Free radical and brain aging : role of metallothionein in the aging of Beagle dog I

Beagle犬表现出多种与年龄相关的脑形态学改变，包括神经元营养不良轴突改变，星形胶质细胞变性和淀粉样变性，其特征是大脑皮层形成s斑块。为了研究金属硫蛋白（MTs）在脑中的作用，我们检测了老年Beagle犬脑中金属硫蛋白的表达模式。MT-I和-II之间的免疫反应性以及MT-I和-II mRNA的信号显示在与年龄相关的严重变化的大脑肥大星形胶质细胞中。这些MT-I和-II阳性星形胶质细胞在丘脑、大脑皮层和髓质中占主导地位，在这些地方观察到显著的年龄相关变化，包括铁和脂褐素沉积。相比之下，MT-I - II在轻度年龄相关变化的狗的大脑中表达相当弱。另一方面，无论年龄相关变化的强度如何，大脑神经元中均显示出MT-III免疫反应性和MT-III mRNA的信号。

Beagle dogs showed a variety of morphological age-related brain changes including neurona dystrophic axonal changes, astrogliosis and amyloidosis characterized by the formation of s plaques in the cerebral cortex. To study the roles of metallothioneins (MTs) in the brain, the expression pattern of metallothioneins in the brain of aged Beagle dogs was examined. Inter MT-I & -II immunoreactivity as well as signals for MT-I & -II mRNA were shown in the hypertrophic astrocytes in the brains with severe age-related changes. These MT-I & -II positive astrocytes dominated in the thalamus, cerebral cortex and medulla, where remarkal age-related changes including iron and lipofucin deposition were observed. In contrast, MT-I II expression was considerably weak in the brains of dogs with mild age-related changes. On other hand, both MT-III immunoreactivity and signals for MT-III mRNA were demonstrated in neurons in the brain regardless of the intensity of the age-related changes.