Inhibition of N-type calcium currents by lamotrigine in rat amygdalar neurones

Lamotrigine (LAG) is a new anticonvulsant drug for the treatment of partial and secondarily generalized seizures. The present study was aimed at elucidating the possible involvement of Ca2+ channels in the action of LAG using whole-cell patch clamp recordings in acutely dissociated amygdalar neurones. Whole-cell Ca2+ currents (I-Ca) were elicited by 200 ms step commands from -70 mV to -10 mV. Application of LAG reduced the I-Ca by an average of 40.3 +/- 3.2% The inhibition of I-Ca by LAG was markedly reduced or eliminated in the presence of the N-type Ca2+ channel blocker omega-conotoxin-GVIA (1 mu M). These results suggest that LAG may exert its anticonvulsant effect through inhibition of presynaptic N-type Ca2+ channels, thereby reducing glutamate release.