Inhibition of phosphorylated calcium/calmodulin-dependent protein kinase IIα relieves streptozotocin-induced diabetic neuropathic pain through regulation of P2X3 receptor in dorsal root ganglia.

Diabetic neuropathic pain (DNP) is frequent among patients with diabetes. We previously showed that P2X3 upregulation in dorsal root ganglia (DRG) plays a role in streptozotocin (STZ)-induced DNP but the underlying mechanism is unclear. Here, a rat model of DNP was established by a single injection of STZ (65 mg/kg). Fasting blood glucose was significantly elevated from the 1st to 3rd week. Paw withdrawal thresholds (PWTs) and paw withdrawal latencies (PWLs) in diabetic rats significantly reduced from the 2nd to 3rd week. Western blot analysis revealed that elevated p-CaMKIIα levels in the DRG of DNP rats were accompanied by pain-associated behaviors while CaMKIIα levels were unchanged. Immunofluorescence revealed significant increase in the proportion of p-CaMKIIα immune positive DRG neurons (stained with NeuN) in the 2nd and 3rd week and p-CaMKIIα was co-expressed with P2X3 in DNP rats. KN93, a CaMKII antagonist, significantly reduce mechanical hyperalgesia and thermal hyperalgesia and these effects varied dose-dependently, and suppressed p-CaMKIIα and P2X3 upregulation in the DRGs of DNP rats. These results revealed that the p-CaMKIIα upregulation in DRG is involved in DNP, which possibly mediated P2X3 upregulation, indicating CaMKIIα may be an effective pharmacological target for DNP management.

Dorsal root ganglia P2X4 and P2X7 receptors contribute to diabetes-induced hyperalgesia and the downregulation of electroacupuncture on P2X4 and P2X7.

Diabetic neuropathic pain (DNP) is highly common in diabetes patients. P2X receptors play critical roles in pain sensitization. We previously showed that elevated P2X3 expression in dorsal root ganglion (DRG) contributes to DNP. However, the role of other P2X receptors in DNP is unclear. Here, we established the DNP model using a single high-dose streptozotocin (STZ) injection and investigated the expression of P2X genes in the DRG. Our data revealed elevated P2X2, P2X4, and P2X7 mRNA levels in DRG of DNP rats. The protein levels of P2X4 and P2X7 in DNP rats increased, but the P2X2 did not change significantly. To study the role of P2X4 and P2X7 in diabetes-induced hyperalgesia, we treated the DNP rats with TNP-ATP (2',3'-O-(2,4,6-trinitrophenyl)-adenosine 5'-triphosphate), a nonspecific P2X1-7 antagonist, and found that TNP-ATP alleviated thermal hyperalgesia in DNP rats. 2 Hz electroacupuncture is analgesic against DNP and could downregulate P2X4 and P2X7 expression in DRG. Our findings indicate that P2X4 and P2X7 in L4-L6 DRGs contribute to diabetes-induced hyperalgesia, and that EA reduces thermal hyperalgesia and the expression of P2X4 and P2X7.

Analgesic effect of electroacupuncture on bone cancer pain in rat model: the role of peripheral P2X3 receptor.

Upregulation of P2X3 receptor (P2X3R) has been strongly implicated in nociceptive signaling including bone cancer pain (BCP). The present study, using rat bone cancer model, aimed to explore the role of P2X3R in regulating rat pain behavior under the intervention of electroacupuncture (EA). The BCP model was successfully established by injection with MRMT-1 breast cancer cell into the medullary cavity of left tibia for 3 × 104 cells/3 µL PBS in rats as revealed by obvious bone destruction, decreased paw withdrawal thresholds (PWTs), and reduced paw withdrawal latencies (PWLs). Western blot analyses showed that P2X3R expression was significantly upregulated in ipsilateral lumbar 4-6 (L4-6) dorsal root ganglia (DRG), but the difference not seen in spinal cord dorsal horn (SCDH). With the in-depth study of P2X3R activation, we observed that intrathecal injection of P2X3R agonist α,ß-meATP aggravated MRMT-1 induced BCP, while injection of P2X3R inhibitor A-317491 alleviated pain. Subsequently, we demonstrated that BCP induced mechanical allodynia and thermal hyperalgesia were attenuated after EA treatment. Under EA treatment, total P2X3R protein expression in ipsilateral DRGs was decreased, and it is worth mentioning that decreased expression of P2X3R membrane protein, which indicated that both the expression and membrane trafficking of P2X3R were inhibited by EA. The immunofluorescence assay showed that EA stimulation exerted functions by reducing the expression of P2X3R-positive cells in ipsilateral DRGs of BCP rats. Ca2+ imaging analysis revealed that the EA stimulation decreased the percentage of α,ß-meATP responsive neurons in DRGs and inhibited calcium influx. Notably, the inhibitory effect of EA on mechanical allodynia and nociceptive flinches was abolished by intrathecal injection of α,ß-meATP. These findings demonstrated EA stimulation ameliorated mechanical allodynia and thermal hyperalgesia in rat model of MRMT-1-induced BCP. EA exerts analgesic effect on BCP by reducing the overexpression and functional activity of P2X3R in ipsilateral DRGs of BCP rats. Our work first demonstrates the critical and overall role of P2X3R in EA's analgesia against peripheral sensitization of MRMT-1-induced BCP and further supports EA as a potential therapeutic option for cancer pain in clinic.

