Mice homozygous for the Gria2tm1Rod targeted mutation (GluR2-deficient) were originally reported to be about one half the size of their normal littermates by two to three weeks of age, leading to some preweaning mortality. Growth retardation and mortality can be diminished by reducing litter size and eliminating some competition for the mother's milk. By eight weeks of age, homozygotes appear similar in size and weight to their unaffected littermates. Neurons from Gria2-deficient mice exhibit a 9-fold increase in Ca2+ permeability and enhanced long-term potentiation (LTP). Antagonists of AMPA and NMDA receptors block all the enhanced LTP seen in homozygous null mice. Changes in pain thresholds, sensitivity to anaesthetics, focal cerebral ischemia, apoptosis of neuronal subpopulations and learning impairments are also observed.
It has been the experience of The Jackson Laboratory that no homozygous animals have been recovered from heterozygous sibling matings.
In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. This is the case for the strain above. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.
