title: Effect of the rd1 mutation on motor performance in R6/2 and wild type mice.
abstract: Homozygosis for the rd1 mutation in the Pbe6b gene results in the loss of the rod beta-subunit of the cyclic GMP phosphodiesterase and, eventually, of all rod and cone photoreceptors. The R6/2 mouse line is a widely used model of Huntington's disease (HD). The original line was made available on a mixed background obtained by crossing, via ovarian transplant, female R6/2 (on a B6CBA mixed background) with male B6CBAF1/J mice. As the CBA/J strain used in the US is homozygous for the rd1 mutation and the breeding scheme does not ensure heterozygosis for the mutation, a significant percentage of the offspring on this mixed background is expected to be homozygous for the rd1 mutation. We investigate here the effect of rd1 homozygosis on motor function and examined the effects of the mutation on the R6/2 phenotype. Homozygosis for the rd1 mutation resulted in increased activity in the open field test and reduced rotarod test performance. In addition, rd1 mutation absence or heterozygosis reduced the differences between the R6/2 and the WT mice. Our recommendation for the neurodegeneration field, and for all mouse studies in general, is to carefully control homozygosis for retinal degeneration mutation, even when using tests of motor function.
authors.affiliation: Senior Principal Scientist at PsychoGenics, Inc.;  Senior Research Scientist, Pfizer Inc.;  Data Manager at Psychogenics, Inc;  Director, PreClinical Research, CHDI Foundation, Inc;  Director of In Vivo Biology, CHDI Foundation Inc and  Senior VP Behavioral R&D at PsychoGenics, Inc.
authors.forename: Liliana
authors.initials: L
authors.lastname: Menalled
authors.forename: Bassem F
authors.initials: BF
authors.lastname: El-Khodor
authors.forename: Monica
authors.initials: M
authors.lastname: Hornberger
authors.forename: Larry
authors.initials: L
authors.lastname: Park
authors.forename: David
authors.initials: D
authors.lastname: Howland
authors.forename: Dani
authors.initials: D
authors.lastname: Brunner