Objective      To study the correlation between delayed gastrointestinal emptying and distribution of substrate P (SP) and observe whether their change affects the expression level of local oligopeptide transporter PEPT1.       Methods      Twenty-four Wistar rats  were randomly divided into type 1 diabetes mellitus (DM) model plus insulin therapy group

type 1 DM model group

and normal control group

8 in each group. One month after rats in type 1 DM model plus insulin therapy group were injected with streptozocin (STZ

60 mg/kg) through the femoral vein to induce type 1 DM model which was treated with long-acting insulin（20 U/day）by subcutaneous injection to control their blood glucose level

rats in type 1 DM model group were injected with STZ (60 mg/kg）through the femoral vein to induce type 1 DM model which was treated with an equal amount of physiological saline

and those in normal control group were injected with an equal amount of physiological saline through the femoral vein

their gastrointestinal emptying function was examined. Distribution of SP in rats with their gastrointestinal emptying significantly delayed from the starting segment of jejulum to the distal ileum was analyzed by immunohistochemistry. Expression level of PEPT1 in mucosal cells taken from the starting segment of jejulum and the distal ileum was measured by Western blotting.       Results      The gastrointestinal emptying rate was lower than 60% and the distribution of SP was significantly less in the starting segment of jejulum and the distal ileum in DM rats (P0.05）. The SP was mainly distributed in submucosal layer of the starting segment of jejulum with no positive staining of its muscular layer and in the distal ileum with positive staining of epithelium mucosae. The expression level of PEPT1 in the starting segment of jejulum and the distal ileum was significantly lower in type 1 DM model group than in control group and non-DM model group (P0.05）.       Conclusion      DM-induced delay of gastrointestinal emptying is closely correlated with the down-regulation of the distribution of SP and the expression level of PEPT1 in the starting segment of jejunum and the distal ileum

which may be related with the malnutrition in DM rats.