Impairment of Hippocampal Mossy Fiber LTD in Mice Lacking mGluR2

Science  02 Aug 1996:
Vol. 273, Issue 5275, pp. 645-647
DOI: 10.1126/science.273.5275.645


Subtype 2 of the metabotropic glutamate receptor (mGluR2) is expressed in the presynaptic elements of hippocampal mossy fiber—CA3 synapses. Knockout mice deficient in mGluR2 showed no histological changes and no alterations in basal synaptic transmission, paired-pulse facilitation, or tetanus-induced long-term potentiation (LTP) at the mossy fiber—CA3 synapses. Long-term depression (LTD) induced by low-frequency stimulation, however, was almost fully abolished. The mutant mice performed normally in water maze learning tasks. Thus, the presynaptic mGluR2 is essential for inducing LTD at the mossy fiber—CA3 synapses, but this hippocampal LTD does not seem to be required for spatial learning.

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