Peripheral neural mechanism of visceral pain and acupoint sensitization in 2, 4, 6-trinitrobenzene sulfonic acid-induced colitis model mice

OBJECTIVES

To explore the neural mechanism of visceral pain and related somatic (acupoints) sensitization by using in vivo calcium imaging of dorsal root ganglia (DRG) neurons.

METHODS

Eight BALB/c mice were randomly divided into control and model groups, with 4 mice in each group. The colitis model was induced by colorectal perfusion of 2, 4, 6-trinitrobenzene sulfonic acid (TNBS) once daily for 7 days. Mice of the control group received colorectal perfusion of normal saline once daily for 7 days. The location and area of the somatic neurogenic inflammation (cutaneous exudation of Evans blue ［EB］) of the 2 groups of mice were observed after intravenous injection of EB. For pain behavioral tests, sixteen C57BL/6J mice were randomly divided into control and model groups, with 8 mice in each group, and a Von Frey filament was used to stimulate the referred somatic reactive regions in colitis mice, and the number of avoidance and paw withdraw reaction within 10 tests was recorded. For in vivo DRG calcium imaging tests, 24 Pirt-GCaMP6s transgenic mice were randomly and equally divided into control group and colitis model group. The responses of the neurons in L6 or L4 DRG to colorectal distension (CRD), lower back brushing, or mechanical stimulation at the hindpaw were observed using confocal fluorescence microscope.

RESULTS

Compared with the control group, the area of EB exudation spot in the hindpaw and lower back regions was increased in the colitis model group (P<0.05), and the avoidance or paw withdraw numbers induced by Von Frey stimulation at the lower back and hindpaw were increased (P<0.01, P<0.05), indicating that colitis induced regional skin (acupoints) sensitization in the lower back and hindpaw regions. Compared with the control group, the percentage of L6 DRG neurons activated by 60 mm Hg CRD in the colitis model mice were apparently increased (P<0.01), the activated neurons mainly involved the medium-sized DRG neurons (P<0.01). In Pirt-GCaMP6s transgenic mice, following brushing the skin of the receptive field (lower back) of L6 DRG neurons, the fluorescence intensity of the brushing-activated DRG neurons and small, medium and large-sized neurons were significantly higher in the colitis model group than those in the control group (P<0.001, P<0.01, P<0.05). After brushing and clamping the skin of the right hindpaw (receptive field of L4 DRG neurons), the percentages of the activated L4 DRG neurons were obviously higher in the colitis model group than those in the control group (P<0.01, P<0.05), while there were no significant changes in the proportion of small, medium and large-sized neurons between the control and colitis model groups.

CONCLUSIONS

Colitis may lead to body surface sensitization at the same and adjacent neuro-segments as well as to an increase of the number and activity of the responsive lumbar DRG neurons, among which the L6 DRG neurons at the same neuro-segment as the rectum colon showed an increase in the number of responders and intensity of calcium fluorescence signal while L4 DRG neurons at the level adjacent to the rectum colon showed an increase in the number of responders, suggesting that there may be different mechanisms of peripheral neural sensitization.

[Relationship between acupoint sensitization and changes in dorsal root ganglion neuron excitability in myocardial ischemia mice]

OBJECTIVE

To investigate the relationship between the sensitization state of acupoints on the surface of the myocardial ischemia (MI) model mice and the changes in the electrophysiological properties of the dorsal root ganglion (DRG) neurons in the corresponding spinal cord segment, and its underlying mechanism.

METHODS

Sixty-eight male C57BL/6J mice were randomly divided into control and model groups (34 mice in each group). The model group received an intraperitoneal injection of 160 mg/kg isoproterenol (ISO) to establish the MI model, and the control group received an injection of the same dose of normal saline as the model group. After modeling for about 6 days, MI proportion was measured by HE staining to verify the pathological changes in the heart tissue. Evans blue (EB) dye was injected into the tail vein of mice to reflect the size, location, distribution, and number of exudates on the body surface. Then, whole-cell membrane currents, intrinsic excitability and membrane properties of different types of DRG neurons were evaluated by electrophysiological experiment in vitro.

