Suspended moxibustion at Tianshu (ST25) inhibits prokineticin 1 and prokineticin receptor 1 expression in the spinal cord of rats with chronic visceral hypersensitivity

Suspended moxibustion can decrease the expression of prokineticin 1 and its receptor in colonic tissue from rats modeling chronic visceral hyperalgesia. This study aimed to verify if rat spinal cord prokineticin 1 and its receptor contribute to the analgesic effect of suspended moxibustion in a rat model of irritable bowel syndrome where rats display chronic visceral hypersensitivity. Results showed that suspended moxibustion at Tianshu （ST25） point significantly decreased visceral sensitivity to colorectal distention in a chronic visceral hyperalgesia rat model; also protein and mRNA expression of prokineticin 1 and prokineticin receptor 1 in the spinal cord of rats was significantly decreased. Experimental findings indicate that prokineticin 1 and prokineticin receptor 1 are involved in the analgesia using suspended moxibustion in rats with chronic visceral

Effects of electroacupuncture on c-Fos expression in the spinal cord and brain of rats with chronic visceral hypersensitivity

BACKGROUND： Visceral hypersensitivity is the main cause of irritable bowel syndrome, c-Fos is a marker of visceral hypersensitivity in the central nervous system. Electroacupuncture can relieve chronic visceral hypersensitivity in rats, but the mechanism is still unknown. OBJECTIVE： To identify c-Fos expression in the spinal cord and cerebral cortex of rats with chronic visceral hypersensitivity, and to test the effects of electroacupuncture on pain sensitivity in rats with chronic visceral hypersensitivity. DESIGN, TIME AND SETTING： A randomized controlled animal experiment was performed at the Animal E：~perimental Center, Shanghai University of Traditional Chinese Medicine, from January to April, 2007. MATERIALS： A total of 24 neonatal, male, Sprague Dawley rats, aged five days old, were equally and randomly assigned into a normal group, a model group, and an electroacupuncture group. Rabbit anti-rat c-Fos antibody and Evision secondary antibody kits （Sigma, USA）, diaminobenzidine kit （Dako, Denmark）, and an LD202H electroacupuncture apparatus （Huawei, Beijing, China） were used in this study. METHODS： Neonatal rats from the model and electroacupuncture groups were used to establish rat models of chronic visceral hypersensitivity by the saccule stimulation method. After model establishment, 0.25 mm diameter electric needles were inserted into Tianshu （ST 25） and Shangjuxu （ST37） at a depth of approximately 0.5 cm, with an square wave （alternating current frequency at 100/20 Hz, amplitude ranged 0.2-0.6 ms, intensity at 1 mA） once for 20 minutes, once a day, for seven days. Rats in the normal and model groups were not treated. MAIN OUTCOME MEASURES： Following 7 days of treatment, c-Fos expression in the spinal cord and cerebral cortex was detected by immunohistochemistry. After the first electroacupuncture treatment, abdominal withdrawal reflex scores were investigated to evaluate the pain threshold for chronic visceral hypersensitivity in rats. RESULTS： Visceral hypersensitivity increased c-Fos staining （P 〈 0.05）, and electroacupuncture significantly decreased the number of these cells to near normal levels （P 〉 0.05）. Abdominal withdrawal reflex scores were significantly lower in the electroacupuncture and normal groups than in the model group （P 〈 0.05） and were similar between the electroacupuncture and normal groups （P 〉 0.05）. CONCLUSION： Electroacupuncture decreases c-Fos expression in the spinal cord and cerebral cortex and increases pain threshold in a chronic visceral hypersensitivity model in rats.

Suspended moxibustion relieves chronic visceral hyperalgesia and decreases hypothalamic corticotropin-releasing hormone levels

AIM:To evaluate the effect of suspended moxibustion(SM) on rectal sensory thresholds and to analyze the possible mechanisms involved in SM treatment of chronic visceral hypersensitivity(CVH) in rats.METHODS:SM was administered once daily to 37-dold CVH rats for 7 d.The two pairs of acupoints(ST25 and ST37,bilateral) were simultaneously treated with SM.Each treatment lasted for 30 min.Rats undergoing treatment with SM were not anesthetized.Untreated CVH rats and normal rats were used as controls.The abdominal withdrawal reflex was determined 30-90 min after the seven treatments.The hypothalamic corticotropin-releasing hormone(CRH) mRNA level was measured using real-time quantitative reverse transcriptionpolymerase chain reaction.RESULTS:We found that SM treatment significantly decreased visceral sensitivity to colorectal distention in this rat model.In treated animals,SM also decreased the relative hypothalamic CRH mRNA expression level to control levels.CONCLUSION:Lower hypothalamic CRH levels may mediate the beneficial effects of SM in this rat irritable bowel syndrome model.

Differential effects of glutamate receptor antagonists on dorsal horn neurons responding to colorectal distension in a neonatal colon irritation rat model

AIM: To investigate and compare the effects of spinal D-(-)-2-amino-7-phosphonoheptanoic acid (AP-7) and 6-cyano-7-nitroquinoxaline-2,3-dione disodium (CNQX),two glutamate receptor antagonists, on the responses of dorsal horn neurons to colorectal distension (CRD) in adult rats exposed to neonatal colon irritation (CI).METHODS: Hypersensitive SD rats were generated by CI during postnatal days 8, 10 and 12. Experiments on adult rats were performed using extracellular single-unit recording. The effects of spinal application of AP-7 (0.001,0.01, 0.1, 1 mmoL) were tested on the CRD-evoked neuronal responses in 16 controls and 17 CI rats. The effects of CNQX (0.2, 2, 5, 10 μmoL) were also tested on the CRD-evoked responses of 17 controls and 18 CI neurons.RESULTS: (1) The average responses of lumbosacral neurons to all intensities of CRD in CI rats were significantly higher than those in control rats; (2) In control rats, AP-7 (0.01 mmoL) had no significant effect on the neuronal response to all intensities of CRD (20,40, 60, 80 mmHg); while AP-7 (0.1 mmoL) inhibited the neuronal response to 80-mmHg CRD. By contrast, in CI rats, AP-7 (0.01-1 mmoL) attenuated the CRD-evoked neuronal responses to all distention pressures in a dosedependent manner; (3) In control rats, CNQX (2 μmoL)had no significantly effect on the neuronal response to all intensities of CRD; however, CNQX (5 μmoL) significantly attenuated the responses to CRD in the 40-80 mmHg range. By contrast, CNQX (2-10 μmoL)significantly decreased the neuronal responses in CI rats to non-noxious and noxious CRD in a dose-dependent manner.CONCLUSION: Our results suggest that spinal N-methyl-D-aspartate (NMDA) and non-NMDA receptors may contribute to the processing of central sensitivity in a neonatal CI rat model, but they may play different roles in it.