Reyna-Neyra Andrea, Arias Clorinda, Ferrera Patricia, Morimoto Sumiko, Camacho-Arroyo Ignacio
Departamento de Biología, Facultad de Química, Universidad Nacional Autónoma de México, 04510 México D.F., México.
J Neurobiol. 2004 Sep 15;60(4):473-80. doi: 10.1002/neu.20042.
The molecular mechanisms involved in the regulation of synaptic plasticity in the hippocampus during the estrous cycle of the rat are not completely understood. Because this process implicates changes in neuronal cytoskeleton organization, we analyzed the content of microtubule associated protein 2 (MAP2) and Tau in the hippocampus and the frontal cortex of the rat by Western blot, as well as the hippocampal distribution of MAP2 during the estrous cycle by immunohistochemistry. In the hippocampus the lowest content of MAP2 was found on diestrus day, and it significantly increased at proestrus. This increase was maintained on estrus and metestrus days. In the frontal cortex MAP2 content did not significantly change during the estrous cycle. In contrast, the content of Tau did not vary during the estrous cycle in either the hippocampus or the frontal cortex. The immunohistochemical analysis showed an increase in dendrite thickness and in dendritic branching in the CA1 region on proestrus day, as well as an aggregation of MAP2 in apical dendrites near to pyramidal somata on this day in comparison with diestrus. We suggest that changes in the content and neuronal distribution of MAP2 are involved in the structural changes that occur in the hippocampus of the rat during the estrous cycle, and that these variations are related to changes in estradiol and progesterone levels.
大鼠发情周期中，海马体突触可塑性调节所涉及的分子机制尚未完全明确。由于这一过程涉及神经元细胞骨架组织的变化，我们通过蛋白质免疫印迹法分析了大鼠海马体和额叶皮质中微管相关蛋白2（MAP2）和Tau的含量，并通过免疫组织化学方法研究了发情周期中MAP2在海马体中的分布情况。在海马体中，MAP2含量在动情间期最低，在发情前期显著增加。这种增加在发情期和动情后期持续存在。在额叶皮质中，MAP2含量在发情周期中没有显著变化。相比之下，海马体和额叶皮质中的Tau含量在发情周期中均无变化。免疫组织化学分析显示，与动情间期相比，发情前期CA1区的树突厚度和树突分支增加，且此时锥体神经元胞体附近的顶端树突中有MAP2聚集。我们认为，MAP2含量和神经元分布的变化参与了大鼠发情周期中海马体发生的结构变化，并且这些变化与雌二醇和孕酮水平的变化有关。
