Cytochemistry of experimental protein malnutrition in primates: effect on the spinal cord of the squirrel monkey, Saimiri sciureus

Synopsis The localization of certain phosphatases, esterases and dehydrogenases in the spinal cord of healthy and severely protein malnourished squirrel monkeys were investigated histochemically. The latter were given drastically reduced levels of proteins in their diets for 15 weeks, and for the purpose of comparison several animals were sacrificed after 9, 11, 13 and 15 weeks on the feeding schedule. Cytochemical investigations were carried out on sections prepared from fresh-frozen spinal cord removed from the animal in the shortest possible time after an appropriate dose of nembutal anaesthesia. The distribution of thiamine pyrophosphatase, inosine diphosphatase, acid phosphatase and ATPase was found to be significantly altered under the impact of dietary abuse. The changes appear to be related to altered protein metabolism, energy transport and general slowing down of the metabolic reactions. The results obtained on phosphatases are reinforced by the distribution of enzymes of the Krebs cycle, pentose shunt and anaerobic metabolic pathways. Whereas the activity of the Krebs cycle enzymes is greatly reduced, the pentose shunt reacts to protein deprivation by increasing the level of activity of its enzymes. Similarly the activities of enzymes of the anaerobic pathway are also enhanced. The significance of these observations and the role of glial cells along with the neuron as a functional unit are discussed.