Tizanidine protects mice against convulsions induced by lidocaine: involvement of alpha 2-adrenoceptors.
The effects of alpha-adrenoceptors agents on seizures induced by intraperitoneal administration of lidocaine (75 mg/kg) were studied in mice. Pretreatment with the selective alpha 2-adrenoceptor agonist, tizanidine, decreased the incidence of seizures induced by lidocaine. Tizanidine increased the latency to the first seizure in those animals which progressed to seizures. The blockade of alpha 2-adrenoceptors with yohimbine or phentolamine counteracted the protection induced by tizanidine. The selective alpha 2-adrenoceptor antagonist, prazosin, did not modify the protection induced by tizanidine. The alpha 2-adrenoceptor agonist clonidine also increased the latency to the first seizure induced by lidocaine. The protective effect of clonidine was also reversed by pretreatment with the selective alpha 2-adrenoceptor antagonist yohimbine. Taken together, these results suggest that alpha 2-adrenoceptors are involved in seizures induced by lidocaine.
Altenburg
S P
SP
Department of Physiology, Fluminense Federal University, Niterói, RJ, Brazil.
Farah
M B
MB
D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology*; D001522:Behavior, Animal / Q000187:drug effects; D003000:Clonidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004347:Drug Interactions; D008012:Lidocaine / Q000494:pharmacology*; D008297:Male; D051379:Mice; D010646:Phentolamine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D018341:Receptors, Adrenergic, alpha-2 / Q000502:physiology*; D012640:Seizures / Q000139:chemically induced / Q000517:prevention & control*; D013997:Time Factors; D015016:Yohimbine / Q000494:pharmacology