title: Effects of anterior thalamic nucleus deep brain stimulation in chronic epileptic rats.
abstract: Deep brain stimulation (DBS) has been investigated for the treatment of epilepsy. In rodents, an increase in the latency for the development of seizures and status epilepticus (SE) has been reported in different animal models but the consequences of delivering stimulation to chronic epileptic animals have not been extensively addressed. We study the effects of anterior thalamic nucleus (AN) stimulation at different current intensities in rats rendered epileptic following pilocarpine (Pilo) administration. Four months after Pilo-induced SE, chronic epileptic rats were bilaterally implanted with AN electrodes or had sham-surgery. Stimulation was delivered for 6 h/day, 5 days/week at 130 Hz, 90 µsec. and either 100 µA or 500 µA. The frequency of spontaneous recurrent seizures in animals receiving stimulation was compared to that recorded in the preoperative period and in rats given sham treatment. To investigate the effects of DBS on hippocampal excitability, brain slices from animals receiving AN DBS or sham surgery were studied with electrophysiology. We found that rats treated with AN DBS at 100 µA had a 52% non-significant reduction in the frequency of seizures as compared to sham-treated controls and 61% less seizures than at baseline. Animals given DBS at 500 µA had 5.1 times more seizures than controls and a 2.8 fold increase in seizure rate as compared to preoperative values. In non-stimulated controls, the average frequency of seizures before and after surgery remained unaltered. In vitro recordings have shown that slices from animals previously given DBS at 100 µA had a longer latency for the development of epileptiform activity, shorter and smaller DC shifts, and a smaller spike amplitude compared to non-stimulated controls. In contrast, a higher spike amplitude was recorded in slices from animals given AN DBS at 500 µA.
authors.affiliation: Disciplina de Neurofisiologia, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Luciene
authors.initials: L
authors.lastname: Covolan
authors.affiliation: Laboratório de Neurociência Experimental e Computacional, Universidade Federal de São João del-Rei, São João del-Rei, Brazil.
authors.forename: Antônio-Carlos G
authors.initials: AC
authors.lastname: de Almeida
authors.affiliation: Disciplina de Neurofisiologia, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Amorim
authors.affiliation: Disciplina de Neurofisiologia, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Clarissa
authors.initials: C
authors.lastname: Cavarsan
authors.affiliation: Laboratório de Neurociência Experimental e Computacional, Universidade Federal de São João del-Rei, São João del-Rei, Brazil.
authors.forename: Maisa Ferreira
authors.initials: MF
authors.lastname: Miranda
authors.affiliation: Laboratório de Neurociência Experimental e Computacional, Universidade Federal de São João del-Rei, São João del-Rei, Brazil.
authors.forename: Mayra C
authors.initials: MC
authors.lastname: Aarão
authors.affiliation: Laboratório de Neurociência Experimental e Computacional, Universidade Federal de São João del-Rei, São João del-Rei, Brazil.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Madureira
authors.affiliation: Laboratório de Neurociência Experimental e Computacional, Universidade Federal de São João del-Rei, São João del-Rei, Brazil.
authors.forename: Antônio M
authors.initials: AM
authors.lastname: Rodrigues
authors.affiliation: Behavioural Neurobiology Laboratory, Centre for Addiction and Mental Health, Toronto, Canada.
authors.forename: José N
authors.initials: JN
authors.lastname: Nobrega
authors.affiliation: Disciplina de Neurofisiologia, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Luiz E
authors.initials: LE
authors.lastname: Mello
authors.affiliation: Disciplina de Neurofisiologia, Universidade Federal de São Paulo, São Paulo, Brazil; Behavioural Neurobiology Laboratory, Centre for Addiction and Mental Health, Toronto, Canada; Division of Neurosurgery, Toronto Western Hospital, University of Toronto, Toronto, Canada.
authors.forename: Clement
authors.initials: C
authors.lastname: Hamani
mesh_terms: D000818:Animals; D020643:Anterior Thalamic Nuclei / Q000503:physiopathology*; D002908:Chronic Disease; D046690:Deep Brain Stimulation; D004827:Epilepsy / Q000503:physiopathology*; D008297:Male; D017208:Rats, Wistar; D012640:Seizures