Learning and gene expression in the cerebral cortex of TR-β mutant
animals. (a) Spatial learning in the Morris water maze
test. Male mice at 4 weeks of age [+/+ (n = 20),
mut/+ (n = 28), mut/mut (n
= 10), TR-β −/+ (n = 6)] were tested for
their ability to learn to escape to a hidden platform. Data are
expressed as mean time (in seconds) ± SEM. Mice were pretrained
in two separate sessions 1 day before the test. Similar results have
been obtained over several mouse generations (data not shown).
(b) Northern blot analysis of myelin basic protein (MBP)
mRNA levels in the cerebral cortex. (c and
d) Northern blot analysis of brain-derived neurotrophic
factor (BDNF) and its receptor (TrkB) mRNA levels in the anterior
forebrain, respectively. (e) H&E staining of hippocampus
(Left, scale bar = 0.5 mm) and immunostaining of
hippocampal CA3 region with anti-BDNF antibody (Right,
scale bar = 50 μm). (Left) The arrowhead
indicates the CA3 region. (Right) The arrow indicates
granule cell bodies stained by the anti-BDNF antibody. DG, dentate
gyrus. *, P = < 0.05 vs. +/+ by
t testing.