EFFECTS OF COLCHICINE ON THE INTESTINAL TRANSPORT OF ENDOGENOUS LIPID - ULTRASTRUCTURAL, BIOCHEMICAL, AND RADIOCHEMICAL STUDIES IN FASTING RATS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 84  (3) , 544-555
Abstract
The involvement of microtubules in the transepithelial transport of exogenous lipid in intestinal absorptive cells has been suggested. Using EM, biochemical and radiochemical methods, the effects of the antimicrotubular agent colchicine on the intestinal mucosa and on the intestinal transport of endogenous lipid of rats in the fasting state were studied. After colchicine treatment, the concentration of triglycerides in intestinal mucosa of rats fasted for 24 h doubled and EM studies showed a striking accumulation of lipid particles in absorptive epithelial cells of the tips of jejunal villi. Colchicine may interfere with the intestinal transepithelial transport of endogenous lipoproteins. Additional studies, using an intraduodenal pulse injection of [14C]linoleic acid, showed that colchicine does not affect the uptake of fatty acids by intestinal mucosa. However, it had divergent effects on fatty acid esterification, enhancing their incorporation into triglycerides relative to phospholipids and caused a significant accumulation of endogenous diglycerides, triglycerides, and cholesterol esters within the absorptive intestinal epithelium. Detailed ultrastructural and morphometric studies revealed a decrease of visible microtubules, and a displacement of the smooth and rough endoplasmic reticulum, and Golgi apparatus. Furthermore, it is shown that after colchicine treatment, microvilli appear at the lateral plasma membrane of intestinal absorptive cells, a change not previously reported. Colchicine apparently causes significant changes in enterocyte ultrastructure, and may perturb the reesterification of absorbed endogenous fatty acids and their secretion in the form of triglyceride-rich lipoproteins from the enterocyte.