Cellular changes of the colon after mechanical bowel preparation

The purpose of this study was to evaluate the effect of mechanical bowel preparation (MBP) on the intracellular environment, specifically evaluating butyrate transport, within the colon of the Sprague-Dawley rat.

Sixty-eight Sprague-Dawley rats were randomized to either an MBP group (n = 34) or a control group (n = 34). Twenty-four hours after the completion of the MBP, both groups were euthanized, and the colons were harvested. The level of cellular apoptosis was investigated after DNA fragmentation, poly(ADP-ribose) polymerase cleavage, and caspase assays. Western blot analysis was performed to measure the expression of the butyrate transporter protein, monocarboxylate transporters 1, and proliferating cell nuclear antigen (a marker for tissue proliferation). Immunohistochemical staining was performed to further investigate cellular proliferation. Statistical significance (P < 0.05) was determined using two-tailed t-test.

Apoptosis was detected without significant differences in both groups. Western Blot analysis demonstrated that the expression of the monocarboxylate transporters 1 protein is downregulated in the MBP group (10.18 ± 3.09) compared with the control group (16.73 ± 7.39, P = 0.001), and proliferating cell nuclear antigen levels showed a decrease in cellular proliferation in the MBP group (13.35 ± 5.88) compared with the control (20.07 ± 7.55, P = 0.018). Immunohistochemistry confirmed a decrease in cellular proliferation after MBP with 23.4 ± 7.8% of the cells staining positive for Ki-67 in the MBP group versus 28.6 ± 7.9% in the control group (P = 0.006).

MBP has a negative impact on cellular proliferation and intracellular transport of butyrate within the rat colon, not related to apoptosis. This is the first study to demonstrate the intracellular effects that MBP has on the rat colon.