Attenuating effects of melatonin on pilocarpine-induced seizures in rats.
Daily melatonin (10-50 mg/kg, i.p.) treatment at 08.30 h or 17.00 h for 1 week of female rats (2-months-old) increased the latency to the appearance of the first convulsion in the pilocarpine-induced seizure model. Other behavior parameters remained unaltered. The anticonvulsant effect of melatonin seemed to be more intense at the light-dark transition. Moreover, the effect of repeated melatonin treatment was also age-related, since it showed a lower threshold in 2-month-old than in 21-day-old rats, and the acute treatment was not efficient. [3H]N-methylscopolamine binding was unaltered in the hippocampus and striatum of adult rats after the association of melatonin and pilocarpine. While muscarinic binding was unaltered in adult rats, it increased in the hippocampus of young rats in the presence of melatonin (50 mg/kg) and pilocarpine, and did not change in the striatum. Melatonin partially recovered [3H]GABA binding in the hippocampus in the presence of pilocarpine-induced seizures, and intensified pilocarpine effects in the striatum of adult rats.
Costa-Lotufo
Letícia V
LV
Department of Physiology and Pharmacology, Laboratory of Neuropharmacology, School of Medicine, Federal University of Ceará, Fortaleza, Brazil. lvcosta@secrel.com.br
Fonteles
Marta Maria de F
MM
Lima
Iri Sandro Pampolha
IS
de Oliveira
Aline A
AA
Nascimento
Viviane S
VS
de Bruin
Veralice M S
VM
Viana
Glauce S B
GS
D000367:Age Factors; D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology*; D005260:Female; D008550:Melatonin / Q000494:pharmacology*; D019832:N-Methylscopolamine / Q000378:metabolism; D010862:Pilocarpine / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D011963:Receptors, GABA-A / Q000187:drug effects; D012640:Seizures / Q000517:prevention & control*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D000927:Anticonvulsants; D011963:Receptors, GABA-A; D010862:Pilocarpine; D005680:gamma-Aminobutyric Acid; D008550:Melatonin; D019832:N-Methylscopolamine