| Abstract: | The Long–Evans Cinnamon rat, an animal model of Wilson’s disease, is an inbred mutant strain with spontaneous hepatitis isolated from Long–Evans rats. The copper concentration in the brains of Long–Evans Cinnamon rats at 4 weeks of age was lower than that of controls, but higher than that of controls at 20 weeks of age. We investigated the tyrosine hydroxylase and 5-hydroxytryptamine immunoreactive fiber densities in the brains of Long–Evans Cinnamon rats aged 4, 10, and 20 weeks by immunohistochemistry, comparing them with Long–Evans Agouti rats used as controls. Tyrosine hydroxylase immunoreactive fiber densities in the cingulate cortex, hippocampus and cerebellum in Long–Evans Cinnamon rats were significantly lower than those of Long–Evans Agouti rats at 4 and 10 weeks of age. On the other hand, 5-hydroxytryptamine immunoreactive fiber densities in the cingulate cortex, caudate-putamen, hypothalamus, and hippocampus in Long–Evans Cinnamon rats were significantly higher than those of controls at 4, 10 and 20 weeks of age. In the cingulate cortex and caudate-putamen, 5-hydroxytryptamine immunoreactive fiber densities became gradually higher with age. The number of aberrant 5-hydroxytryptamine immunoreactive fibers in the cingulate cortex, caudate-putamen, hypothalamus and hippocampus in LEC rats was significantly higher than that of controls. The number of another type of aberrant 5-hydroxytryptamine immunoreactive fibers, which were detected only at 20 weeks of age in the caudate-putamen in LEC rats was significantly higher than that of controls. These results suggest that age-dependent changes in copper concentrations of Long–Evans Cinnamon rats were related to changes in monoaminergic neuron systems. |
