Honrado G I, Paclik L, Fleming A S
Department of Psychology, Erindale College, University of Toronto, Ontario, Canada.
Physiol Behav. 1991 Aug;50(2):357-63. doi: 10.1016/0031-9384(91)90078-3.
Four groups of female golden hamsters were exposed to short photoperiods (SP, LD 10:14) for 4, 14, 20, or 27 weeks and tested for physiological markers (uterine weight and estrous cycles) and behavioral (lordosis, approach and aggressive behaviors) measures while in contact with a stud male. After behavioral testing, females were ovariectomized and, during the next 2 weeks, were tested twice more (with a stud male) after replacement with 0.33 microgram (low dose) and 1.0 microgram (high dose) EB plus progesterone (500 micrograms). Results show that, after 14 weeks of SP conditions, uterine weights and percentage of females showing normal estrous cycles are at a minimum. This is mirrored by minimal levels of lordosis and maximal levels of aggressive and approach behavior at week 14. Physiological measures did not fully recover (to preregression levels) until week 27; however, behavioral measures show an earlier recovery by week 20. SP exposure also affects the circadian patterning of behaviors: Females that show lordosis at week 14 did so later in the day than did females tested at other weeks. Females in the regressed state also fail to show a significant decrease in approach behaviors (and a significant increase in receptive behaviors) over the course of the circadian day, a pattern seen in nonregressed females. Following hormone replacement with the low EB (+P) dose, females do not become receptive; however, at the higher dose, all but the week 14 group show increased receptivity.(ABSTRACT TRUNCATED AT 250 WORDS)
将四组雌性金黄地鼠暴露于短光照周期（SP，光照与黑暗时间比为10:14）下4周、14周、20周或27周，并在与一只种公鼠接触期间，检测其生理指标（子宫重量和发情周期）以及行为指标（脊柱前凸、接近和攻击行为）。行为测试后，对雌性地鼠进行卵巢切除，在接下来的2周内，用0.33微克（低剂量）和1.0微克（高剂量）雌二醇（EB）加孕酮（500微克）替代后，再次与种公鼠进行两次测试。结果显示，在短光照周期条件下14周后，子宫重量和表现出正常发情周期的雌性百分比降至最低。这反映在第14周时脊柱前凸水平最低，攻击和接近行为水平最高。生理指标直到第27周才完全恢复（到退化前水平）；然而，行为指标在第20周时显示出较早恢复。短光照周期暴露还会影响行为的昼夜模式：在第14周表现出脊柱前凸的雌性，其行为发生时间比其他周测试的雌性更晚。处于退化状态的雌性在昼夜过程中接近行为也没有显著减少（接受行为也没有显著增加），而未退化的雌性则有此模式。用低剂量EB（+P）进行激素替代后，雌性不会变得易接受；然而，在高剂量时，除第14周组外，其他组的接受能力均有所增强。（摘要截选至250词）
