Electroacupuncture suppression of a nociceptive reflex is potentiated by two repeated electroacupuncture treatments: the first opioid effect potentiates a second non-opioid effect

Effects of acupuncture and acupressure of the acupoint compared to the tendon on the blood circulation of human tendon in vivo

PURPOSE

The purpose of this study was to compare the effects of acupuncture and acupressure of acupoints on tendon blood circulation with those of both types of stimulation of tendon itself.

METHODS

Before, during (except for acupressure), and after acupuncture and acupressure of the tendon and acupoint, blood circulation of the Achilles tendon was measured using red laser lights.

RESULTS

The blood volume of the treated and non-treated tendons increased after acupuncture of the tendon (effect of time p = 0.030), whereas that tended to increase after acupuncture of the acupoint (effect of time p = 0.063). In addition, no significant difference in the increases in blood volume was found among the four conditions, i.e., after acupuncture stimulation of the tendon and acupoint for the treated and non-treated tendons (p = 0.492). The blood volume of the treated tendon significantly increased after acupressure of the tendon (effect of time p < 0.001), but not of the acupoint (effect of time p = 0.260), whereas that of the non-treated tendon did not change after acupressure of both the tendon and acupoint.

CONCLUSION

These results suggested that acupuncture of the tendon and acupoint acted centrally to enhance blood circulation of both the treated and non-treated tendons during the recovery period, whereas acupressure of the tendon locally increased blood circulation of the treated tendon only, but not the non-treated tendon and both the treated and non-treated tendons after acupressure of acupoint.

Non-invasive neuromodulation: an emerging intervention for visceral pain in gastrointestinal disorders

Gastrointestinal (GI) disorders, which extend from the esophagus to the anus, are the most common diseases of the GI tract. Among these disorders, pain, encompassing both abdominal and visceral pain, is a predominant feature, affecting the patients' quality of life and imposing a substantial financial burden on society. Pain signals originating from the gut intricately shape brain dynamics. In response, the brain sends appropriate descending signals to respond to pain through neuronal inhibition. However, due to the heterogeneous nature of the disease and its limited pathophysiological understanding, treatment options are minimal and often controversial. Consequently, many patients with GI disorders use complementary and alternative therapies such as neuromodulation to treat visceral pain. Neuromodulation intervenes in the central, peripheral, or autonomic nervous system by alternating or modulating nerve activity using electrical, electromagnetic, chemical, or optogenetic methodologies. Here, we review a few emerging noninvasive neuromodulation approaches with promising potential for alleviating pain associated with functional dyspepsia, gastroparesis, irritable bowel syndrome, inflammatory bowel disease, and non-cardiac chest pain. Moreover, we address critical aspects, including the efficacy, safety, and feasibility of these noninvasive neuromodulation methods, elucidate their mechanisms of action, and outline future research directions. In conclusion, the emerging field of noninvasive neuromodulation appears as a viable alternative therapeutic avenue for effectively managing visceral pain in GI disorders.

P-Stim™ auricular electroacupuncture stimulation device for pain relief

Acupuncture is now accepted as a complementary analgesic treatment. Auricular acupuncture is a distinct form of acupuncture. Electrical stimulation of acupoints (electroacupuncture) increases the effects of acupuncture. Recently, an auricular electroacupuncture device, the P-Stim, has become available. Clinical studies in outpatients have investigated the P-Stim in chronic musculoskeletal pain and its use for minor surgery. In chronic cervical or low back pain, auricular electroacupuncture was more effective than conventional auricular acupuncture. The results in acute pain were controversial. Auricular electroacupuncture reduced pain and remifentanil consumption during oocyte aspiration when compared with conventional auricular acupuncture or a sham treatment. However, after third molar tooth extraction, auricular electroacupuncture and auricular acupuncture failed to reduce either postoperative pain or analgesic consumption. Further large-scale studies are required to evaluate the analgesic efficacy of auricular electroacupuncture.

