Effects of age and parity on serum hormone levels in the FVB/N-RC mice.

<p>Serum was collected from 14-wk-old females, aged-nulliparous and aged-multiparous females and analyzed for the indicated hormones as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0043624#s4" target="_blank">Materials and Methods</a>. No significant difference was observed in the serum levels of estrogen, thyroxin (T4), growth hormone (GH) or bioactive prolactin. Triiodothyronine (T3) was significantly higher in serum samples of the aged-nulliparous (*<i>P</i><0.05) and aged-multiparous mice (*<i>P</i><0.05 ) than the 14-wk-old control mice.</p>*<p> = P<0.05 vs. 14-wk-old.</p>**<p>Serum levels of bioactive prolactin are measured in ng/ml.