Potential mechanisms of acupuncture for neuropathic pain based on somatosensory system.

Neuropathic pain, caused by a lesion or disease of the somatosensory system, is common and distressing. In view of the high human and economic burden, more effective treatment strategies were urgently needed. Acupuncture has been increasingly used as an adjuvant or complementary therapy for neuropathic pain. Although the therapeutic effects of acupuncture have been demonstrated in various high-quality randomized controlled trials, there is significant heterogeneity in the underlying mechanisms. This review aimed to summarize the potential mechanisms of acupuncture on neuropathic pain based on the somatosensory system, and guided for future both foundational and clinical studies. Here, we argued that acupuncture may have the potential to inhibit neuronal activity caused by neuropathic pain, through reducing the activation of pain-related ion channels and suppressing glial cells (including microglia and astrocytes) to release inflammatory cytokines, chemokines, amongst others. Meanwhile, acupuncture as a non-pharmacologic treatment, may have potential to activate descending pain control system via increasing the level of spinal or brain 5-hydroxytryptamine (5-HT), norepinephrine (NE), and opioid peptides. And the types of endogenously opioid peptides was influenced by electroacupuncture-frequency. The cumulative evidence demonstrated that acupuncture provided an alternative or adjunctive therapy for neuropathic pain.

[Research progress of acupuncture for peripheral inflammatory response].

Acupuncture can regulate peripheral inflammatory response mainly through somatosensory-vagal/sympathetic nerve-splenic/adrenal/local reflex pathway. Besides, acupuncture may also play an anti-inflammatory role through gut microbiota and neuro-endocrine pathway. The effects of acupuncture have acupoint specificity and time window effect, and are influenced by voltage, current and frequency of electroacupuncture. Future research should focus on the connection and interaction of multiple targets, pathways and mechanisms in the brain, and clarify the multi-target advantages of acupuncture anti-inflammatory.

The Influence of Psychological Status on Acupuncture for Postprandial Distress Syndrome: A Subgroup Analysis of a Multicenter, Randomized Controlled Trial.

BACKGROUND: Postprandial distress syndrome (PDS) is accompanied by a high incidence of mood disorder. Acupuncture is an effective method in relieving dyspepsia symptoms; however, the impact of psychological status on acupuncture for PDS remains mysterious. METHODS: This secondary analysis of a multicenter, randomized controlled trial aims to evaluate the influence of anxiety and depression on acupuncture for PDS. 138 patients received the same acupuncture treatment and were followed up until week 16. The 2 primary outcomes were the response rate based on overall treatment effect and the elimination rate of all 3 cardinal symptoms after 4 weeks of treatment. RESULTS: Of 114 patients, 31 were anxiety patients and 83 were nonanxiety patients or 32 were depressive patients and 82 were nondepressive patients. The response rate and elimination rate at week 4 were 77.4% and 9.7% in anxiety patients versus 84.3% and 27.7% in nonanxiety patients, respectively (P = 0.388; P = 0.041). No significant difference was noted in the response rate (P = 0.552) and elimination rate (P = 0.254) at week 4 between nondepressive and depressive patients. There was no significant intergroup difference in the response rate and elimination rate between non-mood-disorder and mood disorder patients (P > 0.05) during the 12-week post-treatment follow-up, except for the response rate at week 8 (P < 0.05). CONCLUSION: The effect of acupuncture on response rate was similar for both non-mood-disorder and mood disorder patients. However, anxiety but not depression had a negative influence on the elimination rate, especially in postprandial fullness.

[Research progress on mechanism of acupuncture and moxibustion in treatment of irritable bowel syndrome].

The current clinical evidence and underlying mechanisms of acupuncture and moxibustion in the treatment of irritable bowel syndrome (IBS) were summarized, so as to better optimize clinical treatment. The relevant articles of acupuncture and moxibustion in the treatment of IBS in recent years were retrieved and summarized. We found that the clinical efficacy of acupuncture and moxibustion in the treatment of IBS was relatively reliable. However, the mutual relationships among various mechanisms of action such as abnormal gastrointestinal motility, high visceral sensitivity, intestinal microenvironment disorders, and abnormal intestinal-brain interactions need to be further explored. The authors believe that in-depth explorations of the bidirectional regulation of "gut-brain axis", the law of changes in the abundance and diversity of intestinal flora, and the establishment of a more ideal animal model of TCM syndrome differentiation are useful ideas for subsequent research.

Potential Mechanisms and Clinical Effectiveness of Acupuncture in Depression.