"Intensity-response" effects of electroacupuncture on gastric motility and its underlying peripheral neural mechanism

The aim of this study was to explore the "intensity-response" relationship between EAS and the effect of gastric motility of rats and its underlying peripheral neural mechanism by employing ASIC3 knockout (ASIC3-/-), TRPV1 knockout (TRPV1-/-), and C57BL/6 mice. For adult male Sprague-Dawley (n = 18) rats, the intensities of EAS were 0.5, 1, 3, 5, 7, and 9 mA, respectively. For mice (n = 8 in each group), only 1 mA was used, by which C fiber of the mice can be activated. Gastric antrum motility was measured by intrapyloric balloon. Gastric motility was facilitated by EAS at ST36 and inhibited by EAS at CV12. The half maximal facilitation intensity of EAS at ST36 was 2.1-2.3 mA, and the half maximal inhibitory intensity of EAS at CV12 was 2.8 mA. In comparison with C57BL/6 mice, the facilitatory effect of ST36 and inhibitive effect of CV12 in ASIC3-/- mice decreased, but the difference was not statistically significant (P > 0.05). However, these effects in TRPV1-/- mice decreased significantly (P < 0.001). The results indicated that there existed an "intensity-response" relationship between EAS and the effect of gastric motility. TRPV1 receptor was involved in the regulation of gastric motility of EAS.

Effects of electroacupuncture Zusanli (ST36) on food intake and expression of POMC and TRPV1 through afferents-medulla pathway in obese prone rats

OBJECTIVE

The purpose of this study was to determine the effects of electroacupuncture (EA) ST36 on food intake and body weight in obese prone (OP) rats compared to obese resistant (OR) strain on a high fat diet. The influences of EA on mRNA levels of pro-opiomelanocortin (POMC), transient receptor potential vanilloid type-1 (TRPV1), and neuronal nitric oxide synthase (nNOS) were also examined in the medulla regions and ST36 skin tissue.

METHODS

Advanced EA ST36 was conducted in two sessions of 20 min separated by an 80 min interval for 7 days. Food intake and body weight were recorded in conscious rats every day. Real time PCR was conducted in the micropunches of the medulla regions and skin tissues at the end of the treatment.

RESULTS

Food intake and body weight were significantly reduced by advanced EA ST36 in OP rats, but slightly decreased in OR strain and sham-EA rats. Advanced EA ST36 produced a marked increase in POMC mRNA level in the nucleus tractus solitarius (NTS) and hypoglossal nucleus (HN) regions. TRPV1 and nNOS mRNAs were simultaneously increased in the NTS/gracile nucleus regions and in the ST36 skin regions by the EA treatment in OP rats.

CONCLUSIONS

We conclude that advanced EA ST36 produces an up-regulation of anorexigenic factor POMC production in the NTS/HN, which inhibits food intake and reduces body weight. EA-induced expression of TRPV1-nNOS in the ST36 and the NTS/gracile nucleus is involved in the signal transduction of EA stimuli via somatosensory afferents-medulla pathways.

Antinociception of Heterotopic Electro-Acupuncture Mediated by the Dorsolateral Funiculus

We investigated the inhibitory pathways that mediate the antinociceptive effects of heterotopic electro-acupuncture (EA) on formalin injection-induced pain in rats. EA (2 ms, 10 Hz, 3 mA) was delivered to heterotopic acupoints HT7 and PC7 for 30 min; this was followed immediately by subcutaneous injection of formalin into the left hind paw of rats. Naltrexone (10 mg/kg, i.p.), an opioid receptor antagonist, was administered to evaluate the involvement of endogenous opioids. The dorsolateral funiculus (DLF), which is a descending pathway that inhibits pain, was transected at the ipsilateral T10–11 level of the thoracic spinal cord. EA inhibited behavioral responses to formalin injection-induced pain and prevented the pain-induced increase in cFos expression in the lumbar spinal cord. Pretreatment with naltrexone did not inhibit the antinociceptive effects of EA on formalin injection-induced pain. Transection of the DLF ipsilateral to the acupuncture site eliminated the antinociceptive effects of EA. These results suggest that the antinociceptive effects of heterotopic EA are mediated by the DLF and not by endogenous opioids.

