Calcitonin Gene-related Protein Research Articles

Regional and Sex Differences in the Mouse Colonic Innervation Assessed Using a Computerized Quantitative Approach in Three-dimension of the Enteric Nervous System (ENS)

The ENS consists of the submucosal and myenteric plexus (SMP, MP) and controls a variety of gut functions. The quantitative analysis of innervation in the ENS is still a challenge because the ENS forms a mesh-like three-dimensional (3D) network embedded in the gut wall. We developed a computerized approach to perform direct, objective and automatic measurements of innervation in 3D structures of the mouse colonic ENS. The whole mounts of SMP and MP were prepared along the proximal, transverse and distal colon (pC, tC, dC) collected from 8 naïve mice (C57BL/6J, 6 weeks, 4 of each sex). Each 3D image of SMP or MP was reconstructed from Z-stack confocal images with 50-100 or 30-50 optical sections in the frame 1415×1415 or 708×708 μm and 1 μm apart. The Hu C/D, peripheral form of choline acetyltransferase (pChAT), nitric oxide synthase (nNOS), vasoactive intestinal peptide (VIP), tyrosine hydroxylase (TH) and calcitonin gene-related protein (CGRP) immunoreactive (ir) enteric neurons or fibers were digitally traced and automatically measured with Imaris 9.7 for neuroscientists. The co-localization of pChAT and nNOS was determined with ImarisColoc tool. The densities of neurons and nerve fibers, co-localization of pChAT and nNOS were calculated from 6-8 of 3D images/marker/plexus/segment/mouse (total 2304 3D images) and expressed as the percentage of each type of neurons in total neurons, the volume of each type of nerve fibers in the volume of SMP and MP and co-labeled neurons in each type of neurons. The results demonstrate significant differences in the numbers of two major neuronal populations, their co-localization and densities of three representative nerve fibers among three colonic segments, between two plexuses and sexes. 1. pChAT- and nNOS-ir neurons in the MP: the density of pChAT-ir neurons was 1.4- and 2.1-fold lower in the pC than in the tC and dC (p<0.05, p<0.001), and 1.6- and 4.0-fold higher than that of nNOS-ir neurons in the tC and dC (p<0.001, p<0.001), respectively. In contrast, the density of nNOS-ir neurons was 1.4- or 2.3-fold higher in the pC or tC than dC (p<0.001, p<0.01). 2. Co-localization of pChAT and nNOS in the MP: Co-labeled neurons in the nNOS-ir neurons were 1.4- or 1.5-fold lower in the pC or tC than dC (p<0.05, p<0.05). 3. Nerve fibers: The density of VIP-ir fibers in the SMP was 2.4- and 1.8-fold higher in the pC than tC and dC (p<0.001, p<0.001) while 3.0- and 2.4-fold lower than in the MP in both tC and dC (p<0.001, 0.001). TH-ir fibers in the SMP were 1.6-fold lower in both tC or dC than pC (p<0.01, p<0.01), 1.6-, 2.2- and 1.4-fold lower than MP in the pC, tC and dC (p<0.001, p<0.001, p<0.05). In the MP, they were 1.8- and 1.6-fold lower in the dC than in pC and tC (p<0.001, p<0.001). CGRP-ir fibers did not show significant difference between two plexuses among three segments. 4. Sex differences: The co-labeled neurons in the pChAT-ir neurons were 2.2-, 2.7- and 2.2-fold more in the males than females in three segments (p<0.001, p<001, p<0.001) while those in the nNOS-ir neurons were 1.9-fold more in the males than females only in the dC (p<0.05). VIP-ir fibers in the dC-MP were 1.2-fold higher in the males than females (p<0.05). These data and the novel approach developed in this study will contribute to further assessments of the structure-function relationships and pathological alterations in the colon with mouse models. Supported by NIH/SPARC 1OT2OD024899-01. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Reducing the Impact of Headache and Allodynia Score in Chronic Migraine: An Exploratory Analysis from the Real-World Effectiveness of Anti-CGRP Monoclonal Antibodies Compared to Onabotulinum Toxin A (RAMO) Study.

