Abstract
The purpose of this study was to investigate the inhibitory mechanism of colchicine on the osteoclastic bone resorption. Male Wistar rats, weighting 120g on average, were injected intravenously with colchicine at the dose of 1.0 mg/kg. The control rats were injected with physiological saline. They were sacrificed at 1, 2, 4 and 8 hours after the injection. Osteoclasts located in the proximal metaphysis of tibia were examined with an electron microscope. Some specimens were stained for acid phosphatase. After the colchicine injection, the number of microtubules in the cytoplasm decreased and the Golgi apparatus moved from the circumunclear area and spread throughout the cytoplasm. Acid phosphatase-positive trans Golgi network became difficult to detect in the dislocated Golgi apparatus. In the central area of the cell, clusters of small vacuoles and vesicles which contained various quantities of amorphous material appeared. Acid phosphatase activity was detected in these vacuoles and vesicles. The structure of the ruffled border was disturbed. In the organ culture of mouse calvaria, colchicine inhibited PTH-enhanced bone resorption and the release of β-glucuronidase and acid phosphatase dose dependently. The results obtained in this study suggested that the disturbance of microtubules by colchicine causes a functional inhibition of both the Golgi-lysosomal system and the ruffled border and subsequently reduces the bone resorbing activity of osteoclasts.
