Interstitial Cells of Cajal Are Required for Different Intestinal Motility Responses Induced by Acupuncture

The movement of intestinal smooth muscle is regulated by the external autonomic nervous system (ANS) and its internal enteric nervous system (ENS). Previous studies have shown that acupuncture has a bidirectional regulating effect on intestinal motility through the sympathetic and vagal ANSs. ENS can independently regulate the sensory, secretory, and motor functions of the intestine. The interstitial cells of Cajal (ICC), the pacemaker cells in ENS, play a key role in maintaining gastrointestinal motility. However, studies on the role and mechanism of ICC in the regulation of intestinal function by acupuncture are still unclear.

To investigate the effect of ICC on the regulation of intestinal motility by manual acupuncture (MA), we recorded the pressure of warm water-filled manometric balloons in duodenum, jejunum, and distal colon in ICC deficiency WsWs^-/- rats and wild-type littermates WsRC^+/+ rats, and performed MA at ST25 (Tianshu), ST37 (Shangjuxu), LI11 (Quchi), and BL25 (Danchangshu) acupoints. Furthermore, the excretion of phenol red in feces before and after MA at ST37 or ST25 was assessed.

In WsRC^+/+ rats, MA at ST37, LI11, and BL25 promoted duodenal, jejunal, and distal colon motility, whereas MA at ST25 significantly inhibited duodenal and jejunal motility and promoted distal colon motility. ICC deficiency in WsWs^-/- rats led to a reduction in the promoting effect of LI11 on duodenal motility, a decrease in the promoting effect of ST37 on jejunal motility, and a significant reduction in the promoting effect of BL25 on distal colonic motility in those rats. Additionally, ICC absence significantly attenuated the inhibitory effect of ST25 on duodenal motility. MA at ST37 or ST25 did not change the content of phenol red in the feces in WsRC^+/+ and WsWs^-/- rats.

Our results suggest that the absence of ICC impairs the bidirectional regulatory effect of MA on intestinal function. It reveals the important role of ICC in the treatment of intestinal dysfunction diseases by acupuncture and provides a new theoretical basis for the treatment of such diseases by MA.