Duodenum clamping trauma induces significant postoperative intraperitoneal adhesions on a rat model

Abstract

Objective: The purpose of this study was to investigate the histological and morphological changes in the first two postoperative weeks on a rat intraperitoneal adhesion model induced by duodenum clamping trauma.

Method: The rat model of postoperative intraperitoneal adhesions was established in 48 male Wistar rats by laparotomy, followed by the duodenum clamping trauma. Rats were sacrificed respectively on 1(st), 3(rd), 5(th), 7(th) and 14(th) day after the operation. The control rats were sacrificed immediately after the operation (0 day). Then the intraperitoneal adhesions were assessed macroscopically. Histopathology and immunohistochemistry were performed to evaluate the fibrosis, inflammatory responses, neovascularization, and cells infiltration in adhesion tissues. In addition, the changes of the mesothelium covering the surgical sites were examined by scanning electron microscopy.

Results: Our study revealed that duodenum clamping trauma induced by mosquito hemostat can result in significant postoperative intraperitoneal adhesions formation. The extent and tenacity of intraperitoneal adhesions reached their peaks on 3(rd) and 5(th) days, respectively. Histopathological examination showed that all rats developed inflammatory responses at the clamped sites of duodenum, which was most prominent on 1(st) day; the scores of fibrosis and vascular proliferation increased slowly from 3(rd) to 5(th) day. Myofibroblasts proliferated significantly in the adhesion tissues from 3(rd) day, which were examined by immunohistochemical method. And the mesothelium covering the surgical sites and the adhesion tissues healed on 7(th) day.

Conclusion: This study suggests that clamping trauma to the duodenum can result in significant postoperative intraperitoneal adhesions formation, which represents an ideal rat model for intraperitoneal adhesions research and prevention. And myofibroblasts may play an important role in the forming process of intraperitoneal adhesions.

Figure 1. The special devise for the operation.

A mosquito hemostat with curved tips and full teeth, which were shielded by a segment of rubber single Nelaton Catheter. (Black arrowhead: the second ratchet of the hemostat).

Figure 2. Representative macroscopical photos and adhesion scores.

A–F) Macroscopical photos of 0 day, 1^st, 3^rd, 5^th, 7^th and 14^th day. G) Mean of adhesion scores by macroscopical evaluations in all groups. n = 8, #: P<0.05, *: P>0.05. Vs. preceding group. (Surgical site: arrow; adhesion: arrowhead).

Figure 3. Histological micrographs and scores of fibrosis, inflammation and neovascularization (H&E).

A) Micrograph of 0 day (×50, lower left corner; ×200, bar = 100 µm); B–F) Micrographs of 1^st, 3^rd, 5^th, 7^th and 14^th day (×200, bar = 100 µm. Surgical site: arrow; adhesion: arrowhead). G) Mean of fibrosis, inflammation and neovascularization scores by histological evaluations in all groups. #: P<0.05, *: P>0.05. Vs. preceding group.

Figure 4. Micrographs of immunohistochemistry staining and the expression of PCK, Vim and α-SMA of 0, 7^th and 14^th day.

Representative immunohistochemistry staining images stained with PCK (A–C), Vim (D–F) and α-SMA (G–I) antibody of 0 day (A, D, G), 7^th day (B, E, H), 14^th day (C, F, I) (×400, bar = 50 µm, target area: arrow). J) The values of integral optical density for PCK, Vim and α-SMA of 0 7^th and 14^th day. #: P<0.05, *: P>0.05. Vs. preceding group.

Figure 5. SEM images of mesothelium covering the duodenum and adhesion tissues.

A) Normal control from additional rats. B–G) Micrographs showed the destruction and regeneration of the mesothelium on 0 day, 1^st, 3^rd, 5^th, 7^th and 14^th day (×2000, bar = 50 µm. Mesothelial cell: black arrow; RBC: black arrowhead; inflammatory cell: white arrow).