Abstract

A number of patients operated on for Hirschsprung disease continue to have constipation and abdominal distension for years after surgery. Some authors have proposed that ischemia during surgery may induce secondary aganglionosis. The aim of the present study was to study the effects of ischemia on the enteric nervous system of sigmoid colon in an animal model. A surgical model of colonic ischemia was created. 34 adult Sprague-Dawley rats underwent a laparotomy where the marginal arterioles of the sigmoid colon were ligated. After that, a section in the middle segment of the sigmoid colon was performed followed by an anastomosis. The presence of ischemia was assessed by measurement of visible light spectroscopy tissue oximetry and histological examination. Colonic function was assessed by evaluation of stool weight. Rats were killed at 1, 8 and 12 weeks after the operation. 12 rats were sham-operated. Enteric nervous system was evaluated by means of immunohistochemistry with NGFR p75. Quantitative analysis of the number of ganglia and ganglion cells in the myenteric plexus was performed. The surgical model of colonic ischemia significantly decreased tissue oxygenation (pre-surgical = 54.69 +/- A 7.32 %; post-surgical = 27.37 +/- A 9.2 %; p < 0.001). There was no disturbance in body-weight gaining in experimental groups and daily stool output did not vary after surgery (pre-surgical = 4.24 +/- A 0.94 g; post-surgical = 3.82 +/- A 1 g; p = 0.09). All experimental groups showed persistent ganglia. However, there was a significant decrease in the number of ganglia in all the experimental groups compared to control (1w: 45.91 +/- A 7.66; 8w: 44.17 +/- A 10.56; 12w: 36.17 +/- A 15.06 vs control: 56.88 +/- A 8.66; p < 0.01). The number of total ganglion cells was significantly reduced only in the experimental group killed at week 12 compared to control (1w: 539 +/- A 167.58; 8w: 488.58 +/- A 154.41; 12w: 343.94 +/- A 161.91 vs control: 513.96 +/- A 126.97; p < 0.01). The rate of ganglion cells per ganglia was significantly higher in the groups killed at week 1 and 8 versus control group (1w: 11.63 +/- A 2.53; 8w: 11.11 +/- A 2.56; 12w: 9.34 +/- A 1.16 vs control: 9.02 +/- A 1.81; p < 0.05). Long-term follow-up after surgically induced colonic ischemia in the rat showed a decreased number of ganglion cells and ganglia. Nevertheless, it did not produce aganglionosis.