Electroacupuncture may alleviate diabetic neuropathic pain by inhibiting the microglia P2X4R and neuroinflammation.

Diabetic neuropathic pain (DNP) is a common and destructive complication of diabetes mellitus. The discovery of effective therapeutic methods for DNP is vitally imperative because of the lack of effective treatments. Although 2 Hz electroacupuncture (EA) was a successful approach for relieving DNP, the mechanism underlying the effect of EA on DNP is still poorly understood. Here, we established a rat model of DNP that was induced by streptozotocin (STZ) injection. P2X4R was upregulated in the spinal cord after STZ-injection. The upregulation of P2X4R was mainly expressed on activated microglia. Intrathecal injection of a P2X4R antagonist or microglia inhibitor attenuated STZ-induced nociceptive thermal hyperalgesia and reduced the overexpression of brain-derived neurotrophic factor (BDNF), interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF-α) in the spinal cord. We also assessed the effects of EA treatment on the pain hypersensitivities of DNP rats, and further investigated the possible mechanism underlying the analgesic effect of EA. EA relieved the hyperalgesia of DNP. In terms of mechanism, EA reduced the upregulation of P2X4R on activated microglia and decreased BDNF, IL-1ß and TNF-α in the spinal cord. Mechanistic research of EA's analgesic impact would be beneficial in ensuring its prospective therapeutic effect on DNP as well as in extending EA's applicability.

Suppressing PKC-dependent membrane P2X3 receptor upregulation in dorsal root ganglia mediated electroacupuncture analgesia in rat painful diabetic neuropathy.

Painful diabetic neuropathy (PDN) is a common and troublesome diabetes complication. Protein kinase C (PKC)-mediated dorsal root ganglia (DRG) P2X3 receptor upregulation is one important mechanism underlying PDN. Accumulating evidence demonstrated that electroacupuncture (EA) at low frequency could effectively attenuate neuropathic pain. Our previous study showed that 2-Hz EA could relieve pain well in PDN. The study aimed to investigate whether 2-Hz EA relieves pain in PDN through suppressing PKC-mediated DRG P2X3 receptor upregulation. A 7-week feeding of high-fat and high-sugar diet plus a single injection of streptozotocin (STZ) in a dose of 35 mg/kg after a 5-week feeding of the diet successfully induced type 2 PDN in rats as revealed by the elevated body weight, fasting blood glucose, fasting insulin and insulin resistance, and the reduced paw withdrawal threshold (PWT), as well as the destructive ultrastructural change of sciatic nerve. DRG plasma membrane P2X3 receptor level and DRG PKC expression were elevated. Two-hertz EA failed to improve peripheral neuropathy; however, it reduced PWT, DRG plasma membrane P2X3 receptor level, and DRG PKC expression in PDN rats. Intraperitoneal administration of P2X3 receptor agonist αß-meATP or PKC activator phorbol 12-myristate 13-acetate (PMA) blocked 2-Hz EA analgesia. Furthermore, PMA administration increased DRG plasma membrane P2X3 receptor level in PDN rats subject to 2-Hz EA treatment. These findings together indicated that the analgesic effect of EA in PDN is mediated by suppressing PKC-dependent membrane P2X3 upregulation in DRG. EA at low frequency is a valuable approach for PDN control.

Effect of Electroacupuncture on the NTS is modulated primarily by acupuncture point selection and stimulation frequency in normal rats.

