Abstracts

Rationale: The alpha2delta-1 subunit (a2d-1) of voltage-gated calcium channels is a receptor to which astrocyte-secreted thrombospondins (TSPs) bind to promote developmental and posttraumatic synaptogenesis. Overexpression of a2d-1 alone in uninjured transgenic mice (a2d-1 TG mice) results in increased excitatory connectivity and consequent epileptiform seizures in adults. Gabapentinoids, including pregabalin (PGB), are anticonvulsant/antiallodynic drugs that interrupt TSP binding to a2d-1 and have antiepileptogenic effects in cortical injury models. However, little is known about the effects and the critical developmental time window for PGB intervention in transgenic epilepsy models like a2d-1TG mice. To address these questions, we compared the electrophysiological outcomes of PGB treatment administrated at different developmental times in a2d-1TG mice. Methods: We tested the effects of PGB (50 mg/kg ip daily) in a2d-1 TG mice with three different protocols: Group 1: Treatment from P14 to P28. Group 2: Treatment from P20 to P34. Group 3: Treatment from P7 to P28. Littermates treated with saline were used as controls. Miniature EPSCs and epidural EEGs were recorded at least 3 days after the end of treatment to avoid any acute effects of pregabalin. Results: We initially treated TG mice from P14 to P28 or from P20 to P34 and obtained whole cell recordings of miniature EPSCs (mEPSCs) in layer V pyramidal cells in in vitro slices. There were no significant differences in amplitude or frequency of mEPSCs between treated TG mice and saline-treated controls, indicating that already established hyper-connected excitatory circuits were not affected. We obtained epidural EEGs, rather than in vitro mEPSC recordings, from a 3rd group of implanted mice treated with PGB from P7 to P28. EEG signals were filtered (1Hz high-pass; 15Hz low-pass) and a Fourier transform power analysis done. EEGs of both untreated (n=3) and treated (n=5) TG mice showed epileptiform discharges with peak frequency at 2-4 Hz 4 and 5 days after the end of treatment. However, the amplitudes of absolute power at 2-4 Hz were decreased to 1/3-1/2 of controls in the PGB-treated group (0.0012-0.0013 vs 0.0006-0.0009 mV2/Hz). These results suggest that PGB administration from P7 to P28 is effective in attenuating the epileptiform discharges in a2d-1TG mice. Conclusions: Taken together, our preliminary data show that early PGB intervention can attenuate epileptogenic outcomes in a2d-1 TG mice. Results raise the possibility of prevention of epileptogenesis in similar genetic models, once receptors and appropriate agonists or antagonists are identified. Funding: NIH grant NS090075 from the NINDS