Lithocholic acid: a new emergent protector of intestinal calcium absorption under oxidant conditions.

LCA and 1,25(OH)D are vitamin D receptor ligands with different binding affinity. The secosteroid stimulates intestinal Ca absorption. Whether LCA alters this process remains unknown. The aim of our work was to determine the effect of LCA on intestinal Ca absorption in the absence or presence of NaDOC, bile acid that inhibits the cation transport. The data show that LCA by itself did not alter intestinal Ca absorption, but prevented the inhibitory effect of NaDOC. The concomitant administration of LCA avoided the reduction of intestinal alkaline phosphatase activity caused by NaDOC. In addition, LCA blocked a decrease caused by NaDOC on gene and protein expression of molecules involved in the transcellular pathway of intestinal Ca absorption. The oxidative stress and apoptosis triggered by NaDOC were abrogated by LCA co-treatment. In conclusion, LCA placed in the intestinal lumen protects intestinal Ca absorption against the inhibitory effects caused by NaDOC. LCA avoids the reduction of the transcellular Ca movement, apparently by blocking the oxidative stress and apoptosis triggered by NaDOC, normalizing the gene and protein expression of molecules involved in Ca movement. Therefore, LCA might become a possible treatment to improve intestinal calcium absorption under oxidant conditions.