GABAB receptor antagonists: potential new anti-absence drugs

The availability of new antagonists of the GABAB receptor which readily cross the blood-brain barrier has made it possible to investigate the role of GABAB-receptor-mediated transmission in the control of spike-and-wave discharges (SWD) in a strain of rats (GAERS) with genetic absence epilepsy. Systemic administration of R-Baclofen, a GABAB agonist, increased the duration of SWD, or elicited SWD-like oscillations in the cortical EEG of non-epileptic control rats. Conversely, administration of CGP 35348, a GABAB antagonist, either i.p. or p.o., dose-dependently suppressed the spontaneous SWD, as well as the SWD aggravated by concomitant injection of various GABAmimetic drugs, GHB, or anti-convulsants known to exacerbate absence seizures. These results demonstrate the involvement of GABAB-mediated neurotransmission in the development of SWD in generalized non-convulsive epilepsy. GABAB antagonists may thus be considered to be potentially specific anti-absence drugs.