Gastrointestinal motility disorders and acupuncture

During the last decades, numerous studies have been performed to investigate the effects and mechanisms of acupuncture or electroacupuncture (EA) on gastrointestinal motility and patients with functional gastrointestinal diseases. A PubMed search was performed on this topic and all available studies published in English have been reviewed and evaluated. This review is organized based on the gastrointestinal organ (from the esophagus to the colon), components of gastrointestinal motility and the functional diseases related to specific motility disorders. It was found that the effects of acupuncture or EA on gastrointestinal motility were fairly consistent and the major acupuncture points used in these studies were ST36 and PC6. Gastric motility has been mostly studied, whereas much less information is available on the effect of EA on small and large intestinal motility or related disorders. A number of clinical studies have been published, investigating the therapeutic effects of EA on a number of functional gastrointestinal diseases, such as gastroesophageal reflux, functional dyspepsia and irritable bowel syndrome. However, the findings of these clinical studies were inconclusive. In summary, acupuncture or EA is able to alter gastrointestinal motility functions and improve gastrointestinal motility disorders. However, more studies are needed to establish the therapeutic roles of EA in treating functional gastrointestinal diseases.

Ameliorating effects and mechanisms of electroacupuncture on gastric dysrhythmia, delayed emptying, and impaired accommodation in diabetic rats

The aim of this study was to investigate the effects and mechanisms of electroacupuncture (EA) on gastric accommodation, gastric dysrhythmia, and gastric emptying (GE) in streptozotocin (STZ)-induced diabetic rats. Five experiments were performed in five groups of STZ-induced diabetic rats to study the effects of EA at ST-36 (Zusanli) on gastric slow-wave dysrhythmia, delayed GE and intestinal transit, impaired gastric accommodation, and the mechanisms of EA involving the autonomic and opioidergic pathways. We found the following: 1) EA improved gastric dysrhythmia in the diabetic rats. The normal percentage of slow waves was 55.4 +/- 2.9% at baseline and significantly increased to 69.2 +/- 2.2% with EA (P = 0.01); this effect was blocked by naloxone. 2) EA resulted in a 21.4% increase in GE and 18.2% increase in small intestinal transit in the diabetic rats. 3) EA restored diabetes-induced impairment in gastric accommodation. Gastric accommodation was 0.98 +/- 0.13 ml with sham EA and significantly increased to 1.21 +/- 0.15 ml with EA (P = 0.01), and this effect was blocked by naloxone. 4) EA increased vagal activity assessed by the spectral analysis of the heart rate variability. We concluded that EA at ST-36 improves gastric dysrhythmia, delayed GE and intestinal transit, and impaired accommodation in STZ-induced diabetic rats, and the improvement seems to be mainly mediated via the vagal pathway. EA may have a promising therapeutic potential for diabetic gastroparesis.

Acupuncture: what underlies needle administration?

Acupuncture is an ancient Chinese therapy with its mode of action unclear and efficacy inconclusive. A lack of attention given to the role of psychosocial context presented in clinical provision of acupuncture may mainly account for the current dilemma in acupuncture research. This psychosocial context induces various cognitive and affective processes in the patient while receiving this treatment. On the basis of the analysis of these psychological factors involved in clinical provision of acupuncture and in light of prior studies on the placebo effect, the author hypothesizes that acupuncture works through potentiation and modulation of a highly organized and somatotopic network of endogenous opioids that links expectation, attention and body schema. This hypothesis, which focuses on the contextual factors involved in clinical provision of acupuncture, has immediate clinical and experimental implications and will take the acupuncture debate much further forward.

[Electrical point stimulation (P-STIM) via ear acupuncture: a randomized, double-blind, controlled pilot study in patients undergoing laparoscopic nephrctomyX]

AIM

The aim of this study was to determine whether P-STIM-verum in patients undergoing laparoscopic nephrectomies resulted in a lower consumption of analgesics and an improvement of pain scores compared with P-STIM-placebo when administered for acute peri- and postperative pain.

METHODS

The study was carried out in a double-blind, randomized, controlled manner. Forty-four patients were randomised into 2 groups. The P-STIM device was applied to each patient 30 minutes pro-operatively. The Stimulation was applied over 96 hours. The P-STIM-verum group received subthreshold stimulation. The P-STIM-placebo group received no stimulation. Premedication and anaesthesia were applied in a standardised fashion. The efficacy of treatment was evaluated using a postoperative visual analogue scale (at rest and on exertion) and by dermining postoperative analgesic consumption.

RESULTS

The P-STIM-verum group demonstrated better visual analogue at rest and on exertion then the P-STIM-placebo group. The postoperative consumption of morphine-hydrochloride in the first 6 h significantly less in the P-STIM-verum group. The time of first analgesic request was significantly later in the P-STIM-verum group compared with the P-STIM-placebo group.

