Expression of stanniocalcin-1 in gastrointestinal tracts of neonatal and mature rats.

Stanniocalcin-1 (STC-1) produced by ovaries endocrinologically targets to mammary glands and is secreted into milk during lactation. The decline of mother's serum level by STC-1 antiserum administration reduced the milk fat content and the pups' body fat content. Nevertheless, the pups' fecal fat content was increased, suggesting that milk-derived STC-1 could influence intestinal fat absorption. We investigated the STC-1 expression in rat gastrointestinal tissues using immunocytochemistry and in situ hybridization. STC-1 was widely expressed in the chief cells of gastric pits and the cells of intestinal glands. Goblet cells in the small intestine contained STC-1 protein in their mucus. The distribution shows that this peptide is secreted exocrinologically into the gastrointestinal lumen. Quantitative RT-PCR analysis revealed that the expression ratio was higher in the periods of heavy nutritional demand, such as growing and lactation. The endogenous STC-1, similar to milk-derived STC-1, may be involved in digestion and/or absorption in gastrointestinal organs.