RESULTS

Compared with the control group, the heart size was larger, with pathological outcomes showing enlarged myocardial hypertrophy, destroyed structure of cardiomyocytes, with mononuclear cell infiltration among the cardiomyocytes in the model group. Compared with the control group, the number of EB exudation points was significantly increased (P<0.01), which were mainly concentrated in the epidermis near the T1-T5 segment of the spinal cord, "Feishu" (BL13), "Jueyinshu" (BL14) and "Xinshu" (BL15) in the model group. Compared with the control group, the rheobase and action potential amplitude (APA) of DRG medium-sized neurons were obviously decreased (P<0.01, P<0.05), while the whole-cell membrane currents, the spike numbers, the average instantaneous frequency, and the average discharge frequency were markedly increased (P<0.01). There were no significant alterations in the membrane properties and intrinsic excitability induced by depolarized currents of small-sized neurons between groups. Compared with the control group, the whole-cell membrane currents, spike numbers, and the average instantaneous frequency were significantly increased in the model group(P<0.05, P<0.01) while rheobase was significantly decreased (P<0.05) in DRG medium-sized neurons labeled with biotin and CGRP.

CONCLUSION

After the mice were modeled by ISO, the DRG medium-size neurons in the T1-T5 segment of the spinal cord may mediate the sensitization of acupoints on the body surface through their different neuronal membrane properties and intrinsic excitabilities.

[Study on the correlation between the thickness of superficial fascia at Dazhui(GV14) and cervical spondylosis]

OBJECTIVE

To observe the correlation between the thickness of superficial fascia at Dazhui (GV14) acupoint and cervical spondylosis, so as to explore the essence of its morphological and structural changes of acupoint sensitivity.

METHODS

A retrospective study was conducted. According to the diagnostic criteria of "Guidelines for Diagnosis, Treatment and Rehabilitation of Cervical Spondylosis" (2017), 344 cases of cervical spine magnetic resonance imaging (MRI) examination were included and divided into control group (73 cases) and observation group (271 cases). The control group was healthy population, and the observation group was patients with cervical spondylosis conforming to the diagnostic criteria, including cervical spondylosis of neck type, cervical spondylosis radiculopathy, cervical spondylotic myelopathy, cervical spondylosis of vertebral artery type, and sympathetic cervical spondylosis. According to MRI images of cervical spine, the structure of GV14 acupoint including skin, superficial fascia layer and aponeurosis ligament layer were measured.

RESULTS

The acupoint depth and the superficial fascia thickness at GV14 in the observation group were (56.6±8.8) mm and (22.8±7.6) mm, the acupoint depth and the superficial fascia thickness at GV14 were (49.8±7.0) mm and (16.6±6.6)mm in the control group, which were significantly greater in the observation group than in the control group (P<0.01). The superficial fascia thickness at GV14 of cervical spondylotic mye-lopathy, cervical spondylosis of neck type and cervical spondylosis radiculopathy in the observation group was (23.8±8.1)mm, (23.0±7.3)mm and (22.6±6.5)mm, the acupoint depth of GV14 was (58.7±8.8)mm, (56.2±9.1)mm and (55.8±6.4)mm, which were significantly thicker than the superficial fascia thickness and the acupoint depth in the control group (P<0.01). In the observation group，the superficial fascia thickness of GV14 of cervical spondylosis myelopathy was significantly thicker than those of sympathetic cervical spondylosis (17.8±8.1) mm and cervical spondylosis of vertebral artery type (19.9±5.9) mm (P<0.01, P<0.05). In the observation group, the depth of GV14 of cervical spondylosis myelopathy was thicker than that of cervical spondylosis of neck type, cervical spondylosis radiculopathy, sympathetic cervical spondylosis and cervical spondylosis of vertebral artery type(P<0.05，P<0.01)； the depth of GV14 of sympathetic cervical spondylosis was thinner than that of cervical spondylosis of neck type and cervical spondylosis radiculopathy (P<0.01).

CONCLUSION

The superficial fascia thickness at GV14 was correlated with cervical spondylosis, and it is also related to cervical spondylotic myelopathy, cervical spondylosis of neck type and cervical spondylosis radiculopathy. The morphological and structural changes of GV14 in the state of cervical spondylosis were mainly the thickness of the superficial fascia.

[Research on mechanisms of acupoint sensitization in gastric ulcer mice from perspective of dorsal root ganglion neuronal excitability]

OBJECTIVE

To investigate the relationship between acupoint sensitization on the body surface and neuronal intrinsic excitability of the medium- and small-size dorsal root ganglion (DRG) neurons from the perspective of ion channel kinetics in mice with gastric ulcer.

