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Background and Purpose: Chemotherapy‐induced neuropathic pain (CINP) currently has limited effective treatment. Although the roles of oxytocin (OXT) and the oxytocin receptor (OXTR) in central analgesia have been well documented, the expression and function of OXTR in the peripheral nervous system remain unclear. Here, we evaluated the peripheral antinociceptive profiles of OXTR in CINP. Experimental Approach: Paclitaxel (PTX) was used to establish CINP. Quantitative real‐time polymerase chain reaction (qRT‐PCR), in situ hybridization, and immunohistochemistry were used to observe OXTR expression in dorsal root ganglia (DRG). The antinociceptive effects of OXT were assessed by hot‐plate and von Frey tests. Whole‐cell patch clamp was performed to record sodium currents, excitability of DRG neurons, and excitatory synapse transmission. Key Results: Expression of OXTR in DRG neurons was enhanced significantly after PTX treatment. Activation of OXTR exhibited antinociceptive effects, by decreasing the hyperexcitability of DRG neurons in PTX‐treated mice. Additionally, OXTR activation up‐regulated the phosphorylation of protein kinase C (pPKC) and, in turn, impaired voltage‐gated sodium currents, particularly the voltage‐gated sodium channel 1.7 (NaV1.7) current, that plays an indispensable role in PTX‐induced neuropathic pain. OXT suppressed excitatory transmission in the spinal dorsal horn as well as excitatory inputs from primary afferents in PTX‐treated mice. Conclusion and Implications: The OXTR in small‐sized DRG neurons is up‐regulated in CINP and its activation relieved CINP by inhibiting the neural excitability by impairment of NaV1.7 currents via pPKC. Our results suggest that OXTR on peripheral sensory neurons is a potential therapeutic target to relieve CINP. [ABSTRACT FROM AUTHOR]

Chemotherapy-induced peripheral neuropathy (CIPN) is the most common side-effect of anti-cancer therapy. To date, there are no clinically effective analgesics that could prevent and treat CIPN. However, the exact pathogenesis of CIPN is still unclear. In the present study, we use the paclitaxel-induced peripheral neuropathy (PIPN) model, aiming to better understand the transcriptomic level of the Dorsal root ganglia (DRG) neurons in rats with PIPN. mRNA from each DRG sample was reverse transcribed to cDNA and sequenced using next-generation high throughput sequencing technology. Quantitative RT-PCR verification was used to confirm the identified Differentially expressed genes (DEGs) in the DRG of PIPN rats. RNAseq results have identified 384 DEGs (adjusted P-value < 0.05; fold change ≥ 2) in the DRG of rats 14 days after paclitaxel injection in total, including 97 up-regulated genes, and 287 down-regulated genes. GO analysis revealed that these DEGs were majorly involved in neuropeptide activity, chemokine receptor activity, defense response, and inflammatory response. Kyoto Encyclopedia of Gene and Genomes analysis showed that neuroactive ligand-receptor interaction and cytokine-cytokine receptor interaction were involved in sensory neurons of rats with PIPN. Besides, comparison analysis identified that 11 DEGs in the PIPN model are shared with either inflammatory pain (Ces1d, Cfd, Retn, and Fam150b) or neuropathic pain (Atf3, Csrp3, Ecel1, Gal, Sprr1a, Tgm1, and Vip). Quantitative RT-PCR results also confirmed the validation of the RNAseq data. These results suggested that neuroactive ligand-receptor interaction and cytokine-cytokine receptor interaction are majorly involved in sensory neurons of rats with PIPN. Immune, inflammatory responses and neuron functional changes are the major pathogenesis of PIPN. Paclitaxel-induced peripheral neuropathy has shared characteristics with both inflammatory pain and neuropathic pain. [ABSTRACT FROM AUTHOR]

Pain is a major public health problem, causing heavy social and economic burdens to patients and society while consuming tremendous medical resources at the same time. Thus, there is a critical need to find low-cost, efficacious, and therapeutic approaches to help manage pain. While acupuncture is increasingly recognized as a promising pain-relieving method, less is known about a specific form of auricular acupuncture known as Battlefield Acupuncture (BFA). The BFA technique involves the sequential placement of semi-permanent, single-use, French ASP Ⓡ golden needles to five specific acupoints in one or both ears, where they are left in place for 3–4 days or longer [Niemtzow, R.C., Battlefield acupuncture. Med. Acupunct. 19: 225–228, 2007]. The BFA needles (more accurately described as tiny conical darts) pierce the ear in designated locations in a particular order [Levy, C.E., N. Casler and D.B. FitzGerald. Battlefield acupuncture: an emerging method for easing pain. Am. J. Phys. Med. Rehabil. 97: e18–e19, 2018.]. (Figs. 4 and 5) It was developed by Dr. Richard C. Niemtzow in 2001, as a subgroup form of an auricular acupuncture technique based on the somatotopic arrangement of an inverted fetus pattern on the external ear [Romoli, M. Ear acupuncture: historical abstract–differences of ear cartography between the east and the west. Dtsch. Z. Akupunkt. 53: 24–33, 2010.]. Currently, BFA is widely used in the US military, but to our knowledge, there is no review which comprehensively synthesizes the current publications surrounding pain management. This review aims to investigate the effects and safety of BFA in adults with pain. Electronic databases were searched for randomized controlled trials (RCTs) published in English evaluating efficacy and safety of BFA in adults with pain, from database inception to September 6, 2019. The primary outcome was pain intensity change, and the secondary outcome was safety. Nine RCTs were included in this review, and five trials involving 344 participants were analyzed quantitatively. Compared with no intervention, usual care, sham BFA, and delayed BFA interventions, BFA had no significant improvement in the pain intensity felt by adults suffering from pain. Few adverse effects (AEs) were reported with BFA therapy, but they were mild and transitory. BFA is a safe, rapid, and easily learned acupuncture technique, mainly used in acute pain management, but no significant efficacy was found in adult individuals with pain, compared with the control groups. Given the poor methodological quality of the included studies, high-quality RCTs with rigorous evaluation methods are needed in the future. [ABSTRACT FROM AUTHOR]