2-Deoxyglucose-induced long-term potentiation of monosynaptic IPSPs in CA1 hippocampal neurons.
In previous experiments on excitatory synaptic transmission in CA1, temporary (10-20 min) replacement of glucose with 10 mM 2-deoxyglucose (2-DG) consistently caused a marked and very sustained potentiation (2-DG LTP). To find out whether 2-DG has a similar effect on inhibitory synapses, we recorded pharmacologically isolated mononosynaptic inhibitory postsynaptic potentials (IPSPs; under current clamp) and inhibitory postsynaptic currents (IPSCs; under voltage clamp); 2-DG was applied both in the presence and the absence of antagonists of N-methyl-D-aspartate (NMDA). In spite of sharply varied results (some neurons showing large potentiation, lasting for >1 h, and many little or none), overall there was a significant and similar potentiation of IPSP conductance, both for the early (at approximately 30 ms) and later (at approximately 140 ms) components of IPSPs or IPSCs: by 35.1 +/- 10.25% (mean +/- SE; for n = 24, P = 0.0023) and 36.5 +/- 16.3% (for n = 19, P = 0.038), respectively. The similar potentiation of the early and late IPSP points to a presynaptic mechanism of LTP. Overall, the LTP was statistically significant only when 2-DG was applied in the absence of glutamate antagonists. Tetanic stimulations (in presence or absence of glutamate antagonists) only depressed IPSPs (by half). In conclusion, although smaller and more variable, 2-DG-induced LTP of inhibitory synapses appears to be broadly similar to the 2-DG-induced LTP of excitatory postsynaptic potentials previously observed in CA1.
Krnjević
K
K
Anaesthesia Research Department, McGill University, Montreal, Quebec H3G 1Y6, Canada.
Zhao
Y T
YT
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D000963:Antimetabolites / Q000494:pharmacology*; D003847:Deoxyglucose / Q000494:pharmacology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology / Q000502:physiology*; D017774:Long-Term Potentiation / Q000187:drug effects* / Q000502:physiology; D008297:Male; D051379:Mice; D008839:Microelectrodes; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology
D000963:Antimetabolites; D018691:Excitatory Amino Acid Antagonists; D011810:Quinoxalines; D016194:Receptors, N-Methyl-D-Aspartate; C056723:FG 9041; D015763:2-Amino-5-phosphonovalerate; D003847:Deoxyglucose