Cerebral Lesions Produced in Rats by Various Implants; Epileptogenic Effect of Cobalt

Abstract

C ONVULSIVE seizures have been produced experimentally in animals by injection of various drugs, electrical st imulation, freezing of the cortex, and immunological methods. 6 Recurrent seizures or a chronic epileptic state were produced in monkeys by alumina cream. 6 Rats, however, were found to be resistant to these methods. 2 In 1960, the epileptogenic effect of certain metallic powders, particularly cobalt when placed in, or on, the brain of mice and rats, was reported by Kopeloft. 5 This report was confirmed by the electroencephalographic studies of Dow, et al., in 196~3 Chusid and Kopeloff, in 1965, reported the epileptogenic effects of the cobalt powder when implanted in the brain of monkeys? The response in cats, however, was different following cobalt implant since the animals were found to be epileptic only for a few days? The epileptic states in these animals in most of the experiments were evaluated by lowered pharmaeoconvulsive thresholds and/or eleetroencephalography. 2,5 Few studies have been carried out on the morphology of the experimental epilepsy2 a~ Our present experiments were orientated toward understanding the physiopathology of cobalt-induced epilepsy in the rat, as well as the s tudy of comparative morphological lesions produced by various implants.