Markham Julie A, Juraska Janice M
Department of Psychology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Physiol Behav. 2007 Dec 5;92(5):881-8. doi: 10.1016/j.physbeh.2007.06.020. Epub 2007 Jul 3.
Social recognition memory underlies many forms of rodent interaction and can be easily tested in the laboratory. Sex differences in aspects of this memory have been reported among young adults, and some studies indicate an age-related decline among male rats. In contrast, neither the impact of natural fluctuations in ovarian hormones nor the performance of aged female rats on social recognition memory has been previously evaluated. In experiments 1 and 2, the social recognition memory of young adult female Long-Evans rats (age 3-5 months) was compared during proestrus and estrus, and performance was found to be stable across estrous cycle phases. In experiment 3, the social recognition memory of young adults as compared to aged (16.5-19.5 months) rats was tested using the social discrimination procedure, following delays of 15, 45, 90 or 120 min. The estropausal status of aged female rats was tracked during the experiment but was not found to influence memory ability. Males of both ages investigated juveniles (both novel and familiar) more than did females, although despite this difference, both sexes demonstrated robust memory. Interestingly, only young adult females were capable of demonstrating memory following the longest delay. Collectively, our findings indicate that the pattern of age-related changes in social recognition memory is subtle and that aging does not greatly alter the behavioral sex differences observed among young adults.
社会识别记忆是许多啮齿动物互动形式的基础，并且可以在实验室中轻松进行测试。已有报道称，在年轻成年个体中，这种记忆的某些方面存在性别差异，一些研究表明雄性大鼠存在与年龄相关的记忆衰退。相比之下，此前尚未评估卵巢激素自然波动的影响以及老年雌性大鼠在社会识别记忆方面的表现。在实验1和实验2中，对年轻成年雌性Long-Evans大鼠（3 - 5个月龄）在发情前期和发情期的社会识别记忆进行了比较，发现其表现在整个发情周期阶段都很稳定。在实验3中，使用社会辨别程序，对年轻成年大鼠和老年（16.5 - 19.5个月龄）大鼠在延迟15、45、90或120分钟后的社会识别记忆进行了测试。在实验过程中跟踪了老年雌性大鼠的绝经状态，但未发现其会影响记忆能力。两个年龄段的雄性大鼠对幼年大鼠（无论是新奇的还是熟悉的）的探究都多于雌性大鼠，尽管存在这种差异，但两性都表现出了较强的记忆能力。有趣的是，只有年轻成年雌性大鼠在最长延迟后仍能表现出记忆。总体而言，我们的研究结果表明，社会识别记忆中与年龄相关的变化模式很微妙，衰老并不会显著改变在年轻成年个体中观察到的行为性别差异。