CONCLUSIONS

In this study we were able to demonstrate, that pre- and postoperative P-STIM applied in patients undergoing laparoscopic nephrectomies seems to be an effective, simply applied method with few side-effects for reducing pain and postoperative analgesic consumption.

Central Modulation of Pain Evoked From Myofascial Trigger Point

OBJECTIVES

Low-intensity low-frequency electrostimulation delivered within a myofascial trigger point (MTP) has been used as intervention to deactivate MTPs. The therapeutic effect has been suggested to be due to peripheral mechanisms. However, nonpainful stimuli are also known to reduce simultaneous pain through central effects. The primary objective of the present study was to assess if central pain modulation occurs after intervention with low-intensity electrostimulation within an MTP. We hypothesized that intervention induces pain inhibition via the periaqueductal gray (PAG).

METHODS

Twenty-four patients with myofascial pain syndrome participated in the study. During functional magnetic resonance scanning, painful (high-intensity) intramuscular electrostimulation was delivered at random intervals (mean interstimulus interval=10.2 s) within an MTP of the upper left trapezius muscle. In-between scanning sessions, intervention (intramuscular electrostimulation, low-intensity, interstimulus interval=0.5 s) was applied to the same area. Patients were divided into responders and nonresponders according to their change in pressure pain thresholds relative to intervention. In addition to a whole brain search, a region of interest approach was also implemented to test the effect of intervention on PAG signal change.

RESULTS

The main findings were: (1) intervention modulated PAG activity to painful stimuli more in responders than in nonresponders, (2) change in PAG activity from the whole patient population correlated with change in pressure pain threshold, and (3) a network known to regulate affective qualities of the pain experience was (subsignificantly) engaged more in responders than in nonresponders.

DISCUSSION

The applied intervention most likely involves supraspinal pain control mechanisms related to both antinociception and regulation of pain affect.

The Anti-Inflammatory Effects of Low- and High-Frequency Electroacupuncture Are Mediated by Peripheral Opioids in a Mouse Air Pouch Inflammation Model

BACKGROUND

Although acupuncture has been widely used for complementary therapeutic approaches to treat inflammatory diseases and inflammation-induced pain, the potential anti-inflammatory effects of acupuncture treatment remain controversial in clinical trials, and the underlying mechanisms are still unclear.

OBJECTIVE

The objective was to determine whether electroacupuncture (EA) is able to suppress the peripheral inflammatory response (e.g., zymosan-induced leukocyte migration into air pouch). As part of a mechanistic approach, it was further evaluated whether endogenous opioid systems are involved in the "EA-induced anti-inflammatory effect" (EA-AI).

METHODS

EA (1 or 120 Hz) was performed bilaterally in the Zusanli acupoint (ST36) or in a nonacupoint (gluteal muscle) for 30 min in ICR mice under anesthetic condition. The number of leukocytes that migrated into the air pouch was counted 4 hours after zymosan injection. EA was performed at 0, 0.5, 1, or 2 hours prior to zymosan injection, respectively. To evaluate opioid involvement in EA-AI, intrathecal naloxone (36 microg/mouse) and intraperitoneal naloxone methiodide (30 mg/kg) were administered 10 min before EA stimulation.

RESULTS

Both the 1 and 120 Hz frequencies of EA into Zusanli acupoint at the same time with zymosan injection significantly reduced leukocyte migration into the air pouch as compared with those of control groups (i.e., anesthetic control and needling control into Zusanli acupoint without electrical stimulation). The EA stimulation into nonacupoint did not produce any significant anti-inflammatory effect. EA treatment at 0.5 hours prior to zymosan injection also produced an anti-inflammatory effect but 1 and 2 hours prior to zymosan injection did not elicit any effect. Peripheral opioid blockage significantly reversed EA-AI, whereas spinal opioid blockage did not alter EA-AI.

CONCLUSION

EA can suppress peripheral inflammation through a peripheral opioid mechanism. To achieve the full effectiveness of EA, repeated application is recommended for the treatment of a variety of inflammatory diseases.

