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See detailNeuro-functional correlates of the protective effects of exercise against cocaine sensitization and dopamine D2 receptors density: a [18F]Fallypride microPET study.
Becker, Guillaume ULiege; Lespine, Louis-Ferdinand ULiege; Serrano Navacerrada, Maria Elisa ULiege et al

in Molecular Imaging and Biology (in press)

Preclinical studies suggest that free access to a running wheel can attenuate behavioural effects of addictive drugs such as psychomotor sensitization to cocaine in rodents. This phenomenon has an ... [more ▼]

Preclinical studies suggest that free access to a running wheel can attenuate behavioural effects of addictive drugs such as psychomotor sensitization to cocaine in rodents. This phenomenon has an integral role in the process of drug addiction in craving and relapse (Steketee and Kalivas, 2011). Free wheel-running was recently shown to be efficacious at preventing the initiation or the long-term expression of psychomotor sensitization to cocaine in mice or rats (Diaz et al., 2013; Geuzaine and Tirelli, 2014). In the present study, we investigated the neuro-functional correlates of the protection against psychomotor sensitization to cocaine afforded by free wheel-running on dopaminergic neurotransmission, using microPET imaging with [18F]Fallypride, a Dopamine 2 receptor (D2R) antagonist. Sixty-four 28-day-old female C57BL/6J mice were randomly assigned to one of the two housing conditions, defined by the presence or the absence of a running wheel in the cage over a 6-week pre-testing period. Since mice from the two types of housing received either saline (controls) or cocaine (8 mg/kg, i.p.) during testing (9 once-daily sessions to establish sensitization plus 1 single session to test its expression), a basic 2x2 randomized blocks design was generated (2-way ANOVA and planned comparisons; n=10). Experimentation lasted 85 days, with a 42-day period of pre-testing and a 3-week interval preceding the test for long-term expression of sensitization (LTES). All mice underwent a microPET (Focus 120, Siemens) the day after the LTES. The microPET protocol consisted of a 60 min. dynamic acquisition after the injection of 10 MBq of [18F]Fallypride in the tail vein. Wheel-running strongly and significantly attenuated LTES (interaction) to cocaine (Cohen’s d=1.63; t(21)=3.75, p<.001) and cocaine-treated mice exhibited a clear-cut and significant increase (main effect) of the [18F]Fallypride BP (d=0.88, t(31)=2.45, p =.02). Wheel-running induced an overall moderate-sized decrease (main effect) of the [18F]Fallypride BP, but without achieving statistical significance (d=0.64, t(31)=1.79, p =.08). These findings suggest that LTES is associated with an increase of the [18F]Fallypride BP in the mouse striatum, probably reflecting an increase in postsynaptic D2R density in this region. Also, the protecting effect of free running on psychomotor sensitization goes together with a decrease in D2R density in the striatum of exercised mice. We intend to complement the present study with an identical experiment to reach a total number of 80 mice (n=20). This will confer to our study a sufficient power (80%) for the main effect of wheel-running exercise on [18F]Fallypride BP to be detected at an alpha-level of 5%. Finally, autoradiography studies, performed on the same mice with [18F]Fallypride, will strengthen our in vivo results. [less ▲]

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See detailAnxiety-like features and spatial memory problems as a consequence of hippocampal SV2A expression.
Serrano Navacerrada, Maria Elisa ULiege; Bartholomé, Odile ULiege; Van den Ackerveken, Priscillia et al

in PLoS ONE (2019)

The Synaptic Vesicle Protein 2A (SV2A) is a transmembrane protein whose presence is reduced both in animal models and in patients with chronic epilepsy. Besides its implication in the epileptic process ... [more ▼]

The Synaptic Vesicle Protein 2A (SV2A) is a transmembrane protein whose presence is reduced both in animal models and in patients with chronic epilepsy. Besides its implication in the epileptic process, the behavioural consequences of the changes in its expression remain unclear. The purpose of our research is to better understand the possible role(s) of this protein through the phenotype of cKO (Grik4 Cre+/-, SV2A lox/lox) mice, male and female, which present a specific decrease of SV2A expression levels in the hippocampal glutamatergic neurons but without any epileptic seizures. In this study, we compare the cKO mice with cHZ (Grik4 Cre+/-, SV2A lox/+) and WT (Grik4 Cre+/+, SV2A lox/lox) mice through a battery of tests, used to evaluate different features: the anxiety-related features (Elevated Plus Maze), the locomotor activity (Activity Chambers), the contextual fear-related memory (Contextual Fear Conditioning), and the spatial memory (Barnes Maze). Our results showed statistically significant differences in the habituation to a new environment, an increase in the anxiety levels and spatial memory deficit in the cHZ and cKO groups, compared to the WT group. No statistically significant differences due to the genotype appeared in the spontaneous locomotor activity or the fear-linked memory. However, sexual differences were observed in this last feature. These results highlight not only an important role of the SV2A protein in the cognitive and anxiety problems typically encountered in epileptic patients, but also a possible role in the symptomatology of other neurodegenerative diseases, such as the Alzheimer’s disease. [less ▲]

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See detailEvaluating the In Vivo Specificity of [18F]UCB-H for the SV2A Protein, Compared with SV2B and SV2C in Rats Using microPET.
Serrano Navacerrada, Maria Elisa ULiege; Becker, Guillaume ULiege; Bahri, Mohamed Ali ULiege et al

in Molecules (2019), 24(9), 1705

The synaptic vesicle protein 2 (SV2) is involved in synaptic vesicle trafficking. The SV2A isoform is the most studied and its implication in epilepsy therapy led to the development of the first SV2A PET ... [more ▼]

