Metabolomics analysis of stool in rats with type 2 diabetes mellitus after single-anastomosis duodenal-ileal bypass with sleeve gastrectomy

Abstract

Background: Single-anastomosis duodenal-ileal bypass with sleeve gastrectomy (SADI-S) is one of the most effective bariatric procedures in the treatment of type 2 diabetes mellitus (T2DM). However, the mechanisms by which SADI-S improves T2DM are not well-known.

Objective: To explore the effects of SADI-S on metabolites in the stool of rats with T2DM.

Methods: Twenty rats were fed on high-fat diet and administered with a low-dose (30mg/kg) of streptozotocin to establish T2DM models. The rats were then randomly assigned to the SADI-S group (n=10) and sham operation group (n=9). Stool samples were collected from all rats at 8 weeks after surgery and stored at -80 °C. Metabolomics analysis was performed to identify differential metabolites through ultra- performance liquid chromatography-mass spectrometry.

Results: At 8-week after surgery, rats of the SADI-S group showed significantly decreased fasting blood glucose, glucose tolerance test 2-hour, glycated haemoglobin, and body weight compared with those of the sham group. A total of 245 differential metabolites were identified between the two groups. Among them, 16 metabolites such as branched-chain amino acids (valine), aromatic amino acid (phenylalanine), bile acid (cholic acid, lithocholic acid, and β-muricholic acid), short-chain fatty acid (isobutyric acid), and phospholipid [lysoPE(17:0), lysoPE(20:3) and lysoPS(16:0)] were associated to the T2DM remission after SADI-S.

Conclusion: SADI-S improves T2DM in rats by regulating phenylalanine biosynthesis, valine, phenylalanine, alanine, glutamate, proline, bile acid, and phospholipid metabolism pathways.

Keywords: SADI-S; T2DM; bariatric surgery; metabolomics; single-anastomosis duodenal–ileal bypass with sleeve gastrectomy; type 2 diabetes mellitus.

Figure 1

Changes in body weight (A), changes in blood glucose AUC during IPGTT before and after surgery (B) and FBG (C) before and after surgery. Comparison of the HBA1c level at 8 weeks after surgery between the two groups (D). All values are expressed as Mean ± SD. NS indicates no significant difference between the SADI-S group and sham operation group. * represents a significant difference between the SADI-S group and sham operation group (P< 0.05).

Figure 2

Immunofluorescence double-labeling staining images. Morphological and histological evaluation of pancreas tissues between the SADI-S group and the sham operation group. Red represents pancreatic islet α cells, green represents pancreatic islet β cells, and blue represents cell nucleus.

Figure 3

Hematoxylin and eosin (H&E) staining photographs. Morphological and histological evaluation of ileum and jejunum between the SADI-S group and the sham operation group (200×).

Figure 4

PCA score plot of SADI-S group and sham operation group in the positive ion mode and in the negative ion mode (A); quality assurance in the positive ion mode and in the negative ion mode (B). A=SADI-S group, B=sham operation group.

Figure 5

The plot of OPLS-DA score for SADI-S group and sham operation group in the positive ion mode and in the negative ion mode (A); permutations plot in the positive ion mode and in the negative ion mode (B). A=SADI-S group, B=sham operation group.

Figure 6

The effect of SADI-S on metabolic pathway in the negative ion mode (A) and in the positive ion mode (B). The bigger the circle, the more significant is the enrichment. The darker the yellow, the smaller the P value.