BACKGROUND: The effect of electroacupuncture (EA) is affected by both the acupuncture point selection and the frequency of stimulation. However, little is known regarding acupuncture point and simulation frequency selection. Neuronal activation of the nucleus of the solitary tract (NTS) is one of the important targets of EA for modulating gastrointestinal function. This study investigated the effects of various combinations of EA frequencies and acupuncture points on NTS neurons. METHODS: Rats were randomly divided into normal, 2 Hz EA, 100 Hz EA and the alternate 2/100 Hz EA groups. Then rats in each group were randomly divided into the following two subgroups according to the acupuncture point: ST 36 group and ST 25 group. All the rats underwent electrode implantation surgery. Rats in all EA groups received one treatment with EA (a constant square wave at, 2 Hz,100 Hz or 2/100 Hz frequencies with intensities ranging from 1 to 2 mA), and NTS neuronal activation was recorded before and after EA treatment. Finally, to confirm the effect of EA on the NTS, minimal acupuncture was administered and its effect on NTS was detected. RESULTS: ST 36 stimulated with 2 Hz EA significantly increased the population of excited NTS neurons and spike frequency. However, ST 36 stimulated with 100 Hz or 2/100 Hz EA produced only a transient effect on the activity of NTS neurons and did not induce any effect on the spike frequency. Furthermore, the excitatory effect of 100 Hz or 2/100 Hz EA on NTS neurons in the ST 36 group was lower than 2 Hz EA at the same point. When applied to ST 25, 2 Hz EA had no significant excitatory effect on NTS neurons or spike frequency. However, 100 Hz EA or 2/100 Hz EA at ST 25 decreased both NTS neuronal excitability and spike frequency. By comparing the effects of different EA combinations, it was shown 2 Hz EA applied to ST 36 had the strongest excitatory effect on NTS neurons, while 100 Hz EA applied to ST 25 had the greatest inhibitory effect. Minimal acupuncture stimulation produced no effect on NTS neurons. CONCLUSION: EA's effects on NTS were mainly affected by the acupuncture point selection, but the frequency of EA also played a role. Different combinations of acupuncture points and frequency selection may lead to different EA effects on NTS neuronal excitability.

Inhibition of the cAMP/PKA/CREB Pathway Contributes to the Analgesic Effects of Electroacupuncture in the Anterior Cingulate Cortex in a Rat Pain Memory Model.

Pain memory is considered as endopathic factor underlying stubborn chronic pain. Our previous study demonstrated that electroacupuncture (EA) can alleviate retrieval of pain memory. This study was designed to observe the different effects between EA and indomethacin (a kind of nonsteroid anti-inflammatory drugs, NSAIDs) in a rat pain memory model. To explore the critical role of protein kinase A (PKA) in pain memory, a PKA inhibitor was microinjected into anterior cingulate cortex (ACC) in model rats. We further investigated the roles of the cyclic adenosine monophosphate (cAMP), PKA, cAMP response element-binding protein (CREB), and cAMP/PKA/CREB pathway in pain memory to explore the potential molecular mechanism. The results showed that EA alleviates the retrieval of pain memory while indomethacin failed. Intra-ACC microinjection of a PKA inhibitor blocked the occurrence of pain memory. EA reduced the activation of cAMP, PKA, and CREB and the coexpression levels of cAMP/PKA and PKA/CREB in the ACC of pain memory model rats, but indomethacin failed. The present findings identified a critical role of PKA in ACC in retrieval of pain memory. We propose that the proper mechanism of EA on pain memory is possibly due to the partial inhibition of cAMP/PKA/CREB signaling pathway by EA.

[Analgesic Effect and Mechanism of Electroacupuncture on Rats with Chronic Inflammatory Pain].

OBJECTIVE: To observe analgesic effect of electroacupuncture ( EA) on rats with chronic inflammatory pain and its regulatory mechanism on ispilateral dorsal root ganglion (DRG) and spinal dorsal horn (SDH) Mas-related G protein-coupled C receptor (MrgprC). METHODS: Totally 40 healthy male SD rats were divided into 4 groups according to random number table, i.e., the normal (N) group, the model (M) group, the acupuncture (Acu) group, the EA group, 10 rats in each group. The model of chronic inflammatory pain was established by subcutaneous injecting 0. 1 mL complete Freund's adjuvant (CFA) into right hind paw. Paw withdrawal thresholds (PWTs) were measured before modeling, at day 1, 3, 5, 7, and after CFA injection, respectively. Expression levels of MrgprC in ispilateral DRG and SDH were detected by Western blot. The content of bovine adrenal medulla 22 (BAM22) in SDH was detected by immunohistochemical assay. RESULTS: Compared with N group at each time point, PWTs significantly decreased in M group (P <0. 01). Compared with M group, PWTs significantly increased at day 5 of EA and after EA in EA group (P < 0.05, P < 0.01). Compared with Acu group at each time point, post-EA PWTs significantly increased in the EA group (P < 0.05). Compared with N group, expression of MrgprC in ispilateral DRG and ratio of BAM22 positive cells in ispilateral SDH increased in M group (P < 0.01). Compared with M group, expression of MrgprC in ispilateral DRG and ratio of BAM22 positive cells in ispilateral SDH increased in the EA group (P < 0.05). CONCLUSION: EA had favorable analgesic effect on chronic inflammatory pain induced by CFA, and its mechanism might be possibly associated with up-regulating MrgprC expression in ispilateral DRG and BAM22 content in ispilateral SDH.

