Freer Clare, Orsi Nicolas M
J Am Assoc Lab Anim Sci. 2025 Jan 1;64(1):111-119. doi: 10.30802/AALAS-JAALAS-24-044.
The Whitten effect is a widely used tool for manipulating the mouse estrous cycle and generating reproductively active females within the laboratory setting. Typically, peak numbers of sexually receptive mice occur following exposure to male pheromones, resulting in a higher number of successful copulations on the third day after exposure. Although this method has improved efficiencies, the percentage of females mated and subsequently deemed to be pregnant/pseudopregnant remains relatively low, around 50%. In experiment 1, we aimed to 1) further understand cyclicity; 2) determine whether the initial cycle stage plays an importance on day 3 receptivity; and 3) identify any repetitive patterns/cycle stabilization. Mice (n = 27) were assigned to group cages according to cycle stage (proestrus, estrus, metestrus, diestrus). Experiment 2 was developed to determine an optimum treatment to promote receptivity by exposure to various pheromone stimuli. Mice (n = 45) were randomly assigned to 5 treatment groups (PBS-treated sham soiled bedding, male soiled bedding, live male, pregnant females, and lactating females). In both experiments, daily vaginal cytology was performed for 21 days to determine the cycle stage. Results from experiment 1 indicate that the initial cycle stage did not contribute to day 3 receptivity, although synchronization within several groups/cages was noted, and that the greatest numbers of estrous animals were obtained on days 6 and 7. Experiment 2 revealed that exposure to live males and lactating females both significantly improved receptivity compared with the PBS, male soiled bedding, and pregnant female groups. These results indicate that current strategies used for routine synchronization could be further improved through alternative housing regimens without compromising animal welfare.
惠顿效应是在实验室环境中用于调控小鼠发情周期并产生具有生殖活性雌性小鼠的一种广泛应用的工具。通常，接触雄性信息素后，性接受能力强的小鼠数量会达到峰值，这导致在接触后的第三天成功交配的数量增加。尽管这种方法提高了效率，但交配后被认定为怀孕/假孕的雌性小鼠的比例仍然相对较低，约为50%。在实验1中，我们旨在：1）进一步了解周期性；2）确定初始周期阶段对第3天的接受能力是否有影响；3）识别任何重复模式/周期稳定性。根据周期阶段（动情前期、动情期、间情期、动情后期）将小鼠（n = 27）分配到组笼中。开展实验2以确定通过接触各种信息素刺激促进接受能力的最佳处理方法。将小鼠（n = 45）随机分配到5个处理组（经PBS处理的假污垫料、雄性污垫料、活体雄性、怀孕雌性和泌乳雌性）。在两个实验中，均进行了21天的每日阴道细胞学检查以确定周期阶段。实验1的结果表明，初始周期阶段对第3天的接受能力没有影响，尽管注意到几个组/笼内出现了同步现象，并且在第6天和第7天获得了最多的动情期动物。实验2表明，与PBS组、雄性污垫料组和怀孕雌性组相比，接触活体雄性和泌乳雌性均显著提高了接受能力。这些结果表明，在不损害动物福利的情况下，可通过替代饲养方案进一步改进目前用于常规同步的策略。
