Electrical Stimulation of the STN Inhibits Flurothyl-Induced Seizures
Abstract number :
1.119
Submission category :
Year :
2000
Submission ID :
1224
Source :
www.aesnet.org
Presentation date :
12/2/2000 12:00:00 AM
Published date :
Dec 1, 2000, 06:00 AM
Authors :
Fred A Lado, Libor Velisek, Solomon L Moshe, Albert Einstein Coll of Medicine, Bronx, NY.
RATIONALE: Animal studies and anecdotal human case reports have indicated that the subthalamic nucleus (STN) may be a site of anticonvulsant action. We tested the hypothesis that continuous electrical stimulation of the STN inhibits generalized clonic and tonic seizures. METHODS: Adult male rats were implanted with concentric bipolar stimulating electrodes in the STN bilaterally. After 3-4 days recovery from surgery, rats were exposed to flurothyl, a convulsant ether that produces clonic and tonic seizures in a dose-dependent fashion. Animals were tested up to four times with fluorothyl under different stimulation parameters. The dose of flurothyl resulting in clonic or an in tonic seizures was compared in the same animal in stimulated and non-stimulated conditions. Electrical stimulation consisted of continuous trains of biphasic 60 ?s pulses at rates of 130 Hz as well as other frequencies. Stimulation intensity was adjusted to the maximum current that did not produce significant motor side-effects. STN stimulation continued from the onset of flurothyl exposure until tonic seizures occurred. Statistical significance was set at p<0.05. RESULTS: Bilateral stimulation of the STN at 130 Hz produced a significant increase in the seizure threshold for clonic and tonic seizures induced by flurothyl inhalation. Comparison between implanted but unstimulated rats and naive unimplanted controls showed no significant difference in the mean thresholds for clonic and tonic seizures in the two groups. Analysis of STN "misses" - i.e. rats in which the stimulation electrodes were outside of the STN - did not show any anticonvulsant action of stimulation. Preliminary results indicate that compared to 130 Hz stimulation, 800 Hz stimulation of the STN produces different effects on clonic and tonic seizures. CONCLUSIONS: Bilateral stimulation of the STN has an anticonvulsant action against clonic and tonic generalized convulsions produced by flurothyl inhalation. This effect is site specific for the STN, and is not mediated by neigboring regions. Moreover, the anticonvulsant action of STN stimulation results from stimulation, not from the lesion created by electrode implantation.