Chronic migraine (CM) is a disabling and hard-to-treat condition, associated with high disability and high cost. Among the preventive treatments, botulinum toxin A (BoNT-a) and monoclonal antibodies against the calcitonin gene-related protein (anti-CGRP mAbs) are the only disease-specific ones. The assessment of the disease burden is complex, and among others, tools such as the allodynia symptoms checklist (ASC-12) and headache impact test (HIT-6) are very useful. This exploratory study analysed the impact of these two therapies on migraine burden. The RAMO study was a multicentre, observational, retrospective investigation conducted in two headache centres: the Fondazione IRCCS Istituto Neurologico Carlo Besta (Milan) and the Fondazione Policlinico Campus Bio-Medico (Rome). This study involved patients with chronic migraine treated with mAbs or BoNT-A. We conducted a subgroup exploratory analysis on HIT-6 and ASC-12 scores in the two groups. The Wilcoxon rank-sum test, Fisher's exact test, and ANOVA were performed. Of 126 patients, 36 on mAbs and 90 on BoNT-A had at least one available follow-up. mAbs resulted in a mean reduction of -11.1 and -11.4 points, respectively, in the HIT-6 at 6 and 12 months, while BoNT-A was reduced -3.2 and -3.6 points, respectively; the mAbs arm resulted in mean reductions in ASC-12 at 6 and 12 months of follow-up of -5.2 and -6.0 points, respectively, while BoNT-A showed lesser mean changes of -0.5 and -0.9 points, respectively. The adjusted analysis confirmed our results. In this exploratory analysis, anti-CGRP mAbs showed superior effectiveness for HIT-6 and ASC12 compared to BoNT-A. Reductions in terms of month headache days (MHD), migraine disability assessment test (MIDAS), and migraine acute medications (MAM) were clinically relevant for both treatments.

Efficacy of radial shock wave therapy on rat models of adjuvant arthritis

BackgroundExtracorporeal shock wave therapy (ESWT) is an effective treatment for musculoskeletal pain, tendinopathy, and fasciitis with an anti-inflammatory effect. ESWT can be categorized into two groups: radial pressure wave (RPW) and focused shock wave (FSW). Although there have been several studies on the inflammation and pain-improvement mechanisms of FSW, there are few studies on the pain-improvement mechanisms of RPW. This study aimed to elucidate the efficacy of RPW in a rat model of adjuvant arthritis. MethodsNinety-six rats were randomly categorized into three groups: RPW, control, and sham as follows: (I) RPW group, which received RPW application after complete Freund's adjuvant (CFA) injection; (II) Control group, which received only CFA injection; and (III) Sham group, which received only saline injection. All rats were evaluated at 0, 4, 7, 14, 28, and 56 days post-RPW application based on foot circumference, von Frey test, and immunohistochemistry of nerve fibers for calcitonin gene-related peptide (CGRP) and protein gene product (PGP) 9.5 in plantar skins. ResultsThere were no significant differences in foot circumference between the RPW and control groups at any time point. The RPW group showed significant improvements in the von Frey test results on days 7 and 14. The total CGRP-immunoreactive (ir) and PGP9.5-ir nerve fiber lengths in the RPW group decreased on day 0; however, both were increased in the control group. The CGRP-ir and PGP9.5-ir nerve fibers in the RPW group were significantly shorter than those in the control group until day 14 after RPW. ConclusionsRPW improved the mechanical hypersensitivity between days 7 and 14 after application. Like FSW, RPW also induced the degeneration of sensory nerve fibers in the skin in the early period after irradiation, and reinnervation occurred between 14 and 28 days. Thus, our results demonstrate one of the pain relief mechanisms after RPW application.

IL-31-dependent neurogenic inflammation restrains cutaneous type 2 immune response in allergic dermatitis.

Despite robust literature associating IL-31 with pruritic inflammatory skin diseases, its influence on cutaneous inflammation and the interplay between inflammatory and neurosensory pathways remain unmapped. Here, we examined the consequences of disrupting Il31 and its receptor Il31ra in a mouse model of house dust mite (HDM)-induced allergic dermatitis. Il31-deficient mice displayed a deficit in HDM dermatitis-associated scratching, consistent with its well-established role as a pruritogen. In contrast, Il31 deficiency increased the number and proportion of cutaneous type 2 cytokine-producing CD4+ T cells and serum IgE in response to HDM. Furthermore, Il4ra+ monocytes and macrophages capable of fueling a feedforward type 2 inflammatory loop were selectively enriched in Il31ra-deficient HDM dermatitis skin. Thus, IL-31 is not strictly a proinflammatory cytokine but rather an immunoregulatory factor that limits the magnitude of type 2 inflammatory responses in skin. Our data support a model wherein IL-31 activation of IL31RA+ pruritoceptors triggers release of calcitonin gene-related protein (CGRP), which can mediate neurogenic inflammation, inhibit CD4+ T cell proliferation, and reduce T cell production of the type 2 cytokine IL-13. Together, these results illustrate a previously unrecognized neuroimmune pathway that constrains type 2 tissue inflammation in the setting of chronic cutaneous allergen exposure and may explain paradoxical dermatitis flares in atopic patients treated with anti-IL31RA therapy.

