Glutathione plays a role in the chick intestinal calcium absorption

DL-buthionine-S,R-sulfoximine (BSO) administration to vitamin D-deficient chicks treated with cholecalciferol produces a rapid decrease in the Ca²⁺ transfer from lumen-to-plasma and in the intestinal glutathione content. This response was reversed by addition of glutathione monoester to the intestinal sac. Variables related to the Ca²⁺ homeostasis such as plasma Ca and P, and intestinal calbindin D(28k) were not modified by BSO given to vitamin D-deficient chicks treated with cholecalciferol. Intestinal alkaline phosphatase activity, on the contrary, was highly reduced by BSO in vitamin D-deficient chicks treated with vitamin D₃. This effect showed time and dose-dependency. Although the mechanism/s of action of BSO on the intestinal Ca absorption is unknown, it is quite possible that thiol groups of proteins involved in the Ca²⁺ transport are affected by the GSH depletion and/or by block of the antioxidant ability of vitamin D₃. Thus, reactive oxygen compounds would be increased and, therefore, the Ca²⁺ movement from lumen to plasma decreases.