Azam Asgari; Saeed Semnanian; Nafiseh Atapour; Amir Shojaee; Vahid Sheybani; Seyyed Javad Mirnajafi Zadeh
Volume 23, Issue 2 , March and April 2016, , Pages 290-303
Abstract
Background and purpose: Low frequency stimulation (LFS) has anticonvulsant effect. However, its mechanism of action has not been completely determined. In the present study the effect of LFS on evoked inhibitory post synaptic GABAergic currents (eIPSC) is investigated in CA1 pyramidal neurons of the ...
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Background and purpose: Low frequency stimulation (LFS) has anticonvulsant effect. However, its mechanism of action has not been completely determined. In the present study the effect of LFS on evoked inhibitory post synaptic GABAergic currents (eIPSC) is investigated in CA1 pyramidal neurons of the hippocampus in kindled rats. Materials and Methods: In this experimental study animals were kindled through electrical stimulation of amygdala. 24 hours following fully kindling achievement in 20 Wistar rats, the effect of LFS on eIPSCs was assessed in hippocampal slices. Results: Obtained results showed that application of LFS at 200 pulses and at the intensity of 1.5 threshold, increased the amplitude and decay time constant of eIPSCs in both control and kindled rats. When 200 pulses of LFS were administered with an intensity equal to threshold, only eIPSC amplitude was increased in both control and kindled groups significantly (P<0.001). Comparing the effectiveness of LFS on control and kindled groups showed that 200 pulses of LFS at the intensity of 1.5 threshold had higher effect in control than kindled group (P<0.001). Conclusion: Results of the present study showed that LFS application increased eIPSCs parameters in a pulse number and intensity dependent manner. This increment can be considered as a possible anticonvulsant mechanism of LFS.
Homeyra Moradi Chameh; Saeed Semnanian; Mahyar Jan Ahmadi; Amir Shojaee; Azam Asgari; Seyyed Javad Mirnajafizadeh
Volume 22, Issue 4 , September and October 2015, , Pages 649-659
Abstract
Background & Objectives: Amygdala kindling is accompanied with alteration of the electrophysiological characteristics of pyramidal cells in CA1 area of hippocampus. However, it is not clear that when and in which seizure stage do these changes occur during kindling. In the present study, changes ...
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Background & Objectives: Amygdala kindling is accompanied with alteration of the electrophysiological characteristics of pyramidal cells in CA1 area of hippocampus. However, it is not clear that when and in which seizure stage do these changes occur during kindling. In the present study, changes in the electrophysiological properties of hippocampal CA1 pyramidal neurons following partial amygdala kindling in rats were compared to full kindled state. Materials & Methods: Animals were rapidly kindled by 1 ms square waves, 50 Hz, for 3 s. These stimulations were applied to the amygdala 12 times per day at 5 min intervals. Animal received kindling stimulation until achieving stage 2 (partial kindled group) and stage 5 (full kindled group). 24 hours after the last kindling stimulation electrophysiological properties of CA1 pyramidal neurons were assessed by using whole-cell patch clamp technique. Results: Obtained data from amygdala kindling showed that adaptation index, Rheobase, utilization time and the amplitude of afterhyperpolarization potential in partial kindled and full kindled compare to control were significantly decreased and the numbers of action potentials were significantly increased. Conclusion: The present findings showed that in spite of in partial amygdala kindling, the number of stimulations that rats will receive is lower than full kindled animal but it can change neuronal hyperexcitability through alteration of the electrophysiological characteristics.
Saeed Semnanian; Hossein Baharvand; Shiva Khezri; Mohammad Javan
Volume 18, Issue 3 , September and October 2011, , Pages 179-187
Abstract
Background and Purpose: Novel strategies of MS try to stimulate endogenous neural stem cells for demyelination repair. Increased levels of cAMP potentiate the repair mechanisms in CNS by activating PKA or independently. In the present study، we investigated the effect of dbcAMP on neural stem cells ...
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Background and Purpose: Novel strategies of MS try to stimulate endogenous neural stem cells for demyelination repair. Increased levels of cAMP potentiate the repair mechanisms in CNS by activating PKA or independently. In the present study، we investigated the effect of dbcAMP on neural stem cells migration in experimental autoimmune encephalomyelitis (EAE) model of MS. Methods and Materials: Mice were immunized with 300 µg MOG peptide emulsified in complete Freund''s adjuvant (CFA) and pertussis toxin (PT). Control mice received CFA and PT. Groups of EAE- mice received i.p. injections of dbcAMP 10mg/kg from day 9-14 or 9-21. Animals were observed daily for neurological deficit. Nestin expression was used as a marker to detect neural stem cells. The number of Nestin+ cells in SVZ and olfactory bulb (OB) was evaluated using immunohistochemical staining. GraphPad Prism Version 5 was used for analyzing the data. For the clinical signs of EAE، the differences between the same days were compared by unpaired t-test. For the number of Nestin+ cells، the statistical differences between the groups were determined by one-way ANOVA and Tukey post-test. Results: EAE induction caused clinical signs and paralysis of tail and hind limbs. dbcAMP significantly reduced the incidence and severity of EAE in mice immunized with MOG. Maximum of scores reached 0.66±0.13 for dbcAMP treated mice (2.5±0.2 for EAE mice) on 21 dpi (day post inductin). EAE induction did not change number of nestin+ cells in SVZ but it increased it in OB. With developing of scores on 21dpi، the number of cells decreased (5.66±1.20). dbcAMP injection from 9-21 dpi increased these cells in SVZ. With developing of EAE scores on 21 dpi، the number of these cells in OB increased (19.5±2.04) and has significant differences with the control group. The treatment of EAE induced mice with dbcAMP from 9-21 dpi was assosiated with a significant elevation of Nestin+ cells in OB (40±2.73) (P