OBJECTIVE: Synaptic vesicle protein 2A (SV2A) is a unique therapeutic target for pharmacoresistant epilepsy (PRE). As seizure-induced neuronal programmed death, parthanatos was rarely reported in PRE. Apoptosis-inducing factor (AIF), which has been implicated in parthanatos, shares a common cytoprotective function with SV2A. We aimed to investigate whether parthanatos participates in PRE and is mitigated by SV2A via AIF.
METHODS: An intraperitoneal injection of lithium chloride-pilocarpine was used to establish an epileptic rat model, and phenytoin and phenobarbital sodium were utilized to select PRE and pharmacosensitive rats. The expression of SV2A was manipulated via lentivirus delivery into the hippocampus. Video surveillance was used to assess epileptic ethology. Biochemical tests were employed to test hippocampal tissues following a successful SV2A infection. Molecular dynamic calculations were used to simulate the interaction between SV2A and AIF.
RESULTS: Parthanatos core index, PARP1, PAR, nuclear AIF and MIF, γ-H2AX, and TUNEL staining were all increased in PRE. SV2A is bound to AIF to form a stable complex, successfully inhibiting AIF and MIF nuclear translocation and parthanatos and consequently mitigating spontaneous recurrent seizures in PRE. Moreover, parthanatos deteriorated after the SV2A reduction.
CONCLUSIONS: SV2A protected hippocampal neurons and mitigated epileptic seizures by inhibiting parthanatos via binding to AIF in PRE.

Epilepsy is a common neurological disorder that is primarily treated with antiseizure medications (ASMs). Although dozens of ASMs are available in the clinic, approximately 30% of epileptic patients have medically refractory seizures; other limitations in most traditional ASMs include poor tolerability and drug-drug interactions. Therefore, there is an urgent need to develop alternative ASMs. Levetiracetam (LEV) is a first-line ASM that is well tolerated, has promising efficacy, and has little drug-drug interaction. Although it is widely accepted that LEV acts through a unique therapeutic target synaptic vesicle protein (SV) 2A, the molecular basis of its action remains unknown. Even so, the next-generation SV2A ligands against epilepsy based on the structure of LEV have achieved clinical success. This review highlights the research and development (R&D) process of LEV and its analogs, brivaracetam and padsevonil, to provide ideas and experience for the R&D of novel ASMs.

This study investigated the role of synaptic vesicle protein 2A (SV2A) in the regulation of human induced pluripotent stem cell-derived neural stem cells (NSCs). SV2A was highly expressed in NSCs. SV2A knockdown promotes apoptosis, which was associated with an upregulation of genes involved in p53 signaling as determined by transcriptome analysis. Treatment with the small molecule p53 inhibitor pifithrin-α reversed the promotion of NSC apoptosis induced by loss of SV2A. These results demonstrate that SV2A plays an important role in regulating NSC survival via the p53 signaling pathway.

Alzheimer\'s disease (AD), a serious neurodegenerative disease, is pathologically characterized by synaptic loss and dysfunction. Synaptic vesicle protein 2A (SV2A) is an indispensable vesicular protein specifically expressed in synapses and can be used as a biomarker for synaptic density. We found that the expression of SV2A was down-regulated in the hippocampus of AD patients, yet the relation of SV2A to other hallmarks of AD pathology such as amyloid precursor protein (APP), β-amyloid (Aβ), and Tau protein is not thoroughly clear. In addition, SV2A colocalized with APP and was down-regulated at Aβ deposition. Moreover, we found that SV2A deficiency leads to a simultaneous increase in Aβ and Tau hyperphosphorylation, while SV2A overexpression was associated with downregulation of β-site APP cleaving enzyme 1 and apolipoprotein E genes. In addition, evidence gained in the study points to the phosphatidylinositol 3-kinase signaling pathway as a possible mediator in SV2A regulation influencing the incidence and development of AD. With limited effective diagnostic methods for AD, a close interplay between SV2A and AD-related proteins demonstrated in our study may provide novel and innovative diagnostic and therapeutic opportunities.

