Differential Effect of TEA on Long-Term Synaptic Modification in Hippocampal CA1 and Dentate Gyrus in vitro

Song, Dong; Xie, Xiaping; Wang, Zhuo; Berger, Theodore W.

doi:10.1006/nlme.2001.4032

Cited by 35 publications

(24 citation statements)

References 23 publications

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“…Long-term potentiation (LTP) can be induced by high-frequency synaptic input (Bliss and Collingridge, 1993) or by pharmacological manipulation, e.g., application of the K ϩ channel blocker, tetraethylammonium (TEA) (Aniksztejn and Ben-Ari, 1991;Huang and Malenka, 1993;Hanse and Gustafsson, 1994;Huber et al, 1995;Song et al, 2001). As with high-frequency stimulation (HFS)-induced LTP, TEA-induced LTP (TEA-LTP) depends on elevation of [Ca 2ϩ ] i (Huang and Malenka, 1993).…”

Section: Introductionmentioning

confidence: 99%

“…As with high-frequency stimulation (HFS)-induced LTP, TEA-induced LTP (TEA-LTP) depends on elevation of [Ca 2ϩ ] i (Huang and Malenka, 1993). In CA1, TEA-LTP has been reported to consist of both N-methyl-D-aspartate glutamate receptor (NMDA)-dependent and voltage-dependent calcium channel (VDCC)-dependent components (Huber et al, 1995;Song et al, 2001). Both L-type (Huang and Malenka, 1993;Huber et al, 1995) and T-type (Song et al, 2001) VDCCs have been reported to contribute to the VDCC-dependent component.…”

Section: Introductionmentioning

confidence: 99%

“…In CA1, TEA-LTP has been reported to consist of both N-methyl-D-aspartate glutamate receptor (NMDA)-dependent and voltage-dependent calcium channel (VDCC)-dependent components (Huber et al, 1995;Song et al, 2001). Both L-type (Huang and Malenka, 1993;Huber et al, 1995) and T-type (Song et al, 2001) VDCCs have been reported to contribute to the VDCC-dependent component. In DG, both NMDA-dependent long-term depression (LTD) (Song et al, 2001) and T-type VDCC-dependent LTP have been reported (Coogan et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

“…Both L-type (Huang and Malenka, 1993;Huber et al, 1995) and T-type (Song et al, 2001) VDCCs have been reported to contribute to the VDCC-dependent component. In DG, both NMDA-dependent long-term depression (LTD) (Song et al, 2001) and T-type VDCC-dependent LTP have been reported (Coogan et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

“…In a previous investigation (Song et al, 2001), we studied TEA-LTP and TEA-LTD in CA1 and DG, using both intracellular and extracellular recording techniques. We observed a correlation between a strong plateau-like depolarizing potential recorded in the presence of TEA and the induction of LTP.…”

Section: Introductionmentioning

confidence: 99%

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Contribution of T‐type VDCC to TEA‐induced long‐term synaptic modification in hippocampal CA1 and dentate gyrus

2002

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ABSTRACT:We have previously reported that exposure to the K ؉ channel blocker tetraethylammonium (TEA), 25 mM, induces long-term potentiation (LTP) in CA1, but not in the dentate gyrus (DG), of the rat hippocampal slice. During TEA application, stimulation of excitatory afferents results in a strong depolarizing potential after the fast excitatory postsynaptic potential (EPSP) in CA1, but not in DG. We hypothesized that the differential effect of TEA on long-term synaptic modification in CA1 and DG results from different levels of TEA-elicited depolarization in the two cell types. Additional pharmacological studies showed that blockade of T-type voltage-dependent calcium channels (VDCCs) decreased both the magnitude of LTP and the late, depolarizing potential in CA1. Blockade of L-type VDCCs had no such effect. Using computer models of morphologically reconstructed CA1 pyramidal cells and DG granule cells, we tested our hypothesis by simulating the relative intracellular Ca 2؉ accumulation and membrane potential changes mediated by T-type and L-type VDCCs. Simulation results using pyramidal cell models showed that, with decreased maximum conductance of TEA-sensitive potassium channels, synaptic inputs elicited strong depolarizing potentials similar to those observed with intracellular recording. During this depolarization, VDCCs were opened and resulted in a large intracellular Ca 2؉ accumulation that presumably caused LTP. When T-type VDCCs were blocked, the magnitudes of both the Ca 2؉ accumulation and the late depolarizing potential were decreased substantially. Simulated blockade of L-type VDCCs had only a minor effect. Together, our modeling and experimental studies indicate that T-type VDCCs, rather than L-type VDCCs, are primarily responsible for facilitating the depolarizing potential caused by TEA and for the consequent Ca 2؉ influx. Thus, our findings strongly suggest that the induction of TEA-LTP in CA1 depends primarily on T-type, rather than L-type, VDCCs. Simulation results using modeled granule cells suggests that the failure of TEA to induce LTP in DG is partly due to a low density of T-type VDCCs in granule cell membranes. Hippocampus 2002;12:689 -697.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Contribution of T‐type VDCC to TEA‐induced long‐term synaptic modification in hippocampal CA1 and dentate gyrus

