ALTERED SPATIAL-LEARNING AND MEMORY IN MICE LACKING THE MGLUR4 SUBTYPE OF METABOTROPIC GLUTAMATE-RECEPTOR

The glutamate analog, L-2-amino-4-phosphonobutyric acid (L-AP4) is a s elective agonist for several members of the metabotropic glutamate rec eptor (mGluR) family. Activation of presynaptic mGluRs by L-AP4 causes a suppression of synaptic transmission in the central nervous system. In this study, the role of 1 subtype of mGluR in the nervous system w as investigated by analyzing mutant mice lacking the L-AP4-sensitive r eceptor, mGluR4. Experiments designed to probe hippocampal function sh owed no impairments in acquisition of spatial learning in the water ma ze task. However, in a spatial reversal learning task, the mutant mice exhibited significantly accelerated learning performance. Furthermore , in a probe trial administered 6 weeks posttraining, these mice showe d impaired spatial accuracy. The results suggest that the mutant mice differed in their ability to learn and integrate new spatial informati on into previously formed memory traces and that their use of stored s patial information also was altered. Thus, the presynaptically express ed mGluR4 plays a role in the processing of spatial information.