Beneficial effects of turmeric oil and sunflower seed oil in the rapid kindling rat model of epileptogenesis

Purpose: Curcumin, a major Curcuma longa constituent, has shown anticonvulsant effects in preclinical seizure and epileptogenesis models. However, its poor bioavailability and modest, non-persistent effects in the rat rapid kindling model, limits its potential. Therefore, we aimed to investigate whether turmeric oil, a more lipophilic and better bioavailable C. longa fraction, modulates seizure development in the rat rapid kindling model.
Methods: Rats were electrically stimulated via the angular bundle for 4 days (9 stimulations/day, 45 min apart), 1 hour after intraperitoneal (i.p) injection of saline (n=8), vehicle (sunflower seed oil, n=8), or turmeric oil (in vehicle; n=7). Treatment was given for 1 week, followed by a 1-week washout. A kindling re-test was then performed without any injections. Behavioral seizures were scored using Racine's scale. Immunohistochemistry for IBA1 (microgliosis) and vimentin (astrogliosis) performed in the dorsal and ventral hippocampus.
Results: Vehicle and turmeric oil reduced behavioral seizure severity compared with saline. After washout, only turmeric oil exhibited reduced behavioral seizure severity during the initial re-test stimulations. Kindling resulted in reactive microgliosis and astrogliosis in the hippocampus, but the density of IBA1 and vimentin-positive cells did not differ between groups.
Conclusions: Both vehicle and turmeric oil exerted anti-ictogenic effects in the rapid kindling model, without attenuating kindling-induced gliosis. Notably, turmeric oil showed modest short-term persistence of its anti-ictogenic effects after washout, consistent with either a transient residual pharmacological action or a limited modulation of seizure progression within this paradigm, but not allowing firm conclusions regarding disease-modifying effects. These findings also underscore the importance of careful vehicle selection in preclinical epilepsy research.