The effect of fructooligosaccharides was analyzed by cDNA expression arrays.

We have already reported that indigestible fructooligosaccharides (FOS) increased calcium absorption in rat large intestines and that calbindin-D9k (CaBP), which is an intestine-specific calcium-binding protein, is involved in that increasing effect. In this study, not only the CaBP gene, every gene that changed expression profiles as the result of FOS feeding was identified by cDNA expression arrays. Sprague-Dawley male rats were fed an experimental diet containing 10% FOS for 10 d. To compare gene expression with rats fed a control diet, total mRNA was extracted from the colorectum and analyzed using a Rat cDNA Expression Arrays filter. This arrays filter contains probes of 588 genes, and 195 of them showed detectable changes in their expression by FOS feeding. There were six genes that increased their expression more than twice that of the control. Among them, genes related to the induction of cell growth such as Map kinase 1 and Max were included. Expressions that decreased to less than half were observed in 20 genes, such as somatostatin and prohibitin, which prohibit cell growth. These results are consistent with the other observation that FOS increases cell growth in the colorectum. This approach has revealed that cDNA array technology is an effective tool for nutritional sciences that involve the regulation of a large number of genes, especially for molecular mechanisms of regulation, by nutritional constituents.