Oral administration of the casein kinase 2 inhibitor TBB leads to persistent KCa2.2 channel up-regulation in the epileptic CA1 area and cortex, but lacks anti-seizure efficacy in the pilocarpine epilepsy model

CK2 Inhibition Prior to Status Epilepticus Persistently Enhances KCa2 Function in CA1 Which Slows Down Disease Progression

“…Therefore, we performed a long-term video analysis of daytime seizures from nine vehicle-pretreated and 13 TBBpretreated littermates for 7 weeks covering the full period of epileptogenesis (10-60 days after SE; Figures 1F-H). Over this period, vehicle-pretreated animals showed 1.3 ± 1.0 seizures/12 h (n = 9) during daylight, i.e., between 6 a.m. and 6 p.m., consistent with previous data (Bajorat et al, 2011(Bajorat et al, , 2016(Bajorat et al, , 2018. TBBpretreated littermates showed the same overall seizure rates (1.3 ± 1.3 seizures/12 h, n = 13), but developed gross changes in seizure rates during the second half of the observation period ( Figure 1F).…”

“…Epileptiform potentials in the electroencephalogram (EEG) were recorded using a telemetric system [Neuroscore 2.0, Data Science International (DSI), Arden Hills, MN, United States]. Electrode implantation (TA10EA-F20 or TA11CA-F40 from DSI) was performed as previously described (Bajorat et al, 2011(Bajorat et al, , 2016(Bajorat et al, , 2018. Video-EEG monitoring was performed in three TBB-treated pilocarpine-treated epileptic animals and four vehicle-treated epileptic rats under environmentally controlled conditions (12 h light/dark cycles, lights switched on from 6 a.m. to 6 p.m., 22 ± 2 • C, and 40-60% relative humidity in an isolated room).…”

“…Hence, the interictal spike counts were quite representative and not taken from a period with increased seizure rate. Since the clinical course of chronic epilepsy in this model is often associated with an increasing seizure rate and also with seizure clustering (Bajorat et al, 2011(Bajorat et al, , 2016(Bajorat et al, , 2018, this short-term analysis of EEG-detected seizures cannot reflect seizure burden and hence is insufficient to study the TBB effect.…”

“…The significant reduction of the number of burst firing neurons in the epileptic CA1 after TBB pretreatment following ADP normalization is an attractive molecular mechanism for the observed disease modifying properties in vivo. Since we previously demonstrated that K Ca 2.2 was downregulated in isolated CA1 neurons from chronically epileptic tissue and TBB administered during chronic epileptic stages enhanced K Ca 2.2 levels in CA1 from post-SE animals (Schulz et al, 2012;Bajorat et al, 2018), we first performed patch-clamp recordings from visualized CA1 pyramidal neurons in hippocampal slices and confirmed the impaired function of K Ca 2 by recording the mAHP-mediating current density (0.26 ± 0.06 pA/pF, n = 7 versus 1.19 ± 0.38 pA/pF, n = 4, P < 0.05, unpaired t-test, Figure 5A) as previously reported in isolated cells (Schulz et al, 2012). Pretreatment with TBB prior to SE significantly enhanced the mAHP current density (0.92 ± 0.18 pA/pF, n = 14, P < 0.05, unpaired t-test; Figure 5A) suggesting that TBB might indeed enhance K Ca 2 function.…”

“…We recently demonstrated that oral administration of the CK2 blocker 4,5,6,7-tetrabromotriazole (TBB) enhanced K + currents mediating the afterhyperpolarizing potential (AHP) in the pilocarpine model, and even more intriguing, blocked the occurrence of spontaneous epileptic activity in the acute slice model with Mg 2+ removal (Brehme et al, 2014). This compound obviously exerted an anti-epileptogenic potential in the in vitro slice preparation, but is not an anti-seizure drug in this model in vivo (Bajorat et al, 2018). Therefore, we asked whether TBB might have disease modifying effects in the pilocarpine model in vivo, too.…”