ABSTRACT
BACKGROUND: G protein coupled receptor kinase 2 (GRK2) has been demonstrated to play a crucial role in the development of chronic pain. Acupuncture is an alternative therapy widely used for pain management. In this study, we investigated the role of spinal neuronal GRK2 in electroacupuncture (EA) analgesia. METHODS: The mice model of inflammatory pain was built by subcutaneous injection of Complete Freund's Adjuvant (CFA) into the plantar surface of the hind paws. The mechanical allodynia of mice was examined by von Frey test. The mice were subjected to EA treatment (BL60 and ST36 acupuncture points) for 1 week. Overexpression and down-regulation of spinal neuronal GRK2 were achieved by intraspinal injection of adeno associated virus (AAV) containing neuron-specific promoters, and microglial activation and neuroinflammation were evaluated by real-time PCR. RESULTS: Intraplantar injection with CFA in mice induced the decrease of GRK2 and microglial activation along with neuroinflammation in spinal cord. EA treatment increased the spinal GRK2, reduced neuroinflammation, and significantly decreased CFA-induced mechanical allodynia. The effects of EA were markedly weakened by non-cell-specific downregulation of spinal GRK2. Further, intraspinal injection of AAV containing neuron-specific promoters specifically downregulated neuronal GRK2, and weakened the regulatory effect of EA on CFA-induced mechanical allodynia and microglial activation. Meanwhile, overexpression of spinal neuronal GRK2 decreased mechanical allodynia. All these indicated that the neuronal GRK2 mediated microglial activation and neuroinflammation, and subsequently contributed to CFA-induced inflammatory pain. CONCLUSION: The restoration of the spinal GRK2 and subsequent suppression of microglial activation and neuroinflammation might be an important mechanism for EA analgesia. Our findings further suggested that the spinal GRK2, especially neuronal GRK2, might be the potential target for EA analgesia and pain management, and we provided a new experimental basis for the EA treatment of pain.
Subject(s)
Animals , Mice , Electroacupuncture , Microglia/physiology , G-Protein-Coupled Receptor Kinase 2/physiology , Pain Management , Pain/chemically induced , Inflammation/chemically induced , Inflammation/therapy , NeuronsABSTRACT
OBJECTIVE: To observe the effect of bone-edge electroacupuncture (EA) intervention on mechanical pain threshold (PT) and expression of G protein-coupled receptor kinase (GRK5), β-arrestin 2, total and phosphorylated PKC alpha (p-PKCα) proteins in the locus coeruleus (LC) of rats with bone cancer pain induced morphine tolerance, so as to reveal its partial central mechanisms underlying pain relief. METHODS: Forty SD rats were randomly divided into 5 groups, namely sham bone cancer, bone cancer pain, morphine tolerance, bone-edge EA, and sham EA (n＝ 8 rats in each group). The bone cancer with morphine tolerance model was established by intramedullary injection of MRMT-1 cells into the tibial cavity, and then intraperitoneal injection of morphine hydrochloride injection. After successful establishment of morphine tolerance model, the bone-edge EA (2 Hz/100 Hz，0.5－1.5 mA) was applied to bilateral "Zusanli" (ST36) and "Kunlun" (BL60) for 30 min, once a day for 7 days, after inserting the needle-tip to the tibial bone surface. The ipsilateral mechanical paw withdrawal thresholds (PWTs) were detected dynamically. The expression levels of GRK5, β-arrestin 2, PKCα and p-PKCα in the LC area were measured by Western blot. RESULTS: The PWTs of bone cancer pain rats were decreased on day 10 after inoculation of cancer cells (P0.05). The PWTs were significantly increased in the bone-edge EA intervention group (P0.05). In comparison with the sham bone cancer group, the expression of GRK5 protein in morphine tolerance group was significantly decreased (P<0.01); compared with morphine tolerance group, the expression of GRK5 protein in bone-edge EA group was increased(P<0.01). In comparison with the sham bone cancer group, the expression of β-arrestin 2 and p-PKCα in bone cancer group significantly increased (P<0.01). After the intervention, the increased β-arrestin 2 and p-PKCα expressions were reversed in the bone-edge EA group (P<0.01); compared with morphine tolerance group and sham EA group, the expression of PKCα protein was decreased(P<0.01). CONCLUSION: Bone-edge EA can effectively relieve morphine tolerance in bone cancer pain rats, which may be related to its functions in up-regulating GRK5 protein and down-regulating β-arrestin 2, PKCα and p-PKCα proteins in LC. .
