Abstract: This study investigated the influence of predator-induced stress during pregnancy on female offspring sexual behavior, vaginal opening and anogenital distance in root voles. The root voles studied were daughters whose mothers were stressed by placing cages of these mothers at sites located 200 cmfrom the cage of the steppe polecat or by restricted food during pregnancy, in term of reduced amount of taking food due to predation stress; in addition, the root voles were daughters which were stressed by predators after weaning. When mothers were stressed by predators during pregnancy, the daughters not only displayed significantly higher amounts of male-typical courtship such as sniff nose, sniff anogential area, trying to explore opponent, mount and follow, but also delayed the day of vaginal opening and increased the anogenital distance compared to daughters whose mothers were stressed by restricted food or they were not stressed during pregnancy as well as daughters which were stressed after weaning. On the other hand, prenatally stressed daughters significantly decreased sexual attraction for males. These results indicated that predator-induced maternal stress caused a distinct masculinization of female offspring in sexual behavior and body characteristics and sexual attraction. We suggest that the effects are due to the changes of maternal endocrine system induced by stress, and the effects occur only during a critical phase caused sexual differentiation of the female embryonic hypothalamus. We also suggest that the effect of maternal stress on offspring's sexual differentiation may have great significance for population dynamic.

Key words: Root vole (Microtus oeconomus), Maternal stress, Predation, Female offspring, Sexual differentiation

摘要： 本文研究了根田鼠母体捕食应激对其雌性子代雄性化的效应。母体捕食应激使雌性子代在鼻端探究、生殖区探究、试图探究和爬跨及尾随等性行为中花费的时间最多, 阴道开口时间显著延迟, 生殖器与肛门间距离显著增大, 而母体食物限制和断乳应激子代则未明显呈现上述特征。母体捕食应激使其雌性子代显著地降低对雄性个体的性吸引力。因此, 母体捕食应激使雌性子代在性行为、形态特征及性吸引力方面呈现雄性化效应, 主要归结于捕食应激引起母体内分泌的改变所致; 此效应仅产生于胚胎性分化的特定关键时期。全文结果检验了田鼠类母体捕食应激对其雌性子代性分化有显著影响的假设。

关键词: 根田鼠, 母体应激, 捕食, 雌性子代, 性分化