Low and high frequency acupuncture stimulation inhibits mental stress-induced sweating in humans via different mechanisms

Pyramidal and parvalbumin neurons modulate the process of electroacupuncture stimulation for stroke rehabilitation

Electroacupuncture (EA) stimulation has been shown to be beneficial in stroke rehabilitation; however, little is known about the neurological mechanism by which this peripheral stimulation approach treats for stroke. This study showed that both pyramidal and parvalbumin (PV) neuronal activity increased in the contralesional primary motor cortex forelimb motor area (M1FL) after ischemic stroke induced by focal unilateral occlusion in the M1FL. EA stimulation reduced pyramidal neuronal activity and increased PV neuronal activity. These results were obtained by a combination of fiber photometry recordings, in vivo and in vitro electrophysiological recordings, and immunofluorescence. Moreover, EA was found to regulate the expression/function of N-methyl-D-aspartate receptors (NMDARs) altered by stroke pathology. In summary, our findings suggest that EA could restore disturbed neuronal activity through the regulation of the activity of pyramidal and PV neurons. Furthermore, NMDARs we shown to play an important role in EA-mediated improvements in sensorimotor ability during stroke rehabilitation.

Lateral hypothalamic orexin neurons mediate electroacupuncture-induced anxiolytic effects in a rat model of post-traumatic stress disorder

The lateral hypothalamus' orexinergic system has been associated with anxiety-related behaviors, and electroacupuncture (EA) modifies orexin neurons to control the anti-anxiety process. However, in a rat model of post-traumatic stress disorder (PTSD), the important role of LH orexin neurons (OXNs) in the anxiolytic effects induced by EA has not been explored. In this study, rats underwent modified single prolonged stress (MSPS) for seven days before developing EA. The rats were then subjected to elevated plus maze (EPM) and open field (OFT) tests, and western blot and c-Fos/orexin double labeling investigations were carried out to determine the functional activation of LH orexinergic neurons. Compared to MSPS model rats, it has been demonstrated that EA stimulation enhanced the amount of time spent in the central zone (TSCZ) in OFT and the amount of time spent in the open arm (TSOA) in EPM in MSPS model rats (P < 0.01). After behavioral testing, MSPS model rats had decreased activated c-Fos positive OXNs. Still, EA in SPS rats increased that number and elevated orexin type 1 receptors (OXR1) protein expression in the LH. Furthermore, after administering SB334867 (an OXR1 antagonist) to MSPS model rats, the effects of EA therapy on anxiety-like behaviors (ALBs) were significantly diminished. Additionally, when low-dose orexin-A (LORXA) was administered intracerebroventricularly together with EA stimulation in MSPS rats, the anxiolytic effects of the stimulation were substantially enhanced (P < 0.05). The results of this study reveal the mechanisms by which acupuncture may reduce PTSD and advance our understanding of the function of LH orexin signaling in EA's anxiolytic effects.

Transporting Hydrogel via Chinese Acupuncture Needles for Lesion Positioning Therapy

Lesion positioning therapy optimizes medical treatment by directly targeting lesions. However, strong physical barriers greatly hinder its wide use. Here, the Chinese acupuncture needles (CA-needles) with a screw-thread structure at the tip (ST-needle) and the hydrogel with the function of adhesive metal and loaded drug sustained-release structure are designed, through the minimally invasive and precise positioning of lesions by ST-needles, the dry-wet conversion of hydrogel with absorbing fluids and swelling, and the rotation back of ST-needles, the hydrogel is precisely positioned in the subchondral bone with physical barrier to achieve precise positioning therapy for lesions. In vitro experiments show that the ST-needle penetrates the physical barrier of cartilage and enters the subchondral bone. Simultaneously, the hydrogel transfer efficiency of the ST-needle (73.25%) is significantly higher than that of the CA-needle (29.92%) due to the protective effect of the screw-thread structure. In vivo experiments demonstrate that precise positioning in subchondral bone in osteoarthritis rats with ST-needles effectively inhibits abnormal subchondral bone remodeling, alleviating the degeneration and degradation of cartilage. Therefore, ST-needles achieve lesion positioning therapy through minimally invasive penetration of physical barriers, precisely positioning within lesions, and delivering hydrogel to release drugs.