METHODS

Male C57BL/6J mice were randomly divided into control (n=32) and model groups (n=34). The gastric ulcer model was established by injection of 60% glacial acetic acid (0.2 mL/100 g) into the gastric wall muscle layer and submucosa near the pylorus in the minor curvature of the stomach. In contrast, the same dose of normal saline was injected in the same way in the control group. Six days after modeling, Evans blue (EB) solution was injected into the mouse's tail vein for observing the number and distribution of the exudation blue spots on the body surface. Histopathological changes of the gastric tissue were observed by H.E. staining. Then, whole-cell membrane currents and intrinsic excitability of medium- and small-size neurons in the spinal T9-T11 DRGs were measured by in vitro electrophysiology combining with biocytin-ABC method.

RESULTS

In the control group, EB exudation blue spots were not obvious, while in the model group, the blue spots on the body surface were densely distributed in the area of spinal T9-T11 segments, the epigastric region, and the skin around "Zhongwan" (CV12) and "Huaroumen" (ST24) regions, and near the surgical incision region. Compared with the control group, the model group had a high level of eosinophilic infiltrates in the submucosa of gastric tissues, severe gastric fossa structure damage, gastric fundus gland dilation and other pathological manifestations. The number of exudation blue spots was proportional to the degree of inflammatory reaction in the stomach. In comparison with the control group, the spike discharges of type II of medium-size DRG neurons in T9-T11 segments were decreased, and the current of whole-cell membrane was increased, basic intensity was decreased (P<0.05), discharge frequency and discharge number were increased (P<0.01,P<0.000 1); while the discharges of type I small-size DRG neurons were decreased, those of type II neurons increased, the whole-cell membrane current was decreased, and discharge frequency and discharge number were decreased (P<0.01, P<0.000 1).

CONCLUSION

Both the medium- and small-size DRG neurons from the spinal T9-T11 segments involve in gastric ulcer-induced acupoint sensitization via their different spike discharge activities. And intrinsic excitability of these DRG neurons can not only dynamically encode the plasticity of acupoint sensitization, but also can help us understand the neural mechanism of acupoint sensitization induced by visceral injury.

[Effect of electroacupuncture on mood and estrogen receptor α expression in mice with polycystic ovary syndrome induced by bisphenol A exposure]

OBJECTIVE

To compare the effect of electroacupuncture (EA) on "Guanyuan" (CV4) or sensitization points in mice with polycystic ovary syndrome (PCOS), so as to explore its mechanisms underlying improvement of PCOS.

METHODS

In the first part of this study, 26 female ICR mice were randomized into control group (8 mice) and model group (18 mice). The PCOS model was established by gavage of bisphenol A (BPA) at a dose of 100 mg/kg, and the control group were gavage of equal volume of corn oil, once daily, 5 days a week for 4 conse-cutive weeks. Evans blue (EB) dye (0.1 mL/10 g) was injected into the caudal vein after modeling. The size, number and distribution of EB exudation points at the skin were observed. In the second part of this study, 32 mice were randomized into control, model, EA-CV4 and EA-sensitization points groups (8 mice in each group). EA (2 Hz, 2 mA) was applied to the sensitization points or CV4 for 20 min, once daily, 5 days a week for 4 conse-cutive weeks. The body weight was measured once a week for 8 consecutive weeks. The behavior changes were evaluated by open field test and elevated plus maze test. H.E. staining was used to observe the histopathologic changes of the ovary tissue. Serum level of estradiol (E2) was measured by ELISA. The expressions of estrogen receptor α (ER-α) in ovarian and uterine tissues were detected by Western blot and immunofluorescence.

RESULTS

(1) In PCOS mice, the EB exudation points were found to overlap the lower abdomen, lumbosacral, chest, back and lower limbs regions, and the number of EB points was significantly more than that of the control group (P<0.01). (2) After the intervention and compared with the control group, the ovaries showed polycystic changes and an increase of atresia follicles with a larger diameter, the activity time in the central area, the total distance of movement, the times of open-arm entries, the duration in open-arm, the serum E2 content and the expression of ER-α in ovarian tissue were significantly decreased (P<0.01, P<0.05), while the mice's body weight and the expression of ER-α in uterine tissue were increased (P<0.05) in the model group. After the intervention and compared with the model group, a small number of normal follicles and corpus luteum were observed under microscope, the activity time in the central area, the total distance of movement, the times of open-arm entries, the duration in open-arm, the serum E2 content and the expression of ER-α in ovarian tissue were significantly increased (P<0.05, P<0.01), while the mice's body weight and the expression of ER-α in uterine tissue was decreased (P<0.05) in both EA-CV4 and EA-sensitization points groups.

