Repeated transcranial magnetic stimulation prevents kindling-induced changes in electrophysiological properties of rat hippocampal CA1 pyramidal neurons

Previous studies have implicated phospholipase C (PLC)-linked Group I metabotropic glutamate receptors (mGluRs) in regulating the excitability of hippocampal CA1 pyramidal neurons. We used intracellular recordings from rat hippocampal slices and specific antagonists to examine in more detail the mGluR receptor subtypes and signal transduction mechanisms underlying this effect. Application of the Group I mGluR agonist (RS)-3,5-dihydroxyphenylglycine (DHPG) suppressed slow- and medium-duration afterhyperpolarizations (s- and mAHP) and caused a consequent increase in cell excitability as well as a depolarization of the membrane and an increase in input resistance. Interestingly, with the exception of the suppression of the mAHP, these effects were persistent, and in the case of the sAHP lasting for more than 1 h of drug washout. Preincubation with the specific mGluR5 antagonist, 2-methyl-6-(phenylethynyl)-pyridine (MPEP), reduced but did not completely prevent the effects of DHPG. However, preincubation with both MPEP and the mGluR1 antagonist LY367385 completely prevented the DHPG-induced changes. These results demonstrate that the DHPG-induced changes are mediated partly by mGluR5 and partly by mGluR1. Because Group I mGluRs are linked to PLC via G-protein activation, we also investigated pathways downstream of PLC activation, using chelerythrine and cyclopiazonic acid to block protein kinase C (PKC) and inositol 1,4,5-trisphosphate-(IP3)-activated Ca2+ stores, respectively. Neither inhibitor affected the DHPG-induced suppression of the sAHP or the increase in excitability nor did an inhibitor of PLC itself, U-73122. Taken together, these results argue that in CA1 pyramidal cells in the adult rat, DHPG activates mGluRs of both the mGluR5 and mGluR1 subtypes, causing a long-lasting suppression of the sAHP and a consequent persistent increase in excitability via a PLC-, PKC-, and IP3-independent transduction pathway.

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Electrical Low Frequency Stimulation of the Kindling Site Preserves the Electrophysiological Properties of the Rat Hippocampal CA1 Pyramidal Neurons From the Destructive Effects of Amygdala Kindling: The Basis for a Possible Promising Epilepsy Therapy

Brain Stimulation ◽

10.1016/j.brs.2012.11.001 ◽

2013 ◽

Vol 6 (4) ◽

pp. 515-523 ◽

Cited By ~ 14

Author(s):

Zohreh Ghotbedin ◽

Mahyar Janahmadi ◽

Javad Mirnajafi-Zadeh ◽

Gila Behzadi ◽

Saeed Semnanian

Keyword(s):

Pyramidal Neurons ◽

Low Frequency ◽

Electrophysiological Properties ◽

Ca1 Pyramidal Neurons ◽

Low Frequency Stimulation ◽

Hippocampal Ca1 ◽

Amygdala Kindling ◽

Epilepsy Therapy ◽

Frequency Stimulation ◽

Stimulation Of

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Patch-clamp recordings of thermal effects of magnetic stimulation on the physiological characteristic of rat hippocampal neurons

Archives of Biological Sciences ◽

10.2298/abs150828047z ◽

2016 ◽

Vol 68 (3) ◽

pp. 567-573

Author(s):

Yu Zheng ◽

Lei Dong ◽

Ying Kong ◽

Hui Hong ◽

Yang Gao ◽

...

Keyword(s):

Thermal Effects ◽

Hippocampal Neurons ◽

Magnetic Stimulation ◽

Pyramidal Neurons ◽

Brain Research ◽

Low Frequency ◽

Physiological Characteristic ◽

Ca1 Pyramidal Neurons ◽

Hippocampal Ca1 ◽

Invaluable Tool

Transcranial magnetic stimulation (TMS) has proven to be an invaluable tool both in clinical practice and basic brain research. However, many concomitant effects of TMS are still incompletely understood, including thermal effects induced by TMS. The present study investigated how thermal effects induced by magnetic stimulation influence the properties of the spontaneous excitatory postsynaptic current (sEPSC) of hippocampal CA1 pyramidal neurons. We have demonstrated that a 50-Hz low-frequency electromagnetic field with intensities of 7, 14, and 23 mT can induce thermal heating in artificial cerebrospinal fluid(aCSF) from 25 to 40?C over a period of 15 min. We also report that the thermal effects induced by TMS directly influence the properties of sEPSC in hippocampal CA1 pyramidal neurons. Double measures were taken to control the temperature across experiments in order to ensure the accuracy of the temperature measurement of the aCSF. These novel findings provide important insight into the thermal effects induced by TMS as well as their consequences.

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