Positive feedback action of pituitary beta-endorphin on acupuncture analgesia afferent pathway

The Involvement of Descending Pain Inhibitory System in Electroacupuncture-Induced Analgesia

Chronic pain is a major health problem, which can impair quality of life and reduce productivity. Electroacupuncture (EA), a modality of medicine based on the theories of Traditional Chinese Medicine (TCM), presents great therapeutic effects on chronic pain. Its clinical application has gained increasing popularity, and in parallel, more research has been performed on the mechanisms of EA-induced analgesia. The past decades have seen enormous advances both in neuronal circuitry of needle-insertion and in its molecular mechanism. EA may block pain by activating the descending pain inhibitory system, which originates in the brainstem and terminates at the spinal cord. This review article synthesizes corresponding studies to elucidate how EA alleviate pain via the mediation of this descending system. Much emphasis has been put on the implication of descending serotonergic and noradrenergic pathways in the process of pain modulation. Also, other important transmitters and supraspinal regions related to analgesic effects of EA have been demonstrated. Finally, it should be noticed that there exist some shortcomings involved in the animal experimental designed for EA, which account for conflicting results obtained by different studies.

What intrinsic factors influence responsiveness to acupuncture in pain?: a review of pre-clinical studies that used responder analysis

BACKGROUND

Not many studies have investigated individual sensitivity to acupuncture. To explore the intrinsic factors related to individual responses to acupuncture, we reviewed published pre-clinical studies using responder analysis on pain.

METHODS

We searched the PubMed and EMBASE databases to June 2015. We included pre-clinical reports describing responders and non-responders to anti-nociceptive and analgesic effects of acupuncture in animal study. We identified the potential intrinsic factors which might be related with the response to acupuncture.

RESULTS

Totally, 216 potentially relevant articles were retrieved and 14 studies met our inclusion criteria. Rat (n = 1348) and rabbit (n = 56) were used, and only electroacupuncture (EA) was applied as an intervention. Results showed that high levels of cholecystokinin-8 and receptors were associated with poor responsiveness to EA. Endogenous opioids including β-endorphin and met-enkephalin, descending inhibitory norepinephrine and serotonin system, and hypothalamic 5'-AMP-activated protein kinase seemed to be associated with high-level responses. Spinal levels of neurotransmitters and pro-inflammatory cytokines were also differentially expressed depending on the EA sensitiveness. In the central nervous system, hypothalamus, periaqueductal grey, pituitary gland, and spinal cord were suggested to be involved in the EA responsiveness. Identified individual variations did not seem to be accidental, as the responsiveness to EA was replicated over time. However, methodological issues such as reproducibility, cut-off criteria, and clinical relevance need to be further elaborated.

CONCLUSION

Our study suggests that the identification of the biological factors differentiating responders from non-responders is necessary and it may aid in understanding how acupuncture modulates pain.

Comparative evaluation of the therapeutic effect of metformin monotherapy with metformin and acupuncture combined therapy on weight loss and insulin sensitivity in diabetic patients

OBJECTIVE

Obesity induces insulin resistance (IR), the key etiologic defect of type 2 diabetes mellitus (T2DM). Therefore, an incidence of obesity-induced diabetes is expected to decrease if obesity is controlled. Although Metformin is currently one of the main treatment options for T2DM in obese patients, resulting in an average of 5% weight loss, adequate weight control in all patients cannot be achieved with Metformin alone. Thus, additional therapies with a weight loss effect, such as acupuncture, may improve the effectiveness of Metformin.Subjective:We designed this randomized clinical trial (RCT) to compare the effects of Metformin monotherapy with that of Metformin and acupuncture combined therapy on weight loss and insulin sensitivity among overweight/obese T2DM patients, to understand whether acupuncture plus Metformin is a better approach than Metformin only on treating diabetes. To understand whether acupuncture can be an insulin sensitizer and, if so, its therapeutic mechanism.

RESULTS

Our results show that Metformin and acupuncture combined therapy significantly improves body weight, body mass index (BMI), fasting blood sugar (FBS), fasting insulin (FINS), homeostasis model assessment (HOMA) index, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), leptin, adiponectin, glucagon-like peptide-1 (GLP-1), resistin, serotonin, free fatty acids (FFAs), triglyceride (TG), low-density lipoprotein cholesterol (LDLc), high-density lipoprotein cholesterol (HDLc) and ceramides.

