| 1 BackgroundVisceral pain is one of the common clinical symptoms characterized by internal organ pain and high visceral sensitivity.Visceral pain is different from somatic inflammatory pain and neuropathic pain.The location of pain is not clear,its nature is difficult to describe,and it may be accompanied by pain.Long-term recurrent episodes of visceral pain can cause secondary somatic hypersensitivity,negative adverse emotions,nausea,gastrointestinal dysfunction,cardiovascular changes and other autonomic responses.Visceral pain associated with gastrointestinal diseases mainly includes irritable bowel syndrome(IBS),inflammatory bowel disease(IBD)and other functional and inflammatory diseases.Such diseases are equivalent to abdominal pain in Chinese medicine.At present,visceral pain related treatments mainly include drug treatment and surgical treatment.However,the problem of drug addiction and high surgical cost limits its clinical application.Therefore,it is necessary and significant to find more effective alternative therapies for the treatment of visceral pain.At present,research has confirmed that acupuncture as a traditional Chinese medicine treatment can effectively alleviate all kinds of acute and chronic visceral pain.Gastrointestinal functional diseases are clinically dominant diseases of acupuncture and moxibustion.ST25 and ST36 are common points for treating gastrointestinal diseases.With the development of animal models of visceral pain and the maturity of scientific and technological detection methods,more and more scholars have begun to engage in clinical and basic research on acupuncture treatment of visceral pain.The effect of acupuncture analgesia has been initially confirmed,but there are few studies on the inhibitory effect of different electroacupuncture strength on visceral pain response and its mechanism of action.Therefore,this study sought to determine the effect of EA at different acupoints(ST25,ST36 and LI11)with distinct intensities(1 mA or 3 mA)on a visceral pain model induced by CRD,in which the EMG reflex of abdominal muscularture,as well as c-fos expression in NTS produced by various CRD stimuli were compared before and after EA treatment in rats anesthetized with isoflurane.The effect of c-fos expression in the nucleus of the visceral nucleus was explored.The inhibitory effect of different acupoints and different electroacupuncture strength on the visceral nociceptive pain response of colorectal dissection was explored,and the characteristics and possible mechanisms of electroacupuncture at different acupoints to relieve visceral pain were revealed.Provide scientific and reasonable theoretical basis and experimental basis for electroacupuncture treatment of visceral pain.2 ObjectiveIn this study,the visceral pain was induced by colorectal distention stimulation in rats,and the degree of myoelectrical delivery of the rectus abdominis muscle(area,frequency and amplitude under the curve),and the expression of c-fos positive neurons in the nucleus of the medullary visceral zone.The degree is the detection index,and the differences in the effects of different intensity and different acupuncture points on the visceral pain in rats and the possible mechanisms are discussed.3 MethodIn this study,54 SD rats were used,and electrophysiological experiments(n=30)and morphological experiments(n=24)were performed.In the electrophysiological experiment,6 rats were used to observe the threshold of rectus abdominis myoelectricity induced by colorectal dilation stimulation.The other rats were randomly divided into 3 groups:ST36 group,ST25 group,and LI11 group.8 only Morphological experimental rats were randomly divided into 8 groups:normal group,model group,.1 mA ST36 group,1 mA ST25 group,1 mA LI11 group,3mA ST36 group,3 mA ST25 group,3 mA LI11 group,each group.3only.In the electrophysiological experiment,the rats were given an anaerobic injury caused by colorectal distention stimulation under anesthesia with isoflurane(flow rate:1 L,concentration:0.8%).The degree of visceral nociceptive pain in the rectus abdominis myoelectric reaction was recorded by electroacupuncture with different intensities(1 mA and 3 mA)and different acupoints(ST36,ST25,LI11).At the same time,through the immunohistochemical study method,the effects of electroacupuncture stimulation with different intensity and different acupoints on the expression of c-fos positive neurons in the solitary tract nucleus were observed.The area,frequency,amplitude,and expression of c-fos-positive neurons in the nucleus of the solitary tract were compared between the rectus abdominis muscles of the rats before and after different electroacupuncture.4 Results4.1 Electrophysiological study on visceral nociceptive pain response in rat model of colorectal distension stimulation4.1.1Threshold of colorectal distension pressure to produce significant visceral pain by rectus abdominis myoelectric recordingRats given inhalation anesthesia were stimulated with colorectal dilation without synchronized pressure(20,40,50,60,70 and 80mmHg).By calculating the area under the curve of the rectus abdominis muscle,the frequency and amplitude of the discharge,it was observed that the release of the rectus abdominis myoelectricity gradually increased.Compared with before expansion,the rectus abdominis myoelectrical distribution caused by 60mmHg,70mmHg and 80 mmHg expansion pressure increased