Laboratory of Neurochemical Studies, Department of Physiology, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil.
Laboratory of Neurochemical Studies, Department of Physiology, Biosciences Center, Federal University of Rio Grande do Norte, 59072-970 Natal, RN, Brazil.
Exp Gerontol. 2017 Dec 15;100:91-99. doi: 10.1016/j.exger.2017.11.001. Epub 2017 Nov 4.
The normal aging process is accompanied by functional declines in image-forming and non-image forming visual systems. Among the components of these systems, the thalamic lateral geniculate nucleus (LGN) offers a good model for aging studies since its three anatomical subdivisions, namely dorsal lateral geniculate nucleus (dLGN), intergeniculate leaflet (IGL) and ventral lateral geniculate nucleus (vLGN), receives light information from retina and projects to different brain areas involved in visual-related functions. Nevertheless, there is very little data available about quantitative morphological aspects in LGN across lifespan. In this study, we used design-based stereology to estimate the number of neurons, glial cells, the glia/neuron ratio and the volume of the LGN of Wistar rats from 3, 13 or 23months of age. We examined each LGN subdivision processed by immunohistochemistry for NeuN and Nissl counterstain. We observed no significant age-related neuronal loss in any nuclei and a 21% and 33% significant increase in dLGN and IGL glial cells of 23month-old rats. We also observed the glia/neuron relation increases in dLGN of 13month-old rats and in dLGN, IGL and vLGN internal portion of 23month-old ones. Moreover, we report an age-related increase in IGL volume. These results show region-specific glial hyperplasia during aging within LGN nuclei, perhaps due to compensatory responses to inflammation. In addition, we observed the glia/neuron ratio as a more sensitive parameter to quantify age-related alterations. Hence, we provide an updated and expanded quantitative characterization of these visual-related thalamic nuclei and its variability across lifespan.
正常衰老过程伴随着成像和非成像视觉系统的功能下降。在这些系统的组成部分中，丘脑外侧膝状体核（LGN）为衰老研究提供了一个很好的模型，因为它的三个解剖亚区，即背外侧膝状体核（dLGN）、中间膝状体叶（IGL）和腹外侧膝状体核（vLGN），接收来自视网膜的光信息，并投射到不同的大脑区域，参与视觉相关功能。然而，关于整个生命过程中 LGN 的定量形态学方面的数据非常少。在这项研究中，我们使用基于设计的立体学方法来估计 Wistar 大鼠 3、13 或 23 个月龄时 LGN 的神经元、神经胶质细胞数量、神经胶质/神经元比值和体积。我们用免疫组织化学对每个 LGN 亚区进行了 NeuN 和尼氏染色的检测。我们观察到在任何核中都没有与年龄相关的神经元丢失，并且 23 个月龄大鼠的 dLGN 和 IGL 神经胶质细胞分别显著增加了 21%和 33%。我们还观察到 13 个月龄大鼠 dLGN 以及 23 个月龄大鼠 dLGN、IGL 和 vLGN 内部的神经胶质/神经元关系增加。此外，我们报告了 IGL 体积与年龄相关的增加。这些结果表明，在 LGN 核内，随着年龄的增长，存在特定区域的神经胶质细胞增生，这可能是由于对炎症的代偿反应。此外，我们观察到神经胶质/神经元比值是量化与年龄相关变化的更敏感参数。因此，我们提供了这些与视觉相关的丘脑核及其在整个生命过程中的变异性的最新和扩展的定量描述。