Neurobiology of Acupuncture: Toward CAM

It has long been accepted that acupuncture, puncturing and scraping needles at certain points on the body, can have analgesic and anesthetic effects, as well as therapeutic effects in the treatment of various diseases. This therapy, including acupuncture anesthesia, has drawn the attention of many investigators and become a research subject of international interest around the world. Numerous studies have demonstrated that the nervous system, neurotransmitters, endogenous substances and Jingluo (meridians) may respond to needling stimulation and electrical acupuncture. An abundance of information has now accumulated concerning the neurobiological mechanisms of acupuncture, in relation to both neural pathways and neurotransmitters/hormonal factors that mediate autonomic regulation, pain relief and other therapeutics. Early studies demonstrated that the analgesic effects of electroacupuncture (EA) are mediated by opioid peptides in the periaqueductal gray. Recent evidence shows that nitric oxide plays an important role in mediating the cardiovascular responses to EA stimulation through the gracile nucleus-thalamic pathway. Other substances, including serotonin, catecholamines, inorganic chemicals and amino acids such as glutamate and alpha-aminobutyric acid (GABA), are proposed to mediate certain cardiovascular and analgesic effects of acupuncture, but at present their role is poorly understood. The increased interest in acupuncture health care has led to an ever-growing number of investigators pursuing research in the processes of the sense of needling touch, transduction of needling stimulation signals, stimulation parameters and placebos. In this Review, the evidence and understanding of the neurobiological processes of acupuncture research have been summarized with an emphasis on recent developments of nitric oxide mediating acupuncture signals through the dorsal medulla-thalamic pathways.

Electrical Stimulation of Auricular Acupuncture Points Is More Effective Than Conventional Manual Auricular Acupuncture in Chronic Cervical Pain: A Pilot Study

In this prospective, randomized, double-blinded, controlled study, we tested the hypothesis that auricular electroacupuncture relieves pain more effectively than conventional manual auricular acupuncture. We studied 21 chronic cervical pain patients without radicular symptoms with insufficient pain relief (visual analogue scale >5) treated with standardized analgesic therapy. All patients received disposable acupuncture needles on the dominant side on the following acupuncture points: cervical spine, shen men, and cushion. In 10 patients, needles were continuously stimulated (2-mA constant current, 1 Hz monophasic) by using the electrical point stimulation device P-STIM. In 11 control patients, no electrical stimulation was administered. All needles were withdrawn 48 h after insertion. Acupuncture was performed once a week for 6 wk. Patients had to complete a questionnaire assessing pain intensity, psychological well-being, activity, sleep, and demand for rescue medication (lornoxicam and tramadol). The reduction in pain scores was significant in the electrical acupuncture group. Similarly, psychological well-being, activity, and sleep were significantly improved in patients receiving electrical acupuncture, and consumption of rescue medication was significantly less. These results demonstrate that continuous electrical stimulation of auricular acupuncture points by using the new point stimulation device P-STIM improves the treatment of chronic cervical pain in an outpatient population.

IMPLICATIONS

Continuous electrical stimulation of auricular acupuncture points by using the new point stimulation device P-STIM significantly decreases pain intensity and significantly improves psychological well-being, activity, and sleep in chronic cervical pain patients.

Electroacupuncture induces the expression of Fos in rat dorsal horn via capsaicin-insensitive afferents

Fos is expressed in rat dorsal horn neurons after electroacupuncture (E-acupuncture), but it is unclear which types of afferent fibers are involved in the expression. It is thought that the Fos expression is induced via Adelta afferents rather than C afferents, since the threshold of Adelta afferents to electrical stimulation is much lower than that of unmyelinated ones. Therefore, neonatally capsaicin treated rats lacking many C afferents were examined to clarify this. Fos expression in the dorsal horn after injection of formalin into the hindpaw was severely attenuated by neonatal capsaicin treatment. However, Fos expression after E-acupuncture to the pads of the hindpaw was unaffected by the same treatment. These results suggest that E-acupuncture induces the expression of Fos in the dorsal horn neurons via capsaicin-insensitive afferents, presumably Adelta afferents.

