Anterior cingulate cortex neuron subtypes differentially regulate seizures

OBJECTIVE: This study aimed to investigate the regulatory roles of distinct neuronal subtypes within the anterior cingulate cortex (ACC) in acute seizures and to identify cell type-specific mechanisms underlying seizure modulation in this region. METHODS: Acute seizure models were established in mice via pentylenetetrazol injection. In vivo fiber photometry and miniscope calcium imaging were employed to monitor neuronal calcium activity, and multichannel electroencephalography was used to record brain electrical signals simultaneously. Subsequently, bidirectional chemogenetic and optogenetic manipulations were performed on calcium/calmodulin-dependent protein kinase II (CaMKII) excitatory neurons and vesicular γ-aminobutyric acid (GABA) transporter (vGAT)-expressing GABAergic interneurons, as well as parvalbumin (PV) and somatostatin (SST) interneuron subpopulations. RESULTS: Calcium recordings demonstrated that both excitatory and inhibitory neurons in the ACC exhibited significant, temporally coordinated hyperactivity during acute seizures. Inhibition of CaMKII neurons significantly reduced seizure severity, whereas their activation induced spontaneous seizurelike activity. Enhancing GABAergic interneuron activity significantly decreased seizure frequency and severity. Notably, inhibition of GABAergic interneurons resulted in markedly more severe seizures. Further examination of interneuron subtypes revealed functional heterogeneity; activation of SST interneurons effectively suppressed seizures, whereas PV activation did not produce significant antiseizure effects. Critically, inhibition of either PV or SST interneurons triggered spontaneous seizurelike activity, indicating that both subtypes are necessary for maintaining network stability. SIGNIFICANCE: This study elucidates the differential roles of ACC neuronal populations in acute seizure dynamics. Activating GABAergic interneurons or inhibiting CaMKII-positive neurons effectively suppresses seizure activity. Among interneuron subtypes, SST activation reduces seizures, whereas PV activation does not. However, inhibiting either subtype triggers spontaneous epileptiform activity, indicating both are indispensable and play complementary roles in maintaining network homeostasis. These findings reveal the microcircuit mechanisms by which the ACC modulates acute seizures, highlighting that cortical stability relies on both the classical excitation-inhibition balance and the cooperative interplay of multiple interneuron subtypes.