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OBJECTIVE: To investigate the effect of electroacupuncture (EA) on pain behaviors and expression of spinal transcription factor GATA-binding Protein 4 (GATA4) and adenosine A1 receptor in neuropathic pain rats, so as to explore its mechanism underlying pain relief. METHODS: The present study includes 2 parts. In the first part, 18 SD rats were randomly divided into control, adenovirus short-hairpin interference RNA for GATA4 (AV-shGATA4 RNA) and adenovirus empty vector (AV-control short-hairpin RNA, AV-shCTRL) groups, with 6 rats in each group. The expression of GATA4 protein in the lumbar spinal cord (L4-L6) was detected to evaluate the transfection efficiency of AV-shGATA4 RNA (silencing GATA4 expression). In the second part, thirty SD rats were randomly divided into 5 groups, namely sham operation, CCI model, EA, EA+AV-shGATA4 RNA, and EA+AV-shCTRL groups, with 6 rats in each group. The neuropathic pain model was established by chronic constriction injury (CCI) of the right sciatic nerve. On the 7th day following modeling, EA was applied to the right "Zusanli"(ST36) and "Taichong"(LR3) (1 mA，2 Hz /100 Hz) for 30 min. Rats of the EA+AV-shGATA4 RNA and EA+AV-shCTRL groups received intrathecal injection of AV-shGATA4 RNA and AV-shCTRL(1×1011 PFU/mL，10 μL)at the spinal L4-L6 segments, separately, 48 h before EA intervention. The mechanical pain threshold and thermal pain threshold of the affected limb were detected before molding, 7 days following molding and 60 min after EA. The expressions of adenosine A1 receptor and GATA4 protein in the spinal cord (L4-L6) were detected by Western blot. RESULTS: Outcomes of the first part showed that compared with the control group, no significant changes were found in the mechanical and thermal pain thresholds in both AV-shCTRL and AV-shGATA4 RNA groups and in the expression of spinal GATA4 protein of the AV-shCTRL group (P＞0.05). The expression of spinal GATA4 protein of the AV-shGATA4 RNA group was significantly lower than that of the AV-shCTRL group (P 0.05). On the 7th day following modeling, the mechanical and thermal pain thresholds were significantly lowered in compa-rison with their own pre-modeling of each group and with the sham operation group (P0.05), suggesting a critical involvement of GATA4 in EA analgesia. The expression levels of adenosine A1 receptor and GATA4 protein were significantly increased in the model group than in the sham operation group (P0.05), suggesting that the effects of EA in up-regulating the expression of A1 receptor and GATA4 were eliminated after silencing GATA4 protein. CONCLUSION: EA of ST36 and LR3 can relieve pain by increasing the expression of adenosine A1 receptor of the lumbar spinal cord in neuropathic pain rats, which is probably mediated by GATA4 protein.
