Effect of Colchicine on Iron Transport During Stages of Maturation and Enamel Pigmentation in Rat Incisor Enamel: An Autoradiographic Study Using ⁵⁵Fe

¹ Department of Pharmacology, Faculty of Dentistry, Tokyo Medical and Dental University, 1-5-45 Yushima, Burikyo-ku, Tokyo 113, Japan

correspondence Dr. Keiichi Ohya, Department of Pharmacology, Faculty of Dentistry, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113, Japan

An autoradiographic study on rats was carried out with ⁵⁵Fe and colchicine in order to investigate the role of microtubules in the iron transport process from rat incisor ameloblasts to the enamel surface. In the control rats injected with ⁵⁵Fe, autoradiographic silver grains were distributed over the ameloblasts during the whole stage of enamel maturation and over the enamel surface at the enamel pigmentation stage. After the colchicine injection, the area of ameloblasts with smooth distal cell membranes increased in the maturation stage. These ameloblasts were heavily injured, and the iron-containing pigment was released from the cell. The number of silver grains decreased in these ameloblasts. However, the silver grains increased in the area of ameloblasts with ruffled distal cell membranes. At the enamel pigmentation stage, the silver grains over the ameloblasts increased, and those over the enamel surface were reduced. The accumulation and dislocation of the iron-containing pigment was noted in the ameloblasts at this stage. Lumicolchicine injection did not affect the grain distribution. These findings suggest that microtubules regulate the transport and secretion process of iron in rat incisor ameloblasts.