Low-frequency stimulation of afferent Adelta-fibers induces long-term depression at primary afferent synapses with substantia gelatinosa neurons in the rat

Impulses in primary afferent nerve fibers may produce short- or long-lasting modifications in spinal nociception. Here we have identified a robust long-term depression (LTD) of synaptic transmission in substantia gelatinosa neurons that can be induced by low-frequency stimulation of primary afferent Adelta-fibers. Synaptic transmission between dorsal root afferents and neurons in the substantia gelatinosa of the spinal cord dorsal horn was examined by intracellular recording in a transverse slice dorsal root preparation of rat spinal cord. Conditioning stimulation of dorsal roots with 900 pulses given at 1 Hz (10 V, 0.1 msec) produced LTD of EPSP amplitudes in substantia gelatinosa neurons to 41 +/- 10% of control that lasted for at least 2 hr. When A- and C-fibers were recruited, conditioning stimulation was as effective as A-fiber stimulation alone. After LTD, synaptic strength could be increased to its original level by applying a second, high-frequency tetanic stimulus to the dorsal root, indicating that LTD is reversible and not attributable to damage of individual synapses. Bath application of the GABAA receptor antagonist bicuculline and glycine receptor antagonist strychnine did not affect LTD. When NMDA receptors were blocked by bath application of D-2-amino-5-phosphonovaleric acid, LTD was abolished or strongly reduced. Loading substantia gelatinosa neurons with Ca2+ chelator BAPTA also blocked or reduced LTD. After incubation of slices with calyculin A, a selective and membrane permeable inhibitor of protein phosphatases 1 and 2A, LTD was not attenuated. We propose that this form of LTD may be relevant for long-lasting segmental antinociception after afferent stimulation.

Treatment alternatives for patients with masticatory myofascial pain

Alternative therapies are used by many people, and the dental literature has reported that some alternative therapies are comparable to splint therapy in the effective treatment of masticatory myofascial pain. The authors review the efficacy of alternative therapies and discuss their clinical implications. This review is intended to help dental practitioners to select alternative therapies they can use with or instead of splint therapy for treating patients who have a primary diagnosis of myofascial pain.

Electroacupuncture modifies the expression of c-fos in the spinal cord induced by noxious stimulation

The present study was designed to investigate the effect of 4 Hz vs. 100 Hz electroacupuncture (EA) on c-fos expression in the spinal cord induced by noxious stimulation (NS). A second objective was to evaluate the sensitivity of these two different frequencies of EA stimulation to the opiate antagonist, naloxone. Mechanical NS was applied to the right hindpaw following 30 min of either 4 Hz or 100 Hz EA treatment and the resulting c-fos expression in the spinal cord dorsal horn was compared to that obtained in rats exposed only to the noxious stimulation. The involvement of endogenous opioids in the EA response to 4 Hz or 100 Hz stimulation frequencies was evaluated by pretreating rats with naloxone (5 mg/kg, i.p.) 10 min prior to EA. Both 4 Hz and 100 Hz EA reduced the number of c-fos-immunoreactive neurons in the spinal dorsal horn induced by noxious stimulation by 58% and 50%, respectively. The suppression of c-fos expression induced by 4 Hz EA was completely reversed by prior treatment with naloxone. On the other hand, the suppression of c-fos induced by 100 Hz EA was only partially blocked by this opiate antagonist. These data indicate that both high- and low-frequency EA are capable of inhibiting the expression of c-fos in the dorsal horn induced by NS. Low-frequency EA appears to be mediated primarily by endogenous opioid systems, while non-opioid mechanisms may be involved in mediating the analgesic effect of high frequency EA. These results support the hypothesis that EA has a direct inhibitory effect on spinal cord dorsal horn neurons and extend the results of previous studies which indicate low frequency EA is mediated by opiate sensitive circuitry, while high frequency EA is predominantly mediated by non-opioid neurotransmitters.

Electroacupuncture suppresses a nociceptive reflex: naltrexone prevents but does not reverse this effect

Rats were anesthetized with a continuous infusion of pentobarbital. First we showed that electroacupuncture (EA) suppressed the tail flick nociceptive reflex. Naltrexone (a long acting opiate antagonist) was given either intravenously or intrathecally to attempt to block this EA effect. The naltrexone prevented this EA effect when injected before the onset of EA treatment, but failed to reverse the EA effects when injected immediately after termination of EA treatment. We discuss the possibility that the endorphins set up a cascade effect whereby the subsequent EA suppression of tail flick is no longer dependent on endorphin and hence cannot be affected by opiate antagonists. This finding may clarify some of the confusion in the acupuncture endorphin literature.