Universidade Federal do Pará-UFPA, Instituto de Ciências Biológicas, Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto, Belém, PA, Brazil.
BMC Neurosci. 2012 Feb 29;13:23. doi: 10.1186/1471-2202-13-23.
Chewing imbalances are associated with neurodegeneration and are risk factors for senile dementia in humans and memory deficits in experimental animals. We investigated the impact of long-term reduced mastication on spatial memory in young, mature and aged female albino Swiss mice by stereological analysis of the laminar distribution of CA1 astrocytes. A soft diet (SD) was used to reduce mastication in the experimental group, whereas the control group was fed a hard diet (HD). Assays were performed in 3-, 6- and 18-month-old SD and HD mice.
Eating a SD variably affected the number of astrocytes in the CA1 hippocampal field, and SD mice performed worse on water maze memory tests than HD mice. Three-month-old mice in both groups could remember/find a hidden platform in the water maze. However, 6-month-old SD mice, but not HD mice, exhibited significant spatial memory dysfunction. Both SD and HD 18-month-old mice showed spatial memory decline. Older SD mice had astrocyte hyperplasia in the strata pyramidale and oriens compared to 6-month-old mice. Aging induced astrocyte hypoplasia at 18 months in the lacunosum-moleculare layer of HD mice.
Taken together, these results suggest that the impaired spatial learning and memory induced by masticatory deprivation and aging may be associated with altered astrocyte laminar distribution and number in the CA1 hippocampal field. The underlying molecular mechanisms are unknown and merit further investigation.
咀嚼失衡与神经退行性变有关，是人类老年痴呆症和实验动物记忆缺陷的危险因素。我们通过对 CA1 星形胶质细胞层状分布的体视学分析，研究了长期减少咀嚼对年轻、成熟和老年雌性白化瑞士小鼠空间记忆的影响。软食（SD）用于减少实验组的咀嚼，而对照组则喂食硬食（HD）。在 3 个月、6 个月和 18 个月大的 SD 和 HD 小鼠中进行了检测。
食用 SD 不同程度地影响了 CA1 海马区星形胶质细胞的数量，SD 组小鼠在水迷宫记忆测试中的表现不如 HD 组小鼠。两组 3 月龄小鼠均可在水迷宫中记住/找到隐藏平台。然而，6 月龄的 SD 组小鼠出现了明显的空间记忆功能障碍，而 HD 组小鼠则没有。SD 和 HD 组 18 月龄的小鼠均表现出空间记忆下降。与 6 月龄小鼠相比，老年 SD 组小鼠在 pyramidale 和 oriens 层的星形胶质细胞增生。在 HD 组小鼠的 lacunosum-moleculare 层，衰老导致 18 月龄时星形胶质细胞萎缩。
综上所述，这些结果表明，咀嚼剥夺和衰老引起的空间学习和记忆受损可能与 CA1 海马区星形胶质细胞层状分布和数量的改变有关。其潜在的分子机制尚不清楚，值得进一步研究。
