The effect of vitamin D₃ and paricalcitol on penicillin-induced epileptiform activity in rats

Epilepsy is a disease characterized by seizures which impair human life considerably. Vitamin D is of different systemic effects on metabolism and its deficiency is known to have a high prevalence among epilepsy patients. Paricalcitol, a vitamin D receptor agonist, has relatively fewer side effects. This study aimed to investigate the anticonvulsant effect of vitamin D₃ (cholecalciferol) and paricalcitol on penicillin-induced epileptiform activity.

21 male Wistar rat weighing 180-240 g were used. After anesthetized by 1.25 g/kg urethane intraperitoneally (i.p.), rats were placed in the stereotaxic frame and tripolar electrodes were placed on the skull. The single microinjection of penicillin (2.5 μl, 500 IU, i.c.) into left sensorimotor cortex induced epileptiform activity. A single dose of 60.000 IU/kg (i.p.) vitamin D₃ was administered 14 days before intracortical penicillin (500 IU) injection. Paricalcitol (10 μg/kg, i.p.) was administered 30 min before intracortical penicillin (500 IU) administration and recorded for the following 180 min.

Vitamin D₃ pretreatment and paricalcitol diminished the frequency of epileptiform activity (p < 0.001) without changing the amplitude (p > 0.05) compared to the penicillin-injected group. Vitamin D₃ pretreatment and paricalcitol led to an important delay in the onset of penicillin-induced epileptiform activity (p < 0.001 and p < 0.05, respectively). Vitamin D₃ increased the latency of penicillin-induced epileptic activity compared to paricalcitol group (p < 0.001).

Results indicate that vitamin D₃ and paricalcitol decreased the frequency and increased the latency of the penicillin-induced epileptic activity. Vitamin D₃ was more effective than paricalcitol.