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Showing 4 results for Low Frequency Stimulation

Mehdi Sadegh, Javad Mirnajafi-Zadeh, Mohammad Javan, Yaghoub Fathollahi, Mohammad Mohammad-Zadeh, Ali Jahanshahi, Zahra Deljo,
Volume 11, Issue 1 (4-2007)

Introduction: Low-frequency stimulation (LFS) has a delaying effect on kindled seizures acquisition. In the present study we examined the role of galanin receptors in the inhibitory effects of LFS on kindled seizures induced by electrical stimulation of perforant path. Methods: Animals were stimulated daily at the AD threshold intensity with a rapid kindling procedure. LFS was applied immediately after cessation of each kindling stimulation. M35 (0.5 and 1.0 nM per site), a nonselective galanin receptor antagonist, was microinjected daily into the dentate gyrus before the beginning of stimulation protocol and behavioral seizure stages and afterdischarge durations were recorded. Results: LFS application had a suppressive effect on the kindling rate. It significantly increased the number of stimulations needed to reach seizure stages 3, 4 and 5. LFS also decreased the cumulative afterdischarge duration during the days of stimulation. Intra-dentate gyrus microinjection of M35 reduced the inhibitory effect of LFS on kindling rate, significantly. Conclusion: These data indicate that galanin receptors may have a role in mediating part of the inhibitory effects of LFS on perforant path kindled seizures.
Mohammad Mohammad-Zadeh, Javad Mirnajafi-Zadeh, Yaghoub Fathollahi, Mohammad Javan, Parviz Ghorbani,
Volume 11, Issue 2 (8-2007)

Introduction: Previous studies have been shown that low frequency stimulation (LFS) has an inhibitory effect on kindling acquisition. However, the mechanism of this effect has not been completely determined. In the present study, the effect of LFS of the perforant path on seizures induced by rapid perforant path kindling was investigated. Methods: Animals were kindled by electrical stimulation of perforant path. One group of animals (n=6) received LFS (0.1 ms pulses at 1 Hz, 200 pulse, and 50-150 µA) after termination of each kindling stimulations. In control groups, animals received only kindling stimulations (n=8) or LFS (n=4). Basal field potential recording and paired pulse stimulations were done before kindling stimulations every days. Results: Application of LFS significantly retarded the kindling acquisition and increased the number of stimulations to achieve different seizure stages [F(4,60)=10.9, P<0.0001]. LFS also prevented increment of slope of field excitatory postsynaptic potentials and population spike amplitude during kindling (P<0.001) (There was %88.6±1.7 increment in fEPSP and %94±2.3 increment in PS in kindled group and %3.5±.05 increment in fEPSP and %12.3±0.1 decrease in PS in kindled+LFS group). In addition, LFS prevented the marked increase in early (10-50 ms intervals) and late (300-1000 ms intervals) paired pulse depression induced by kindling significantly (P<0.01). Conclusion: According to obtained results, it may be suggested that LFS of perforant path has a significant antiepileptogenic effect on perforant path kindled seizures through inhibition of synaptic transmission in dentate gyrus. Meanwhile, LFS prevents compensatory increase in the paired pulse depression during kindling acquisition.
Maryam Zeraati, Javad Mirnajafi-Zadeh, Mohammad Javan, Saeed Semnanian, Simin Namvar,
Volume 14, Issue 2 (7-2010)

Introduction: Considering high prevalence of epileptic disease and considering that 40 percent of epileptic patients are resistant to drug therapy, it needs more researches to find new therapeutic ways. LFS is among the new methods for epilepsy treatments. One possible mechanism involved in the anticonvulsant effect of LFS is increased adenosine. Therefore, in this study the role of adenosine production from ATP by ectonucleotidase enzyme pathway in exerting the anticonvulsant effects of LFS were evaluated. Methods: Animals were kindled by electrical stimulation of perforant path in a rapid kindling manner (12 stimulation per day). One group of animals received LFS after kindling stimulation. In one another group, AOPCP a blocker of ectonucleotidase inhibitor was micro injected (50 micro molar) intra cerebro ventricular each day before LFS stimulation. Some group of animals were also received AOPCP (50 and 100 micro molar) but were not applied to LFS. Seizure behavior and electrophysiological parameters (including ADD and field potential) were recorded. Results: Like previous investigations, application of LFS, decreased all seizure parameters significantly. Microinjection of AOPCP had no significant effect on anticonvulsant actions of LFS. However microinjection of AOPCP at doses of 100 micro molar in animals that received just kindling stimulations, increased the seizure parameters significantly. Conclusion: The results show that adenosine production via ectonucleotidase enzyme pathway may has no role in anticonvulsant effects of LFS however endogenous adenosine produced through this pathway has an important role in kindling development.
Simin Namvar, Javad Mirnajafi-Zadeh, Mohammad Javan, Maryam Zeraati,
Volume 14, Issue 3 (10-2010)

Introduction: Application of low-frequency stimulation (LFS) is a new method for treatment of drug resistant epileptic patients. Previous studies demonstrated that activation of receptors coupled to Gi proteins is one of the mechanisms of the anticonvulsant effect of LFS. Thus, in this study, alterations in the expression of RGS4 and RGS10 proteins, as negative regulators of Gi proteins, were investigated. Methods: Animals were kindled by perforant path stimulation in a rapid kindling manner (12 stimulation per day, 1 ms pulse duration at 50 Hz). LFS (8 stimulation per day, 0.1 ms pulse duration at 1 Hz, 200 pulses) was applied to the perforant path 5 minute after the termination of kindling stimulations. After electrophysiological recordings for 6 days, the dentate gyrus of the animals was removed and RGS4 and RGS10 protein expression was studied by western blotting technique. Results: Application of LFS significantly retarded kindling acquisition and increased the number of stimulations to achieve different stages of seizure. LFS also significantly reduced after discharge duration. In addition, application of LFS after kindling stimulation reduced the expression of RGS4 and RGS10 proteins. Conclusion: Results of the present study showed that LFS has anticonvulsant effects on the perforant path kindling. Application of LFS following kindling stimulation reduced the expression of RGS4 and RGS10 proteins. Reduction of the expression of these proteins results in the longer activation of signaling pathways of Gi proteins, which may be responsible for LFS anticonvulsant effects.

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