This study was carried out on adult female Sprague-Dawley rats to observe the position, size, and sensitivity change of inflammatory reactions on body surfaces induced by colorectal import of inflammatory irritant mustard oil. Colorectal distension (CRD) was adopted as a visceral noxious stimulus to record the activities of spinal dorsal horn wide-dynamic range (WDR) neurons activities at spinal segments L1–L3. The study also observed the activations of WDR neurons by electro-acupuncture (EA) on acupoints of Zusanli-Shangjuxu before and after different intensities of CRD stimulation and the dose-response relationship between stimulus and response. The results show that in the case of visceral inflammation, the number of exudation points of neurogenic reaction on body surfaces increased along with the severity of visceral inflammation (Li et al. 2006). The area of peripheral receptive fields of WDR neurons also enlarged along with the intensity of visceral inflammatory response. The activation effect of EA on WDR neurons was positively correlated with the severity of visceral inflammation. Therefore, we concluded that the function of acupoints can be sensitized by visceral noxious stimuli. When the function of internal organs was damaged, the number of reaction points on body surfaces, the size of acupoints' receptive fields, and the sensitivity of acupoints changed accordingly.

ObjectiveTo examine the effect of electroacupuncture (EA) treatment on abnormal defaecation in a rat model of chronic heterotypic stress (CHS) and investigate the underlying mechanisms.Methods20 male Sprague-Dawley rats were randomly divided into three groups: normal (n=6), CHS (n=7), and CHS+EA (n=7). Rats in the CHS group and CHS+EA groups received four different types of stressors for 7 days. For rats in the CHS+EA group, EA was applied at ST36 in the bilateral hind legs for 30 min before each stress-loading session. Rats in the normal group did not receive stressors or EA treatment. The faecal pellets of each rat were collected and weighed at a fixed time every day. Protein expression of corticotrophin-releasing factor (CRF) in the hypothalamus and colorectal tissues was measured by Western blotting at the end of the experiment on the 7th day.ResultsAfter 7 consecutive days of CHS, the number of faecal pellets, faecal wet weight, and faecal water content were significantly increased in the CHS group compared with the normal group (p=0.035, p=0.008 and p=0.008, respectively). All three parameters were significantly decreased in CHS+EA versus CHS groups (p=0.030, p=0.011 and p=0.006, respectively). Stress significantly increased CRF expression in both the hypothalamus and colorectal tissues. The excessive CRF responses seen following CHS were significantly suppressed by EA treatment.ConclusionsEA treatment can ameliorate stress loading induced abnormal defaecation in rats and decrease protein expression of CRF centrally (hypothalamus) and peripherally (colorectal tissues), suggesting a potentially therapeutic role for EA in stress-related responses.

Acupuncture at homotopic acupoints or heterotopic acupoints is known to either inhibit or facilitate gastrointestinal motility, depending on the acupoint location. However, little effort has been made to investigate the roles of specific receptors (such as adrenergic and muscarinic acetylcholine receptors) in mediating the effects of acupuncture at heterotopic and homotopic acupoints. Different adrenergic receptor subtypes or cholinergic receptor subtypes are predominantly expressed in various sections of the gut, resulting in variations between the effects of acupuncture at heterotopic or homotopic acupoints on gastrointestinal motility. Here, we investigated the role of β1/β2 receptors and M2/M3 receptors in gastrointestinal motility regulated by acupuncture at ST37, a heterotopic acupoint, and ST25, a homotopic acupoint, by simultaneously recording intraluminal pressures in the distal colon and stomach or jejunum and examining fecal phenol red excretion in β1/2 receptor-knockout mice and M2/3 receptor-knockout mice. We found that knockout of the M2/3 receptor significantly inhibited ST37 acupuncture-induced enhancement of gastric motility, jejunal motility, and colonic motility. Additionally, knocking out of the β1/2 receptor significantly diminished the ST25 acupuncture-induced inhibition of gastric motility and jejunal motility without significantly altering the enhancement of colonic motility induced by acupuncture at ST25. Acupuncture at ST37 significantly accelerated gastrointestinal transition in β1/2 receptor-knockout mice and their wild-type littermates. However, this acceleration of gastrointestinal transition was markedly diminished in M2/3 receptor-knockout mice relative to their wild-type littermates. Acupuncture at ST25 significantly increased gastrointestinal transition in β1/2 receptor-knockout mice and significantly decreased gastrointestinal transition in M2/3 receptor-knockout mice without altering gastrointestinal transition in wild-type littermates of either. Our study revealed that M2/3 receptors are required for the gastrointestinal motility associated with whole gastrointestinal transition enhanced by acupuncture at heterotopic acupoints, whereas β1/2 receptors are required for the same gastrointestinal motility processes inhibited by acupuncture at homotopic acupoints. Therefore, our findings reveal important biological mechanisms underlying acupuncture treatment of disorders involving gastrointestinal motility dysfunction.

Background Central injection of corticotrophin-releasing factor (CRF) mimics the effect of stress on gastrointestinal (GI) responses, including inhibition of GI motility. This study was designed to explore the effects of electroacupuncture (EA) on disordered jejunal motility in a rat model of stress induced by intracisternal (IC) injection of CRF. Methods A stress model was established by IC injection of CRF in Sprague–Dawley rats. GI motility was evaluated by assessing gastric emptying (GE), gastrointestinal transit (GIT) and jejunal motility in vivo. EA was performed at ST36. The functional roles of CRF receptor subtype 1 and subtype 2 (CRFr1 and CRFr2) were examined by IC administration of the corresponding selective CRF antagonists. Protein expression of CRFr1 and CRFr2 in the hypothalamus and jejunum was detected by Western blotting. Results IC injection of CRF significantly inhibited GE, GIT and jejunal motility. EA treatment remarkably improved the disturbed GI motility. Intriguingly, the disordered jejunal motility induced by central CRF was abolished by IC injection of a selective CRFr2 antagonist, indicating the essential role of central CRFr2 in mediating the stress-induced jejunal motor disorder. EA at ST36 decreased central and peripheral expression of CRFr2, which might be one of the potential mechanisms underlying the beneficial effect of EA on jejunal dysmotility in this rat model of stress. Conclusion This study suggested that EA at ST36 could ameliorate disordered jejunal motility induced by stress, and that this might be associated with the down-regulation of CRFr2.

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