Electroacupuncture alleviates retrieval of pain memory and its effect on phosphorylation of cAMP response element-binding protein in anterior cingulate cortex in rats.

BACKGROUND: Recent evidence suggests that persistent pain and recurrent pain are due to the pain memory which is related to the phosphorylation of cAMP response element-binding protein (p-CREB) in anterior cingulate cortex (ACC). Eletroacupuncture (EA), as a complementary Chinese medical procedure, has a significant impact on the treatment of pain and is now considered as a mind-body therapy. METHODS: The rat model of pain memory was induced by two injections of carrageenan into the paws, which was administered separately by a 14-day interval, and treated with EA therapy. The paw withdrawal thresholds (PWTs) of animals were measured and p-CREB expressions in ACC were detected by using immunofluorescence (IF) and electrophoretic mobility shift assay (EMSA). Statistical comparisons among different groups were made by one-way, repeated-measures analysis of variance (ANOVA). RESULTS: The second injection of carrageenan caused the decrease of PWTs in the non-injected hind paw. EA stimulation applied prior to the second injection, increased the values of PWTs. In ACC, the numbers of p-CREB positive cells were significantly increased in pain memory model rats, which were significantly reduced by EA. EMSA results showed EA also down-regulated the combining capacity of p-CREB with its DNA. Furthermore, the co-expression of p-CREB with GFAP, OX-42, or NeuN in ACC was strengthened in the pain memory model rats. EA inhibited the co-expression of p-CREB with GFAP or OX-42, but not NeuN in ACC. CONCLUSIONS: The present results suggest the retrieval of pain memory could be alleviated by the pre-treatment of EA, which is at least partially attributed to the down-regulated expression and combining capacity of p-CREB and the decreased expression of p-CREB in astrocytes and microglia cells.

[Gastric dynamics analysis of TEAS combined SNP induced general anesthesia when controlled hypotension dropped to 60% of the MAP baseline].

OBJECTIVE: To observe the effect of gastric dynamics by transcutaneous electrical acupoint stimulation (TEAS) combined general anesthesia when controlled hypotension dropped to 60% of the mean arterial prenssure (MAP) baseline, and to provide experimental evidence for organ protection in clinical controlled hypotension. METHODS: Eighteen male beagles were randomly divided into three groups, the general anesthesia group (blank), the general anesthesia induced controlled hypotension group (control), and the general anesthesia combined TEAS induced controlled hypotension group (experiment), 6 in each group. Controlled hypotension was performed in the latter two groups with isoflurane inhalation and intravenous injection of sodium nitroprusside (SNP). The mean arterial pressure (MAP) was lowered to 60% of the MAP baseline and kept for 60 min. Controlled hypotension was not performed in Beagles of the control group. For Beagles in the experiment group, TEAS [2/100 Hz, (4 ± 1) mA] was applied to bilateral Hegu (LI4), Quchi (LI11), Zusanli (ST36), and Sanyinjiao (SP6) from stable physiological conditions to the end of maintaining stages. Changes of EGG frequencies and EGG amplitudes were monitored. Serum levels of gastrin (GAS) and motilin (MTL) were also detected at corresponding time points during and after experiment. RESULTS: As for the pressure control effect of TEAS combined general anesthesia in the controlled hypotension, during the process of controlled hypotension (T1-T4), MAP levels of two controlled pressure groups remained relatively stable, and were kept at 60% of the MAP baseline. When the blood pressure dropped to the target low MAP and maintained at 60 min (T1-T4), EGG amplitudes of Beagles in all the three groups showed decreasing tendency. But it was more obviously lower than its basic level in the control group (P <0.05), while it was not obviously decreased in the experiment group (P < 0.05). EGG frequencies of Beagles in all the three groups showed no obvious change during this stage. By the end of the MAP rising stage (T8), the EGG amplitude of the experimental group was significantly higher than that of the control group and the blank group (P < 0.05), while it didn' t show any obvious increase in the control group. During this period, EGG frequencies of the two controlled hypotension groups decreased more than those of the blank group. Two h after rising blood pressure (at T9), EGG amplitudes and frequencies in the two controlled hypotension groups basically restored to their respective baselines and levels of the blank group at T9. At 2 h (T9) after controlled hypotension, serum levels of GAS and MTL were lower than those of basic levels in the two controlled hypotension groups (P <0.05). However, serum levels of GAS and MTL had an increasing trend in the two controlled hypotension groups at 24-72 h (T10-T12). Besides, the increasing speed and amplitude was better in experiment group than in the control group at T10-T12. However, there was no statistical difference between the two groups (P > 0.05). At 72 h (T12) serum levels of GAS and MTL had basically restored to their basic levels in the two controlled hypotension groups and that of the blank control group. CONCLUSION: EGG amplitudes could be effectively improved in TEAS combined general anesthesia for controlled hypotension at 60% of the MAP baseline, the recovery of the serum GAS level accelerated, gastric power improved and stomach protected.

