Abstract

Using amygdaloid-kindling model of epilepsy, effects of acute estradiol treatment on seizure parameters were investigated in male rats. Fully kindled male rats were treated with various doses of estradiol benzoate (EB, 10, 30 and 50 mug/kg, i.p.) and kindling parameters such as seizure stage (SS), afterdischarge duration (ADD) and stage 5 duration (S5D) were elicited at various times (0.25, 1.5, 3 h and every 24 h for 96 h) post-drug administration. While the 10-mug/kg dose of EB failed to change seizure parameters, administration of the 30- and 50-mug/kg doses caused significant prolongation of ADD and S5D (was not changed significantly by the latter dose) at various time intervals post-drug administration. Pretreatment with the 3 mg/kg dose of tamoxifen citrate (TAM) inhibited the EB (30 mug/kg) effect, while pretreatment with the 10-mg/kg dose produced significant prolongation of ADD and S5D. These results suggest that in male amygdaloid kindled rats, acute estradiol treatment leads to an intensification of seizure that is manifested by increases in ADD and S5D. As the effect is evident 0.25 h post-EB administration and duel action of TAM in opposing the EB effect at low doses and potentiating it at the higher doses, the possibility of a genomic effect may be ruled out. The variable effects of TAM might be explained by its partial agonistic property on estrogen receptors (C) 2001 Elsevier Science B.V. All rights reserved.