Major depressive disorder is the most common mental disorder with significant economic burden and limited treatments. Acupuncture has emerged as a promising non-pharmacological treatment for reducing depressive symptoms. However, the potential mechanisms and clinical effectiveness of acupuncture are not fully understood. This review aimed to: (1) summarize the available evidence on the mechanisms and clinical effectiveness of acupuncture for depression, and then (2) compare with pharmacological interventions, guiding future studies. Studies with animal models of depression and patients have shown that acupuncture could increase hippocampal and network neuroplasticity and decrease brain inflammation, potentially to alleviating depressive disorders. Overall clinical studies indicated that acupuncture could relieve primary depression, particularly milder cases, and was helpful in the management of post-stroke depression, pain-related depression, and postpartum depression both as an isolated and adjunct treatment. It was emphasized that acupuncture combined with antidepressant pharmacological treatment not only enhanced the improvement of primary and secondary depressive symptoms but also reduced the side effects of the medical treatment, which is the main cause for high dropout rates with drug treatment. In summary, substantial evidence from animal and human researches supported the beneficial effect of acupuncture in depression. However, most clinical trials of acupuncture were small, and it is unclear whether their findings can be generalized, so more studies are needed.

Effect of Electroacupuncture on Gut Microbiota in Participants With Knee Osteoarthritis.

A close relationship between knee osteoarthritis (KOA) and gut microbiota has recently been described. Herein, we aim to investigate the effect of electroacupuncture (EA) on gut microbiota in participants with KOA. We conducted a study of 60 participants with KOA and 30 matched healthy controls (HCs). Sixty participants were allocated to either EA group (n=30) or sham acupuncture (SA) group (n=30). Five obligatory acupoints and three adjunct acupoints were punctured in the EA group. Eight non-acupoints that were separated from conventional acupoints or meridians were used for the SA group. Participants in both groups received 24 sessions within eight weeks. Fecal microbial analyses by 16S ribosomal RNA gene sequencing were carried out after collecting stools at T0 and T8 weeks (Four samples with changed defecation habits were excluded). The results showed that both Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) total score (P=0.043) and NRS score (P=0.002) decreased more in EA group than those in SA group. Moreover, EA could reverse more KOA-related bacteria including Bacteroides, [Eubacterium]_hallii_group, Agathobacter and Streptococcus. The number of significantly different genera between KOA patients and HCs were less after EA treatment than that after SA treatment. This meant that EA modified the composition of the gut microbiome, making it closer to healthy people, while not significantly affecting the microbial diversity. Two genera including Agathobacter (P=0.0163), Lachnoclostridium (P=0.0144) were statistically increased than baseline in EA group (paired Wilcoxon rank sum test). After EA treatment, Bacteroides (P=0.0394) was more abundant and Streptococcus (P=0.0306) was significantly reduced in patients who demonstrated adequate response than in those with inadequate response (Wilcoxon rank-sum test). Spearman correlation test between gut microbe and KOA clinical outcomes indicated that Bacteroides and Agathobacter was negatively correlated with NRS score, WOMAC total score, and WOMAC pain, stiffness and pain scores (P<0.001 or 0.05 or 0.01), while Streptococcus was positively correlated with them (P<0.05 or 0.01). Our study suggests that EA contributes to the improvement of KOA and gut microbiota could be a potential therapeutic target.

Potential Mechanisms of Acupuncture for Functional Dyspepsia Based on Pathophysiology.

Functional dyspepsia (FD), a common disorder of gastrointestinal function, originated from the gastroduodenum. Although the therapeutic effect of acupuncture has been investigated by various high-quality randomized controlled trials, the potential mechanisms showed obvious heterogeneity. This review summarized the potential mechanisms of acupuncture on FD in order to guide for future laboratory and clinical studies. Here, we argued that the primary cause of FD was gastroduodenal low-grade inflammation and acid exposure, which impaired mucosal integrity, caused brain-gut axis dysfunction, and impaired brain network connectivity, all of which generated various symptom patterns. Overall the clinical studies indicated that acupuncture was a promising treatment to alleviate symptoms in FD patients, whose efficacy was influenced by acupoints and individual variance. Mechanistically, studies with animal models of FD and patients have shown that acupuncture, a non-invasive strategy for nerve stimulation, may have the potential to control intestinal inflammation and suppress acid-secretion via different somatic autonomic reflex pathways, regulate the brain-gut axis through intestinal microbiota, and has the potential to ameliorate FD-symptoms. The cumulative evidence demonstrated that acupuncture is a promising treatment to alleviate symptoms of FD patients.