CONCLUSIONS

Consequently, Metformin and acupuncture combined therapy is more effective than Metformin only, proving that acupuncture is an insulin sensitizer and is able to improve insulin sensitivity possibly by reducing body weight and inflammation, while improving lipid metabolism and adipokines. As a result, electro-acupuncture (EA) might be useful in controlling the ongoing epidemics in obesity and T2DM.

Systematic review and meta-analysis of the effects of acupoint stimulation on smoking cessation

Smoking represents a serious worldwide public health problem because of its close association with the development of chronic disease and cancer. Acupoint stimulation has been used as treatment mode for smoking cessation but its efficacy remains controversial. This systematic review and meta-analysis aimed to determine the effects of acupoint stimulation on smoking cessation rate and daily cigarette consumption. Electronic literature searches in eight electronic databases up to March 2011 were performed to identify acupoint stimulation for smoking cessation. The outcomes assessed were smoking cessation rate and cigarette consumption. We assessed abstinence from smoking at the earliest and last measured time points, and at the 3- and 6-month follow-ups. Meta-analysis was performed using CMA software. A total of 20 RCTs were included in the meta-analysis. A significant effect of acupoint stimulation was found in smoking cessation rates and cigarette consumption at immediate, 3- and 6-month follow-ups, with effect sizes 1.24 (95%CI = 1.07 ~ 1.43, p = 0.003), -2.49 (95%CI = -4.65 ~ -0.34, p = 0.02), 1.70 (95%CI = 1.17 ~ 2.46, p = 0.01), and 1.79 (95%CI = 1.13 ~ 2.82, p = 0.01), respectively. Multi-modality treatments, especially acupuncture combined with smoking cessation education or other interventions, can help smokers to eschew smoking during treatment, and to avoid relapse after treatment.

THE TREATMENT OF OBESITY BY ACUPUNCTURE

The present study is an investigation of the results of the studies on the effects of acupuncture application therapy on obesity. It has been reported that acupuncture application in obesity treatment is effective in procuring weight loss. It can affect appetite, intestinal motility, and metabolism, as well as emotional factors such as stress. Increases in neural activity in the ventromedial nuclei of the hypothalamus, in tone in the smooth muscle of the stomach and in levels of enkephalin, beta endorphin, and serotonin in plasma and brain tissue have also been observed with the application of acupuncture. It has been observed that acupuncture application to obese people increases excitability of the satiety center in the ventromedial nuclei of the hypothalamus. Acupuncture stimulates the auricular branch of the vagal nerve and raises serotonin levels. Both of these activities have been shown to increase tone in the smooth muscle of the stomach, thus suppressing appetite. Among other things, serotonin enhances intestinal motility. It also controls stress and depression via endorphin and dopamine production. In addition to these effects, it is thought that the increase in plasma levels of beta endorphin after acupuncture application can contribute to the body weight loss in obese people by mobilizing the body energy depots through lipolithic effect.

Electroacupuncture activates corticotrophin-releasing hormone-containing neurons in the paraventricular nucleus of the hypothalammus to alleviate edema in a rat model of inflammation

BACKGROUND

Studies show that electroacupuncture (EA) has beneficial effects in patients with inflammatory diseases. This study investigated the mechanisms of EA anti-inflammation, using a rat model of complete Freund's adjuvant (CFA)-induced hind paw inflammation and hyperalgesia.

DESIGN

Four experiments were conducted on male Sprague-Dawley rats (n = 6-7/per group). Inflammation was induced by injecting CFA into the plantar surface of one hind paw. Experiment 1 examined whether EA increases plasma adrenocorticotropic hormone (ACTH) levels. Experiments 2 and 3 studied the effects of the ACTH and corticotropin-releasing hormone (CRH) receptor antagonists, ACTH(11-24) and astressin, on the EA anti-edema. Experiment 4 determined whether EA activates CRH neurons in the paraventricular nucleus of the hypothalammus. EA treatment, 10 Hz at 3 mA and 0.1 ms pulse width, was given twice for 20 min each, once immediately post and again 2 hr post-CFA. Plasma ACTH levels, paw thickness, and paw withdrawal latency to a noxious thermal stimulus were measured 2 h and 5 h after the CFA.