The synaptic vesicle protein 2 (SV2) is involved in synaptic vesicle trafficking. The SV2A isoform is the most studied and its implication in epilepsy therapy led to the development of the first SV2A PET radiotracer [18F]UCB-H. The objective of this study was to evaluate in vivo, using microPET in rats, the specificity of [18F]UCB-H for SV2 isoform A in comparison with the other two isoforms (B and C) through a blocking assay. Twenty Sprague Dawley rats were pre-treated either with the vehicle, or with specific competitors against SV2A (levetiracetam), SV2B (UCB5203) and SV2C (UCB0949). The distribution volume (Vt, Logan plot, t* 15 min) was obtained with a population-based input function. The Vt analysis for the entire brain showed statistically significant differences between the levetiracetam group and the other groups (p < 0.001), but also between the vehicle and the SV2B group (p < 0.05). An in-depth Vt analysis conducted for eight relevant brain structures confirmed the statistically significant differences between the levetiracetam group and the other groups (p < 0.001) and highlighted the superior and the inferior colliculi along with the cortex as regions also displaying statistically significant differences between the vehicle and SV2B groups (p < 0.05). These results emphasize the in vivo specificity of [18F]UCB-H for SV2A against SV2B and SV2C, confirming that [18F]UCB-H is a suitable radiotracer for in vivo imaging of the SV2A proteins with PET. [less ▲]

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See detailFully Automated Synthesis and Evaluation of [ 18 F]BPAM121: Potential of an AMPA Receptor Positive Allosteric Modulator as PET Radiotracer
Manos-Turvey, A.; Becker, Guillaume ULiege; Francotte, Pierre ULiege et al

in ChemMedChem (2019), 14(7), 788-795

Alzheimer's disease (AD) remains a significant burden on society. In the search for new AD drugs, modulators of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) are of particular ... [more ▼]

Alzheimer's disease (AD) remains a significant burden on society. In the search for new AD drugs, modulators of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) are of particular interest, as loss of synaptic AMPARs has been linked to AD learning and memory deficits. Previously reported fluorine-containing BPAM121, an AMPA positive allosteric modulator (pam) with high activity, low toxicity, and slow metabolism, was considered to be a perfect 18 F-labeled candidate for positron emission tomography (PET) AD diagnostic investigations. For the preclinical use of this compound, an automated synthesis avoiding human radiation exposure was developed. The detailed production of [ 18 F]BPAM121 in relatively high quantity using a commercial FASTlab synthesizer from GE Healthcare coupled with a full set of quality controls is presented, along with procedures for the synthesis of the tosylated precursor and the fluorinated reference. To evaluate the clinical usefulness of [ 18 F]BPAM121 as a potential AD diagnostic, some in vivo studies in mice were then realized, alongside blocking and competition studies. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim [less ▲]

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See detailQuantification of [18F]UCB-H Binding in the Rat Brain: From Kinetic Modelling to Standardised Uptake Value
Serrano Navacerrada, Maria Elisa ULiege; Bahri, Mohamed Ali ULiege; Becker, Guillaume ULiege et al

in Molecular Imaging and Biology (2018)

Purpose: [18F]UCB-H is a specific positron emission tomography (PET) biomarker for the Synaptic Vesicle protein 2A (SV2A), the binding site of the antiepileptic drug levetiracetam. With a view to ... [more ▼]

Purpose: [18F]UCB-H is a specific positron emission tomography (PET) biomarker for the Synaptic Vesicle protein 2A (SV2A), the binding site of the antiepileptic drug levetiracetam. With a view to optimising acquisition time and simplifying data analysis with this radiotracer, we compared two parameters: the distribution volume (Vt) obtained from Logan graphical analysis using a Population-Based Input Function, and the Standardised Uptake Value (SUV). Procedures: Twelve Sprague Dawley male rats, pre-treated with three different doses of levetiracetam were employed to develop the methodology. Three additional kainic acid (KA) treated rats (temporal lobe epilepsy model) were also used to test the procedure. Image analyses focused on: (i) length of the dynamic acquisition (90 versus 60 min); (ii) correlations between Vt and SUV over 20-min consecutive time-frames; (iii) and (iv) evaluation of differences between groups using the Vt and the SUV; and (v) preliminary evaluation of the methodology in the KA epilepsy model. Results: A large correlation between the Vt issued from 60 to 90-min acquisitions was observed. Further analyses highlighted a large correlation (r 9 0.8) between the Vt and the SUV. Equivalent differences between groups were detected for both parameters, especially in the 20–40 and 40– 60-min time-frames. The same results were also obtained with the epilepsy model. Conclusions: Our results enable the acquisition setting to be changed from a 90-min dynamic to a 20-min static PET acquisition. According to a better image quality, the 20–40-min time-frame appears optimal. Due to its equivalence to the Vt, the SUV parameter can be considered in order to quantify [18F]UCB-H uptake in the rat brain. This work, therefore, establishes a starting point for the simplification of SV2A in vivo quantification with [18F]UCB-H, and represents a step forward to the clinical application of this PET radiotracer. [less ▲]

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See detailTHE SV2A PROTEIN: IMAGING SYNAPTIC DENSITY DURING THE PROGRESSION OF THE TEMPORAL LOBE EPILEPSY IN THE KASE RAT MODEL
Serrano Navacerrada, Maria Elisa ULiege; Bahri, Mohamed Ali ULiege; Becker, Guillaume ULiege et al

Poster (2018, October 18)

Introduction The temporal lobe epilepsy (TLE) is the most common epileptic disorder. New antiepileptic drugs target the Synaptic Vesicle protein 2A (SV2A) (1). Nevertheless, the prevailing literature ... [more ▼]

