Abstracts

Rationale: Identifying new molecular targets for controlling seizure activity is crucial for developing new therapeutic strategies for epilepsy. While the role of Ca2+ signaling, specifically the transient receptor potential canonical 3 (TRPC3) channels, in the pathophysiology of chemically induced seizures is well-established, their contribution to inherited seizure susceptibility remains unclear. Inherited seizure susceptibility in genetically epilepsy-prone rats (GEPR-3s) has been linked to increased voltage-gated Ca2+ channel currents in the inferior colliculus neurons, which can affect intraneuronal Ca2+ homeostasis. This study aims to investigate the effects of JW-65, a potent and selective TRPC3 channel inhibitor, on acoustically evoked seizure susceptibility in adult male and female GEPR-3s.


Methods: Adult male (16) and female (16) GEPR-3s were used. For acute treatment, male (n=9) and female (n=9) GEPR-3s were used, with each group having its respective controls (vehicle-treated). JW-65 was intraperitoneally administered at doses of 5, 10, 20, and 40 mg/kg of body weight 0.5 h before acoustically evoked seizure testing. For the five-day treatment, GEPR-3s were randomly divided into male (n=7) and female (n=7) groups, each with their respective controls. Initially, the vehicle for JW-65 was administered, and then the GEPR-3s were tested for seizures at 0.5, 1, 2, 4, and 24 h posttreatment. JW-65 was then administered intraperitoneally daily at 10 mg /kg body weight for five consecutive days, with seizure testing carried out on the fifth day. Seizure testing involved placing the GEPR-3s in an acoustic chamber, and pure tones (100–105 decibels) were delivered until either seizure was elicited or a maximum of 60 s. Testing for acoustically evoked susceptibility was conducted at 0.5 h, 1 h, 2 h, and 4 h post-treatment. Each JW-65 dosage experiment was performed at least seven days apart to allow for washout. Additionally, the estrous cycle was monitored to find that all female GEPR-3s were in the estrus phase.


Results: The results showed that acute administration of low doses of JW-65 significantly decreased the occurrence of WRSs and GTCSs by 55-89%, as well as the seizure severity, in both male and female GEPR-3s. JW-65 treatment also delayed the seizure onset and reduced the duration of seizures in the GEPR‐3s. Interestingly, female GEPR-3s were more responsive to JW-65’s antiseizure effects than males. The findings suggest that TRPC3 channels play a role in the mechanisms underlying seizure termination while also impacting the seizure threshold. Furthermore, JW-65 treatment for five consecutive days completely suppressed acoustically evoked seizures in male and female GEPR-3s.


Conclusions: These findings highlight the potential of inhibiting TRPC3 channels as a promising strategy targeting a Ca2+ signaling mechanism in the management of inherited generalized tonic-clonic epilepsy.


Funding: NIH grants R01AA027660 (PN), R61 NS124923 (WL), and R14 NS 135658 (WL)