Ivabradine reduces seizure susceptibility in a genetic model of mixed epilepsies

Ivabradine is an approved medication that lowers heart rate by inhibiting hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which are critical regulators of neuronal excitability. This study investigated the effects of ivabradine on seizure susceptibility in genetically epilepsy-prone rats (GEPR-3s), known for their seizure phenotypes driven by the brainstem and limbic system. In the initial experiments, male and female GEPR-3s were administered ivabradine at acute doses (0, 5, 10, or 20 mg/kg, p. o.) or at repeated doses (5 mg/kg, p. o.). Following treatment, GEPR-3s were evaluated for acoustically evoked generalized tonic-clonic seizures (GTCS). Seizure severity, latency, and duration were recorded at various time intervals (0.5, 1, 2, 4, and 24 h). In subsequent experiments, GEPR-3s underwent repeated episodes of acoustically evoked seizure or audiogenic kindling, leading to generalized clonic seizures (GCSs) seen in fully kindled GEPR-3s. The results revealed that acute administration of ivabradine significantly decreased the incidence and severity of GTCSs, while increasing seizure latencies and reducing seizure durations in both male and female GEPR-3s. Furthermore, repeated administration of ivabradine over five days resulted in notable suppression of GTCSs in both sexes. Additionally, acute ivabradine treatment effectively decreased the severity of GCSs in kindled GEPR-3s. In conclusion, Ivabradine exhibits notable anticonvulsant effects by modulating seizure activity within both the brainstem and limbic networks of the GEPR-3, an inherited model of epilepsy characterized by mixed seizure phenotypes.