Anticonvulsant effects of melatonin in amygdala-kindled rats

Different doses of melatonin (50-100 mg/kg i.p.) were tested for their abil ity to suppress complex partial seizures in the amygdala kindling model of the rat. Thirty minutes after injection of 75 or 100 mg/kg melatonin, the c urrent threshold necessary to elicit epileptic afterdischarges (ADT) was si gnificantly increased by about 200 or 250%, respectively. These doses were also sufficient to suppress generalised seizures at threshold current. All doses of melatonin decreased body temperature by more than 0.5 degrees C, b ut caused no pronounced ataxia. Seizure susceptibility in terms of ADT chan ged with the time of the day but seems not to depend on the circadian varia tion of endogenous melatonin, since the highest ADT was found in the mornin g when endogenous melatonin levels are low. (C) 1998 Elsevier Science Irela nd Ltd. All rights reserved.