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A novel form of long‐term depression in the CA1 area of the adult rat hippocampus independent of glutamate receptors activation
Author(s) -
Berretta Nicola,
Cherubini Enrico
Publication year - 1998
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.1998.00301.x
Subject(s) - long term depression , metabotropic glutamate receptor , neuroscience , ionotropic effect , hippocampus , cnqx , stimulation , glutamate receptor , metabotropic receptor , chemistry , receptor , nmda receptor , psychology , ampa receptor , biochemistry
Abstract In young rats, low frequency (1–2 Hz) stimulation of the Schaffer collaterals for 15 min induces in the CA1 area of the hippocampus a homosynaptic and N ‐methyl‐ d ‐aspartate receptor‐dependent form of long‐term depression (LTD) of synaptic efficacy. In the adults, while a similar stimulation paradigm is able to depress previously potentiated synapses, it leads to conflicting results when applied to naive synapses. In the present experiments, different stimulation paradigms have been used to induce LTD in the CA1 area of the adult rat hippocampus in vitro . Thus, stimulation of the afferent pathway at frequencies higher than those used to produce LTD in young animals (5–10 Hz, for 15 min) reliably induced a homosynaptic form of LTD. This form of LTD was associated with a significant increase in paired‐pulse facilitation ratio and was insensitive to ionotropic (CNQX, 10 μ m and CPP, 20 μ m ) and metabotropic (S‐MCPG, 1 m m ) glutamate receptors antagonists, suggesting a presynaptic mechanism for both LTD induction and expression. In conclusion, our experiments clearly show that LTD is not a purely developmental phenomenon but is present also in mature rats, which possess the whole machinery for LTD induction and this will greatly enhance the flexibility and the storing capacity of neuronal circuits.