2-Deoxyglucose-induced long-term potentiation in CA1 is not prevented by intraneuronal chelator.
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(beta-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) [Ca(2+)](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.
Zhao
Y T
YT
Anaesthesia Research Department, McGill University, Montreal, Quebec H3G 1Y6, Canada.
Krnjević
K
K
D000818:Animals; D002614:Chelating Agents / Q000008:administration & dosage / Q000494:pharmacology*; D003847:Deoxyglucose / Q000494:pharmacology*; D004533:Egtazic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects* / Q000502:physiology; D006624:Hippocampus / Q000502:physiology*; D066298:In Vitro Techniques; D017774:Long-Term Potentiation / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008845:Microinjections; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D002614:Chelating Agents; D004533:Egtazic Acid; D003847:Deoxyglucose