Electroacupuncture mediates extracellular signal-regulated kinase 1/2 pathways in the spinal cord of rats with inflammatory pain.

BACKGROUND: Activation of extracellular signal-regulated kinase1/2 (ERK1/2) in dorsal horn of the spinal cord by peripheral inflammation is contributed to inflammatory pain hypersensitivity. Although electroacupuncture (EA) has been widely used to alleviate various kinds of pain, the underlying mechanism of EA analgesia requires further investigation. This study investigated the relationship between EA-induced analgesia and ERK signaling involved in pain hypersensitivity. METHODS: The rats were randomly divided into control, model, EA and sham EA groups. Inflammatory pain model was induced by injecting of 100 µl Complete Freund's adjuvant (CFA) into the plantar surface of a hind paw. Rats in the EA group were treatment with EA (constant aquare wave, 2 Hz and 100 Hz alternating frequencies, intensities ranging from 1-2 mA) at 5.5 h, 24.5 h and 48.5 h. Paw withdrawal thresholds (PWTs) were measured before modeling and at 5 h, 6 h, 25 h and 49 h after CFA injection. Rats were killed and ipsilateral side of the lumbar spinal cords were harvested for detecting the expressions of p-ERK1/2, Elk1, COX-2, NK-1 and CREB by immunohistochemistry, real-time PCR, western blot analysis and EMSA. Finally, the analgesic effect of EA plus U0126, a MEK (ERK kinase) inhibitor, on CFA rats was examined. RESULTS: Inflammatory pain was induced in rats by hindpaw injection of CFA and significantly increased phospho-ERK1/2 positive cells and protein levels of p-ERK1/2 in the ipsilateral spinal cord dorsal horn (SCDH). CFA up-regulated of cyclooxygenase-2 (COX-2) mRNA and protein expression at 6 h after injection and neurokinin-1 receptor (NK-1) expression at 49 h post-injection, in the SCDH. EA, applied to Zusanli (ST36) and Kunlun (BL60), remarkably increased the pain thresholds of CFA injected rats, significantly suppressed ERK1/2 activation and COX-2 protein expression after a single treatment, and decreased NK-1 mRNA and protein expression at 49 h. EA decreased the DNA binding activity of cAMP response element binding protein (CREB), a downstream transcription factor of ERK1/2, at 49 h after CFA injection. Moreover, EA and U0126 synergistically inhibited CFA-induced allodynia. CONCLUSIONS: The present study suggests that EA produces analgesic effect by preventing the activation of ERK1/2-COX-2 pathway and ERK1/2-CREB-NK-1 pathway in CFA rats.

Different Acupuncture Therapies for Postherpetic Neuralgia: An Overview of Systematic Reviews and Meta-analysis.

BACKGROUND: Postherpetic neuralgia (PHN) is the most common complication of herpes zoster infection and affects patients' quality of life. Acupuncture therapy is regarded as a competitive method of treatment for analgesia. OBJECTIVE: To summarize evidence from systematic reviews (SRs) and evaluate the effectiveness and safety of different acupuncture therapies for treating PHN. METHODS: Eight electronic databases were searched from their inception to August 5, 2022, including 4 international electronic databases (PubMed, EMBASE, the Cochrane Library, and Web of Science) and 4 Chinese databases (Chinese Biomedical Database, China National Knowledge Infrastructure, VIP Database and Wanfang Database). Methodological quality was assessed by A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2). The Risk of Bias in Systematic Review (ROBIS) tool was used to assess the risk of bias in SRs. Evidence level was assessed by the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. RESULTS: Totally, 7 SRs were included, including 128 studies and 9,792 patients. In AMSTAR 2, most of the SRs were of low or critically low levels since they had more than 1 critical deficiency. In ROBIS, 1 SR (14.29%) was rated as high risk, and the other 6 (85.71%) were rated as low risk. In the GRADE system, 9 outcomes (28.13%) were valued as high level, 5 (15.63%) as moderate level, 1 (3.13%) as low, and 17 (53.13%) as very low. In the effectiveness of acupuncture therapy, the group "moxibustion vs. original medical treatment" [mean difference (MD)=-1.44, 95% confidence interval (CI): -1.80 to -1.08, I2=99%, P<0.00001] was of the highest heterogeneity and the group "bloodletting vs. original medical treatment" (MD=-2.80, 95% CI: -3.14 to -2.46, I2=0, P<0.00001) was of the lowest heterogeneity. Six SRs have reported the safety of their studies and no serious events were shown in the treatment and control groups. CONCLUSIONS: Acupuncture therapy seems to be effective in treating PHN. Despite the evidence that suggested the advantages of acupuncture therapy in relieving pain and promoting efficacy and safety, the methodological quality was quite low. Further studies should pay more attention to the quality of original studies and evidence for SRs to confirm these findings. (PROSPERO registration No. CRD42022344790).

