The Effect of Polyethylene Glycol-Electrolyte on Dextran Sulfate Sodium-Induced Colitis in Rats

The Effect of Polyethylene Glycol-Electrolyte on Dextran Sulfate Sodium-Induced Colitis in Rats Chifumi Yamamoto, Kunihiko Aoyagi, Yoshihiro Hayashi, Isamu Morita, Shotaro Sakisaka Background & Aims: Polyethylene glycol-electrolyte (PEG-EL) is the most commonly used agent for mechanical bowel cleansing. Adverse events related to PEG-EL have included serum electrolyte disturbance, gastrointestinal discomfort and rectal mucosal abnormalities. However, there have been few studies evaluating the effect of PEG-EL on colitis, such as ulcerative colitis. The aim of this study was to evaluate the safety of PEG-EL in cases of both normal colon and dextran sulfate sodium (DSS)-induced colitis. Methods: Exp. 1; Twenty Male Wistar rats were divided into two groups, the DSS-induced colitis group and the normal colon group. Colitis was induced by administering 3% DSS in drinking water over a period of 6 days. Following the administration of DSS or distilled water, each group received either PEG-EL (Niflec , Ajinomoto Pharma, Tokyo, Japan) or distilled water for 14 hours (each group, n Z 5). Colitis was evaluated by tissue myeloperoxidase (MPO) activity and by the inflammation score as described by Cooper. A blood sample was taken from the portal vein to measure WBC, RBC and Hb. Exp. 2; The effect of PEG-EL in the DSS-induced colitis group (each group, n Z 5) was evaluated in the same way as in Exp. 1, 12, 24 and 48 hours after the administration of either PEG-EL or distilled water. Results: Exp. 1; PEG-EL did not change the inflammation score in either the normal colon group (0 vs. 0) or the DSS-induced colitis group (2.15 G 0.6 vs. 2.2 G 0.6, p Z 0.89). Similarly, MPO activity, RBC and Hb showed no significant change. However, WBC was significantly increased in the DSS-induced colitis group which received PEG-EL (69,440 G 1971 vs. 51,040 G 2288, p Z 0.019). Exp. 2; At 12, 24 and 48 hours, there was no significant difference in either the inflammation score or MPO activity in any of the groups (see Table). However, there was a tendency to be a delay in decreasing MPO activity at 12 hrs in the DSS-induced colitis group which received PEG-EL (see Table). Conclusions: The present study shows that PEG-EL histologically affected neither the normal colon nor DSS-induced colitis. However, the improvement in colitis showed an inclination to be delayed in the DSS-induced colitis group which received PEG-EL. Consequently, it is essential that adequate care is taken when we use PEG-EL for patients with colitis.