Effects of pelvic nerves denervation on the expression of transit receptor potential vanilloid 1 in distal colonic mucosa of rats

Objective To explore the effects of pelvic nerves denervation (PND) on the expression of transit potential receptor vanilloid 1 (TRPV1) in distal colonic mucosa of rats. Methods The experimental study was conducted. One hundred and eight adult male rats were randomly divided into the control group, sham operation group and PND group: (1) 36 rats in the control group remained untreated and were fed regularly; (2) 36 in the sham operation group received open exclusion for 15 minutes, and then sew up the incision; (3) 36 in the PND group received laparotomy with pelvic nerve transection before abdominal closure. The expression of TRPV1 protein in distal colonic mucosa was respectively detected by Western blot at postoperative day 1, 3 and 7. Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) was used to detect the mRNA level of TRPV1 in the distal colonic mucosa. Measurement data with normal distribution were represented as ±s. Repeated measurement data were analyzed by repeated measures ANOVA. Comparisons at the same time intervals among the 3 groups were analyzed using one-way ANOVA. Pairwise comparison was done by the independent-samples t test. Results (1) The results of immunohistochemical staining: the average density of TRPV1 in distal colonic mucosa at postoperative day 1, 3 and 7 was respectively 0.180±0.016, 0.179±0.015 and 0.183±0.026 in the control group, with no statistically significant difference (F=0.088, P>0.05). The average density of TRPV1 in distal colonic mucosa at postoperative day 1, 3 and 7 was respectively 0.132±0.017, 0.160±0.023 and 0.173±0.020 in the sham operation group, with a statistically significant difference (F=8.699, P 0.05), while significant differences were respectively detected between the control group and the PND group and between the sham operation group and the PND group (t=6.543, 3.361, P 0.05). (2) The results of Western blot: the relative expressions of TRPV1 in distal colonic mucosa at postoperative day 1, 3 and 7 were respectively 1.02±0.13, 1.00±0.15 and 1.00±0.10 in the control group, with no statistically significant difference (F=0.084, P>0.05). The relative expressions of TRPV1 in distal colonic mucosa at postoperative day 1, 3 and 7 were respectively 0.51±0.13, 0.93±0.14 and 1.01±0.16 in the sham operation group, with a statistically significant difference (F=20.930, P 0.05), while significant differences were respectively detected between the control group and the PND group and between the sham operation group and the PND group (t=4.127, 3.398, P 0.05). (3) The results of RT-qPCR: the mRNA levels of TRPV1 in distal colonic mucosa at postoperative day 1, 3 and 7 were respectively 1.00±0.15, 1.10±0.21 and 1.09±0.18 in the control group, with no statistically significant difference (F=0.489, P>0.05). The mRNA levels of TRPV1 in distal colonic mucosa at postoperative day 1, 3 and 7 were respectively 0.58±0.12, 0.99±0.19 and 1.13±0.23 in the sham operation group, with a statistically significant difference (F=13.964, P 0.05), while significant differences were respectively detected between the control group and the PND group and between the sham operation group and the PND group (t=4.411, 3.505, P 0.05). Conclusion The expression of TRPV1 in distal colonic mucosa of rats is significantly down-regulated after pelvic nerves denervation, however, it is gradually recovered with passage of time, which is consistent with the trend of gradual recovery of colonic transit function after pelvic nerve injury. Key words: Pelvic nerve injury; Intestinal motility; Transit receptor potential vanilloid 1