significantly,showing the area under the rectus abdominis myoelectric curve,and the discharge frequency and amplitude were significantly increased(P<0.01).4,1.2Comparison of the inhibitory effects of different acupuncture points on the myoelectric activity of rectus abdominis induced by 60 mmHg colorectal expansion pressureAfter 1 mA electroacupuncture at ST25 point,the area under the curve of rectus abdominis myoelectricity(24.25±14.28)mV?Sec,discharge frequency(19.6316.77)Hz and amplitude(23.80±6.44)mV,before electroacupuncture(42.29± 6.08)The difference of mV*Sec,(34.25±4.91)Hz,(42.04±9.12)mV was statistically significant(P<0.05).There was no significant difference in the area,discharge frequency and amplitude of the rectus abdominis myoelectric curve between the electroacupuncture 1 mA ST36 and LI11 acupoints before the electroacupuncture(P>0.05).4.1.3Comparison of different acupoint3 mA intensity electroacupuncture stimulation on the inhibition of rectus abdominis myoelectric activity induced by 60 mmHg colorectal expansion pressureAfter3 mA electroacupuncture at ST36,the area under the curve of rectus abdominis myoelectricity(16.38±2.99)mV*Sec,discharge frequency(10.49±2.64)Hz and amplitude(22.79±5.57)mV were significantly reduced,before electroacupuncture The difference was statistically significant(P<0.01)between(43.66±9.69)mV*Sec,(31.10±3.19)Hz,and(39.98±5.47)mV After3 mA electroacupuncture at ST25 point,the area under the curve of rectus abdominis myoelectricity(14.47±15.65)mV*Sec,discharge frequency(12,41±4.58)Hz and amplitude(8.63±4.28)mV were significantly reduced,before electroacupuncture(55.61±11.51)mV*Sec,(35.29±5.65)Hz,(44.94±6.67)mV compared with the difference was statistically significant(P<0.01).After 3 mA electroacupuncture at the LI11 point,there was no significant difference in the area,discharge frequency and amplitude of the rectus abdominis myoelectric curve compared with before electroacupuncture(P>0.05).4.2 Experimental study on visceral nociceptive pain response in rat model of colorectal distension stimulation4.2.1 Effect of electroacupuncture on the expression of c-fos in solitary tract nucleus induced by 60 mmHg pressure colorectal distentionColorectal dilation can cause early gene c-fos expression in the visceral sensory central solitary tract nucleus neurons.After30 minutes of continuous administration of 60 mmHg colorectal distention,the expression of c-fos positive neurons in the solitary tract nucleus was(58.17±4.59)and the fluorescence intensity was(3.59±0.55)AU,which was higher than that of the normal group.4.67±1.10)and(0.54±0.12)AU increased significantly(P<0.01).4.2.2Comparison of the influence of 1mA intensity electroacupuncture at different acupoints on the positive cell count of c-fos neurons in the solitary nucleus of rats,and the comparison of the average fluorescence intensityUnder the stimulation of 60 mmHg colorectal expansion pressure,the number of c-fos positive cells in the solitary nucleus after 1 mA electroacupuncture at ST25 Point was(38.33±3.97),and the fluorescence intensity(1.371±0.16)AU was significantly lower than that of the model group.(P<0.05).The 1 mA electroacupuncture at ST36 and LI11 had no significant inhibitory effect on c-fos positive cells in the solitary tract nucleus(P>0.05).4.2.3Comparison of the influence of3 mA intensity electroacupuncture at different acupoints on the positive cell count of c-fos neurons in the solitary tract nucleus of rats,and the comparison of the average fluorescence intensityUnder the stimulation of 60 mmHg colorectal expansion,the number of c-fos positive cells in the solitary nucleus after3 mA electroacupuncture at ST36 was(36.83±5.12),and the fluorescence intensity was(1.86±0.32)AU,which was significantly lower than that of the model group.(P<0.05).The number of c-fos positive cells(31.50±3.62)and the fluorescence intensity(1.401±0.27)AU after 3 mA electroacupuncture at ST25 point were significantly lower than those in the model group(P<0.05).The 3 mA electroacupuncture at LI11 had no obvious inhibitory effect on c-fos positive cells in the solitary tract nucleus(P>0.05).These results are consistent with the results of noxious EMG.5 Conclusions1.60mmHg of colorectal distention can induce visceral pain in rats,which is manifested by a significant increase in the area,frequency and amplitude of the curve of the rectus abdominis.2.1 mA electroacupuncture ST25 points can significantly reduce the release of rectus abdominis myoelectricity caused by noxious stimulation and down-regulate the expression of c-fos in the nucleus of the medulla oblongata.3.3mA electroacupuncture ST36 and ST25 can significantly reduce the release of rectus abdominis myoelectricity caused by noxious stimulation and down-regulate the expression of c-fos in the nucleus of the medulla oblongata.4.The 1 mA and 3mA electroacupuncture points have no significant effect on the release of rectus abdominis myoelectricity caused by noxious stimulation and the expression of c-fos in the nucleus of the nucleus.In summary,the electroacupuncture at ST25 and ST36 can significantly improve the release of rectus abdominis myoelectricity caused by noxious stimulation and down-regulate the expression of c-fos in the nucleus of the nucleus of the medulla,but the inhibition of the same segment of the ST25 point the amount of stimulation required for visceral pain is small. |
PDF Full Text Request