Introduction The temporal lobe epilepsy (TLE) is the most common epileptic disorder. New antiepileptic drugs target the Synaptic Vesicle protein 2A (SV2A) (1). Nevertheless, the prevailing literature addressing the relation between this protein and the epilepsy is limited (2, 3). This study provides insights on the role of the SV2A protein during the four stages of TLE (4, 5), throughout its in vivo study with the [18F]UCB-H radiotracer (6). Methods Twenty-four male Sprague-Dawley were subjected to multiple injections (7) of i) Saline (Sham), or ii) 5mg/kg of Kainic Acid (KA). The rats not reacting to KA (NKA) were also scanned. In each TLE stages, a [18F]UCB-H dynamic scan was performed, followed by a T2-structural MRI. EEG recordings were performed to determine the number of crises. Data processing was done with PMOD 3.6. Results were expressed as SUV and statistically analyzed with the SPSS and the SPM. Results During the acute phase, statistically significant differences were found between Sham and KA in striatum, cerebellum, and medulla. In the latent phase, these SUV differences were detected between the NKA and KA in the same regions along with hippocampus and thalamus. When the spontaneous crises started, these group differences became statistically significant in all the regions but the cortex. During the chronic phase, all the regions showed statistically significant differences between groups. Furthermore, the voxel-wise analysis highlighted statistically significant differences in voxels at the level of amygdala and hippocampus. Conclusions These results show that [18F]UCB-H is able to detect early modifications in SV2A expression (3 days after the TLE model creation), in particular in regions implicated in the epileptic process. This radiotracer can potentially be used as a suitable biomarker for the early detection of the epileptic disease, being able to distinguish between stages in this neurodegenerative disease. [less ▲]

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See detailEPILEPSY AND THE SV2A PROTEIN: new insights about the disease.
Serrano Navacerrada, Maria Elisa ULiege; Raedt, Robrecht; Becker, Guillaume ULiege et al

Conference (2018, September 13)

Around two million of people worldwide are affected by neurodegenerative diseases, such as Alzheimer, Parkinson or Epilepsy. Despite the social and the economic impact of these diseases, their causes ... [more ▼]

Around two million of people worldwide are affected by neurodegenerative diseases, such as Alzheimer, Parkinson or Epilepsy. Despite the social and the economic impact of these diseases, their causes still remain unclear. In the case of the epilepsy, for example, around 25% of the patients suffer drug-resistant epilepsy, for which there is no medicament able to mitigate the epileptic crises or the associated symptomatology, such as cognitive problems and mood disorders. In 1974, UCB Pharma synthetized a new antiepileptic drug with a high therapeutic index: the Levetiracetam. The target of this medicament is the Synaptic Vesicle Protein 2A (SV2A) whose specific role in the pathology is still unknown. The main goal of my thesis is to better understand the relationship between this protein and the epilepsy. On the one hand, the production and phenotyping of conditional knockout mice for the SV2A protein allowed us to discover a possible implication of this protein in the spatial memory and anxiety process, an important part of the epileptic symptomatology. On the other hand, the synthesis of the radiotracer [18F]UCB-H, with a high affinity for the SV2A protein, enabled the in vivo evaluation (with the mPET technique) of a rat model of the temporal lobe epilepsy through the disease process. Results showed a strong correlation between the severity of the epilepsy (EEG technique) and the SV2A levels in different brain regions, highlighting the importance of this protein in the development of the disease. In summary, although further studies in humans are necessary, this protein emerges as an important key in clinical diagnosis and medical research, being implicated in all the aspects of the epileptic disease. [less ▲]

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See detailEPILEPSY AND THE SV2A PROTEIN: new insights about the disease.
Serrano Navacerrada, Maria Elisa ULiege; Raedt, Robrecht; Becker, Guillaume ULiege et al

Conference (2018, September 13)

Around two million of people worldwide are affected by neurodegenerative diseases, such as Alzheimer, Parkinson or Epilepsy. Despite the social and the economic impact of these diseases, their causes ... [more ▼]

Around two million of people worldwide are affected by neurodegenerative diseases, such as Alzheimer, Parkinson or Epilepsy. Despite the social and the economic impact of these diseases, their causes still remain unclear. In the case of the epilepsy, for example, around 25% of the patients suffer drug-resistant epilepsy, for which there is no medicament able to mitigate the epileptic crises or the associated symptomatology, such as cognitive problems and mood disorders. In 1974, UCB Pharma synthetized a new antiepileptic drug with a high therapeutic index: the Levetiracetam. The target of this medicament is the Synaptic Vesicle Protein 2A (SV2A) whose specific role in the pathology is still unknown. The main goal of my thesis is to better understand the relationship between this protein and the epilepsy. On the one hand, the production and phenotyping of conditional knockout mice for the SV2A protein allowed us to discover a possible implication of this protein in the spatial memory and anxiety process, an important part of the epileptic symptomatology. On the other hand, the synthesis of the radiotracer [18F]UCB-H, with a high affinity for the SV2A protein, enabled the in vivo evaluation (with the mPET technique) of a rat model of the temporal lobe epilepsy through the disease process. Results showed a strong correlation between the severity of the epilepsy (EEG technique) and the SV2A levels in different brain regions, highlighting the importance of this protein in the development of the disease. In summary, although further studies in humans are necessary, this protein emerges as an important key in clinical diagnosis and medical research, being implicated in all the aspects of the epileptic disease. [less ▲]

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See detailDecrease in SV2A expression in the hippocampus involves changes in cognition and anxiety-like features.
Serrano Navacerrada, Maria Elisa ULiege; Bartholomé, Odile ULiege; Van Den Ackerveken, Priscilla ULiege et al

Poster (2018, July)

The Synaptic Vesicle Protein 2A (SV2A) is a transmembrane protein whose link with the epilepsy has been reported in multiples articles. However, the behavioral consequences of the decrease in its ... [more ▼]

