Korean J Physiol Pharmacol.  2017 Jul;21(4):423-428. 10.4196/kjpp.2017.21.4.423.

Reduction of long-term potentiation at Schaffer collateral-CA1 synapses in the rat hippocampus at the acute stage of vestibular compensation

• Lee GW
• Kim JH
• Kim MS

• KMID: 2384456
• DOI: http://doi.org/10.4196/kjpp.2017.21.4.423

Abstract

Vestibular compensation is a recovery process from vestibular symptoms over time after unilateral loss of peripheral vestibular end organs. The aim of the present study was to observe time-dependent changes in long-term potentiation (LTP) at Schaffer collateral-CA1 synapses in the CA1 area of the hippocampus during vestibular compensation. The input-output (I/O) relationships of fEPSP amplitudes and LTP induced by theta burst stimulation to Schaffer's collateral commissural fibers were evaluated from the CA1 area of hippocampal slices at 1 day, 1 week, and 1 month after unilateral labyrinthectomy (UL). The I/O relationships of fEPSPs in the CA1 area was significantly reduced within 1 week post-op and then showed a non-significant reduction at 1 month after UL. Compared with sham-operated animals, there was a significant reduction of LTP induction in the hippocampus at 1 day and 1 week after UL. However, LTP induction levels in the CA1 area of the hippocampus also returned to those of sham-operated animals 1 month following UL. These data suggest that unilateral injury of the peripheral vestibular end organs results in a transient deficit in synaptic plasticity in the CA1 hippocampal area at acute stages of vestibular compensation.

Keyword

Hippocampus; Long-term potentiation; Unilateral labyrinthectomy; Vestibular compensation

MeSH Terms

Animals
Compensation and Redress*
Hippocampus*
Long-Term Potentiation*
Neuronal Plasticity
Rats*
Synapses*

Figure

• 

  Fig. 1 Typical recording of field excitatory post-synaptic potentials (fEPSPs) evoked by application of single pulse electrical shock to Schaffer collaterals-commissural fibers in the CA1 area of the hippocampus.

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  Fig. 2 Stimulus intensity-dependent changes in the amplitudes of fEPSPs in the stratum radiatum layer of the CA1 area at 1 day, 1 week, and 1 month after UL. (A) Contralesional CA1 area, (B) ipsilesional CA1 area (n=15, *p<0.05, **p<0.01, sham vs. UL).

• 

  Fig. 3 Typical recordings of long-term potentiation induction (LTP) of fEPSPs in the stratum radiatum layer of the CA1 area evoked by theta burst stimulation. (A) Sham animal, (B) UL 1 day. Arrows indicate application of theta burst stimulation to induce LTP.

• 

  Fig. 4 Comparison of induction rates of LTP between the contralesional (contra) and ipsilesional (ipsi) CA1 areas of hippocampal slices following UL (n=15, *p<0.05, **p<0.01).

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