Intervention of electroacupuncture on spinal p38 MAPK/ATF-2/VR-1 pathway in treating inflammatory pain induced by CFA in rats.

BACKGROUND: Previous studies have demonstrated that p38 MAPK signal transduction pathway plays an important role in the development and maintenance of inflammatory pain. Electroacupuncture (EA) can suppress the inflammatory pain. However, the relationship between EA effect and p38 MAPK signal transduction pathway in inflammatory pain remains poorly understood. It is our hypothesis that p38 MAPK/ATF-2/VR-1 and/or p38 MAPK/ATF-2/COX-2 signal transduction pathway should be activated by inflammatory pain in CFA-injected model. Meanwhile, EA may inhibit the activation of p38 MAPK signal transduction pathway. The present study aims to investigate that anti-inflammatory and analgesic effect of EA and its intervention on the p38 MAPK signal transduction pathway in a rat model of inflammatory pain. RESULTS: EA had a pronounced anti-inflammatory and analgesic effect on CFA-induced chronic inflammatory pain in rats. EA could quickly raise CFA-rat's paw withdrawal thresholds (PWTs) and maintain good and long analgesic effect, while it subdued the ankle swelling of CFA rats only at postinjection day 14. EA could down-regulate the protein expressions of p-p38 MAPK and p-ATF-2, reduced the numbers of p-p38 MAPK-IR cells and p-ATF-2-IR cells in spinal dorsal horn in CFA rats, inhibited the expressions of both protein and mRNA of VR-1, but had no effect on the COX-2 mRNA expression. CONCLUSIONS: The present study indicates that inhibiting the activation of spinal p38 MAPK/ATF-2/VR-1 pathway may be one of the main mechanisms via central signal transduction pathway in the process of anti-inflammatory pain by EA in CFA rats.

Transcutaneous electrical nerve stimulation attenuates CFA-induced hyperalgesia and inhibits spinal ERK1/2-COX-2 pathway activation in rats.

BACKGROUND: Transcutaneous electrical nerve stimulation (TENS) is a non-pharmacologic treatment for pain relief. In previous animal studies, TENS effectively alleviated Complete Freund's Adjuvant (CFA)- or carrageenan-induced inflammatory pain. Although TENS is known to produce analgesia via opioid activation in the brain and at the spinal level, few reports have investigated the signal transduction pathways mediated by TENS. Prior studies have verified the importance of the activation of extracellular signal-regulated kinase (ERK) signal transduction pathway in the spinal cord dorsal horn (SCDH) in acute and persistent inflammatory pains. Here, by using CFA rat model, we tested the efficacy of TENS on inhibiting the expressions of p-ERK1/2 and of its downstream cyclooxygenase-2 (COX-2) and the level of prostaglandin E2 (PGE2) at spinal level. METHODS: Rats were randomly divided into control, model and TENS groups, and injected subcutaneously with 100 µl CFA or saline in the plantar surface of right hind paw. Rats in the TENS group were treated with TENS (constant aquare wave, 2 Hz and 100 Hz alternating frequencies, intensities ranging from 1 to 2 mA, lasting for 30 min each time) at 5 h and 24 h after injection. Paw withdrawal thresholds (PWTs) were measured with dynamic plantar aesthesiometer at 3d before modeling and 5 h, 6 h, and 25 h after CFA injection. The ipsilateral sides of the lumbar spinal cord dosral horns were harvested for detecting the expressions of p-ERK1/2 and COX-2 by western blot analysis and qPCR, and PGE2 by ELISA. RESULTS: CFA-induced periphery inflammation decreased PWTs and increased paw volume of rats. TENS treatment significantly alleviated mechanical hyperalgesia caused by CFA. However, no anti-inflammatory effect of TENS was observed. Expression of p-ERK1/2 protein and COX-2 mRNA was significantly up-regualted at 5 h and 6 h after CFA injection, while COX-2 and PGE2 protein level only increased at 6 h after modeling. Furthermore, the high expression of p-ERK1/2 and COX-2, and over-production of PGE2 induced by CFA, were suppressed by TENS administration. CONCLUSIONS: TENS may be an effective therapy in controlling inflammatory pain induced by CFA. Its analgesic effect may be associated with the inhibition of activation of the spinal ERK1/2-COX-2 pathway.

