Glutamatergic neurotransmission expression profiling in the mouse hippocampus after perforant-path transection

The goal is to determine cellular and molecular mechanisms that regulate regenerative and neurodegenerative responses within the adult mouse dentate gyrus after axotomy of the principal glutamatergic input, the perforant path (PP).

A "molecular fingerprint" of the dentate gyrus was generated to provide an extensive, concurrent representation of genes, with an emphasis on glutamate receptor subunits and related markers of glutamatergic neurotransmission. Reorganization of the hippocampal formation was evaluated by regional microdissection of the dentate gyrus, followed by terminal continuation RNA amplification and custom-designed cDNA microarray analysis after unilateral PP transections at five time-points (0, 1, 10, 14, and 30 days post-lesion). Gene-expression profiles garnered from the ipsilateral side of PP transected hippocampal formation (including the dentate gyrus) were compared and contrasted with those of naive subjects, sham surgical subjects, and mice subjected to unilateral occipital cortex lesions. Specific gene array observations were validated by immunoblot analysis.

Results indicated selective regulation of specific transcripts, including AMPA and NMDA glutamate-receptor subunits, excitatory amino acid transporters, glutamate receptor interacting protein genes, and glial-associated markers across the time-course of the lesion study.

The goal was to identify messenger RNAs from specific classes of relevant transcripts that change over time in relationship to the synaptic and cellular alterations to help understand mechanisms that underlie lesion-induced synaptic plasticity.