Reversal of long-term potentiation (depotentiation) induced by tetanus stimulation of the input to CA1 neurons of guinea pig hippocampal slices

In hippocampal slices, temporary (10–20 min) replacement of glucose with 10 mM 2-deoxyglucose is followed by marked and very sustained potentiation of EPSPs (2-DG LTP). To investigate its mechanism, we examined 2-DG's effect in CA1 neurons recorded with sharp 3 M KCl electrodes containing a strong chelator, 50 or 100 mM ethylene glycol-bis(β-aminoethyl ether)- N, N, N′, N′-tetraacetic acid (EGTA). In most cases, field EPSPs were simultaneously recorded and conventional LTP was also elicited in some cells by tetanic stimulation of stratum radiatum. 2-DG potentiated intracellular EPSP slopes by 48 ± 5.1% (SE) in nine cells recorded with plain KCl electrodes and by 52 ± 6.2% in seven cells recorded with EGTA-containing electrodes. In four of the latter cells, tetanic stimulation (twice 100 Hz for 1 s) failed to evoke LTP (2 ± 1.1%), although field EPSPs were clearly potentiated (by 28 ± 6.9%). Thus unlike tetanic LTP, 2-DG LTP is not readily prevented by postsynaptic intraneuronal injection of EGTA. These findings agree with other evidence that the rise in postsynaptic (somatic) [Ca2+]i caused by 2-DG is not the principal trigger for the subsequent 2-DG LTP and that it may be a purely presynaptic phenomenon.

Download Full-text

Extracellular phosphorylation of membrane protein modifies theta burst-induced long-term potentiation in CA1 neurons of guinea-pig hippocampal slices

Neuroscience Letters ◽

10.1016/0304-3940(95)11342-8 ◽

1995 ◽

Vol 187 (2) ◽

pp. 133-136 ◽

Cited By ~ 20

Author(s):

Satoshi Fujii ◽

Ken-Ichi Ito ◽

Hiroyuki Osada ◽

Takuya Hamaguchi ◽

Yoichiro Kuroda ◽

...

Keyword(s):

Membrane Protein ◽

Guinea Pig ◽

Hippocampal Slices ◽

Long Term Potentiation ◽

Ca1 Neurons ◽

Term Potentiation ◽

Theta Burst

Download Full-text

Endogenous adenosine regulates the effects of low-frequency stimulation on the induction of long-term potentiation in CA1 neurons of guinea pig hippocampal slices

Neuroscience Letters ◽

10.1016/s0304-3940(99)00980-5 ◽

2000 ◽

Vol 279 (2) ◽

pp. 121-124 ◽

Cited By ~ 17

Author(s):

Satoshi Fujii ◽

Yoichiro Kuroda ◽

Ken-Ichi Ito ◽

Masatomo Yoshioka ◽

Kenya Kaneko ◽

...

Keyword(s):

Guinea Pig ◽

Hippocampal Slices ◽

Low Frequency ◽

Long Term Potentiation ◽

Ca1 Neurons ◽

Endogenous Adenosine ◽

Low Frequency Stimulation ◽

Term Potentiation ◽

Frequency Stimulation

Download Full-text

Extracellular adenosine 5′-triphosphate plus activation of glutamatergic receptors induces long-term potentiation in CA1 neurons of guinea pig hippocampal slices

Neuroscience Letters ◽

10.1016/s0304-3940(99)00776-4 ◽

1999 ◽

Vol 276 (1) ◽

pp. 21-24 ◽

Cited By ~ 20

Author(s):

Satoshi Fujii ◽

Hiroshi Kato ◽

Yoichiro Kuroda

Keyword(s):

Guinea Pig ◽

Hippocampal Slices ◽

Long Term Potentiation ◽

Extracellular Adenosine ◽

Ca1 Neurons ◽

Term Potentiation

Download Full-text

On the Respective Roles of Nitric Oxide and Carbon Monoxide in Long-Term Potentiation in the Hippocampus

Learning & Memory ◽

10.1101/lm.6.1.63 ◽

1999 ◽

Vol 6 (1) ◽

pp. 63-76 ◽

Cited By ~ 1

Author(s):

Min Zhuo ◽

Jarmo T. Laitinen ◽

Xiao-Ching Li ◽

Robert D. Hawkins

Keyword(s):

Nitric Oxide ◽

Carbon Monoxide ◽

Heme Oxygenase ◽

Guanylyl Cyclase ◽

Hippocampal Slices ◽

Long Term Potentiation ◽

No Synthase ◽

Term Potentiation ◽

Stimulation Of

Perfusion of hippocampal slices with an inhibitor nitric oxide (NO) synthase blocked induction of long-term potentiation (LTP) produced by a one-train tetanus and significantly reduced LTP by a two-train tetanus, but only slightly reduced LTP by a four-train tetanus. Inhibitors of heme oxygenase, the synthetic enzyme for carbon monoxide (CO), significantly reduced LTP by either a two-train or four-train tetanus. These results suggest that NO and CO are both involved in LTP but may play somewhat different roles. One possibility is that NO serves a phasic, signaling role, whereas CO provides tonic, background stimulation. Another possibility is that NO and CO are phasically activated under somewhat different circumstances, perhaps involving different receptors and second messengers. Because NO is known to be activated by stimulation of NMDA receptors during tetanus, we investigated the possibility that CO might be activated by stimulation of metabotropic glutamate receptors (mGluRs). Consistent with this idea, long-lasting potentiation by the mGluR agonist tACPD was blocked by inhibitors of heme oxygenase but not NO synthase. Potentiation by tACPD was also blocked by inhibitors of soluble guanylyl cyclase (a target of both NO and CO) or cGMP-dependent protein kinase, and guanylyl cyclase was activated by tACPD in hippocampal slices. However, biochemical assays indicate that whereas heme oxygenase is constitutively active in hippocampus, it does not appear to be stimulated by either tetanus or tACPD. These results are most consistent with the possibility that constitutive (tonic) rather than stimulated (phasic) heme oxygenase activity is necessary for potentiation by tetanus or tACPD, and suggest that mGluR activation stimulates guanylyl cyclase phasically through some other pathway.

Download Full-text