scholarly journals Effects of Ethanol on Synaptic Plasticity and NMDA Currents in the Juvenile Rat Dentate Gyrus

2020 ◽  
Vol 6 (1) ◽  
pp. 123-136 ◽  
Author(s):  
Scott D. Sawchuk ◽  
Hannah M.O. Reid ◽  
Katie J. Neale ◽  
James Shin ◽  
Brian R. Christie
Keyword(s):  
Dentate Gyrus ◽  
Hippocampal Slices ◽  
Age Groups ◽  
Low Frequency ◽  
Nmda Antagonist ◽  
Perforant Path ◽  
Whole Cell ◽  
Low Frequency Stimulation ◽  
Acute Ethanol ◽  
Frequency Stimulation

Background and Objectives: We examined how acute ethanol (EtOH) exposure affects long term depression (LTD) in the dentate gyrus (DG) of the hippocampus in juvenile rats. EtOH is thought to directly modulate n-methyl-D-aspartate receptor (NMDAr) currents, which are believed important for LTD induction. LTD in turn is believed to play an important developmental role in the hippocampus by facilitating synaptic pruning. Methods: Hippocampal slices (350μm) were obtained at post-natal day (PND) 14, 21, or 28. Field EPSPs (excitatory post-synaptic potential) or whole-cell EPSCs (excitatory post-synaptic conductance) were recorded from the DG (dentate gyrus) in response to medial perforant path activation. Low-frequency stimulation (LFS; 900 pulses; 120 s pulse) was used to induce LTD. Results: Whole-cell recordings indicated that EtOH exposure at 50mM did not significantly impact ensemble NMDAr EPSCs in slices obtained from animals in the PND14 or 21 groups, but it reliably produced a modest inhibition in the PND28 group. Increasing the concentration to 100 mM resulted in a modest inhibition of NMDAr EPSCs in all three groups. LTD induction and maintenance was equivalent in magnitude in all three age groups in control conditions, however, and surprisingly, NMDA antagonist AP5 only reliably blocked LTD in the PND21 and 28 age groups. The application of 50 mM EtOH attenuated LTD in all three age groups, however increasing the concentration to 100 mM did not reliably inhibit LTD. Conclusions: These results indicate that the effect of EtOH on NMDAr-EPSCs recorded from DGCs is both age and concentration dependent in juveniles. Low concentrations of EtOH can attenuate, but did not block LTD in the DG. The effects of EtOH on LTD do not align well with it’s effects on NNMDA receptors.

Effect of low frequency stimulation of perforant path on kindling rate and synaptic transmission in the dentate gyrus during kindling acquisition in rats

2007 ◽  
Vol 75 (2-3) ◽  
pp. 154-161 ◽  
Author(s):  
Mohammad Mohammad-Zadeh ◽  
Javad Mirnajafi-Zadeh ◽  
Yaghoub Fathollahi ◽  
Mohammad Javan ◽  
Parviz Ghorbani ◽  
...  
Keyword(s):  
Synaptic Transmission ◽  
Dentate Gyrus ◽  
Low Frequency ◽  
Perforant Path ◽  
Low Frequency Stimulation ◽  
Frequency Stimulation ◽  
Stimulation Of

Low-frequency stimulation at the troughs of theta-oscillation induces long-term depression of previously potentiated CA1 synapses

1996 ◽  
Vol 75 (2) ◽  
pp. 877-884 ◽  
Author(s):  
P. T. Huerta ◽  
J. E. Lisman
Keyword(s):  
Hippocampal Slices ◽  
Field Potential ◽  
Low Frequency ◽  
Long Term Depression ◽  
Low Frequency Stimulation ◽  
Bath Application ◽  
Stable Conditions ◽  
Theta Frequency ◽  
Frequency Stimulation

1. The induction of long-term weakening of synaptic transmission in rat hippocampal slices was examined in CA1 synapses during cholinergic modulation. 2. Bath application of the cholinergic agonist carbachol (50 microM) activated an oscillation of the local field potential in the theta-frequency range (5-12 Hz), termed theta. It was previously shown that a stimulation train of 40 single shocks (at 0.1 Hz) to the Schaffer collateral-commisural afferents, each synchronized with positive peaks of theta, caused homosynaptic long-term enhancement in CA1. Furthermore, long-term depression (LTD) was sporadically observed when the stimulation train was given at negative troughs of theta. Here we have sought to determine stable conditions for LTD induction during theta. 3. Synaptic weakening was reliably obtained, by giving 40 shocks (at 0.1 Hz) at theta-troughs, only in pathways that had been previously potentiated. This decrement, termed theta-LTD, was synapse specific because it did not occur in an independent pathway not stimulated during theta. The interval between the initial potentiating tetanus and theta-LTD induction could be as long as 90 min. 4. theta-LTD could be saturated; after consecutive episodes of theta-LTD induction, no significant further depression was obtained. Moreover, theta-LTD could be reversed by tetanic stimulation. 5. theta-LTD could prevent the induction of LTD by 600-900 pulses at 1 Hz. This suggests that the two protocols may share common mechanisms at the synaptic level. 6. We conclude that single presynaptic spikes that occur at low frequency and are properly timed to the troughs of theta may be a relevant mechanism for decreasing the strength of potentiated synapses.

scholarly journals A Comparison of the Dynamics of S100B, S100A1, and S100A6 mRNA Expression in Hippocampal CA1 Area of Rats during Long-Term Potentiation and after Low-Frequency Stimulation

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
Pavel D. Lisachev ◽  
Mark B. Shtark ◽  
Olga O. Sokolova ◽  
Vladimir O. Pustylnyak ◽  
Mary Yu. Salakhutdinova ◽  
...  
Keyword(s):  
Mrna Level ◽  
Hippocampal Slices ◽  
Low Frequency ◽  
Fold Increase ◽  
Long Term Potentiation ◽  
Low Frequency Stimulation ◽  
Term Potentiation ◽  
Mrna Content ◽  
Frequency Stimulation ◽  
Ca1 Area

The interest in tissue- and cell-specific S100 proteins physiological roles in the brain remains high. However, necessary experimental data for the assessment of their dynamics in one of the most important brain activities, its plasticity, is not sufficient. We studied the expression of S100B, S100A1, and S100A6 mRNA in the subfield CA1 of rat hippocampal slices after tetanic and low-frequency stimulation by real-time PCR. Within 30 min after tetanization, a 2–4 fold increase of the S100B mRNA level was observed as compared to the control (intact slices) or to low-frequency stimulation. Subsequently, the S100B mRNA content gradually returned to baseline. The amount of S100A1 mRNA gradually increased during first hour and maintained at the achieved level in the course of second hour after tetanization. The level of S100A6 mRNA did not change following tetanization or low-frequency stimulation.

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