The Synaptic Vesicle Protein 2A (SV2A) is a transmembrane protein whose link with the epilepsy has been reported in multiples articles. However, the behavioral consequences of the decrease in its expression remain still unclear. The purpose of our research is to better understand the role of this protein through the evaluation of cKO (Grik4 +/-, SV2A lox/lox) mice of both sexes, which present a specific decrease in the hippocampus. After a first evaluation of the SV2A levels in the hippocampus with the in vitro [18F]UCB-H autoradiography, differences in brain metabolism were assessed with [18F]FDG in mPET and ex vivo autoradiography. Finally, the phenotype of cKO mice was analyzed with a behavioral test battery. Our results showed a strong reduction of SV2A expression in the whole hippocampus of cKO mice, with regard to the WT mice, not accompanied by statistically significant differences in brain metabolism between groups, either in vivo or ex vivo. No statistically significant differences were found in spontaneous locomotor activity or fear-linked memory. However, cKO males showed significant more anxiety than WT (less percent of entries in open arms) and females presented spatial memory deficits measured in the Barnes Maze (less time spend in quadrant during the test). These results could explain the comorbidity between anxiety, memory impairment and epilepsy present both in animal models and in humans, suggesting an important role of SV2A in the symptomatology of other neurodegenerative diseases, such as the Alzheimer disease, or in anxiety-related pathologies. [less ▲]

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See detail[18F]UCB-H BINDING QUANTIFICATION IN RAT BRAIN: FROM MODELLING TO SUV
Serrano Navacerrada, Maria Elisa ULiege; Bahri, Mohamed Ali ULiege; Becker, Guillaume ULiege et al

Poster (2018, March 22)

Introduction Image quantification in Positron Emission Tomography (PET) is usually achieved through the invasive and sometimes infeasible arterial blood sampling [1, 2]. Alternative methods have been ... [more ▼]

Introduction Image quantification in Positron Emission Tomography (PET) is usually achieved through the invasive and sometimes infeasible arterial blood sampling [1, 2]. Alternative methods have been proposed, but a validation of their results is necessary [3, 4]. In the scope of improving the use of [18F]UCB-H, a specific biomarker for the Synaptic Vesicle protein 2A (SV2A) [5, 6, 7, 8], we have compared the distribution volume (VT) obtained through full kinetic modelling using a Population Based Input Function (PBIF) [9], and the Standardized Uptake Value (SUV). Methods Twelve Sprague Dawley male rats were pre-treated with vehicle (saline), 1 or 10 mg/kg of SV2A ligand (Keppra®, IP). Thirty minutes later, [18F]UCB-H was injected (IV) and a 90 min microPET dynamic acquisition was started followed by a T2 structural MRI. Primary image analysis was focused in examining tracer measurement stability through 10 min time windows. Subsequently, we calculated the correlation between VT (90 minutes) and SUV values over consecutive 20-minute time frames searching for the optimal frame to perform a static acquisition [10]. Finally, we did a supplementary test-retest static acquisition, from 60 to 80 minutes, in order to test group differences in SUV. Results/Discussion Evaluation of ten minutes time windows showed more stability in VT than in SUV measures, for all the groups. This change in signal seems to decrease in late time frames. We found also a strong correlation (R2>0.6) between dynamic VT and twenty minutes frame SUV, especially between 20 min and 60 min. From this, we can infer that an optimal frame to perform a static acquisition with [18F]UCB-H would be between 50 and 80 minutes. Using a static acquisition from 60 to 80 minutes, the SUV highlighted statistically significant differences between the group injected with vehicle and the other groups (p<0.01), but not between groups pre-treated with 1mg/kg and 10mg/kg of Keppra®. Conclusions Our work shows that a strong correlation between the SUV and the VT parameter based on a PBIF does exist. This opens the way to a possible simplification for SV2A in vivo imaging with [18F]UCB-H. Despite the fact that SUV is affected by many factors [11] and that it can overestimate results relative to VT [10], it is able to detect important differences in SV2A expression. Based on these results, SUV could become an interesting and easy to obtain parameter to study group differences in the context of several diseases. References 1. Acton PD et al. Radiologic Clinics of North America. 2004; 42(6):1055. 2. Kinahan PE & Fletcher JW. Seminars in Ultrasound, CT and MRI 2010; 31(6): 496. 3. Heurling K et al. Brain Res. 2017; 1670:220. 4. Tomasi G et al. Molecular Imaging and Biology. 2012; 14(2):131. 5. Bretin F et al. EJNMMI res. 2013; 3(1):35. 6. Warnock GI et al. J Nucl Med. 2014; 55(8):1336. 7. Bretin F et al. Molecular Imaging and Biology. 2015; 17(4):557. 8. Salmon E et al. Alzheimer's & Dementia. 2017; 13(7):781. 9. Becker G et al. Molecular Pharmaceutics. 2017; 14(8):2719. 10. Lockhart SN et al. PLoS One. 2016; 11(6):e0158460. 11. Boellaard R. J Nucl Med. 2009; 50(Suppl 1):11S-20S. Acknowledgement This work was funded by University of Liège, F.R.S.-FNRS, Walloon Region and UCB Pharma. Alain Plenevaux is research director from F.R.S.-FNRS. [less ▲]

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See detailIncreased hippocampal volume in exercising mice: comparison of control conditions with in vivo voxel based morphometry
Becker, Guillaume ULiege; Lespine, Louis-Ferdinand ULiege; Bahri, Mohamed Ali ULiege et al

Poster (2018, March)

Introduction Both human and animal studies have shown that physical exercise (primarily aerobic exercise) may have facilitating effects on brain plasticity and cognition. In rodents, improvements of ... [more ▼]