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OBJECTIVE: To observe the effect of electroacupuncture (EA) on expression of high mobility group protein 1 (HMGB 1) and related downstream effectors of proinflammatory cytokines in the hippocampus in chronic neuropathic pain rats, so as to investigate its mechanism underlying neuropathic pain relief. METHODS: Male SD rats were randomized into sham, model, and EA groups, with 12 rats in each group. The neuropathic pain model was established by ligature of the left sciatic nerve to induce chronic constriction injury (CCI). EA was applied to bilateral "Zusanli"(ST 36) and "Yanglingquan"(GB 34) for 30 min, once daily for 7 days. The mechanical withdrawal threshold (WMT) was detected using an electronic von Frey anesthesiometer. The expression level of HMGB 1 in the hippocampus was determined using quantitative RT-PCR and Western blot, separately, and the contents of hippocampal TNF-α and IL-1 β were detected by ELISA. RESULTS: Compared with the sham group, the MWT values were markedly decreased on day 7, 10 and 14 after modeling in the model group (P<0.001). On day 10 and 14 after modeling, the MWT values were significantly up-regulated in the EA group relevant to those of the model group (P<0.05, P<0.01). The expression levels of HMGB1 mRNA and protein, and the contents of hippocampal TNF-α and IL-1 β were markedly increased in the model group relevant to the sham group (P<0.001), and significantly down-regulated in the EA group relevant to the model group (P<0.001, P<0.01, P<0.05). CONCLUSION: EA stimulation of ST 36-GB 34 can relieve pain in chronic neuropathic pain rats, which may be related to its actions in down-regulating the levels of HMGB 1 and its downstream proinflammatory cytokines TNF-α and IL-1 β in the hippocampus.
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OBJECTIVE: To observe the analgesic effect and safety of electroacupuncture (EA) intervention for patients undergoing total knee arthroplasty (TKA). METHODS: A total of 40 patients undergoing TKA were randomly assigned to control group (simple multi-mode analgesia, n＝20) and EA group (EA combined with multi-mode analgesia, n＝20). Both groups were treated with epidural anesthesia during surgical operation, and conventional epidural automatic analgesia and oral Celecoxib after surgery. Following surgery, EA was applied to Liangqiu (ST 34)-Xuehai (SP 10), Yinlingquan (SP 9)-Zusanli (ST 36), Fenglong (ST 40)-Qiuxu(GB 40) on the operation side for 30 min, once daily for 7 consecutive days. The patients' pain state during rest and motion was assessed by using visual analogue scale (VAS). The active and passive knee flexion range of motion (ROM), use of painkillers including the number of patient's controlled epidural analgesia (PCEA) during 48 h after surgery, and other complications were recorded. RESULTS: After the treatment, the VAS scores under rest and motion state were both significantly lower in the EA group than in the control group on day 3, 5 and 7 after surgery (P0.05). The white blood cell (WBC) count in both groups were decreased gradually from day 1 to 7 after surgery, and plasma C-reactive protein content on day 5 and 7 were also lowered in both groups, without statistical differences between the two groups in the post-operative complications, dosages of additional postoperative analgesic drugs, and levels of plasma WBC and C-reactive protein (P>0.05). CONCLUSION: EA can effectively improve the early postoperative pain of TKA, reduce the incidence of postoperative complications and the use of analgesic drugs in TKA patients.
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For the purpose of estimating the analgesic mechanisums of the electroacupuncture stimulation and relating the adrenocortical function with its analgesic effect, the deviation value of the pain threshold by the stimulation and β-endorphin, Met-enkephalin lebels in the cerebrospinal fluid [CSF] and also cortisol lebel in the blood were observed in experimented dogs.<br>The both lebels of CSF and cortisol lebel in blood were significantly increased by the electroacupuncture analgesia. These result suggest that in this analgesia, the hypophysis-adrenal cortex system was activated simultaneously with the production of an endogeneous opiate. Using a new designed pain meter system [non-contact thermal stimulator] for the small animals, increasing of the pain threshold lebels was observed objectively.
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The effects of electro-and chemo-stimulating (ES, CS) supraoptic nucleus (SON) on analgesia and electroacupuncture (EA) analgesia were observed using potassium inotophoresis induced tail-flick in rats. The results showed that: different electrical current (12.5 ~ 50 ?A) stimulating SON elevated the PT (P
ABSTRACT
After being stimulated by the application of electroacupuncture (EA) to “KOTAN” leg point (bilaterally), chickens became sedated and showed and showed analgesia with little response to skin clamping. Following the observation of M waves of Motor nerves and evoked responses of Sensory nerves, it was found that while efferent information was temporarily inhibited during EA stimulation, afferent information was depressed during EA and the effect continued for several hours after termination of EA. It is suggested that these phenomena may be controled by neurohumoral mechanisms.