Orexinergic and canabinoid CB1 receptor interaction in WAG/Rij rats with genetic absence epilepsy

Aim: It is subjected that orexin and cannabinoids are involved in many neurological systems such as epilepsy and that both systems are interrelated. This study goal is to research the effect and interrelationship of orexinergic and cannabinoid systems in WAG/Rij rats. Methods: In our study, Wistar and WAG/Rij rats were used to electrocorticogram recordings. Wistar rats were placed in a stereotaxic device under urethane, WAG/Rij rats under ketamine/xylazine anesthesia, tripolar electrodes were fixed to the skull. After producing epileptiform activity by intracortical (i.c.) penicillin in Wistar rats, 0,6 µg hemopressin, 7,5 µg ACEA, 0,50 µg AM251 and also 2, 4, 8, 16 µg doses of OX-A with 1.5, 3, 6 and 12 µg i.c.v. doses of SB334867 appliyed and effective doses determined. After 3 hours of baseline recording in WAG/Rij rats, the effective doses of the substance were applied by i.c.v., and recording continued for 3 more hours. Interaction groups were also subjected to the same procedure. Records were analyzed in terms of seizure duration and number, spike number and amplitude. Results and Conclusions: 8 µg OX-A and 12 µg SB334867 significantly decreased the duration and number of seizures, spike number, excluding amplitude, in WAG/Rij rats (p<0.05). While hemopressin and ACEA decreased absence seizure activity, AM251 increased it. According to the interaction group data, it is thought that the effect of orexins to cannabinoid pathway may be higher than hemopressin, and that OX-A has an anticonvulsant effect through another mechanism besides binding to cannabinoidergic pathway. It is also seen that the orexinergic system dominates the cannabinoidergic system.