Accepted

Pannexin-1 (Panx1) is a large-pore ion and solute permeable channel highly expressed in the nervous system, where it subserves diverse processes, including neurite outgrowth, dendritic spine formation, and N-methyl D-aspartate (NMDA) receptor (NMDAR)-dependent plasticity. Moreover, Panx1 dysregulation contributes to neurological disorders, including neuropathic pain, epilepsy, and excitotoxicity. Despite progress in understanding physiological and pathological functions of Panx1, the mechanisms that regulate its activity, including its ion and solute permeability, remain poorly understood. In this study, we identify endoplasmic reticulum (ER)-resident stromal interaction molecules (STIM1/2), which are Ca sensors that communicate events within the ER to plasma membrane channels, as binding and signaling partners of Panx1. We demonstrate that Panx1 is activated to its large-pore configuration in response to stimuli that recruit STIM1/2 and map the interaction interface to a hydrophobic region within the N terminus of Panx1. We further characterize a Panx1 N terminus-recognizing antibody as a function-blocking tool able to prevent large-pore Panx1 activation by STIM1/2. Using either the function-blocking antibody or re-expression of Panx1 deletion mutants in Panx1 knockout (KO) neurons, we show that STIM recruitment couples Ca entry via NMDARs to Panx1 activation, thereby identifying a model of NMDAR-STIM-Panx1 signaling in neurons. Our study highlights a previously unrecognized and important role of the Panx1 N terminus in regulating channel activation and membrane localization. Considering past work demonstrating an intimate functional relation between NMDARs and Panx1, our study opens avenues for understanding activation modality and context-specific functions of Panx1, including functions linked to diverse STIM-regulated cellular responses.

The six-minute walk test (6MWT) is a commonly used measure of functional capacity. This study is the first to investigate the test-retest reliability, minimal detectable difference (MDD) and the minimal clinically important difference (MCID) for people attending a persistent pain service. Relationships between change in 6MWT performance and change in self-reported physical, functional and psychological outcome measures were also explored.

Evidence shows that miRNAs are deeply involved in nervous system diseases, but whether miRNAs contribute to the bortezomib (BTZ)-induced neuropathic pain remains unclear. We aimed to investigate whether miRNAs contribute to bortezomib (BTZ)-induced neuropathic pain and explore the related downstream cascades. The level of miRNAs in the spinal dorsal horn was explored using miRNA microarray and PCR. MiR-672-5p was significantly downregulated in dorsal horn neurons in the rats with BTZ treatment. Intrathecal injection of miR-672-5p agomir blunted the increase of the amplitude and frequency of sEPSCs in dorsal horn neurons and mechanical allodynia induced by BTZ. In addition, the knockdown of miR-672-5p by intrathecal injection of antagomir increased the amplitude and frequency of sEPSCs in dorsal horn neurons and decreased the mechanical withdrawal threshold in naïve rats. Furthermore, silico analysis and the data from subsequent assays indicated that REEP6, a potential miR-672-5p-regulating molecule, was increased in the spinal dorsal horn of rats with BTZ-induced neuropathic pain. Blocking REEP6 alleviated the mechanical pain behavior induced by BTZ, whereas overexpressing REEP6 induced pain hypersensitivity in naïve rats. Importantly, we further found that miR-672-5p was expressed in the REEP6-positive cells, and overexpression or knockdown of miR-672-5p reversely regulated the REEP6 expression. Bioinformatics analysis and double-luciferase reporter assay showed the existence of interaction sites between REEP6 mRNA and miR-672-5p. Overall, our study demonstrated that miR-672-5p directly regulated the expression of REEP6, which participated in the neuronal hyperexcitability in the spinal dorsal horn and neuropathic pain following BTZ treatment. This signaling pathway may potentially serve as a novel therapeutic avenue for chemotherapeutic-induced mechanical hypersensitivity.

Headaches are a very common condition that most people will experience many times during their lives. This article presents the primary headaches, which are a large group of diseases where the headache is not a symptom of another known disease. Tension-type headache affects approximately 80% of the general population, and the prevalence of migraine is estimated at 10-12%. Clinical data and experience to date have demonstrated that botulinum toxin may be an effective prophylactic treatment for chronic headache types. It has been used in neurology for the treatment of dystonia and blepharospasm. Now it has been approved to treat chronic migraine and has been shown to confer significant benefit in refractory cases. Based on clinical experience botulinum toxin has also been tried in other headache disorders. While it is intuitively attractive to think that due to its effect on pain by sensory modulation, there may also be efficacy in its use in chronic tension-type headache and cluster headache, so far, there is little evidence to support this. Botulinum toxin is effective in pain control through its interaction with the SNARE complex, which inhibits the release of neurotransmitters, such as glutamate, substance P and calcitonin gene-related peptide. OnabotulinumtoxinA is effective not only in headache frequency and pain intensity but in other parameters, including quality of life.

Muscles and the deep fascia surrounding them have been suggested to play an important role in various musculoskeletal pain conditions including low back pain. Both have been shown to host rich nociceptive innervation and to undergo changes in individuals with chronic pain. However, evidence for the respective contribution of muscle and fascia sensitization in humans with myofascial pain syndrome is lacking. Here, we studied the sensitization of muscle and fascia in individuals with myofascial low back pain. Twenty individuals with acute (5) and chronic (15) myofascial low back pain of the quadratus lumborum muscle and a matched control group of twenty healthy individuals were recruited and clinically evaluated. All participants underwent ultrasound-guided needling of their subcutaneous tissue, deep fascia and quadratus lumborum muscle. Reported pain intensity and episodes of muscle twitching were recorded and analyzed. Among pain patients, both muscles and deep fascia demonstrated pain hypersensitivity, but muscles were significantly more sensitized than the deep fascia. No difference between acute- or chronic-pain patients was observed. Results of this study suggest that while both deep fascia and muscle show pain sensitization in both early and chronic stages of low back pain, muscles are more sensitized than fascia.

Scratching and scratch-induced injuries including neuroanatomical alterations are key characteristics in chronic pruritus entities of different origin. The aim of this study was to link gene expression (array hybridization, qPCR) with DNA methylation (array hybridization) and neuroanatomy (PGP9.5 staining) in chronic nodular prurigo (CNPG), atopic dermatitis (AD), brachioradial pruritus (BRP) and matched healthy controls. Specific signatures of gene expression as well as DNA methylation clearly discriminated pruritic lesional from non-pruritic skin in CNPG and from healthy skin of volunteers, respectively. While intraepidermal nerve fiber density was indiscriminately reduced, the level of epidermal branching, assessed by a semi-quantitative pattern analysis, differentiated entities (CNPG>BRP>AD). Correspondingly, repellent SEMA3A showed highest expression in AD, while axonal growth promoting NGF was most prominent in CNPG and BRP. Overexpression of genes for nerve fiber regeneration (NELL2/NFKB/ARTN) was found in AD and CNPG, but not in BRP. Our findings suggest that differential branching patterns rather than mere innervation density separate chronic itch conditions and reflect disease-specific local expression profiles. In pruritic dermatoses (AD, CNPG), nerve injury and subsequent sprouting may primarily result from chronic scratching whereas genuine neuropathy is expected to underlie BRP.