Comparison of intestinal cold preservation injury on pituitary adenylate cyclase-activating polypeptide in knockout and wild-type mice.

Tissue injury caused by cold preservation remains a problem in small intestinal transplantation. Pituitary adenylate cyclase-activating polypeptide (PACAP) has a central role in intestinal physiology. The objective of the present study was to compare the effects of cold ischemia injury in PACAP-38 knockout and wild-type mice after cold storage of small bowel. Cold ischemia was produced using small bowel preservation in University of Wisconsin solution at 4 degrees C in 20 PACAP-38 wild-type mice for 1, 3, and 6 hours (groups 1, 2, and 3, respectively) and 20 PACAP-38 knockout mice for 1, 3, and 6 hours (groups 4, 5, and 6, respectively). Biopsy samples of small bowel were obtained after laparotomy (control) and at the end of preservation periods. To determine oxidative stress, malondialdehyde, reduced glutathione, and superoxide dismutase concentrations were measured. Tissue damage was assessed using a quantitative method on sections stained with hematoxylin-eosin. After 6 hours, tissue lipid peroxidation was increased significantly in PACAP-38 knockout mice (mean +/- SD, 153.04 +/- 7.2 micromol/g) compared with sham-operated mice (110.44 +/- 5.5 micromol/g) and wild-type mice (120.0 +/- 1.1 micromol/g) (P < .05). The capacity and activity of the endogenous antioxidant system decreased significantly after 3 and 6 hours of preservation (reduced glutathione, 808.7 +/- 5.2 micromol/g and 720.4 +/- 8.7 micromol/g; and superoxide dismutase, 125.1 +/- 1.4 IU/g and 103.3 +/- 1.9 IU/g vs 212.11 +/- 5.8 IU/g; P < .05). Quantitative histologic analysis demonstrated destruction of mucosal and submucosal layers and crypts in knockout mice compared with wild-type mice. These processes depended on duration of cold preservation. These findings demonstrate that PACAP-38 has a key role in protection against intestinal cold preservation injury.

Changes and effect of PACAP-38 on intestinal ischemia-reperfusion and autotransplantation.

Tissue injury caused by cold preservation and reperfusion during small bowel transplantation remains an unsolved problem. Increasing evidence suggests that pituitary adenylate cyclase-activating polypeptide (PACAP) has protective effects in several ischemia-reperfusion (I/R) models. This study investigated the effect of PACAP-38 on oxidative stress in autotransplanted intestine. We established sham-operated, I/R, and autotransplanted groups in Wistar rats (n = 55). We applied ischemia for 1 (GI), 2 (GII), or 3 hours (GIII). In autotransplanted groups, we performed total orthotopic intestinal autotransplantation. Grafts were preserved in University of Wisconsin (UW) solution for 1 (GIV), 2 (GV), 3 (GVI), or 6 (GVII) hours and in PACAP-38-containing UW for 1 (GVIII), 2 (GIX), 3 (GX), or 6 (GXI) hours. Reperfusion lasted 3 hours in each group. Endogenous PACAP-38 values were measured by radioimmunoassay. Oxidative stress parameters malondialdehyde (MDA), reduced glutathione (GSH), and superoxide dismutase (SOD) were measured in tissue homogenates. Concentration of endogenous PACAP-38 significantly decreased in GI to GIII compared with the sham-operated animals following I/R periods (P < .05). Cold preservation in UW and reperfusion of the intestine increased the level of tissue MDA in GIV to GVII, which correlated with the duration of cold storage. The content of GSH decreased in GIV to GVII to levels that were significantly different between GIV and GVIII and between GVII and GXI. SOD activity decreased dramatically in GIV to GVII with significantly higher activity in GIX to GXI. Our findings confirmed that I/R decreased endogenous PACAP-38 concentration. Administration of PACAP-38 to UW solution mitigated the oxidative injury during intestinal autotransplantation.