Localization and photoaffinity labelling of the levetiracetam binding site in rat brain and certain cell lines.
Levetiracetam (2S-(2-oxo-1-pyrrolidinyl)butanamide, KEPPRA, a novel antiepileptic drug, has been shown to bind to a specific binding site located in the brain (Eur. J. Pharmacol. 286 (1995) 137). To identify the protein constituent of the levetiracetam binding site in situ, we synthesized the photoaffinity label [3H]ucb 30889 ((2S)-2-[4-(3-azidophenyl)-2-oxopyrrolidin-1-yl]butanamide), a levetiracetam analog with higher affinity for the levetiracetam binding site. This radioligand was used to map the levetiracetam binding site within the brain and to study its cellular and subcellular distribution. Autoradiography experiments using [3H]ucb 30889 in rat brain revealed a unique distribution profile that did not match that of classical receptors known to be involved in the generation of epileptic seizures. There was a high level of binding in the dentate gyrus, the superior colliculus, several thalamic nuclei, the molecular layer of the cerebellum and to a lesser extent in the cerebral cortex, the striatum and the hypothalamus. The levetiracetam binding site was restricted to neuronal cell types, undifferentiated PC12 cells and was highly enriched in synaptic vesicles. [3H]ucb 30889 was also used in photoaffinity labelling studies and shown to bind covalently to a membrane protein with a molecular weight of approximately 90 kDa.
Fuks
Bruno
B
UCB S.A, Pharma Sector, In vitro Pharmacology, Building R4, Chemin du Foriest, 1420, Braine-l'Alleud, Belgium. bruno.fuks@ucb-group.com
Gillard
Michel
M
Michel
Philippe
P
Lynch
Berkley
B
Vertongen
Pascale
P
Leprince
Pierre
P
Klitgaard
Henrik
H
Chatelain
Pierre
P
D000818:Animals; D001665:Binding Sites / Q000502:physiology; D001921:Brain / Q000166:cytology / Q000378:metabolism*; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D000077287:Levetiracetam; D008297:Male; D051379:Mice; D009474:Neurons / Q000378:metabolism; D019920:Photoaffinity Labels / Q000378:metabolism*; D010889:Piracetam / Q000031:analogs & derivatives / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013572:Synaptic Vesicles / Q000378:metabolism
D019920:Photoaffinity Labels; D000077287:Levetiracetam; D010889:Piracetam