自家蛍光法によるラット神経系リポフスチンの研究

Lipofuscin of the neurones of the rat brain was studied by the autofluorescent method. The validity and specificity of the autofluorescent method for lipofuscin were investigated in the present studies. In comparison to the ordinary histochemical methods, the autofluorescent method for lipofuscin was advantageous for investigating the fine distribution of pigment in the cytoplasm of the neurones, because the bright, yellowish gold autofluorescence was easy to recognize against the dark background. Autofluorescent granules were distributed mainly in the cytoplam of the neurones and neuropil. In the neurones, the types of distribution of the lipofuscin are classified as follows: 1) a coarse granular distribution with clump formation near the nucleus (clump type); 2) a fine granular structure, distributed diffusely in the cytoplasm (diffuse); 3) intermediate type of the 1) and 2). In young and infant rats, lipofuscin is distributed diffusely in the cytoplam in fine granules. As the ageing process advances, the clump type of lipofuscin distribution is more and more frequently noted.<BR>The autofluorescent granules were first seen in the neuropil, particularly in the neurophil existing in the surroundings of the spinal cord, in the 1-month old rats. The granules appeared in an indefinite and variable form having a variety of different sizes and, being very fine, developed a green-yellow autofluorescence. In the 3-months old rats, lipofuscin was noted as fine granules having an orange-yellow fluorescence in the cytoplasm of the anterior column, which was diffused but not yet clumping. In this stage, lipofuscin was rarely found in the dorsal root of ganglion or in the thalamus, and, if found, was not in the cytoplasm. In the 6-month old animals, lipofuscin granules increased in number and were found in the neurones of the cerebral cortex, hippocampus, caudate nucleus, thalamus, brain stem and spinal cord.<BR>In the animals 12-months old, lipofuscin accumulation was much more advanced and distributed densely in the cytoplams of the neurones of the cerebral cortex, hippocampus, basal ganglia, thalamus, brain stem and spinal cord. Dorsal ganglia also showed a marked lipofuscin content in the cytoplasms of the neurones. The distribution of the lipofuscin in the fluorescent studies corresponded well to the findings of the ordinary histochemical methods, such as the PAS and Sudan III stainings.<BR>The decrease of the lipofuscin content in the neurones of the spinal cord, cerebral cortex, cerebellar cortex and dorsal ganglia in the centrophenoxine administered rats was well demonstrated by the present fluo rescent methods.<BR>The validity and specificity of the autofluorescent method for lipofuscin were discussed briefly in the present paper.