5-HT in the dorsal raphe nucleus is involved in the effects of 100-Hz electro-acupuncture on the pain-depression dyad in rats

The pain-depression dyad is becoming widespread in the clinic and is attracting increasing attention. A previous study by our group found that 100-Hz electro-acupuncture (EA), but not 2-, 50- and 2/100-Hz EA, was effective against the reserpine-induced pain-depression dyad. This finding is in contrast to the fact that low-frequency EA is commonly used to treat supraspinal-originating diseases. The present study aimed to investigate the mechanism underlying the effects of 100-Hz EA on the pain-depression dyad. Repeated reserpine injection was found to induce allodynia and depressive behaviors in rats. It decreased 5-hydroxytryptamine (5-HT) levels and immunoreactive expressions in the dorsal raphe nucleus (DRN). 100-Hz EA alleviated the pain-depression dyad and upregulated 5-HT in the DRN of reserpine-injected rats. Intracerebroventricular injection of para-chlorophenylalanine, an inhibitor of 5-HT resynthesis, suppressed the upregulation of 5-HT in the DRN by 100-Hz EA and partially counteracted the analgesic and anti-depressive effects of 100-Hz EA. The present study was the first to demonstrate that 5-HT in the DRN is involved in mediating the analgesic and anti-depressive effects of 100-Hz EA on the pain-depression dyad. This finding provided a scientific basis for high-frequency EA as a potential treatment for the pain-depression dyad.

Effects of Acupuncture, RU-486 on the Hypothalamic-Pituitary-Adrenal Axis in Chronically Stressed Adult Male Rats

We have recently reported that pretreatment with electroacupuncture (EA) at stomach meridian point 36 (St36) prevents the chronic cold-stress increase in the hypothalamus-pituitary-adrenal axis (HPA), an action that may be under central control. Given that treatment for stress-related symptoms usually begins after onset of the stress responses, the objectives of the present study were to determine the efficacy of EA St36 on HPA hormones when EA St36 is given after stress was initiated, if the results are long lasting, and if blocking the glucocorticoid receptor (GR) using RU-486 had the same effects as EA St36. Adult male rats were placed in 4 groups of animals, 3 of which were exposed to cold and 1 of which was a nontreatment control group. After exposure to the cold stress, 2 groups were treated with either EA St36 or sham-EA, repeated over 10 days. The increase in ACTH and corticosterone observed in stress-only rats was prevented in EA St36 animals, and the effects remained intact 4 days after withdrawal of EA but continuation of cold stress. When the GR was blocked with RU-486, the efficacy of EA St36 remained unchanged. GR blockade did significantly elevate ACTH, which is not seen with EA St36, suggesting that EA St36 does act centrally. The elevated HPA hormones in stress-only rats were associated with a significant increase in depressive and anxious behavior; this was not observed in the stressed EA St36 animals. The results indicate that EA specifically at St36 vs sham-EA is effective in treating chronic poststress exposure.

Acupuncture blocks cold stress-induced increases in the hypothalamus-pituitary-adrenal axis in the rat

Electroacupuncture (EA) is used to treat chronic stress; however, its mechanism(s) of action in allaying stress remains unclear. The interplay of stress hormones of the hypothalamus-pituitary-adrenal axis (HPA) and the sympathetic nervous system (SNS) is critical in the stress response. Our objective was to determine whether EA at acupoint, stomach 36 (EA St₃₆) is effective in preventing chronic cold stress-induced increased hormone levels in the rat by examining four groups of animals, three of which were exposed to cold and one of which was a non-treatment control group. Before exposure to the cold, two groups were treated with either EA St₃₆, or Sham-EA, before 10 days of cold stress. The EA St₃₆ animals demonstrated a significant decrease in peripheral HP hormones (ACTH and CORT) compared with stress animals (P<0.05). These effects were specific; rats receiving Sham-EA had elevation of these hormones, similar to the stress-only animals. These effects were mirrored centrally in the brain; CRH levels were significantly (P<0.05) reduced in EA St₃₆ animals compared with the other animals. Finally, EA effect on peripheral and adrenal SNS hormones (norepinephrine (NE) and neuropeptide Y (NPY) respectively) was examined, with no significant difference noted in adrenal tyrosine hydroxylase or circulating NE in any of the groups. However, EA St₃₆ was effective in preventing stress-induced elevation is adrenal Npy mRNA. These results indicate that EA St₃₆ blocks the chronic stress-induced elevations in the HPA and the sympathetic NPY pathway, which may be a mechanism for its specific stress-allaying effects.

The Effect of Low versus High Frequency Electrical Acupoint Stimulation on Motor Recovery After Ischemic Stroke by Motor Evoked Potentials Study

Electrical acupoint stimulation (EAS) has been used to treat motor dysfunction of stroke patients with reportedly effective results. When we operate EAS treatment, we can modulate the intensity and frequency of stimulation. The purpose of this study is to evaluate the effect of different frequencies in treating motor dysfunction of ischemic stroke patients with EAS. The subjects of this study were 62 ischemic stroke patients with motor dysfunction in Kyunghee oriental medical center. They have been hospitalized after 1 week to 1 month from onset. They were treated with 2 Hz or 120 Hz EAS for 2 weeks, and had motor evoked potentials (MEPs) tests before and after 2 weeks of EAS treatment. We measured latency, central motor conduction time (CMCT) and amplitude of MEPs. After 2 weeks of treatment, we compared MEPs data of the affected side between the 2 Hz group and the 120 Hz group. The 2 Hz group showed more significant improvement than the 120 Hz group in latency, CMCT and amplitude ( p = 0.008, 0.002, 0.002). In the case of the affected side MEPs data divided by normal side MEPs data, the 2 Hz group also showed higher improvement rate than the 120 Hz group in latency, CMCT and amplitude with significant differences ( p = 0.003, 0.000, 0.008). These results suggest that low frequency EAS activates the central motor conduction system better than high frequency EAS, and EAS with low frequency could be more helpful for motor recovery after ischemic stroke than that with high frequency.

