ABSTRACT
Objective: Electrical low frequency stimulation [LFS] is a new therapeutic method that moderates hyperexcitability during epileptic states. Seizure occurrence is accompanied by some changes in action potential [AP] features. In this study, we investigated the inhibitory action of LFS on epileptiform activity [EA] induced-changes in AP features in hippocampal CA1 pyramidal neurons
Materials and Methods: In this experimental study, we induced EA in hippocampal slices by increasing the extracellular potassium [K+] concentration to 12 mM. LFS [1 Hz] was applied to the Schaffer collaterals at different pulse numbers [600 and 900] at the beginning of the EA. Changes in AP features recorded by whole-cell patch clamp recording were compared using phase plot analysis
Results: Induction of EA depolarized membrane potential, decreased peak amplitude, as well as the maximum rise and decay slopes of APs. Administration of 1 Hz LFS at the beginning of EA prevented the above mentioned changes in AP features. This suppressive effect of LFS depended on the LFS pulse number, such that application of 900 pulses of LFS had a stronger recovery effect on AP features that changed during EA compared to 600 pulses of LFS. The constructed phase plots of APs revealed that LFS at 900 pulses significantly decreased the changes in resting membrane potential [RMP], peak amplitude, and maximum rise and decay slopes that appeared during EA
Conclusion: Increasing the numbers of LFS pulses can magnify its inhibitory effects on EA-induced changes in AP features
ABSTRACT
Objective: Hippocampal insults have been observed in multiple sclerosis [MS] patients. Fibroblast growth factor-2 [FGF2] induces neurogenesis in the hippocampus and enhances the proliferation, migration and differentiation of oligodendrocyte progenitor cells [OPCs]. In the current study, we have investigated the effect of FGF2 on the processes of gliotoxin induced demyelination and subsequent remyelination in the hippocampus
Materials and Methods: In this experimental study adult male Sprague-Dawley rats received either saline or lysolecithin [LPC] injections to the right hippocampi. Animals received intraperitoneal [i.p.] injections of FGF2 [5 ng/g] on days 0, 5, 12 and 26 post-LPC. Expressions of myelin basic protein [Mbp] as a marker of myelination, Olig2 as a marker of OPC proliferation, Nestin as a marker of neural progenitor cells, and glial fibrillary acidic protein [Gfap] as a marker of reactive astrocytes were investigated in the right hippocampi by reverse transcriptase-polymerase chain reaction [RT-PCR]
Results: There was reduced Mbp expression at seven days after LPC injection, increased expressions of Olig2 and Nestin, and the level of Gfap did not change. FGF2 treatment reversed the expression level of Mbp to the control, significantly enhanced the levels of Olig2 and Nestin, but did not change the level of Gfap. At day-28 post- LPC, the expression level of Mbp was higher than the control in LPC-treated animals that received FGF2. The levels of Olig2, Nestin and Gfap were at the control level in the non-treated LPC group but significantly higher in the FGF2-t reated LPC group
Conclusion: FGF2 enhanced hippocampal myelination and potentiated the recruitment of OPCs and neural stem cells [NSCs] to the lesion area. Long-term application of FGF2 might also enhance astrogliosis in the lesion site
ABSTRACT
Background: Low frequency stimulation [LFS] has been recently suggested as an antiepileptic method in treating the drugresistant epileptic syndromes such as temporal lobe epilepsy. So far, in the most clinical and experimental studies, LFS has been applied to the seizure focus itself. Considering the role of dentate gyrus in spreading of the limbic seizures, in the present study the effect of LFS of dentate gyrus on amygdala kindling-induced seizures was investigated
Materials and methods: To kindle the animals, using stereotaxic instrument, a tripolar electrode was inserted into right basolateral area of amygdala and a bipolar electrode was ipsilaterally placed in dentate gyrus of male Wistar rats. After a 10 days recovery period, animals divided into two groups. The animals of kindled group were received daily electrical stimulations. In kindled+LFS group, LFS was delivered to dentate gyrus 1 min after cessation of amygdala kindling stimulation. The maximum seizure stage and duration of afterdischarges were evaluated after kindling stimulation. The effect of LFS on behavioral seizure stages and afterdischarges was compared using Kruskall Wallis and repeated measures 2-way AVOVA. A P value less than 0.05 was considered as significant level
Results: The required time to achieve a stage 5 seizure was 12 days in kindled group animals. However, animals of kindled+LFS group did not show more than stage 2 seizure following 12 days of stimulation. LFS of dentate gyrus significantly prevented the increment of behavioral seizure stages and afterdischarge duration in kindled-LFS group compared with kindled group
Conclusion: The results of this study demonstrated that application of LFS in the dentate gyrus can be an effective therapeutic method for controlling the amygdala kindling-induced seizures. Furthermore, this study provide further evidences showing LFS of brain areas involved in spreading the seizures, other than seizure focus can have anticonvulsant affect