GABA_B receptor activation exacerbates spontaneous spike-and-wave discharges in DBA/2J mice

Abstract 

Rich evidence has highlighted that stimulation of γ-amino-butyric acid (GABA)_B receptors increases the occurrence of spike-and-wave discharges (SWDs), the electroencephalographic (EEG) landmark of absence epilepsy (AE). Recent findings suggest that the outcomes of GABA_B activation in vivo are contingent on the chemical characteristics of the agonist. In particular, the endogenous ligand γ-hydroxybutyrate (GHB) and its precursor γ-butyro-lactone (GBL) have been shown to elicit different effects than the prototypical GABA_B agonist baclofen. In view of these premises, the present study was aimed at the characterization of the effects of baclofen (0.5–10mg/kg, i.p.) and GBL (5–100mg/kg, i.p.) on the spontaneous SWDs and locomotor activity of DBA/2J mice.

While both baclofen and GBL dose-dependently increased SWDs episodes, high doses of the latter (100mg/kg, i.p.) reduced the occurrence of these phenomena and increased the number of isolated spikes. Interestingly, both compounds elicited a dose-dependent reduction of locomotor activity, in comparison with their vehicle-treated controls. The GABA_B selective antagonist, SCH50911 (50mg/kg, i.p.), reversed the changes in SWD occurrence and locomotion induced by baclofen and GBL, but failed to elicit intrinsic effects on either paradigm. These results indicate that GABA_B receptor signaling might exert differential effects on SWDs in DBA/2J mice.

Keywords: DBA/2J mice, Absence rodent models, GABA_B receptors, Baclofen, GBL, EEG pattern