[Immunohistochemistry of the distribution of alpha-tubulin in rat-incisor tooth germs and changes in it caused by vinblastine administration].

Abstract

The present work used 2 groups of Wistar rats, weighing 100g each. Rats in the first group served as the controls; those in the second group were given 2 mg/kg of vinblastine in single intravenous injections. The animals were then fixed by perfusion with a mixture of 0.1% glutaraldehyde and 4% paraformaldehyde. After having been dissected out of the jaws, upper incisors were demineralized in EDTA and prepared into longitudinal sections (3 microns thick) for immunohistochemical demonstration of alpha-tubulin by means of indirect methods using an anti-alpha-tubulin monoclonal antibody as the primary antibody and peroxidase-labeled anti-mouse sheep IgG as the secondary antibody. 1. Control group. In controls, diffuse alpha-tubulin reaction was observed in the distal cytoplasm of inner enamel epithelial cells, differentiating ameloblasts, and ameloblasts in the stage of matrix formation. In the ameloblasts, the reaction was especially strong in the distal ends and Tomes processes in the matrix-formation stage. It gradually decreased until the transitional stage, in which the ameloblasts regained intense reaction to alpha-tubulin. Reaction to alpha-tubulin was generally low in the enamel-maturation stage in both smooth-ended and ruffle-ended ameloblasts but grew somewhat intense in the stage in which ferritines were precipitated in the cells. Although dental papilla cells reacted only faintly to alpha-tubulin, when they started differentiating into odontoblasts, reaction grew stronger in their distal end regions and in processes extending from the distal ends into the dentin. But this reaction decreased and ceased at a middle dentin level. Fairly high reaction was observed in the cells of the outer enamel epithelium, the stratum intermedium, the stellate reticulum, the papillary layer, the pulp and the dental sac. 2. Experimental group. Reaction to alpha-tubulin described in the preceding sections generally decreased in from 1 to 6 hours after vinblastine administration. Reaction recovery appeared to begin at from 12 to 24 hours and almost reached control degree by 48 hours after administration. Following the decrease of alpha-tubulin reaction in ameloblasts and odontoblasts, their shapes and polarities changed dramatically. In other cells, however, in spite of decreased alpha-tubulin reactions, no noticeable morphological alteration took place.