RESULTS

EA significantly increased ACTH levels 5 h (2 folds) after CFA compared to sham EA control, but EA alone in naive rats and CFA alone did not induce significant increases in ACTH. ACTH(11-24) and astressin blocked EA anti-edema but not EA anti-hyperalgesia. EA induced phosphorylation of NR1, an essential subunit of the N-methyl-D-aspartic acid (NMDA) receptor, in CRH-containing neurons of the paraventricular nucleus.

CONCLUSION

The data demonstrate that EA activates CRH neurons to significantly increase plasma ACTH levels and suppress edema through CRH and ACTH receptors in a rat model of inflammation.

Electroacupuncture treatment of obesity with psychological symptoms

The aim was to study the effect of placebo EA, electroacupuncture (EA), and diet on obesity and accompanying psychological symptoms. One hundred and sixty-five volunteer women participated in the study. There were three groups: (i) Placebo EA, (ii) EA, and (iii) diet restriction group. EA was performed by using three ear and six body points. There was a 4.8% reduction in weight of patients with EA application, whereas patients with a diet restriction and placebo EA had a 2.5% and 2.7% weight reduction, respectively. There were significant decreases in phobia, anger, anxiety, obsession, paranoid symptoms, and depression in the EA groups compared to those of the placebo EA and diet groups. It was suggested that electroacupuncture may be an effective therapy for obesity including the psychological signs and symptoms in women.

Smoking cessation after acupuncture treatment

Acupuncture is applied, especially in treatment of pain, hemiplegia, obesity, and psychological illnesses including addiction. Recently, ear and body acupuncture have been frequently used in the treatment of smoking. An increase in levels of endorphin, enkephalin, epinephrine, norepinephrine, serotonin, and dopamine in the central nervous system and plasma has been reported as the most important mechanism of acupuncture. That is, acupuncture application may increase the levels of endorphin, enkephalin, epinephrine, norepinephrine, serotonin, and dopamine in the central nervous system and plasma. The authors think that acupuncture application provides the patients with deterioration in the taste of smoking, decrease in desire of smoking, and the obstruction of psychological symptoms that appear as a result of smoking cessation. Because of these effects it is presumed that acupuncture application may be used as an important method for smoking cessation treatment.

Changes in levels of serum insulin, C-Peptide and glucose after electroacupuncture and diet therapy in obese women

Our purpose was to investigate the effects of electroacupuncture (EA) therapy on body weight and on levels of serum insulin, c-peptide and glucose in obese women. 52 healthy women were included in this study and were allocated into three groups: 1) Placebo EA group (n = 15; mean age = 41.8 +/- 4.6 and mean body mass index {BMI} = 33.2 +/- 3.5); 2) EA group (n = 20; mean age = 42.1 +/- 4.4 and BMI = 35.9 +/- 3.6) and 3) Diet restriction group (n = 20; mean age = 42.9 +/- 4.3 and BMI = 34.7 +/- 2.7). EA was applied to the ear points Hunger and Shen Men on alternating days and to the body points LI 4, LI 11, St 36 and St 44 once a day for 30 minutes over 20 days. Diet restriction that entailed a 1450 kilocalorie (kcal) diet program was applied to the three groups for 20 days. An increase in weight loss was observed when weight loss in the EA group (p < 0.000) was compared to that in the diet restricted and placebo EA groups using the Tukey HSD test. There were increases in the serum insulin (p < 0.001) and c-peptide levels (p < 0.000) in the women treated with EA compared to those in the women treated with the placebo EA and diet restriction groups. A decrease was observed in the glucose levels (p < 0.01) in both the EA and diet restriction groups compared to those in the placebo EA group. Our results suggest that EA therapy is an effective method in treating obesity. EA therapy also helps serum glucose levels to decrease through the increase of serum insulin and c-peptide levels.