Patients with temporal lobe epilepsy (TLE) usually suffer from cognitive deficits and recurrent seizures. Brivaracetam (BRV) is a novel anti-epileptic drug (AEDs) recently used for the treatment of partial seizures with or without secondary generalization. Different from other AEDs, BRV has some favorable properties on synaptic plasticity. However, the underlying mechanisms remain elusive.
The aim of this study was to explore the neuroprotective mechanism of BRV on synaptic plasticity in experimental TLE rats.
The effect of chronic treatment with BRV (10 mg/kg) was assessed on Pilocarpine induced TLE model through measurement of the field excitatory postsynaptic potentials (fEPSPs) in vivo. Differentially expressed synaptic vesicle protein 2A (SV2A) were identified with immunoblot. Then, fast phosphorylation of synaptosomal-associated protein 25 (SNAP-25) during long-term potentiation (LTP) induction was performed to investigate the potential roles of BRV on synaptic plasticity in the TLE model.
An increased level of SV2A accompanied by a depressed LTP in the hippocampus was shown in epileptic rats. Furthermore, BRV treatment continued for more than 30 days improved the over-expression of SV2A and reversed the synaptic dysfunction in epileptic rats. Additionally, BRV treatment alleviates the abnormal SNAP-25 phosphorylation at Ser187 during LTP induction in epileptic ones, which is relevant to the modulation of synaptic vesicles exocytosis and voltagegated calcium channels.
BRV treatment ameliorated the over-expression of SV2A in the hippocampus and rescued the synaptic dysfunction in epileptic rats. These results identify the neuroprotective effect of BRV on TLE model.

Long-term therapy with older antiepileptic drugs (AEDs), but not levetiracetam (LEV), may increase the risk of atherosclerosis (AS), suggesting that LEV may have a potential anti-AS effect. The synaptic vesicle 2A (SV2A) is known to the specific binding site of LEV. Numerous studies have documented that SV2A is a membrane protein specifically expressed in nervous system. Interestingly, our previous research showed that SV2A also existed in human CD8+ T lymphocytes. Therefore, we hypothesized that LEV was associated with decreased risk of AS by regulating monocytes chemotaxis and adhesion. We showed that SV2A protein were detected in THP-1 human monocytic leukemia cells. LEV (300 μM) inhibited the chemotaxis and adhesion of THP-1 cells after transfection with plasmids expressing SV2AWT, but not SV2AR383Q which was a known functional mutation site of human SV2A. Furthermore, RT-PCR and western blot analysis demonstrated that LEV (300 μM) decreased the expression level of chemokine-related receptors (CX3CL1, CCR1, CCR2, and CCR5),and reduced levels of phosphorylated AKT (p-AKT) in THP-1 cells with SV2AWT expressing plasmids. Taken together, these findings indicated that LEV has an inhibitory effect on THP-1 monocyte adhesion and chemotaxis, suggesting that SV2A may serve as a novel therapeutic target to prevent AS.

Synaptic vesicle protein 2A (SV2A) involvement has been reported in the animal models of epilepsy and in human intractable epilepsy. The difference between pharmacosensitive epilepsy and pharmacoresistant epilepsy remains poorly understood. The present study aimed to observe the hippocampus SV2A protein expression in amygdale-kindling pharmacoresistant epileptic rats. The pharmacosensitive epileptic rats served as control. Amygdaloid-kindling model of epilepsy was established in 100 healthy adult male Sprague-Dawley rats. The kindled rat model of epilepsy was used to select pharmacoresistance by testing their seizure response to phenytoin and phenobarbital. The selected pharmacoresistant rats were assigned to a pharmacoresistant epileptic group (PRE group). Another 12 pharmacosensitive epileptic rats (PSE group) served as control. Immunohistochemistry, real-time PCR and Western blotting were used to determine SV2A expression in the hippocampus tissue samples from both the PRE and the PSE rats. Immunohistochemistry staining showed that SV2A was mainly accumulated in the cytoplasm of the neurons, as well as along their dendrites throughout all subfields of the hippocampus. Immunoreactive staining level of SV2A-positive cells was 0.483 ± 0.304 in the PRE group and 0.866 ± 0.090 in the PSE group (P < 0.05). Real-time PCR analysis demonstrated that 2(-ΔΔCt) value of SV2A mRNA was 0.30 ± 0.43 in the PRE group and 0.76 ± 0.18 in the PSE group (P < 0.05). Western blotting analysis obtained the similar findings (0.27 ± 0.21 versus 1.12 ± 0.21, P < 0.05). PRE rats displayed a significant decrease of SV2A in the brain. SV2A may be associated with the pathogenesis of intractable epilepsy of the amygdaloid-kindling rats.

