Effect of colchicine on the Golgi complex of rat pancreatic acinar cells.

Abstract

Colchicine administered to adult rats at a dosage of 0.5 mg/100 g of body wt effected a disorganization of the Golgi apparatus in pancreatic acinar cells. The results obtained after various periods of treatment (10 min to 6 h) showed changes in all components of the Golgi complex and occurrence of large vacuoles that predominated in cytoplasmic areas outside the Golgi region. The alterations in Golgi stacks concerned elements of the proximal and distal side: accumulation of transport vesicles, formation of small, polymorphic secretion granules and alterations in the cytochemical localization of enzymes and reaction product after osmification. Transport vesicles accumulated and accompanied short, dilated cisternae, which lack mostly the reaction products of thiamine pyrophosphatase, IDPase and acid phosphatase and osmium deposits after prolonged osmification. After 4-6 h of treatment, accumulated transport vesicles occupied extensive cellular areas; stacked cisternae were not demonstrable in these regions. The changes on the distal Golgi side included GERL [Golgi-associated endoplasmic reticulum-lysosome] elements: condensing vacuoles were diminished; they were substituted by small, polymorphic zymogen granules, which appeared to be formed by distal Golgi cisternae and by rigid lamellae. Unusually extended coated regions covered condensing vacuoles, rigid lamellae and polymorphic secretion granules. A cytochemical distinction between Golgi components and GERL was possible neither in controls nor after colchicine treatment. The cytochemical alterations in Golgi components were demonstrable 20-30 min following administration of colchicine; at 45 min, initial morphological changes-augmentation of transport vesicles and formation of polymorphic zymogen granules-became apparent. Twenty min after administration of colchicine, conspicuous groups of large vacuoles occurred. They were located mostly in distinct fields between cisternae of the endoplasmic reticulum and were accompanied by small osmium-reactive vesicles. Stacked cisternae were not demonstrable in these fields. Vacuoles and vesicles were devoid of reaction products of thiamin pyrophosphatase, IDPase and acid phosphatase. Formation of stacked Golgi cisternae is impaired after colchicine treatment. The colchicine-induced disintegration of the Golgi complex suggests a regulatory function of microtubules in the organization of the Golgi apparatus.