The mechanism of acupuncture and clinical applications

This study presents the result of the studies explaining the effects of acupuncture on various systems and symptoms. It has been determined that endomorphin-1, beta endorphin, encephalin, and serotonin levels increase in plasma and brain tissue through acupuncture application. It has been observed that the increases of endomorphin-1, beta endorphin, encephalin, serotonin, and dopamine cause analgesia, sedation, and recovery in motor functions. They also have immunomodulator effects on the immune system and lipolithic effects on metabolism. Because of these effects, acupuncture is used in the treatment of pain syndrome illnesses such as migraine, fibromyalgia, osteoarthritis, and trigeminal neuralgia; of gastrointestinal disorders such as disturbance at gastrointestinal motility and gastritis; of psychological illnesses such as depression, anxiety, and panic attack; and in rehabilitation from hemiplegia and obesity.

Cutaneous analgesia, hemodynamic and respiratory effects, and beta-endorphin concentration in spinal fluid and plasma of horses after acupuncture and electroacupuncture

OBJECTIVE

To determine cutaneous analgesia, hemodynamic and respiratory effects, and beta-endorphin concentration in spinal fluid and plasma of horses after acupuncture and electroacupuncture (EA).

ANIMALS

8 healthy 10- to 20-year-old mares that weighed between 470 and 600 kg.

PROCEDURE

Each horse received 2 hours of acupuncture and 2 hours of PAES at acupoints Bladder 18, 23, 25, and 28 on both sides of the vertebral column as well as sham needle placement (control treatment). Each treatment was administered in a random order. At least 7 days elapsed between treatments. Nociceptive cutaneous pain threshold was measured by use of skin twitch reflex latency (STRL) and avoidance to radiant heat (< or = 50 degrees C) in the lumbar area. Skin temperature, cardiovascular and respiratory variables, and beta-endorphin concentration in spinal fluid (CSF-EN) and plasma (plasma-EN) were measured.

RESULTS

Acupuncture and PAES significantly increased STRL and skin temperature. The CSF-EN was significantly increased from baseline values 30 to 120 minutes after onset of PAES, but it did not change after acupuncture and control treatments. Heart and respiratory rates, rectal temperature, arterial blood pressure, Hct, total solids and bicarbonate concentrations, base excess, plasma-EN, and results of blood gas analyses were not significantly different from baseline values after acupuncture, PAES, and control treatments.

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of PAES was more effective than acupuncture for activating the spinal cord to release beta-endorphins into the CSF of horses. Acupuncture and PAES provided cutaneous analgesia in horses without adverse cardiovascular and respiratory effects.

Effects of electroacupuncture on the mechanical allodynia in the rat model of neuropathic pain

The analgesic effects of acupuncture on the mechanical allodynia in the rat model of neuropathic pain have not yet been studied. The aim of the present study is: first, to determine if electroacupuncture (EA) or morphine attenuates the mechanical allodynia; and secondly, to examine if the EA effect may be mediated by endogenous opioids. To produce neuropathic pain, the right superior caudal trunk was resected between the S3 and S4 spinal nerves. Twenty-one days after the neuropathic surgery, low frequency EA stimulation (2 Hz, 0.3 ms, 0.07 mA) delivered to Houxi (S13) for 30 min relieved significantly the signs of mechanical allodynia. Intraperitoneal (i.p.) morphine (0.5 or 1.5 mg/kg) also relieved the signs of mechanical allodynia in a dose-dependent manner. In addition, the antiallodynic effect of Houxi EA was blocked by pretreatment with naloxone (2 mg/kg, i.p.). However, combined application of EA and morphine did not show an obvious synergistic effect. These results suggest that low frequency EA or morphine can relieve the mechanical allodynia signs and the EA effect can be mediated by endogenous opioid systems.