Comparison of electroacupuncture frequency-related effects on heart rate variability in healthy volunteers: a randomized clinical trial

This study aimed to compare the effects of high frequency electroacupuncture (EA) and low-frequency EA on the autonomic nervous system by using a heart rate variability measuring device in normal individuals. Fourteen participants were recruited and each participated in the high-frequency and low-frequency sessions (crossover design). The order of sessions was randomized and the interval between the two sessions was over 2 weeks. Participants received needle insertion with 120-Hz stimulation during the high-frequency session (high-frequency EA group), and with 2-Hz stimulation during the low-frequency session (low-frequency EA group). Acupuncture needles were directly inserted perpendicularly to LI 4 and LI 11 acupoints followed by delivery of electric pulses to these points for 15 minutes. Heart rate variability was measured 5 minutes before and after EA stimulation by a heart rate variability measuring system. We found a significant increase in the standard deviation of the normal-to-normal interval in the high-frequency EA group, with no change in the low-frequency EA group. Both the high-frequency and low-frequency EA groups showed no significant differences in other parameters including high-frequency power, low-frequency power, and the ratio of low-frequency power to high-frequency power. Based on these findings, we concluded that high-frequency EA stimulation is more effective than low-frequency EA stimulation in increasing autonomic nervous activity and there is no difference between the two EA frequencies in enhancing sympathovagal balance.

TRPV1 expression in acupuncture points: response to electroacupuncture stimulation

The present study was to examine the distribution of transient receptor potential vanilloid type-1 (TRPV1) receptor immunoreactivity in the acupuncture points (acupoint), and determine the influences of electroacupuncture (EA) stimulation on TRPV1 expression. EA stimulation of BL 40 was conducted in two sessions of 20 min separated by an 80 min interval in anesthetized rats. Sections of skin containing BL 40, and its non-meridian control were examined by immunolabeling with antibodies directed against TRPV1. Without EA, the number of subepidermal nerve fibers expressing TRPV1 was higher in the acupoint than in non-acupoint control skin (p<0.01). The subepidermal nerve fibers showed the co-localization of TRPV1 with peripherine, a marker for the C-fibers and A-δ fibers. The expression of TRPV1 in nerve fibers is significantly increased by EA stimulation in acupoints (p<0.01). However the upregulation in the non acupoint meridian and the non-meridian control skin was short of statistical significance. Double immunostaining of TRPV1 and neuronal nitric oxide synthase (nNOS) revealed their co-localization in both the subepidermal nerve fibers and in the dermal connective tissue cells. These results show that a high expression of TRPV1 endowed with nNOS in subepidermal nerve fibers exists in the acupoints and the expression is increased by EA. We conclude that the higher expression of TRPV1 in the subepidermal nerve fibers and its upregulation after EA stimulation may play a key role in mediating the transduction of EA signals to the CNS, and its expression in the subepidermal connective tissue cells may play a role in conducting the local effect of the EA.

How might acupuncture work? A systematic review of physiologic rationales from clinical trials

BACKGROUND

Scientific interest in acupuncture has led numerous investigators to conduct clinical trials to test the efficacy of acupuncture for various conditions, but the mechanisms underlying acupuncture are poorly understood.

METHODS

The author conducted a PubMed search to obtain a fair sample of acupuncture clinical trials published in English in 2005. Each article was reviewed for a physiologic rationale, as well as study objectives and outcomes, experimental and control interventions, country of origin, funding sources and journal type.

RESULTS

Seventy-nine acupuncture clinical trials were identified. Twenty-six studies (33%) offered no physiologic rationale. Fifty-three studies (67%) posited a physiologic basis for acupuncture: 33 (62% of 53) proposed neurochemical mechanisms, 2 (4%) segmental nervous system effects, 6 (11%) autonomic nervous system regulation, 3 (6%) local effects, 5 (9%) effects on brain function and 5 (9%) other effects. No rationale was proposed for stroke; otherwise having a rationale was not associated with objective, positive or negative findings, means of intervention, country of origin, funding source or journal type. The dominant explanation for how acupuncture might work involves neurochemical responses and is not reported to be dependent on treatment objective, specific points, means or method of stimulation.

CONCLUSION

Many acupuncture trials fail to offer a meaningful rationale, but proposing a rationale can help investigators to develop and test a causal hypothesis, choose an appropriate control and rule out placebo effects. Acupuncture may stimulate self-regulatory processes independent of the treatment objective, points, means or methods used; this would account for acupuncture's reported benefits in so many disparate pathologic conditions.