Opposite effects of ursodeoxycholic acid and sodium deoxycholate on intestinal calcium absorption

RIVOIRA M; RODRÍGUEZ V; MARCHIONATTI A; PEREZ A; GUIZZARDI S; TOLOSA DE TALAMONI N

Bs As

Congreso; AAOMM; 2013

We have demonstrated that sodium deoxycholate (NaDOC) inhibits the intestinal Ca2+ absorption. The aim of this study was to find out if ursodeoxycholic acid (UDCA)could block this effect. Four week old chicks were used: 1) controls, 2) treated withNaDOC, 3) treated with UDCA and 4) treated with UDCA+NaDOC. Intestinal calciumabsorption was measured by the ligated intestinal loop technique. Glutathione (GSH),carbonyl content, changes in mitochondria membrane permeability and the activity ofalkaline phosphatase (AP) and antioxidant enzymes were determined by spectrophotometry.Ca2+-ATPase pump (PMCA), Na+/Ca2+ exchanger (NCX1) and calbindin D28K(CB) protein and gene expressions were analyzed by RT-qPCR and Western blot.UDCAalone increased the intestinal Ca2+ absorption. The combined treatment restored the inhibitory effect caused by NaDOC on the intestinal Ca2+ absorption. UDCA increased the protein and gene expression of PMCA,NCX1 and CB and the combined treatment returned the values to control ones. AP activity did not change with UDCA, but decreased with NaDOC, which was prevented by simultaneous UDCA administration. NaDOC decreased the GSH content and increased protein carbonyl content and SOD activity. NaDOC altered the internal mitochondrial membrane permeability, which was avoided by UDCA. In conclusion, UDCA promotes intestinal absorption of Ca2+, while NaDOC produces inhibitory effect. The combined treatment avoids the inhibitory effect of NaDOC because the oxidative stress is blocked. The stimulatory effect of UDCA on the intestinal Ca2+ absorption would be through an increase in gene and protein expression of molecules involved in the transcellular Ca2+ pathway.