CONCLUSION

EA at sensitization points and CV4 can regulate the expression of estrogen and ER-α in PCOS mice, and improve the anxiety like behavior. EB exudation points on the body surface can not only reflect the functional changes of organs, but also treat diseases through body surface stimulation, suggesting a dual role in diagnosis and treatment.

[Roles of nociceptors in acupoint sensitization: recent advances]

Hyperalgesia and functional plasticity are the important components of acupoint sensitization. Reveal of the neuromechanism of acupoint sensitization may play a positive role in promoting the development of acupuncturology in the world. The nociceptors, including Aδ and C subtypes distributing in the acupoint region and target organs, are responsible for the transmission of signals of peripheral noxious stimuli and acupuncture-liking stimulation to the dorsal horns of the spinal cord and supraspinal levels. A previous study reveals that the C type nociceptors are involved in the acupoint sensitization. Recent studies indicate that there exists a subtype of mechanical responsiveness in the C type receptors, named "silent nociceptor" which is awa-kened when diseases occur, being very similar to the dynamic sensitization characteristics of acupoints. Hence, we, in the present review, make a discussion about the role of C-type silent nociceptor in the hyperalgesia and functional plasticity of the sensitized acupoint according to previous studies and recent advances, so as to provide more ideas and opportunities for the investigation on the scientific characteristics of acupoints.

[Association between skin microecology and acupoint sensitization]

The skin microecology interacts with the immune system for a lifetime, and the skin microecology is in dynamic balance in the physiological state. The flora with the same physical and chemical properties on the surface of the skin can maintain a relatively stable state in a certain period of time, and there are dynamic changes of microflora in both physiology and disease state. Combined with the study of the relationship among skin microorganisms, skin diseases and visceral diseases, the relationship between skin microecological changes and visceral pathological state is explored. On this basis, it is proposed that the sensitized acupoint is an abnormal manifestation of the body homeostasis imbalance on the body surface, and the local substance variation on the sensitization acupoint may induce microbial changes. In terms of treatment, moxibustion and other surface treatments that function through immunity may also involve microorganisms.

[Photoacoustic imaging study on spatial structure of microvessels around acupoints in mice with acute myocardial ischemia]

OBJECTIVE

To observe the changes of microvascular structure of acupoints caused by myocardial ischemia, so as to explore the application of photoacoustic imaging technology in the research of acupoint sensitization.

METHODS

Twelve BALB/c mice were randomly divided into normal, sham operation and acute myocardial ischemia (AMI) model groups, with 4 mice in each group. AMI model was established by ligating the left anterior descending coronary artery. Electrocardiogram (ECG) was recorded by physiological signal acquisition system at 12 h and on the 14^th day after modeling, and serum cardiac troponin T (cTnT) and creatine kinase isoenzyme MB (CK-MB) levels were detected by enzyme-linked immunosorbent assay. The microvascular structure changes of acupoints "Feishu"(BL13), "Jueyinshu"(BL14), "Quze"(PC3) and "Chize"(LU5) were observed by photoacoustic imaging technology, and distance (DM), inflection count metric (ICM), sum of angle metric(SOAM)and microvessel density (MVD) were calculated by microvascular quantification algorithm.

RESULTS

Compared with the normal and sham operation groups, the ST segment of ECG was obviously elevated, serum cTnT and CK-MB were significantly increased in AMI model group at 12 h and on the 14^th day after AMI (P<0.01). The ICM of BL14 in AMI model group was significantly decreased on the 14^th day than that on the 7^th day after AMI. Compared with the normal group, the ICM of BL14 was significantly increased in AMI model group on the 7^th day after AMI(P<0.05). There were no significant changes in DM, ICM, SOAM and MVD at other acupoints on the 7^th and 14^th day (P>0.05) among the three groups.

CONCLUSION

The change of ICM may be one of the characteristics of acupoint sensitization and photoacoustic imaging technology can be used to study the structure of acupoint microvessels.

[Acupoint sensitization enhances inhibitory effect of electroacupuncture on jejunum mobility in rats]

OBJECTIVE

To observe the effect difference of electroacupuncture (EA) at the sensitized and non-sensitized acupoint "Tianshu" (ST25) on the motility of jejunum in rats.

