Meek L R, Schrump S E, Smith D A, Schulz K M, Dittel P L, Merkle C J
University of Minnesota, Morris, 109 Camden Hall, Morris, MN 56267, USA.
Physiol Behav. 2001 May;73(1-2):121-4. doi: 10.1016/s0031-9384(01)00463-2.
After weaning, adult female meadow voles were maintained for 7 weeks in either long (LD, 14 h light/day) or short photoperiods (SD, 10 h light/day). They were then ovariectomized and implanted with 3-week, timed-release estrogen pellets (0.0, 0.001, 0.05, or 0.5 mg/pellet of 17-beta-estradiol). An additional group received a sham ovariectomy (intact) and a 0.0-mg/pellet control (no estrogen) pellet. One week after surgery, females were paired with an LD sexually experienced male. Each pair was videotaped continuously until the first intromission or for 2 weeks. LD sham animals mated significantly earlier than did SD sham animals (P=.05). However, there were no differences in mating latencies between LD and SD control groups or between any of the LD and SD groups receiving estrogen replacement (P>.05). In addition, no ovariectomized animals receiving either the control or the 0.001-mg/pellet estrogen dosage mated within the 2-week time period, while all shams and all animals receiving either the 0.05- or 0.5-mg/pellet doses mated. The results indicate that there is some minimal amount of estrogen that is necessary for meadow voles to enter behavioral estrus and that LD and SD females do not differ in their sensitivity to estrogen, since animals in both photoperiods mate with similar latencies as long as enough estrogen is present.
断奶后，成年雌性草甸田鼠在长光照周期（LD，14小时光照/天）或短光照周期（SD，10小时光照/天）下饲养7周。然后对它们进行卵巢切除，并植入3周的缓释雌激素丸剂（17-β-雌二醇剂量分别为0.0、0.001、0.05或0.5毫克/丸）。另一组接受假卵巢切除术（完整）和0.0毫克/丸的对照丸剂（无雌激素）。手术后一周，将雌性与一只经历过LD光照周期的性成熟雄性配对。每对都连续录像，直到首次插入或持续2周。LD假手术动物比SD假手术动物交配显著更早（P = 0.05）。然而，LD和SD对照组之间或接受雌激素替代的任何LD和SD组之间的交配潜伏期没有差异（P>0.05）。此外，在2周时间内，接受对照或0.001毫克/丸雌激素剂量的卵巢切除动物均未交配，而所有假手术动物以及所有接受0.05或0.5毫克/丸剂量的动物均交配。结果表明，草甸田鼠进入行为发情期需要一定量的最低雌激素，并且LD和SD雌性对雌激素的敏感性没有差异，因为只要有足够的雌激素，两个光照周期的动物交配潜伏期相似。
