Effects of GABAB receptor antagonists on two models of focal epileptogenesis.
The acute effects of two GABAB receptor antagonists (phaclofen and CGP-35348) were studied in two types of epileptogenic activity: that produced by intracortical injections of baclofen and that appearing after withdrawal of chronic intracerebral GABA infusion (the GABA-withdrawal syndrome, GWS). Intracortical baclofen induced two types of electrographic paroxysmal discharges: one consisting of single spike-and-wave (pattern I) and another of polyspike-and-wave patterns (pattern II). Both patterns showed similar latencies and temporal evolution of spike frequency discharges. Phaclofen, applied directly into the baclofen-induced epileptogenic focus, suppressed pattern II but was ineffective in modifying both pattern I and the GWS. CGP-35348, administered systemically, inhibited both patterns I and II. Intracortical microinjection of baclofen or phaclofen in rats showing a GWS had no effect, nor the systematically given CGP 35348. These results indicate a differential participation of GABAB receptors in GABA-related epileptic syndromes of cortical origin.
Brailowsky
S
S
Departamento de Neurociencias, Universidad Nacional Autónoma de México. sbrailow@ifcsun 1.ifisiol.unam.mx
Montiel
T
T
Meneses
S
S
Di Scala
G
G
D000818:Animals; D001418:Baclofen / Q000031:analogs & derivatives* / Q000494:pharmacology; D004195:Disease Models, Animal; D004828:Epilepsies, Partial / Q000378:metabolism*; D018756:GABA Antagonists / Q000494:pharmacology*; D058788:GABA-B Receptor Antagonists; D008297:Male; D009943:Organophosphorus Compounds / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D018756:GABA Antagonists; D058788:GABA-B Receptor Antagonists; D009943:Organophosphorus Compounds; C052329:phaclofen; C066430:CGP 35348; D001418:Baclofen