METHODS

Male SD rats were randomly divided into blank control, sensitized ST25 (sensitization), and non-sensitized ST25 (non-sensitization) groups (n=16 in each group). The sensitization and non-sensitization were induced by injection of 15% mustard oil (20 μL) and Paraffin oil (20 μL) into the left ST25 area respectively. The rats' behavior reactions were assessed by recording the numbers and duration of licking the local sensitized skin region. At the end of experiments and after regular trans-cardiac perfusion and fixing with 10% neutral formaldehyde, the skin and muscular tissues of the ST25 region (1 cm×1 cm) were taken for H.E. staining to observe the local histopathologic changes. The intestinal motility was detected by recording the contraction pressure waves of jejunum through a small balloon-connected pressure transducer and an amplifier, followed by calculating the ratios of amplitude and frequency of contraction waves between pre- and post-EA stimulation. EA (2 Hz, 0.2-6.0 mA) was applied to the sensitized and non-sensitized ST25 regions for 20 s for comparing their effects on jejunum motility.

RESULTS

Compared with the blank control group, mustard oil injection but not Paraffin oil injection resulted in histological edema and neutrophils infiltration in tissues of ST25 region, and also striking increase of the number and duration of licking (P<0.01), suggesting a sensitization of ST25 area after mustard oil injection. The ratios of spontaneous contraction amplitude and frequency of jejunum were remarkably decreased in mustard oil-treated rats compared to baseline and Paraffin oil group (P<0.001，P<0.01). The maximum inhibitory effect of EA on the intestinal movement amplitude was significantly higher in the sensitization group than in the blank control and non-sensitization groups (P<0.05，P<0.01), and there was a dose-effect relationship between the current intensity of EA (0.5-3.0 mA) and the inhibitory rate 50% of the contraction amplitude (not the frequency) in the sensitization group (P<0.001), but not in the blank control and non-sensitization groups (P>0.05). Additionally, 1.5 mA EA stimulation at the sensitized ST25 (not at the non-sensitized ST25) had an inhibitory effect on the contraction amplitude (P<0.05) rather than on the contraction frequency (P>0.05) in comparison with the blank control group.

CONCLUSION

Sensitization of acupoint ST25 can modulate the motility of jejunum and enhances the inhibitory effect of EA on the contraction amplitude of jejunum in rats. The inhibitory effect of sensitized ST25 EA is evidently stronger than that of the non-sensitized ST25 EA.

[Multivariate statistical analysis of Evans blue exudation spots and acupoint sensitization distribution in rats with acute intestinal mucosal injury]

OBJECTIVE

To observe the distribution characters of Evans Blue (EB) exudation spots in the abdominal area in acute intestinal mucosal injury (AIMI) rats by using latitude and longitude grid counting and multivariate statistical analysis and to explore the feasibility of these methods.

METHODS

Twenty-four SD rats were randomly divided into blank control, 7.5%, 10%, and 12.5% mustard oil groups (n＝6 rats in each group). The AIMI model was established by mustard oil enema, followed by injection of EB (0.1 mL/100g) into the tail vein. At 5, 10, 15, 20 and 25 h after EB injection, the rats under anesthesia were fixed in supine position for observing and photographing the abdominal subcutaneous EB exudation spots. The H．E. staining was used to observe histopathological changes of colonic mucosa. The longitude and latitude grids of the abdominal region were constructed (by taking the midpoint of the superior sternum as the origin) to determine the position of the blue spots. That the coordinate grids of the two regions can be connected geometrically is termed as "characteristic region". The data were processed by using multivariate statistical analysis.

RESULTS

① H．E. staining showed edema and inflammatory cell infiltration after colonic enema of different concentrations of mustard oil. ② Clustering analysis indicated that the distribution of exudation points in the "characteristic grid" had no temporal variation trend, and was not related with the concentration of mustard oil (P>0.05). ③ Factor analysis and contour analysis about the exudation spots of EB at 7.5% concentration showed that the "characteristic region Ⅱ" of different factors presented a tendency of time-dependent exudation, i．e. reduction of exudation degree along with time (P<0.05), and it is located near "Tianshu" acupoint. ④At 5 h after injection of EB, the 8 "characteristic regions" presented an EB-concentration-dependent tendency (reduction in exudation degree along with the increase of EB-concentration), among which the exudation degree of region C (near "Tianshu" acupoint) of the abdomen was higher (P<0.05).

