Laboratory of Brain and Cognitive Development, Institute of Psychology, University of Lausanne, Lausanne, Switzerland.
Faculty of Psychology, UniDistance Suisse, Brig, Switzerland.
Hippocampus. 2023 Oct;33(10):1094-1112. doi: 10.1002/hipo.23567. Epub 2023 Jun 19.
Immature neurons expressing the Bcl2 protein are present in various regions of the mammalian brain, including the amygdala and the entorhinal and perirhinal cortices. Their functional role is unknown but we have previously shown that neonatal and adult hippocampal lesions increase their differentiation in the monkey amygdala. Here, we assessed whether hippocampal lesions similarly affect immature neurons in the entorhinal and perirhinal cortices. Since Bcl2-positive cells were found mainly in areas Eo, Er, and Elr of the entorhinal cortex and in layer II of the perirhinal cortex, we also used Nissl-stained sections to determine the number and soma size of immature and mature neurons in layer III of area Er and layer II of area 36 of the perirhinal cortex. We found different structural changes in these regions following hippocampal lesions, which were influenced by the time of the lesion. In neonate-lesioned monkeys, the number of immature neurons in the entorhinal and perirhinal cortices was generally higher than in controls. The number of mature neurons was also higher in layer III of area Er of neonate-lesioned monkeys but no differences were found in layer II of area 36. In adult-lesioned monkeys, the number of immature neurons in the entorhinal cortex was lower than in controls but did not differ from controls in the perirhinal cortex. The number of mature neurons in layer III of area Er did not differ from controls, but the number of small, mature neurons in layer II of area 36 was lower than in controls. In sum, hippocampal lesions impacted populations of mature and immature neurons in discrete regions and layers of the entorhinal and perirhinal cortices, which are interconnected with the amygdala and provide major cortical inputs to the hippocampus. These structural changes may contribute to some functional recovery following hippocampal injury in an age-dependent manner.
表达 Bcl2 蛋白的不成熟神经元存在于哺乳动物大脑的各个区域，包括杏仁核以及内嗅皮层和边缘皮层。它们的功能作用尚不清楚，但我们之前的研究表明，新生和成年海马损伤会增加猴子杏仁核中它们的分化。在这里，我们评估了海马损伤是否同样影响内嗅皮层和边缘皮层中的不成熟神经元。由于 Bcl2 阳性细胞主要存在于内嗅皮层的 Eo、Er 和 Elr 区以及边缘皮层的 II 层，我们还使用尼氏染色切片来确定 Er 区 III 层和 36 区 II 层中不成熟和成熟神经元的数量和胞体大小。我们发现这些区域的结构变化不同，这与损伤时间有关。在新生期损伤的猴子中，内嗅皮层和边缘皮层中的不成熟神经元数量通常高于对照组。新生期损伤猴子的 Er 区 III 层中的成熟神经元数量也较高，但 36 区 II 层中没有差异。在成年期损伤的猴子中，内嗅皮层中的不成熟神经元数量低于对照组，但在边缘皮层中与对照组没有差异。Er 区 III 层中的成熟神经元数量与对照组没有差异，但 36 区 II 层中较小的成熟神经元数量低于对照组。总之，海马损伤影响了内嗅皮层和边缘皮层的离散区域和层中的成熟和不成熟神经元群体，这些区域与杏仁核相互连接，并为海马提供主要的皮质输入。这些结构变化可能以年龄依赖的方式促进海马损伤后的一些功能恢复。