Introduction Both human and animal studies have shown that physical exercise (primarily aerobic exercise) may have facilitating effects on brain plasticity and cognition. In rodents, improvements of various forms of learning and memory induced by wheel-running have been associated with numerous neuroplastic changes such as increased hippocampal neurogenesis. A few studies, using magnetic resonance imaging (MRI), consistently reported hippocampal volumetric increase relative to non-exercising mice. However, the control group is commonly limited either to a locked wheel or no wheel. Methods In the present study, we intended to test whether 6 weeks of voluntary wheel-running exercise during adulthood induced a detectable volumetric change in mice brain in comparison to non-exercised control mice housed either with a locked wheel or without such wheel. 54 C57Bl6 males were randomly assigned to one of the three groups and individually housed for 6 weeks before imaging session. MRI (Agilent 9.4T) acquisition consisted in 3D T2 volume sequence (voxel size: 0.21 mm isotropic) using a dedicated surface coil receiver. We used Dartel soware for the preprocessing of the data, and the Voxel Based Morphometry was done with SPM mouse toolbox (F test, threshold p < .001 uncor). A small volume correction was applied to limit the analysis to the hippocampus. Results/Discussion VBM analysis shows significant clusters with increased grey matter volume in the hippocampus (cluster sizes 1531 and 3460, p < .001) when we compare the wheel vs locked wheel groups. Regarding the wheel vs no wheel comparison, significant clusters were observed in the hippocampus (cluster sizes 955 and 238, p < .001). Interestingly, no dierences were found when we compare the two control groups (locked wheel vs no wheel). Conclusions In this study, we replicate previous studies depicting an increased hippocampal volume under physical exercise in mice using VBM. Moreover, we certified here that attempting to study the impact of physical exercise on brain volume, control groups with a locked wheel or no wheel are equivalent. [less ▲]

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See detailSv2a protein levels in the kainic acid epilepsy rat model during the acute phase
Serrano Navacerrada, Maria Elisa ULiege; Becker, Guillaume ULiege; Bahri, Mohamed Ali ULiege et al

in Epilepsia (2017, December), 58(Supplement S5), 1225

Introduction The Kaïnic Acid model (KA) is one of the most validated models of temporal lobe epilepsy (TLE) (Lévesque et al.,2016). Its administration induces status epilepticus (SE), characterized by an ... [more ▼]

Introduction The Kaïnic Acid model (KA) is one of the most validated models of temporal lobe epilepsy (TLE) (Lévesque et al.,2016). Its administration induces status epilepticus (SE), characterized by an extensive neuronal damage in limbic structures (Sperk et al.,1983). Post-mortem studies, such as the epilepsy model presented in (Wang et al., 2014), show a reduction of SV2A protein levels during the chronic phase, however, no data have been reported during the acute phase (0-48h after KA injection).. The present pilot study is undertaken to evaluate in vivo, with the specific radiotracer [18F]UCB-H (Bretin et al., 2015; Warnock et al., 2014), the SV2A expression 24h after a SE produced by KA administration. Methods Two Sprague-Dawley rats were scanned at two different times: baseline, and 24h after three systemic injections of 5mg/kg KA. The scanning process consisted of a first scan with microPET (Focus 120), during 1 hour, using [18F]UCB-H (41 ± 5 MBq IV tail vein). This is followed by MRI (9.4T Agilent, anatomical T2). A coregistration was performed with PMOD 3.6 software. Data were expressed as SUV and AUC were calculated for the different brain regions. Results [18F]UCB-H microPET images exhibited a small reduction (around 10%) in SV2A brain levels after KA injections compared to the baseline, marked in thalamus, hippocampus and amygdale. MRI images obtained 24h after KA injections are in accordance with previous histological studies, revealing inflammatory edema, tissue necrosis and increased ventricle volume (Sperk et al.,1983). Conclusions These preliminary results obtained in KA treated rats show that [18F]UCB-H is able to detect alterations in SV2A levels in relevant regions for epilepsy. This radiotracer emerges as a valuable tool to follow in vivo SV2A through longitudinal studies. KA model in rats deserves as a tool for the study of epilepsy, exhibiting the same features than the human disease. References [1] Lévesque et al., J Neurosci Methods, 2016 [2] Sperk et al., Neuroscience, 1983 [3] Wang et al., J Mol Neurosci., 2014 [4] Bretin et al., Molecular Imaging and Biology, 2015 [5] Warnock et al., J Nucl Med., 2014 [5] Van Nieuwenhuyse et al., Brain Research, 2015 [6] Hellier et al., Epilepsy Res., 1998 [less ▲]

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See detailPharmacokinetic characterization of [18F]UCB-H PET radiopharmaceutical in the rat brain.
Becker, Guillaume ULiege; Warnier, Corentin; Serrano Navacerrada, Maria Elisa ULiege et al

in Molecular Pharmaceutics (2017), 14(8), 2719-2725

The synaptic vesicle glycoprotein 2A (SV2A), a protein essential to the proper nervous system function, is found in presynaptic vesicles. Thus, SV2A targeting, using dedicated radiotracers combined with ... [more ▼]

The synaptic vesicle glycoprotein 2A (SV2A), a protein essential to the proper nervous system function, is found in presynaptic vesicles. Thus, SV2A targeting, using dedicated radiotracers combined with positron emission tomography (PET), allows the assessment of synaptic density in the living brain. The first-in-class fluorinated SV2A specific radioligand, [18F]UCB-H, is now available at high-activity through an efficient radiosynthesis compliant with the current good manufacturing practices (cGMP). We report here a non-invasive method to quantify [18F]UCB-H binding in rat brain with microPET. Validation study in rats confirmed the need of high enantiomeric purity to target SV2A in vivo. We demonstrated the reliability of a population-based input function to quantify SV2A in preclinical microPET setting. Finally, we investigated the in vivo metabolism of [18F]UCB-H and confirmed the negligible amount of radiometabolites in the rat brain. Hence, the in vivo quantification of SV2A using [18F]UCB-H microPET seems a promising tool for the assessment of the synaptic density in the rat brain, and opens the way for longitudinal follow-up in neurodegenerative diseases rodents’ models. [less ▲]

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See detailNoninvasive quantification of [18F]UCB-H binding using microPET and population-based input function.
Becker, Guillaume ULiege; Warnier, C; Serrano Navacerrada, Maria Elisa ULiege et al

Poster (2017, February 19)

Introduction: [18F]UCB-H is a validated radiotracer with a high affinity for the synaptic vesicle glycoprotein 2A (SV2A), known as the binding site of the antiepileptic drug levetiracetam [1, 2]. Due to ... [more ▼]

