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Microinfusion of morphine sulfate (50 nmol), [d-Ala2]-Met-enkephalin (35 nmol) or dynorphin A 1-13 (1 nmol) bilaterally into the substantia nigra significantly attenuated seizures induced by maximal electroshock in rats. This action was accompanied by stereotyped behavioral hyperactivity. These anticonvulsant and behavioral effects were antagonized by(More)
The substantia nigra gamma-aminobutyric acid (GABA) system is crucial for seizure control. Our previous work indicates that in 16-day-old rat pups, nigral administration of the GABAA receptor agonist muscimol facilitates flurothyl-induced seizures, whereas it suppresses seizures in adult rats. To determine whether the proconvulsant effect of muscimol in rat(More)
Rats were implanted with infusion cannulas in the substantia nigra (SN), and intracranial electrodes for recording the electroencephalogram (EEG). These rats received intravenous injections of bicuculline, producing repetitive high voltage spike-and-wave complexes. Pretreatment with bilateral intranigral infusions of the GABA agonist muscimol reduced the(More)
The administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to C57 black mice causes an acute seizure syndrome the severity of which is dose dependent; there is also a good correlation between the seizure inducing potential of MPTP and the neostriatal dopamine (DA) depletion caused by MPTP. The simultaneous administration of MPTP and MAO B(More)
Baclofen-displaced [3H]GABA (gamma-aminobutyric acid) binding to GABAB sites was assayed in brain regions obtained from adult and 14- to 17-day-old rats. The substantia nigra of rat pups exhibited a 3- to 5-fold higher density (Bmax) of GABAB binding sites than the nigra of adult rats. In contrast, the density of GABAB sites was lower in hippocampal and(More)
GABAergic transmission in the substantia nigra pars reticulata (SNR) has an important role in the control of experimental seizures. In the flurothyl seizure model, SNR microinjection of the selective GABAA receptor agonist muscimol results in a biphasic dose-response curve in adults: Intermediate doses are anticonvulsant, but high doses have proconvulsant(More)
Bilateral lesions of substantia nigra (SN) were evaluated for anticonvulsant effects in rats. Electrolytic and kainic acid lesions of SN reduced bicuculline-elicited seizure activity; lesions in the ventral midbrain tegmentum adjacent to SN were without an anticonvulsant effect. Lesions of SN also reduced the incidence and duration of tonic hindlimb(More)
Bilateral intranigral microinfusion of antagonist analogs of substance P significantly attenuated convulsions induced by maximal electroshock or intravenous bicuculline in rats. Infusions of substance P antagonists placed adjacent to the substantia nigra in the vicinity of the lateral hypothalamus were without anticonvulsant action. Our data indicate an as(More)