Experimental protein malnutrition in primates—cytochemistry of the nervous system

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Abstract
Experimental protein malnutrition was induced in groups of young juvenile squirrel monkeys by feeding them ad libitum diets very low in protein content, whereas a diet containing 25% protein content was fed to the control animals. Detailed cytochemical studies have clearly shown the sensitivity of the nervous system to dietary abuse. The motor neurons of the spinal cord and the Purkinje cells of the cerebellum are very sensitive to protein deficiency, and the number of oligodendroglia cells increases sharply. Gallocyanin stained preparations from the malnourished animals show significant decrease in the amount of RNA in the Purkinje cells of cerebellum and the anterior horn cells of the spinal cord. The larger neurons show prominent chromatolysis with concomitant increase in the number of oligodendrocytes surrounding such nerve cells. The different layers of the cerebellar cortex of the malnourished animals, as well as some of the neurons of the spinal cord, showed decreased activity of succinate dehydrogenase and increased levels of thiamine pyrophosphatase and lactate dehydrogenase. Although ATPase activity appeared to remain unchanged quantitatively, it showed profound disturbance in its in situ localization, especially in the mitochondrial ATPase located in the cytoplasm. The enzyme activity in the nuclear membrane appeared unchanged. These studies emphasize the importance of studying in situ changes in the anatomically heterogeneous nervous tissue, rather than of working only with biochemical methods using homogenized material.