Introduction: [18F]UCB-H is a validated radiotracer with a high affinity for the synaptic vesicle glycoprotein 2A (SV2A), known as the binding site of the antiepileptic drug levetiracetam [1, 2]. Due to the absence of reference region, the major drawback of SV2A microPET imaging in the living rat brain is the invasiveness and the complexity of the arterial input function measurement needed for a full quantification. We provide here evaluation of a population-based input function (PBIF) to estimate input function of [18F]UCB-H. Methods: Standard arterial input functions were measured with an arteriovenous shunt and a β-microprobe system from eight anesthetized Sprague-Dawley (SD) rats, as previously described [2]. The distribution volume (Vt) for [18F]UCB-H was calculated with Logan graphic analysis. After normalization, all individual AIFs were averaged to provide the PBIF, and the Logan graphical analysis was computed on each individual rat using the PBIF instead of individual AIF. Correlations analyses were computed between Vt obtained with each methods (individual AIF vs PBIF). Finally, another cohort of five SD rats was scanned with [18F]UCB-H, and Vt were computed using the PBIF and Logan analysis. Single blood samples were harvested at 15 min after radiotracer injection, just to ensure the consistency of the metabolic parent fraction. Results: The Vt computed with individual AIFs were higly consistent with previously reported values, so are the Vt computed with the PBIF [2]. Individual AIFs Vt and PBIF Vt are highly correlated through all brain areas for the height subjects (r2 =0.9). Coefficients of variance are slightly higher with the PBIF method compare to the individual AIF method (14 % and 9 % respectively for the whole brain). Finally, Vt measurement in the second cohort were consistent with previously reported values, and the metabolization profile matched the parent fraction described by Warnock and coll. [2]. Conclusions: The present study described a method for the noninvasive estimation of the AIF using a PBIF, carrying a potential that might substitute for conventional invasive, indivi- dual AIF measurement. We propose that this method can provide a reasonable solution for longitudinal quantitative [18F]UCB-H microPET studies. [less ▲]

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See detailEvaluating the specificity of [18F] UCB-H for the isoform SV2A, compared with isoforms SV2B and SV2C
Serrano Navacerrada, Maria Elisa ULiege; Becker, Guillaume ULiege; Bahri, Mohamed Ali ULiege et al

Poster (2017, February 01)

Background: SV2A is the most studied isoform of the Synaptic Vesicle 2 proteins, which are involved in the synaptic vesicle trafficking, being important in normal and pathological process, like the ... [more ▼]

Background: SV2A is the most studied isoform of the Synaptic Vesicle 2 proteins, which are involved in the synaptic vesicle trafficking, being important in normal and pathological process, like the epilepsy (1, 2). [18F]UCB-H was developed like a tool to study the role of this isoform with neuroimaging techniques (3, 4). The objective of this study was to evaluate its specificity to this isoform comparing with the others, through a competition assay in rats with ex-vivo autoradiography and mPET imaging. Methods: Forty male Sprague-Dawley were used in ex-vivo autoradiography experiments (N=20) and in microPET imaging (N=20). Animals were pre-treated 30 minutes before the injection of [18F]UCB-H with a dose IP either of vehicle, Keppra (SV2A ligand), UCB068 (SV2B ligand) or UCB054 (SV2C ligand). Ex-vivo autoradiography was carried out 5 minutes after radiotracer injection while mPET images were acquiring with a dynamic scanner of 1 hour. Data were expressed in Standard Uptake Value and then, the area under the curve was calculated for the total process. Results: In ex-vivo autoradiography, ANOVA of two-ways showed statistical significant differences in brain uptake of [18F]UCB-H among the groups pretreated with Keppra or the ligand for SV2B and the control group. Regarding mPET data, statistical significant differences were found between the group injected with keppra and the rest of groups. Conclusion: Even if a considerable affinity between the ligands UCB068 and UCB054, and the receptor for the isoform SV2A exists, it is only detected during the first 5 minutes (ex-vivo technique), being certainly due to a nonspecific binding. This binding is not strong enough to show a direct competition with the radiotracer during a mPET acquisition. These results allow us to conclude that [18F]UCB-H is a suitable radiotracer for the imaging of the isoform SV2A in vivo, allowing us the clinical study about the molecular base of a disease with a high population impact, like the epilepsy. [less ▲]

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See detailBehavioural phenotyping of SV2A lox/lox mice: Motor and anxiety-like features
Serrano Navacerrada, Maria Elisa ULiege; Bartholomé, Odile ULiege; Van Den Ackerveken, Priscilla ULiege et al

Poster (2017)

Background: Epilepsy is one of the most common neurological disorders (Alexopoulos, 2004). Current anti-epileptic drugs, such as Levetiracetam (Keppra®) or Brivaracetam, mainly target the trans-membrane ... [more ▼]

