Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
J Neuroendocrinol. 2011 Apr;23(4):345-54. doi: 10.1111/j.1365-2826.2011.02112.x.
Nulliparous female mice that have not experienced mating, pregnancy or parturition show near immediate spontaneous maternal behaviour when presented with foster pups. The fact that virgin mice display spontaneous maternal behaviour indicates that the hormonal events of pregnancy and parturition are not necessary to produce a rapid onset of maternal behaviour in mice. However, it is not known how similar maternal behaviour is between virgin and lactating mice. In the present study, we show that naturally postpartum females are faster to retrieve pups and spend more time crouching over pups than spontaneously maternal virgin females, and that these differences diminish with increased maternal experience. Moreover, 4 days of experience with pups induced pup retrieval on a novel T-maze. Furthermore, the effects of experience on subsequent maternal responsiveness are not dependent on gonadal hormones because ovariectomised females with 4 days of pup experience show pup retrieval on a novel T-maze similar to that of postpartum mice. Four days of maternal experience also induced T-maze pup retrieval in ovariectomised aromatase knockout female mice that was not significantly different from the maternal responsiveness of ovariectomised wild-type littermates. These data suggest that maternal experience can induce maternal behaviour in females that have never been exposed to oestradiol at any time in development or adulthood. Finally, ovariectomised pup-experienced females continue to retrieve pups on a novel T-maze 1 month after the initial experience, suggesting that, even in the absence of oestradiol, maternal experience produces long-lasting modifications in maternal responsiveness.
未生育、未经交配、妊娠或分娩的雌性小鼠在接触寄养幼崽时会立即表现出近乎自发的母性行为。处女鼠表现出自发的母性行为这一事实表明，妊娠和分娩的激素事件对于在小鼠中快速产生母性行为并不是必需的。然而，尚不清楚处女鼠和哺乳期鼠的母性行为有多么相似。在本研究中，我们表明，自然分娩后的雌性比自发的处女雌性更快地取回幼崽并更多时间蹲伏在幼崽身上，并且这些差异随着母性经验的增加而减少。此外，4 天的幼崽经验可诱导在新颖的 T 迷宫中取回幼崽。此外，经验对后续母性行为反应的影响不依赖于性腺激素，因为 4 天幼崽经验的卵巢切除雌性在新颖的 T 迷宫中取回幼崽的情况与产后小鼠相似。4 天的母性经验也诱导卵巢切除芳香化酶敲除雌性小鼠在新颖的 T 迷宫中取回幼崽，其与卵巢切除野生型同窝仔的母性行为反应无显著差异。这些数据表明，母性经验可以诱导从未在发育或成年期的任何时间接触过雌激素的雌性表现出母性行为。最后，卵巢切除并经历过幼崽的雌性在初始经验后 1 个月继续在新颖的 T 迷宫中取回幼崽，这表明，即使在没有雌激素的情况下，母性经验也会产生持久的母性行为反应改变。
