Cost Katherine Tombeau, Williams-Yee Zari N, Fustok Judy N, Dohanich Gary P
Program in Neuroscience and Department of Psychology, Tulane University, New Orleans, LA 70118, USA.
Behav Neurosci. 2012 Jun;126(3):457-64. doi: 10.1037/a0028363.
Male rodents typically display an advantage over female conspecifics in tasks that assess memory for the identity or location of objects. However, the performance of female rodents on object recognition and object location tasks often is enhanced by elevated levels of ovarian steroids. The novel object-in-place task, combines elements of object recognition and object location tasks used to assess rodent object memory. Until now, only male rats have been tested on the object-in-place task, therefore, a study was conducted to compare the performance of males to females under different hormone conditions. Rats were given a sample phase to study the locations of four objects in an open field. After various delays, a test phase was administered with the locations of two objects reversed. Increased investigation of moved objects indicates memory for these objects and their original locations. Rats were able to discriminate moved from unmoved objects after a brief 5-min delay, regardless of biological sex or hormone status. However, gonadally intact males, but not diestrous females, were able to discriminate object locations after a 30-min delay. In contrast, ovariectomized females treated with estradiol and progesterone discriminated moved from unmoved objects after a 60-min delay while ovariectomized vehicle-treated females and gonadally intact males did not. Results indicate that female rats outperform males on a memory task that combines object recognition and location but only when circulating levels of the ovarian steroids, estradiol and progesterone, are elevated and only when memory is challenged by an extended retention interval.
在评估对物体身份或位置的记忆的任务中，雄性啮齿动物通常比雌性同种动物表现出优势。然而，卵巢类固醇水平升高往往会提高雌性啮齿动物在物体识别和物体位置任务中的表现。新颖的物体在位任务结合了用于评估啮齿动物物体记忆的物体识别和物体位置任务的要素。到目前为止，只有雄性大鼠接受过物体在位任务的测试，因此，进行了一项研究来比较不同激素条件下雄性和雌性的表现。给大鼠一个样本阶段，让它们在开阔场地中研究四个物体的位置。经过各种延迟后，进行测试阶段，将两个物体的位置颠倒。对移动物体的调查增加表明对这些物体及其原始位置有记忆。无论生物性别或激素状态如何，大鼠在短暂的5分钟延迟后就能区分移动的物体和未移动的物体。然而，性腺完整的雄性大鼠，而不是处于动情间期的雌性大鼠，在30分钟延迟后能够区分物体位置。相比之下，用雌二醇和孕酮治疗的去卵巢雌性大鼠在60分钟延迟后能够区分移动的物体和未移动的物体，而去卵巢的用载体治疗的雌性大鼠和性腺完整的雄性大鼠则不能。结果表明，在一项结合物体识别和位置的记忆任务中，雌性大鼠比雄性大鼠表现更好，但前提是卵巢类固醇雌二醇和孕酮的循环水平升高，并且只有当记忆受到延长的保留间隔的挑战时才会如此。