Background: Epilepsy is one of the most common neurological disorders (Alexopoulos, 2004). Current anti-epileptic drugs, such as Levetiracetam (Keppra®) or Brivaracetam, mainly target the trans-membrane Synaptic Vesicle Protein 2A (Hamann et al., 2008). Studies on homozygous SV2A KO mice phenotype, prove the mice to suffer severe seizures and die within 3 weeks (Crowder et al., 1999), establishing a link between this protein and the epilepsy. In 2009, the availability of heterozygous SV2A (+/-) mice as research tool enabled shedding light on the role of protein SV2A, revealing no motor differences but anxiety-like features in these mice compared with the WT (Lamberty et al., 2009), and a pro-epileptic phenotype (Crowder et al., 1999; Kaminski et al., 2008). Recently, a floxed SV2A mouse model has been produced with the Cre/loxP recombination system, this model allows invalidating the protein in CA3 hippocampal region, not followed by epileptic seizures (Menten-Dedoyart et al., 2016). Objectives: Perform a first behavioural phenotyping of SV2A lox/lox mice. Methodology: Two experiments were conducted in parallel to evaluate the effect of 3 different genotypes in the phenotype: WT (Grik4-/-, SV2A lox/lox), HZ (Grik4 +/-, SV2A lox/+) and cKO (Grik4 +/-, SV2A lox/lox) in male (n = 42) and female (n = 33) separately . Mice were housed individually along the experiment, with standard food and water ad libitum. After an acclimatization period of 2 weeks, anxiety-like features as well as exploration abilities were evaluated in an elevated plus-maze (EPM) single session of 5 minutes). 3 days later, spontaneous locomotor activity and habituation to the environment were measured during 1 hour, 3 consecutive days, in the activity chambers (ACT). Results: One-way ANOVA in EPM data presented no significant differences between groups, either in males or in females. A significant difference was found, between time spent in close arms vs open arms (p<0.01; η2p = 0.738 males; η2p = 0.805 females). Mixed between-within subjects ANOVA in ACT reflected no significant differences between groups in both sexes, regarding spontaneous locomotor activity and acclimatization to the activity chamber (p>0.05). Statistical significant differences were found between the 3 days (p<0.01; η2p = 0.716 males; η2p = 0.663 females). Conclusion: Results indicate that a decrease in the hippocampal expresion of SV2A protein does not lead to major behavioral changes. Regarding locomotor activity, the results found in heterozygous SV2A (+/-) mice are in line with (Lamberty et al., 2009), however, our mice did not present anxiety-like features, being necessary a global decrease in brain SV2A levels and not only a partial loss in a restricted region of the brain. Further analyses increasing the number of mice per group, will allow us to intensify our power value from 50-60% (females-males) up to 80%, with large effect size and a signification of p<0.05. An additional test to evaluate the spatial memory may help us better understand the effect a specific reduction in SV2A hippocampal expression has on the phenotype of mice. [less ▲]

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See detailIN VIVO STUDY OF THE SV2A PROTEIN IN THE KAINIC ACID EPILEPSY RAT MODEL
Serrano Navacerrada, Maria Elisa ULiege; Becker, Guillaume ULiege; Bahri, Mohamed Ali ULiege et al

Poster (2017)

Introduction Epilepsy is one of the commonest neurological disorders [1]. Antiepileptic drugs mainly target the SV2A protein [2] but its actual role is still largely unknown. [18F]UCB-H was developed to ... [more ▼]

Introduction Epilepsy is one of the commonest neurological disorders [1]. Antiepileptic drugs mainly target the SV2A protein [2] but its actual role is still largely unknown. [18F]UCB-H was developed to study in vivo SV2A brain proteins [3, 4]. The present pilot study was undertaken to evaluate for the first time in vivo in rats SV2A expression in the Kaïnic Acid (KA) epilepsy model [5]. Although this model is well studied in mice, few reports were devoted to rats. Imaging-wise, rats are very interesting thanks to a bigger brain size (reduction of the partial volume effect). Methods Three male Sprague-Dawley were used, one injected with saline and two with multiple KA injections (3 x 5mg/kg) [6]. 75 days later, when spontaneous seizures started to appear, microPET (Focus 120 ) was performed under isoflurane anesthesia (2.5-3 % in air) for 1 hour with [18F]UCB-H (41 ± 5 MBq IV tail vein) followed by MRI (9.4T Agilent, anatomical T2). Coregistration was done with PMOD 3.6 software. Data were expressed as SUV and areas under the curve were calculated for the different regions. Results [18F]UCB-H microPET images showed an important reduction (20-30%) for SV2A after KA injections mainly localized in amygdala, hippocampus, lateral parietal association cortex and cingulate cortex. The rest of the brain was globally unchanged. MRI revealed atrophy and inflammation in amygdala and hippocampus. Conclusions These preliminary results obtained in KA treated rats showed that [18F]UCB-H was able to detect important modifications for SV2A in relevant regions for epilepsy and appears as a valuable tool to follow in vivo SV2A through longitudinal studies. KA model in rats deserves for further development and validation as a tool for the study of epilepsy. [less ▲]

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See detailIN VIVO STUDY OF THE SV2A PROTEIN IN AN EPILEPTIC RAT MODEL
Serrano Navacerrada, Maria Elisa ULiege; Becker, Guillaume ULiege; Bahri, Mohamed Ali ULiege et al

Poster (2017)

Introduction Epilepsy is one of the commonest neurological disorders, affecting more than 60 million people worldwide [1]. New and effective antiepileptic drugs mainly target the SV2A protein [2] but its ... [more ▼]

Introduction Epilepsy is one of the commonest neurological disorders, affecting more than 60 million people worldwide [1]. New and effective antiepileptic drugs mainly target the SV2A protein [2] but its actual role is still largely unknown. [18F]UCB-H was developed as a tool to study in vivo the brain expression of this isoform [3, 4]. Due to the fact that only post-mortem studies were reported so far [5] the present pilot study was undertaken in order to evaluate for the first time in vivo in rats the SV2A expression in the validated Kaïnic Acid (KA) epilepsy model [6]. Methods Three male Sprague-Dawley were used, one injected with saline (Sham) and two with multiple KA systemic injections (5mg/kg x 3) [9]. SV2A brain levels were estimated at day 75, when spontaneous seizures started to appear. Animals were anesthetized (2.5 to 3 % isoflurane), and scanned for 1 hour with [18F]UCB-H (41 ± 5 MBq IV tail vein) in a Focus 120 microPET system and with MRI (9.4T Agilent, anatomical T2). Coregistration was done with PMOD 3.6 software. Data were expressed in SUV and areas under the curve were calculated for the different regions. Results [18F]UCB-H microPET images showed an important reduction (20-30%) for SV2A after KA injections mainly localized in amygdala, hippocampus, lateral parietal association cortex and cingulate cortex. The rest of the brain was globally unchanged. MRI revealed atrophy and inflammation in amygdala and hippocampus. Conclusions These preliminary results in KA treated rats presenting spontaneous seizures showed that [18F]UCB-H microPET was able to detect important reductions for the SV2A proteins in relevant regions for epilepsy [5]. Accordingly to this, we can infer that the KA model in rats deserves for further development and validation as a tool for the study of epilepsy. [18F]UCB-H appears as a valuable tool to follow in vivo SV2A proteins through longitudinal protocols and in turn to better understand its actual role in epilepsy. References/acknowledgements This work was funded by University of Liège, F.R.S.-FNRS, Walloon Region and UCB Pharma. Alain Plenevaux is research director from F.R.S.-FNRS. [1] Alexopoulos, Epileptology, 2004 [2] Hamann et al., Eur J Pharmacol, 2008 [3] Bretin et al., Molecular Imaging and Biology, 2015 [4] Warnock et al., J Nucl Med., 2014 [5] Wang et al., J Mol Neurosci., 2014 [6] Hellier et al., Epilepsy Res., 1998 [less ▲]