Effects of acupuncture on radial artery hemodynamics: controlled trials in sensitized and naive subjects

Palpation of the radial pulses is an important technique in traditional Chinese medicine. Two double-blind randomized trials of the effects of real and sham acupuncture on radial artery hemodynamics were conducted in 19 patients regularly exposed to acupuncture (sensitized subjects) and in 8 healthy subjects devoid of previous exposure (naive subjects), respectively. Radial artery diameter and pulse waveform were measured with a high-resolution echotracking system and aplanation tonometry, respectively, before and during a 20-min acupuncture period. In sensitized patients, arterial diameter significantly increased during real acupuncture, compared with the sham group (+7.5 +/- 2.8 vs. -2.9 +/- 2.7%, respectively; P < 0.01). By contrast, in naive subjects, arterial diameter did not change during real or sham acupuncture. In both populations, no significant difference was observed between real and sham acupuncture, concerning the time course of blood pressure, radial artery distensibility, and pressure waveform. Our results demonstrate that real acupuncture is associated with an objective vasodilatation of the radial artery in patients regularly exposed to acupuncture, but not in naive subjects.

Activation of anterior lobe corticotrophs by electroacupuncture or noxious stimulation in the anaesthetized rat, as shown by colocalization of Fos protein with ACTH and beta-endorphin and increased hormone release

A marked expression of the c-fos proto-oncogene has been recently reported in cells of the anterior lobe of the pituitary gland in rats subject to electroacupuncture or noxious thermal stimulation under pentobarbital anaesthesia. The present study was undertaken to identify the activated pituitary cells. Following both kinds of stimulation, most Fos-immunoreactive anterior lobe cells showed colocalization with adrenocorticotropic hormone or beta-endorphin immunoreactivity. No c-fos expression occurred in pituitary cells immunoreactive for growth hormone, prolactin, luteinizing hormone, or thyrotropin-stimulating hormone. A marked rise of adrenocorticotropic hormone and beta-endorphin concentrations occurred in plasma. In the hypothalamus, c-fos expression was increased in the mediobasal nuclei-namely, the arcuate nucleus-and in the paraventricular nucleus, but more in the former. It is suggested that somatosensory noxious input, or the partly noxious input evoked by electroacupuncture, activate the hypothalamo-pituitary-adrenocortical axis as in common forms of stress, but with a specific activation of the mediobasal hypothalamic nuclei and no stimulation of intermediate lobe cells. Opiate release from the pituitary gland may contribute to acupuncture analgesia or the intrinsic antinociceptive reactions triggered by noxious stimulation.

The acupuncture point and its connecting central pathway for producing acupuncture analgesia

Characteristics of the acupuncture point in producing acupuncture analgesia (AA) were examined by the inhibition of noxious responses in the brain stem reticular formation, potentials, and neuronal activity in the dorsal periaqueductal central gray (D-PAG), and analgesia caused by low frequency stimulation of the acupuncture point. As a result, stimulation of the muscle beneath the acupuncture point was found to be effective in producing AA. AA measured by tail flick, vocalization, and writhing tests was abolished by hypophysectomy, and by antiserum of beta-endorphin administered into the 3rd ventricle. The pathway from the D-PAG to the anterior hypothalamus (AA-AH) in the AA afferent pathway from the acupuncture point to the pituitary gland was determined. The lateral hypothalamus, lateral septum, cingulate bundle, dorsal-hippocampus, and habenulo-interpeduncular tract were found, in addition to regions previously found, to belong to the AA afferent pathway. A network of divergence and convergence in their rostral and caudal relations was observed. The AA afferent pathway diverges from the D-PAG, converges to the HP, and then projects to the AA-AH.

Descending pain inhibitory system involved in acupuncture analgesia

The descending pain inhibitory system (DPIS) associated with acupuncture analgesia (AA), caused by low frequency stimulation of an acupuncture point, was identified by the results of lesion and stimulation procedures previously determined to differentiate the afferent and efferent paths in rats. The DPIS starts in the posterior arcuate nucleus and descends to the hypothalamic ventromedian nucleus (HVM) from whence it divides into two pathways: one path, the serotonin mediated path, descends through the ventral periaqueductal central gray (V-PAG) and then to the raphe magnus (RM). The other, the noradrenaline mediated path, descends through the reticuloparagigantocellular nucleus (NRPG) and part of the reticulogigantocellular nucleus (NRGC). The afferent and efferent paths are both present in the RM and NRGC, and were separately identified by means of the analgesia (SPA) produced by stimulation of the separate regions in AA responders and nonresponders, because SPA of these regions in nonresponders produced only efferent pathway mediated analgesia.