Quantitative PCR (qPCR) detection showed that the mRNA expression levels of tight junction proteins Occludin, Claudin-1 and ZO-1 in small intestinal tissues were significantly lower than those in the control group (p < 0.05, Figures 1C–E), suggesting the successful construction of the rat AP model. The gene discussed is CLDN1; the disease is alkaline phosphatase measurement.