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See detail[18F]UCB-H RADIOTRACER AS A TOOL TO UNDERSTAND THE ROLE OF THE SV2A PROTEIN
Serrano Navacerrada, Maria Elisa ULiege; Becker, Guillaume ULiege; Bahri, Mohamed Ali ULiege et al

Poster (2017)

Background: SV2A is the most studied isoform of the Synaptic Vesicle 2 proteins, which are involved in the synaptic vesicle trafficking, being important both in normal as in pathological process (1, 2 ... [more ▼]

Background: SV2A is the most studied isoform of the Synaptic Vesicle 2 proteins, which are involved in the synaptic vesicle trafficking, being important both in normal as in pathological process (1, 2). Until now, only one study in vivo has been reported, showing a reduction of SV2A levels in the epilepsy (3). [18F]UCB-H was developed like a current tool to study the role of SV2A with in vivo techniques (4, 5), and as a tool in clinical investigations. The objective of this research was to evaluate the radiotracer specificity to this isoform comparing with the others, through a competition assay in rats with ex-vivo autoradiography and mPET imaging. Methods: Forty male Sprague-Dawley were used in ex-vivo autoradiography experiments (N=20) and in microPET imaging (N=20). Animals were pre-treated 30 minutes before the injection of [18F]UCB-H with a dose IP either of vehicle, Keppra (SV2A ligand), UCB068 (SV2B ligand) or UCB054 (SV2C ligand). Ex-vivo autoradiography was carried out 5 minutes after radiotracer injection while mPET images were acquiring with a dynamic scanner of 1 hour. Standard Uptake Value (SUV) and Distribution Volume (VT) were calculated and the correlation between both parameters was determined. Results: In ex-vivo autoradiography, ANOVA of two-ways showed statistical significant differences in brain uptake of [18F]UCB-H among the groups pretreated with Keppra or the ligand for SV2B and the control group. Regarding mPET data, statistical significant differences were found between the group injected with keppra and the rest of groups. Pearson Correlation between SUV and VT was strong, with a value of 0.955. Conclusion: Even if a considerable affinity between the ligands UCB068 and UCB054, and the receptor for the isoform SV2A exists, it is only detected during the first 5 minutes (ex-vivo technique), being certainly due to a nonspecific binding. This binding is not strong enough to show a direct competition with the radiotracer during a mPET acquisition. These results allow us to conclude that [18F]UCB-H is a suitable radiotracer for the imaging of the isoform SV2A in vivo, allowing us the clinical study about the molecular base of a disease with a high population impact, like the epilepsy. 1) Van Vliet et al., 2009. Epilepsia 2) Crèvecœur et al., 2013. BMC Neurosci. 3) Finnema et al., 2016; Sci Transl Med. 4) Bretin et al., 2013.EJNMMI Res 5) Bretin et al., 2015.Mol Imaging Biol [less ▲]

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See detailEVALUATING THE SPECIFICITY OF [18F]UCB-H FOR THE ISOFORM SV2A, COMPARED WITH ISOFORMS SV2B AND SV2C
Serrano Navacerrada, Maria Elisa ULiege; Aerts, Joël ULiege; Bahri, Mohamed Ali ULiege et al

Poster (2016, November 18)

Background: SV2A is the most studied isoform of the Synaptic Vesicle 2 proteins, which are involved in the synaptic vesicle trafficking, being important in normal and pathological process, like the ... [more ▼]

Background: SV2A is the most studied isoform of the Synaptic Vesicle 2 proteins, which are involved in the synaptic vesicle trafficking, being important in normal and pathological process, like the epilepsy (1, 2). [18F]UCB-H was developed like a tool to study the role of this isoform with neuroimaging techniques (3, 4). The objective of this study was to evaluate its specificity to this isoform comparing with the others, through a competition assay in rats with ex-vivo autoradiography and mPET imaging. Methods: Forty male Sprague-Dawley were used in ex-vivo autoradiography experiments (N=20) and in microPET imaging (N=20). Animals were pre-treated 30 minutes before the injection of [18F]UCB-H with a dose IP either of vehicle, Keppra (SV2A ligand), UCB068 (SV2B ligand) or UCB054 (SV2C ligand). Ex-vivo autoradiography was carried out 5 minutes after radiotracer injection while mPET images were acquiring with a dynamic scanner of 1 hour. Data were expressed in Standard Uptake Value and then, the area under the curve was calculated for the total process. Results: In ex-vivo autoradiography, ANOVA of two-ways showed statistical significant differences in brain uptake of [18F]UCB-H among the groups pretreated with Keppra or the ligand for SV2B and the control group. Regarding mPET data, statistical significant differences were found between the group injected with keppra and the rest of groups. Conclusion: Even if a considerable affinity between the ligands UCB068 and UCB054, and the receptor for the isoform SV2A exists, it is only detected during the first 5 minutes (ex-vivo technique), being certainly due to a nonspecific binding. This binding is not strong enough to show a direct competition with the radiotracer during a mPET acquisition. These results allow us to conclude that [18F]UCB-H is a suitable radiotracer for the imaging of the isoform SV2A in vivo, allowing us the clinical study about the molecular base of a disease with a high population impact, like the epilepsy. [less ▲]

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