[Effect of electroacupuncture on phosphorylation of NR2B at Tyr 1742 site in the spinal dorsal horn of CFA rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) on phosphorylation of spinal NR2B at Tyr 1742 site in complete Freund's adjuvant (CFA) induced inflammatory pain rats. METHods Forty male Sprague Dawley rats were randomly divided into normal group (N group, n = 10), the model group (CFA group, n = 15), and the EA group (n = 15). The inflammatory pain model was established by subcutaneous injecting CFA (0.1 mL per rat) into the right hind paw. Paw withdrawal thresholds (PWTs) were measured before CFA injection (as the base), as well as at 24 h, 25 h, 3rd day, and 7th day after CFA injection. Phosphorylation of NR2B at Tyr 1742 site in the ispilateral spinal dorsal horn at the 3rd day post-injection were detected using immunohistochemical assay. RESULTS: PWTs in the CFA group were significantly lower than those of the N group at every detective time point post-injection (P < 0.01). PWTs were obviously lower in the EA group than in the N group at 24 h post-injection (P < 0.01). It showed increasing tendency, markedly higher than those of the CFA group at 25 h and 3rd day post-injection (P < 0.01). Compared with the N group, the ratio of p-NR2B positive cells in the ispilateral spinal dorsal horn of rats in the CFA group was up-regulated. Compared with the CFA group, the ratio of p-NR2B positive cells in the ispilateral spinal dorsal horn of rats showed a decreasing tendency in the EA group. CONCLUSION: EA might effectively inhibit CFA-induced inflammatory pain possibly associated with down-regulating phosphorylation of NR2B at Tyr 1742 site in the ispilateral spinal dorsal horn.

[Efficacy of preventing postoperative nausea and vomiting after thyroid tumor surgery by TAES at neiguan (P1): a clinical observation].

OBJECTIVE: To observe the clinical efficacy of transcutaneous acupoint electrical stimulation (TAES) combined intravenous injection and/or Neiguan (P6) injection with droperidol in preventing and treating post-operative nausea and vomiting (PONV) after thyroid tumor surgery. METHODS: Recruited were 120 female patients who underwent selective thyroid tumor surgery were randomly assigned to the control group, the TAES group, the IV group (intravenous injection of droperidol), and the P6 group [Neiguan point (P6) injection of droperidol], respectively, 30 cases in each group. Thirty min before anesthesia induction, 2 mL 0.9% normal saline injection was intravenously injected to those in the control group. Patients in the TAES group received TEAS at bilateral P6 points. 2.5 mg (1 mL) droperidol added in 1 mL 0.9 normal saline was intravenously injected to those in the IV group and injected at bilateral P6 points of those in the P6 group. The occurrence and severity of PONV were observed within 0 - 6 h and within 6 - 24 h after operation in each group. RESULTS: Compared with the control group, the incidence and the severity of PONV within 0 - 6 h and within 6 - 24 h after thyroid surgery were significantly reduced in the three treatment groups (P < 0.05). There was no statistical difference in the incidence or the severity of PONV among the TAES, IV and P6 groups (P > 0.05). CONCLUSIONS: TEAS at P6 could dramatically reduce the occurrence and the severity of PONV after thyroid tumor surgery. Besides, it got equivalent effect to that by intravenous injecting droperidol or by injecting droperidol at P6.

[Enhancing the training of translational researchers is the essential way to accelerate the translational medicine of acupuncture and moxibustion].

Talent team construction is the foundation of translational medicine research of acupuncture and moxibustion. In college education and continuing education after graduation, with the idea of translational medicine, it is necessary to cultivate both the ability of basic research and clinical skills for the students of traditional Chinese medicine, especially those majored in acupuncture and moxibustion, as well as train the acupuncture-moxibustion researchers who qualified with medical practitioner to contact with clinical practice, discover clinical scientific problems and research priorities, and engage in basic research at the same time. Acupuncture-moxibustion practitioners with higher education should be trained to be able to engage in basic and development researches on the premise of improving their clinical ability, so as to cultivate more translational research talents, build translational research team, and promote the pace of research and application of acupuncture-moxibustion translational medicine.