CONCLUSION

The multivariate statistical analysis method can be used to identify the abdominal "characteristic regions" of exudation spots of EB in rats with AIMI, and the characteristic region has acupoint sensitization characteristics related to the time and severity of mucosal injury.

[Myofascial trigger point: an indicator of acupoint sensitization]

OBJECTIVE

The present study is to investigate the characteristic distribution of primary pain points and referred pain areas in patients with knee-joint pain diseases, therefore revealing the correlation between the myofascial trigger point and acupoint sensitization.

METHODS

A total of 483 patients (320 men and 163 women, 36 to 72 years in age) with knee-joint pain recruited from 4 clinical centers were observed from July, 2017 to April, 2019 in the present study. The areas of primary and referred pain in these patients were detected by thumb-pressing and marked on human anatomic atlas.

RESULTS

Of the 483 enrolled participants, 336 had lesion sites or tender points around the injured knee joint, and 147 with myofascial pain syndrome showed referred pain spots (zones) in the knee joint area. In 105 patients with patellar tendonitis, epiphysitis of the tibial tubero-sity, or quadriceps tendonitis, the pain area was mainly distributed in the anterior region of the knee. In 76 patients with medial collateral ligament injury, medial meniscal lesion, goose foot bursitis or semimembranosus ending-point inflammation, the pain points mainly occurred in the medial area of the knee. In 127 patients with lateral collateral ligament, lateral meniscus lesion, iliotibial band tendonitis, popliteus or triceps tendinitis, the pain spots were found in the lateral region of the knee. In 28 patients with posterior cruciate ligament injury or popliteal fossa tendonitis, the local pain was found to be at the back of the knee. Referred pain areas were normally detected in the lateral femoral muscles (43 cases), anterior femoral muscles (39 cases), adductor group of femur (26 cases), posterior popliteal fossa muscles group (15 cases), hamstrings (13 cases) and medial leg (11 cases)．.

CONCLUSION

The primary pain areas or spots of the knee injury mainly distribute around the joint, whereas those of each muscle group lesion are often located in their respective skeletal muscle. Most of the referred pain areas often occur in the distal end of skeletal muscle and around the knee joint. Primary myofascial trigger points may be considered to be an indicator of acupoint sensitization.

[Correlation Between Referred Pain Region and Sensitized Acupoints in Patients with Stable Angina Pectoris and Distribution of Sensitized Spots in Rats with Myocardial Ischemia]

OBJECTIVE

To observe the correlation between the referred pain regions of stable angina pectoris (SAP) and the acupoints in coronary heart disease (CHD) patients and to investigate the rule of regional sensitized point distribution in rats.

METHODS

A total of 1 046 CHD patients with SAP from 8 hospitals in China were recruited in the present study. The tenderness was palpated along the left and right chest, back, shoulder, upper limb, etc. by a specially-assigned researcher in each hospital. Among them, 77 patients accepted pain threshold (PT) measurement by using a hand-held esthesiometer. In animal experiments, 14 SD rats were subjected to occlusion of the left anterior descending branch of the left coronary artery for 4 h for establishing myocardial ischemia (MI) model, and other 4 normal rats were used as the sham-operation control group. Four hours after MI, all the rats accepted tail venous injection of 5% Evans blue (50 mg/kg) for examining the distribution of the blue dye exudation spots at the body surface where the mechanical PT was also detected by a von Frey.

RESULTS

In 1 046 CHD patients, 987 (94.36%) were found to have at least one tenderness spot. The tenderness spots were found at the left chest (87.47%), right chest (13.67%), left arm (ulnar side, 41.30%), right upper limb (4.68%), left shoulder back (30.21%), right shoulder back (7.07%), etc., accompanied with rash or pigmentation, subcutaneous induration, cord-like tissue contracture, skin sag, etc. The mechanical PT level was significantly lower at the tenderness spots of the left upper limb than at non-tender points of the right upper limb in CHD patients (P<0.001). Tenderness and cutaneous abnormal changes in angor pectoris patients distributed mostly on the left chest, back, shoulder and upper limb, and some also on the right. Tender points scattered on, near or outside acupoints. A similar distribution of the blue exudation spots and lower mechanical PT spots were found in MI rats, but not in sham-MI rats.

CONCLUSION

In the case of MI, a regular "referred sensitization" response frequently occurs in the dermatomere area innervated by the corresponding segments (T 1－T 5) in both CHD patients and MI rats, which may be closely associated with the formation of acupoints in ancient China.