Acupuncture Alleviates Colorectal Hypersensitivity and Correlates with the Regulatory Mechanism of TrpV1 and p-ERK.

Here we used a mouse model of zymosan-induced colorectal hypersensitivity, a similar model of IBS in our previous work, to evaluate the effectiveness of the different number of times of acupuncture and elucidate its potential mechanism of EA treatment. Colorectal distension (CRD) tests show that intracolonic zymosan injection does, while saline injection does not, induce a typical colorectal hypersensitivity. EA treatment at classical acupoints Zusanli (ST36) and Shangjuxu (ST37) in both hind limbs for 15 min slightly attenuated and significantly blunted the hypersensitive responses after first and fifth acupunctures, respectively, to colorectal distention in zymosan treatment mice, but not in saline treatment mice. Western blot results indicated that ion channel and TrpV1 expression in colorectum as well as ERK1/2 MAPK pathway activation in peripheral and central nerve system might be involved in this process. Hence, we conclude that EA is a potential therapeutic tool in the treatment and alleviation of chronic abdominal pain, and the effectiveness of acupuncture analgesia is accumulative with increased number of times of acupuncture when compared to that of a single time of acupuncture.