To investigate the influence of the ileo-rectal anastomosis bypass procedure on on the 5-HT in the blood plasma of therats with STC.

72 SD rats were completed after the model was successful (5 dead in the process of modeling) and completed the ileo rectal anastomosis operation. The final control group was 10, 12 in the model group, 10 in the recovery group and 35 in the operation group (3 in the operation), and the content of 5-HT in the serum and colon of the rats was measured and compared. Statistical analyses were performed using SPSS17.0 software. Two-sided test was used in all statistical tests. The value of 5-HT in the serum and colon were presented by ±s. Comparisons between two groups were made by independent t test. Only differences of P<0.05 were considered to be significant.

5-HT in serum: Compared with normal control group, 5-HT in model group was increased considerably (P=0.002<0.01). There was no significant difference between operation group and recovery group (P=0.171>0.05), but operation group was still higher than model group. 5-HT in colon: Compared with normal control group, 5-HT was significant increased in model group, recovery group, and operation group (P<0.01); While there was no significant deviation between control group and recovery group. Operation group was higher than recovery group (P=0.001<0.05).

5-HT was significantly increased in the rats of STC model constipation. The ileo-rectal anastomosis bypass procedure do a great improvement in symptom of STC rats, but 5-HT in rats after surgery is still increased, The role of 5-HT in gastrointestinal motility should be further studied.