Maeng Lisa Y, Shors Tracey J
Department of Psychology, Rutgers University, Piscataway, NJ 08854, USA.
Behav Neurosci. 2012 Feb;126(1):137-41. doi: 10.1037/a0026707. Epub 2011 Dec 19.
Women experience profound hormonal fluctuations throughout their reproductive lives. They are especially susceptible to disturbances in mood and cognition during the transition from pregnancy into postpartum and motherhood (Brummelte & Galea, 2010). Their behavioral and hormonal responses to stressful stimuli are also altered during this time. These changes are not limited to humans but occur in many mammalian species. Virgin female rats express a severe learning deficit in associative eyeblink conditioning after a stressful life event (Wood, Beylin, & Shors, 2001; Wood & Shors, 1998), but lactating females or those that are caring for young learn well even after the stressor (Leuner & Shors, 2006). However, we do not know whether maternal experience persistently alters learning after a stressful event. Here we hypothesized that females that had been maternal at some time in their lives would learn well even after exposure to a stressful event. To test this hypothesis, females that had at least one brood of young and expressed a normal estrous cycle were exposed to an acute stressful event that reliably impairs learning in virgin females. Animals were trained 24 hr later with classical eyeblink conditioning. Exposure to the stressor suppressed learning in virgins but not in females that had been mothers at some time in their lives. These data suggest that maternal experience induces a protective mechanism in mothers, which promotes associative learning long after the offspring have left their care.
女性在其整个生殖生活中经历着深刻的激素波动。在从怀孕过渡到产后及为人母的阶段，她们尤其容易受到情绪和认知紊乱的影响（布鲁姆尔特和加利亚，2010年）。在此期间，她们对应激刺激的行为和激素反应也会发生改变。这些变化并非人类所特有，在许多哺乳动物物种中也会出现。未生育的雌性大鼠在经历应激性生活事件后，在联想性眨眼条件反射中表现出严重的学习缺陷（伍德、贝林和肖尔斯，2001年；伍德和肖尔斯，1998年），但哺乳期的雌性大鼠或那些照顾幼崽的雌性大鼠即使在经历应激源后也能学得很好（勒纳和肖尔斯，2006年）。然而，我们尚不清楚母性经历是否会在应激事件后持续改变学习能力。在这里，我们假设在生命中的某个阶段曾为人母的雌性大鼠即使在经历应激事件后也能学得很好。为了验证这一假设，让至少育有一窝幼崽且表现出正常发情周期的雌性大鼠暴露于一种能可靠地损害未生育雌性大鼠学习能力的急性应激事件中。24小时后，用经典眨眼条件反射对动物进行训练。暴露于应激源会抑制未生育雌性大鼠的学习，但不会抑制在生命中的某个阶段曾为人母的雌性大鼠的学习。这些数据表明，母性经历会在母亲体内诱导一种保护机制，这种机制在后代不再需要其照顾很久之后仍能促进联想学习。
