Histochemical demonstrations of actinomycininduced changes of certain oxidative and hydrolytic enzymes of rat incisor pulps

Abstract

Levels of succinic and lactic dehydrogenases, cytochrome oxidase, alkaline and acid phosphatase activities of the rat incisor pulp were examined following a sublethal dose injection of actinomycin D. Control animals injected with physiological saline were pair-fed. Succinic dehydrogenase and cytochrome oxidase activities were low in the pulp and presented insignificant alterations throughout the experiment. Lactic dehydrogenase and alkaline phosphatase activities of the dental pulp dropped rapidly during the first several days of the experiment and returned to the normal level by the end of the third week. Acid phosphatase activity showed rapid recovery after an initial drop, reached a peak on day 7, and returned to normal by the end of the second week. The significant increase in acid phosphatase activity occurred at the time when cytoplasmic degenerations are most pronounced. While succinic dehydrogenase and cytochrome oxidase activities remained constant during theexperiment, the normally higher lactic dehydrogenase activity showed a marked reduction in the experimental animals suggesting the dependence of pulp cells on anaerobic glycolysis, which is suppressed by actinomycin D. Variations in the level of enzyme activities observed in control animals are attributed to pair-feeding. Results of the present work give further supports to data obtained from previous ultrastructural studies.