The multistep preparation of (11)C-levetiracetam ((11)C-LEV) was carried out by a one-pot radiosynthesis with 8.3 ± 1.6% (n = 8) radiochemical yield in 50 ± 5.0 min. Briefly, the propionaldehyde was converted to propan-1-imine in situ as labeling precursor by incubation with ammonia. Without further separation, the imine was reacted with (11)C-HCN to form (11)C-aminonitrile. This crude was then reacted with 4-chlorobutyryl chloride and followed by hydrolysis to yield (11)C-LEV after purification by chiral high-performance liquid chromatography (HPLC). Both the radiochemical and enantiomeric purities of (11)C-LEV were >98%.

OBJECTIVE: To evaluate the safety and tolerability of adjunctive brivaracetam (BRV), a high-affinity synaptic vesicle protein 2A (SV2A) ligand, in adults with uncontrolled epilepsy. Efficacy was also assessed in patients with focal seizures as a secondary objective, and explored by descriptive analysis in patients with generalized seizures.
METHODS: This was a phase III, randomized, double-blind, placebo (PBO)-controlled flexible dose trial (N01254/NCT00504881) in adults (16-70 years) with uncontrolled epilepsy (up to 20% could be patients with generalized epilepsy). After a prospective 4-week baseline, patients were randomized (3:1) to b.i.d. BRV or PBO, initiated at 20 mg/day and increased, as needed, to 150 mg/day during an 8-week dose-finding period. This was followed by an 8-week stable-dose maintenance period. The treatment period comprised the dose-finding period plus the maintenance period (16 weeks).
RESULTS: A total of 480 patients were randomized (BRV 359, PBO 121); of these, 431 had focal epilepsy and 49 had generalized epilepsy. Ninety percent BRV- and 91.7% PBO-treated patients completed the study. Similar proportions of patients (BRV 66.0%, PBO 65.3%) reported adverse events (AEs) during the treatment period. AEs led to treatment discontinuation in 6.1% and 5.0% of BRV- and PBO-treated patients, respectively. The incidence of AEs declined from the dose-finding (BRV 56.0%, PBO 55.4%) to the maintenance (BRV 36.8%, PBO 40.9%) period. The most frequent AEs during the treatment period were headache (BRV 14.2% vs. PBO 19.8%), somnolence (BRV 11.1% vs. PBO 4.1%), and dizziness (BRV 8.6% vs. PBO 5.8%). The incidence of psychiatric AEs was similar for BRV and PBO (BRV 12.3%, PBO 11.6%). In patients with focal seizures, the baseline-adjusted percent reduction in seizure frequency/week in the BRV group (n = 323) over PBO (n = 108) was 7.3% (p = 0.125) during the treatment period. The median percent reduction in baseline-adjusted seizure frequency/week was 26.9% BRV versus 18.9% PBO (p = 0.070), and the ≥50% responder rate was 30.3% BRV versus 16.7% PBO (p = 0.006). In patients with generalized seizures only, the number of seizure days/week decreased from 1.42 at baseline to 0.63 during the treatment period in BRV-treated patients (n = 36), and from 1.47 at baseline to 1.26 during the treatment period in PBO-treated patients (n = 13). The median percent reduction from baseline in generalized seizure days/week was 42.6% versus 20.7%, and the ≥50% responder rate was 44.4% versus 15.4% in BRV-treated and PBO-treated patients, respectively.
CONCLUSIONS: Adjunctive BRV given at individualized tailored doses (20-150 mg/day) was well tolerated in adults with uncontrolled epilepsy, and our results provided support for further evaluation of efficacy in reducing focal and generalized seizures.