"The anterior cingulate cortex (ACC) which plays a role in pain, emotions and behavior can generate epileptic seizures. To date, little is known on the neuronal mechanisms leading to epileptiform synchronization in this structure," scientists in Montreal, Canada report (see also Seizure).

"Therefore, we investigated the role of excitatory and inhibitory synaptic transmission in epileptiform activity in this cortical area. In addition, since the ACC presents with a high density of opioid receptors, we studied the effect of opioid agonism on epileptiform synchronization in this brain region. We used field and intracellular recordings in conjunction with pharmacological manipulations to characterize the epileptiform activity generated by the rat ACC in a brain slice preparation. Bath-application of the convulsant 4-aminopyridine (4AP, 50 mc M) induced both brief and prolonged periods of epileptiform synchronization resembling interictal- and ictal-like discharges, respectively. Interictal events could occur more frequently before the onset of ictal activity that was contributed by N-methyl-D-aspartate (NMDA) receptors. Mu-opioid receptor activation abolished 4AP-induced ictal events and markedly reduced the occurrence of the pharmacologically isolated GABAergic synchronous potentials. Ictal discharges were replaced by interictal events during GABAergic antagonism; this GABA-independent activity was influenced by subsequent mu-opioid agonist application. Our results indicate that both glutamatergic and GABAergic signaling contribute to epileptiform synchronization leading to the generation of electrographic ictal events in the ACC," wrote G. Panuccio and colleagues.

The researchers concluded: "In addition, mu-opioid receptors appear to modulate both excitatory and inhibitory mechanisms, thus influencing epileptiform synchronization in the ACC.."

Panuccio and colleagues published their study in Epilepsia (Epileptiform synchronization in the cingulate cortex. Epilepsia, 2009;50(3):521-536).

For additional information, contact M. Avoli, 3801 University, Room 794, Montreal, PQ H3A 2B4, Canada.

The publisher's contact information for the journal Epilepsia is: Wiley-Blackwell Publishing, Inc., Commerce Place, 350 Main St., Malden 02148, MA, USA.

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