@article{af08521918ed4998a12de9dd11a4a64e,
title = "Systemic morphine blocks the seizures induced by intracerebroventricular (i.c.v.) injections of opiates and opioid peptides",
abstract = "Intracerebroventricular (i.c.v.) injections of the endorphins and of morphine in rats produce highly characteristic, naloxone sensitive, electrographic seizures. In contrast, systemic injections of morphine have been shown to exert a marked anticonvulsant effect. The present study demonstrates that systemic morphine pretreatment can prevent the occurrence of electrographic seizures induced by i.c.v. morphine, Leu-enkephalin and β-endorphin and that the anti-epileptic effect of morphine can be reversed by naloxone. Male albino rats, previously prepared for chronic i.c.v. injections and EEG recording, were pretreated with 0-100 mg/kg of intraperitoneal (i.p.) morphine. Thirty five minutes later morphine (520 nmol), Leu-enkephalin (80 nmol) or β-endorphin (5 nmol) were injected i.c.v. Pretreatment with i.p. morphine blocked the occurrence of seizures induced by morphine and both endogenous opioids. Lower doses of systemic morphine (50 mg/kg) were necessary to block i.c.v. morphine seizures than the dose (100 mg/kg) necessary to block seizures induced by i.c.v. Leu-enkephalin and β-endorphin. Naloxone (1 mg/kg) administered 25 min following 50 mg/kg of i.p. morphine and preceding the injections of i.c.v. morphine reversed the antiepileptic effect of systemic morphine. These results demonstrate the possible existence of two opiate sensitive systems, one with excitatory-epileptogenic effects and the other possessing inhibitory-antiepileptic properties. The possible relationship between these findings and the known heterogeneity of opiate receptors and opiate actions is discussed.",
keywords = "anticonvulsant action, convulsant action, endogenous opioids, naloxone, opiates",
author = "Gideon Urca and Hanan Frenk",
note = "Funding Information: This work was supported by a grant of the Israel National Council for Research and Development to H.F., and by a grant from the Israel National Academy of Sciences to G.U. The naloxone used was a gift from Endo Laboratories, Garden City, N.Y.",
year = "1982",
month = aug,
day = "19",
doi = "10.1016/0006-8993(82)90148-2",
language = "אנגלית",
volume = "246",
pages = "121--126",
journal = "Brain Research",
issn = "0006-8993",
publisher = "Elsevier B.V.",
number = "1",
}