Expression of transient receptor potential ankyrin 1 correlating to the recovery of colonic transit after pelvic nerve denervation in rats.

BACKGROUND: It has been reported that colorectal motility dysfunction due to pelvic nerve (PN) damage is restored overtime. However, the adaptive mechanism is unknown. Previous studies implied that transient receptor potential ankyrin 1 (TRPA1) mediated sensory nerve signal input plays a crucial role in gut motility regulation. The present study aimed to observe the colorectal motility restoration in rats after PN transection and to explore the change of TRPA1 protein expression in this adaptive process.

METHODS: Seventy-eight adult rats were divided into two groups randomly: sham and PN cut. Colonic transit function was determined with radioisotope method by calculating the geometric center (GC) of the distribution of 51 Cr at postoperative days (POD) 1, 3, and 7. Expression of TRPA1 in the proximal and distal colon mucosa was detected with Western blotting at POD 1, 3, and 7.

RESULTS: At POD 1, the colonic transit in PN cut group was significantly delayed (GC = 4.91 ± 0.41, P < 0.05), when compared with the sham group (GC = 5.76 ± 0.85). A significant trend toward recovery was noted in the PN cut group at POD 3 (GC = 5.58 ± 0.36) and POD 7 (GC = 6.44 ± 0.78). Western blot demonstrated attenuated expression of TRPA1 in the distal colon mucosa after PN denervation at POD 1 (0.39 ± 0.12) compared with that of the shams. A significant trend of increasing expression of TRPA1 was demonstrated in the PN cut group at POD 3 (0.78 ± 0.10) and at POD 7 (1.06 ± 0.13).

CONCLUSIONS: Delayed colonic motility due to PN denervation gradually restored overtime, which may relate to the corresponding expression of TRPA1 in the distal colonic mucosa of rats.