Abstract
In studies of stress, it can be difficult to obtain blood rapidly enough to avoid
confounding steroid measures. Noninvasive urinary steroid measures may provide an
alternative insofar as they reflect systemic steroids. In Experiment 1, we profiled
urinary corticosterone, progesterone, and estradiol in ovariectomized female mice
following 1 h on an elevated platform. This increased urinary corticosterone for 3 h
and progesterone for 4 h. In Experiment 2, blood and urine samples were obtained at
0–6 h following stressor offset. Females showed increased serum corticosterone and
progesterone immediately after stressor offset. Urinary corticosterone was increased
at both 0 and 2 h post-stress, while an increase in progesterone 2–6 h after stressor
offset was not significant. Estradiol was not influenced by this mild stressor. In
Experiment 3, mice were exposed to a more severe 1 h stressor, a rat across a wire-mesh
grid. In serum, both corticosterone and progesterone were elevated immediately after
stressor offset and returned to baseline within 2 h. In urine, this severe stressor
elevated corticosterone immediately and 2 h after stressor offset, and in progesterone
2 h after stressor offset. Estradiol in serum was not dynamic, but it was significantly
elevated in urine 4 h after stressor offset. Urinary measures generally reflected
systemic measures; however, with a different time course resulting in a longer return
to baseline. We suggest that the relative value of serum or urinary steroid measures
in mice depends upon the experimental design, and that estradiol may only respond
when the stressor is severe.
Key words
stress - corticosterone - progesterone - estradiol - serum - urine