2002

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Hypothyroidism impairs late LTP in CA1 region but not in dentate gyrus of the intact rat hippocampus: MAPK involvement

2003

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Thyroid hormone activates extracellular signal-regulated kinases (ERK1 and ERK2), which are important in late long-term potentiation (L-LTP). The aim of this study was to determine the possible mechanism underlying the impairment of L-LTP as a result of hypothyroidism. We investigated the effect of hypothyroidism on L-LTP of the two associative pathways in the hippocampus: the Schaffer collateral synapses and the perforant path synapses. We also examined the effect of hypothyroidism on ERK1 and ERK2 levels in both the CA1 and dentate gyrus (DG) regions of the hippocampus. Electrophysiological recordings from hippocampi of anesthetized rats show that hypothyroidism impairs L-LTP in CA1 region, but not in the DG. Western blot analysis of the CA1 region shows that hypothyroidism decreases phosphorylated ERK1 and ERK2 levels without affecting their total levels. In the DG of the hypothyroid rat, however, there was no significant change in the levels of phosphorylated or total ERKs. The correlation between the effect of hypothyroidism on L-LTP and enzyme levels suggests that hypothyroidism-induced impairment of L-LTP in CA1 may be due to decreased levels of phosphorylated ERK1 and ERK2.

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Role of phosphorylated CaMKII and calcineurin in the differential effect of hypothyroidism on LTP of CA1 and dentate gyrus

2005

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Hypothyroidism impairs early long-term potentiation (LTP) in the CA1 but not in the dentate gyrus (DG) of hippocampus of anesthetized adult rats. Protein levels and activities of signaling molecules in both the CA1 and DG of surgically thyroidectomized and sham-operated euthyroid rats were measured. Basal levels of total calmodulin kinase II (CaMKII) protein in both the CA1 and DG were decreased in hypothyroidism. Marked reduction of basal P-CaMKII levels and CaMKII activity was seen in CA1, but not in the DG of the same hypothyroid animals. Basal levels of calmodulin and protein kinase Cgamma (PKCgamma) were decreased in CA1 but remained unchanged in the DG of hypothyroid rats. Basal calcineurin levels and activity, although enhanced in CA1, were reduced in the DG of hypothyroid rats. These findings suggest that the DG may possess a compensatory mechanism whereby calcineurin levels are reduced, to allow sufficient CaMKII activity to produce an apparently normal LTP in hypothyroid rats.

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Differential Effect of TEA on Long-Term Synaptic Modification in Hippocampal CA1 and Dentate Gyrus in vitro

Cited by 35 publications

References 23 publications

Contribution of T‐type VDCC to TEA‐induced long‐term synaptic modification in hippocampal CA1 and dentate gyrus

Contribution of T‐type VDCC to TEA‐induced long‐term synaptic modification in hippocampal CA1 and dentate gyrus

Hypothyroidism impairs late LTP in CA1 region but not in dentate gyrus of the intact rat hippocampus: MAPK involvement

Role of phosphorylated CaMKII and calcineurin in the differential effect of hypothyroidism on LTP of CA1 and dentate gyrus

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