| Backround and Objective:Intestinal disorders (such as irritable bowel syndrome) and inflammatory boweldisease often appear visceral hypersensitivity. Visceral hyperalgesia is the mostimportant pathological mechanisms of visceral pain. The intestinal wall of functionalbowel disease also has a similar inflammatory response such as inflammatory boweldisease. The chronic inflammatory stimuli in bowel triggered visceral nociceptivesignals, which caused visceral pain. Adenosine triphosphate (ATP) and itsactivated-P2X7receptor play an important role in the transmission of nociceptive pain.Peripheral nociceptors after nociceptive stimuli formed the afferent nerve impulsesthrough primary sensory dorsal root ganglia. Moxibustion may have anti-inflammatory and immunomodulatory effects. Thermal acupoint moxibustion is atreatment method of hanging moxibustion characterized by generating heat, thermalexpansion, heat transfer, and heat in the distal but not in local portion. Clinical studieshave shown that thermal moxibustion may be a better treatment of irritable bowelsyndrome, but its mechanism is unclear. In this study, we are to observe therelationships between the analgesic effect of thermal moxibustion a rat “Dachangshuâ€after colorectal distension and the change of P2X7receptor expression in dorsal rootganglia after the chronic inflammatory stimuli in bowel.Methods:(1) Model of visceral hyperalgesia in neonatal rats by colorectaldistension (colorectal distension, CRD) was established, and then acupoint thermalmoxibustion at rat “Dachangshu†for40min was used to imitate thermal moxibustiontherapy.(2) Abdominal withdrawal reflex (AWR) score and visceral hyperalgesiathreshold after acupoint thermal moxibustion were detected in control group, modelgroup, non-acupoint moxibustion group, and acupoint moxibustion group.(3) Theco-expression of GFAP (satellite glial cell marker) and P2X7receptor was observedby double immunofluorescence.(4) P2X7mRNA in dorsal root ganglia was detectedby RT-PCR.(5) P2X7receptor protein expression in the rat dorsal root ganglia by immunohistochemistry and Western Blot.Results:1. Pain threshold in model of visceral hyperalgesia after the CRD stimuli inneonatal rats for8weeks was significantly reduced in comparison with that in controlgroup. AWR score of20,40,60,80mmHg in model group was significantly higherthan that in control group (p<0.01). The results showed that continuous CRDstimulation in neonatal rat can form visceral hyperalgesia model.2. Compared with that in model group, the pain threshold value in acupointmoxibustion group rats was increased (p <0.01). There was no difference betweennon-acupoint moxibustion group and model group (p>0.05). AWR score in20,40,60,80mmHg in acupoint moxibustion group was significantly decreased in comparisonwith that in model group (p<0.01). No difference between non-acupoint moxibustiongroup and model group (p>0.05).3. The results in immunohistochemistry test showed that the DRG P2X7receptorimmunoreactivity in model group was significantly higher than that in controlgroup(p<0.01). Compared with those in model group, P2X7receptor expression levelsin “Dachangshu†acupoint moxibustion group were significantly decreased (p<0.01).No difference between non-acupoint moxibustion group and model group (p>0.05).4. Results in reverse transcription-polymerase chain reaction (RT-PCR) showedthat DRG P2X7mRNA expression levels in model group were significantly increasedcompared with those in control group (p<0.01). P2X7mRNA expression levels in“Dachangshu†acupoint moxibustion group were significantly decreased comparedwith those in model group (p<0.01). There was no difference between non-acupointmoxibustion group and model group (p>0.05).5. Results in double immunofluorescence analysis showed that the co-expressionlevel of DRG P2X7receptor and glial fibrillary acidic protein (GFAP) in model groupwas significantly increased compared with that in control group. The co-expressionlevel of P2X7receptor and GFAP in “Dachangshu†acupoint moxibustion group wassignificantly lower than that in model group. No difference between non-acupointmoxibustion group and model group. 6. Results in Western blot showed that the DRG P2X7receptor protein value inmodel group was significantly increased in comparison with that in control group(p<0.01). Compared with those in model group, P2X7receptor expression levels in“Dachangshu†acupoint moxibustion group were significantly decreased (p<0.01). Nodifference between non-acupoint moxibustion group and model group (p>0.05).Conclusion:Thermal moxibustion at “Dachangshu†acupoint inhibited the nociceptivetransmission by decreasing DRG P2X7receptor mRNA and protein expression levelsupregulated by visceral pain, reducing the abnormal expression of GFAP in DRG,which reduced AWR score in visceral pain model, improveed their pain threshold. Sothermal moxibustion at “Dachangshu†acupoint can produce a therapeutic effect tobowel dysfunction disorders (such as irritable bowel syndrome) induced by visceralhyperalgesia and inflammatory bowel disease. |
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