THE INHIBITORY EFFECT OF MAGNESIUM-HYDROXIDE ON THE BILE ACID-INDUCEDCELL-PROLIFERATION OF COLON EPITHELIUM IN RATS WITH COMPARISON TO THEACTION OF CALCIUM LACTATE

The modulating effects of magnesium hydroxide and calcium lactate on t he cholic acid-induced hyperproliferation of cells in rat colon epithe lium were investigated. Rats were divided into six groups (10 rats/gro up) and fed the following diets for 8 weeks: 0.25% cholic acid alone ( group 1), cholic acid plus 0.2% magnesium hydroxide (group 2), cholic acid plus 1.18% calcium in the form of calcium lactate (group 3), calc ium lactate alone (group 4), magnesium hydroxide alone (group 5) and t he basal diet alone (group 6). At the end of the experiment, all rats were killed for the immunocytochemical examination of 5-bromo-2'-deoxy uridine (BrdU) incorporation in the cell nuclei of colonic epithelium. Magnesium hydroxide reduced the cholic acid-induced BrdU incorporatio n by 33% at the distal part and 40% at the proximal part. Calcium lact ate also reduced the BrdU incorporation by 48% and 51% respectively. E xposure of magnesium hydroxide or calcium lactate alone had no influen ce on BrdU incorporation. The results suggest that magnesium hydroxide might exert anti-carcinogenic effects as does calcium by reducing inc reased cell proliferation of colonic epithelium induced by toxic effec ts of bile acids, which are regarded as colon tumor promoters or cocar cinogens.