Expression of human Calbindin-D9k correlated with age, vitamin D receptor and blood calcium level in the gastrointestinal tissues

Objective Calbindin-D9k (CaBP-9k) has been thought to be one of the important factors of calcium absorption and metabolism in the intestine. The understanding of CaBP-9k role in the gastrointestinal tissues is important in human in relation with aging and gender, and whether there is any relationship with mineral homeostasis and risk for the development of age-related calcium disorders such as osteoporosis. Design and methods The expression of CaBP-9k and vitamin D receptor (VDR) was analyzed in the human gastrointestinal tissues with different ages and gender. In addition, the correlation among CaBP-9k expression, age and calcium concentration in blood was elucidated in these tissues. Results A significant increase in the expression of CaBP-9k mRNA was observed in the bulb and 2nd portion of duodenum over age in both men and women. However, no significant age-associated change in VDR mRNA level was detected in the duodenum. The concentration of blood calcium level decreased with age in both men and women. Conclusion The duodenal CaBP-9k may be not involved in calcium absorption in these tissues. The functional significance of the increase in the intestinal CaBP-9k expression with age is not currently clear and requires further investigation.