Electroacupuncture Alleviates Diabetic Neuropathic Pain and Downregulates p-PKC and TRPV1 in Dorsal Root Ganglions and Spinal Cord Dorsal Horn.

Diabetic neuropathic pain (DNP) is a common complication of diabetes. Streptozotocin (STZ)-induced changes of protein in dorsal root ganglion (DRG) and spinal cord dorsal horn (SCDH) are critical for DNP genesis. However, which proteins change remains elusive. Here, the DNP model was established by a single intraperitoneal injection of STZ, accompanied by increased fasting blood glucose (FBG), decreased body weight (BW), and decreased paw withdrawal latency (PWL). Proteins change in L4-L6 DRGs and SCDH of rats were detected. Western blot and immunofluorescence results showed that expression levels of phosphorylated protein kinase C (p-PKC), transient receptor potential vanilloid-1 (TRPV1), Substance P (SP) and calcitonin gene-related peptide (CGRP) in the DRG and the SCDH of rats were increased after STZ injection. A preliminary study from our previous study showed that 2 Hz electroacupuncture (EA) effectively alleviates DNP. However, the analgesic mechanism of EA needs further elucidation. Here, EA at the bilateral Zusanli (ST36) and KunLun (BL60) acupoints was applied for one week, and to investigate the effect on DNP. EA reversed thermal hyperalgesia in DNP rats and downregulated the expression of p-PKC, TRPV1, SP, and CGRP in DRG and SCDH.

Transcutaneous electrical acupoint stimulation in adult patients receiving gastrectomy/colorectal resection: A randomized controlled trial.

BACKGROUND: Acupuncture promotes the recovery of gastrointestinal function and provides analgesia after major abdominal surgery. The effects of transcutaneous electrical acupoint stimulation (TEAS) remain unclear. AIM: To explore the potential effects of TEAS on the recovery of gastrointestinal function after gastrectomy and colorectal resection. METHODS: Patients scheduled for gastrectomy or colorectal resection were randomized at a 2:3:3:2 ratio to receive: (1) TEAS at maximum tolerable current for 30 min immediately prior to anesthesia induction and for the entire duration of surgery, plus two 30-min daily sessions for 3 consecutive days after surgery (perioperative TEAS group); (2) Preoperative and intraoperative TEAS only; (3) Preoperative and postoperative TEAS only; or (4) Sham stimulation. The primary outcome was the time from the end of surgery to the first bowel sound. RESULTS: In total, 441 patients were randomized; 405 patients (58.4 ± 10.2 years of age; 247 males) received the planned surgery. The time to the first bowel sounds did not differ among the four groups (P = 0.90; log-rank test). On postoperative day 1, the rest pain scores differed significantly among the four groups (P = 0.04; Kruskal-Wallis test). Post hoc comparison using the Bonferroni test showed lower pain scores in the perioperative TEAS group (1.4 ± 1.2) than in the sham stimulation group (1.7 ± 1.1; P = 0.04). Surgical complications did not differ among the four groups. CONCLUSION: TEAS provided analgesic effects in adult patients undergoing major abdominal surgery, and it can be added to clinical practice as a means of accelerating postoperative rehabilitation of these patients.

Effect of Electroacupuncture on Activation of p38MAPK in Spinal Dorsal Horn in Rats with Complete Freund's Adjuvant-Induced Inflammatory Pain.

Activation of mitogen-activated protein kinases (MAPKs), especially p38 MAPK, plays an important role in the development of central sensitization related to persistent inflammatory pain. Electroacupuncture (EA) is well known to relieve persistent inflammatory pain. However, little is known about relationship between EA and p38 MAPK. Inflammatory pain rat model was induced by intraplantar injection of complete Freund's adjuvant (CFA). Male adult SD rats were randomly divided into the saline group, CFA group, and CFA + EA group. EA (constant saquare wave, 2 Hz and 100 Hz alternating frequencies, intensities ranging from 1 to 2 mA) was applied to bilateral "Zusanli" (ST 36) and "Kunlun" acupoints (BL 60) for 30 min, once per day. The paw edema and paw withdrawal threshold (PWT) were measured at preinjection and days postinjection 1, 3, and 14. Spinal p-p38MAPK- immunoreactivty (p-p38MAPK-IR) cells were detected by immunohistochemistry at postinjection day 3 and 14. EA significantly inhibited paw edema at postinjection days 14 and increased PWT at postinjection days 3 and 14. Moreover, the increasing number of spinal p-p38MAPK-IR cells which was induced by CFA injection was suppressed by EA stimulation. These results indicate that anti-inflammatory and analgesic effect of EA might be associated with its inhibition of spinal p38 MAPK activation and thereby provide a potential mechanism for the treatment of inflammatory pain by EA.