Effect of melatonin on cognitive changes caused by epileptic seizures in rats

Cognitive function impairments are common among epilepsy patients. It was also reported that these cognitive function impairments are also caused by antiepileptic drugs, which are used to control epileptic seizures. These types of impairments are serious especially for the children with incomplete brain development. Previous clinical and experimental studies already proved that melatonin secreted from pineal gland is also related to epilepsy as well as other many other physiological process. In this research, the effect of melatonin on epileptic seizures induced by pentilentetrazol (PTZ) and the learning and motor functions associated to epilepsy in prepubertal Sprague Dawley rats was studied. Three different dosages of melatonin (20, 40 ve 80 mg/kg), 400 mg/kg sodium valproate and 120 mg/kg topiramate were orally applied to PTZ injected rats every other day during the time-course of 21 days. Seizures after PTZ injections were observed and recorded during the chronic treatment. Passive avoidance, radial arm maze, open field and Chimney tests were used to observe learning and motor functions after melatonin and antiepileptic drug application.According to results, it is detected that melatonin did not prevent seizure induced by PTZ and antiepileptic drugs provided effective for this seizures. Melatonin and antiepileptic drug treated groups, including PTZ treated rats, did not show any impairment on cognitive functions in learning tests. On the other hand, statistically serious decrease of locomotor activity was observed in PTZ and high dose melatonin treated groups.In conclusion, the application of 20, 40, and 80 mg/kg melatonin for 21 days on prepubertal rats did not cause any negative effect on seizure induced by PTZ and learning function. However, low dose melatonin (20 mg/kg) application meliorated the disruption of locomotor activity.