The number of active electrodes significantly increased during 4AP stimulation in both F (from 4 to 12; P < 0.001) and M (from 3 to 6; P < 0.05); the increase was significantly higher in F than in M (P < 0.05). The other parameters did not differ between the sexes as well as conditions. ß-amyloid, ?-synuclein, and TDP-43 were not detected in any of the samples, but tau protein was present in some samples. A trend to correlation of the tau protein content with spike frequency was observed, namely during 4AP stimulation in both F and M (rs = 0.47, P = 0.150, and rs = 0.83, P = 0.133, respectively). Conclusion: Tau protein was detected in hippocampal samples from patients with drug-resistant epilepsy, however, other investigated NAPs were absent. To our knowledge, this is the first study showing a correlation trend between the tau protein content and the level of electrical activity in human TLE samples ex vivo.
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