Unveiling the role of neutrophils in chronic spontaneous urticaria: Beyond mast cells.

Mast cells and eosinophils are considered pivotal contributors to the pathogenesis of chronic spontaneous urticaria (CSU). However, emerging evidence suggests that neutrophils also play a central role. Cutaneous mast cells and macrophages orchestrate the recruitment of neutrophils through the regulation and activation of diverse processes, including heightened local vascular permeability and chemokine release. Studies have demonstrated increased activation and elevated levels of neutrophil-related cytokines in CSU patients. Moreover, neutrophils have been proposed as antigen-presenting cells during the late-phase reaction of immunoglobulin E-mediated allergy and have been associated with the expression of calcitonin gene-related protein and vascular endothelial growth factor in CSU. Histopathological analysis of lesional skin in CSU patients revealed significantly higher eosinophil and neutrophil counts than unaffected skin. However, the extent of neutrophil infiltration in the skin does not appear to correlate with the number of neutrophils in peripheral blood. The utility of the neutrophil-lymphocyte ratio as a marker for disease activity or remission in CSU remains inconclusive. Neutrophil-targeted therapy may confer benefits for CSU patients who exhibit resistance to antihistamines. Omalizumab has demonstrated its ability to reduce neutrophil counts, the neutrophil-lymphocyte ratio, and the neutrophil-monocyte ratio in peripheral blood. While dapsone and colchicine are recommended as alternative treatment options for CSU, their evidential support from published studies remains limited. Inhibitors targeting interleukin-1 and neutrophil-related cytokines have been proposed as potential therapeutic interventions for patients exhibiting neutrophil predominance. Further research is warranted to gain deeper insights into the involvement of neutrophils in CSU and to explore potential therapeutic interventions.

Gene expression changes in the cerebellum are associated with persistent post-injury pain in adolescent rats exposed to early life stress

Chronic pain develops following injury in approximately 20% of adolescents, at twice the rate in females than males. Adverse childhood experiences also increase the risk for poor health outcomes, such as chronic pain. Emerging literature suggests the cerebellum to be involved in pain processing, however detailed explorations into how the cerebellum contributes to pain are lacking. Therefore, this study aimed to characterise chronic pain outcomes and cerebellar gene expression changes following early life stress and injury in both sexes. The adverse childhood experience of neglect was modelled using a maternal separation (MS) paradigm, which was combined with a subsequent injury (mild traumatic brain injury (mTBI) or plantar incision surgery) in adolescent male and female Sprague-Dawley rats. We measured behavioural nociceptive sensitivity, systemic modulators of pain such as calcitonin gene-related protein (CGRP) and Substance P, as well as gene expression of IL1β, GFAP, GR, MR, GABRA1, CNR1, MAOA, and DAT1 in the cerebellum to examine associations between pain and neuroinflammation, the stress response, inhibitory neurotransmission, and monoaminergic function. We found increases in mechanical nociceptive sensitivity following plantar incision surgery. Sex differences were observed in anxiety-like behaviour and neuroinflammation, whereas systemic pain modulators showed cumulative effects with the addition of stressors. Most interestingly however, the increases in nociceptive sensitivity were associated with the suppressed expression of cerebellar genes that regulate stress, inhibition, cannabinoid function, and dopaminergic function, alongside sex-dependent distinctions for genes involved in inflammation and injury. This study highlights a novel link between nociception and molecular function in the cerebellum. Further investigation into how the cerebellum contributes to pain in males and females will facilitate novel therapeutic insights and opportunities.

Epithelial thinning in vaginal atrophy related to lowering of calcitonin gene-related protein, vascular endothelial growth factor, and nerve growth factor expressions in a menopausal rat model

Context: Vaginal atrophy has been observed as a common sexual problem in post-menopausal women. The targeted protein to counteract menopause problems related to vaginal epithelial thinning is currently a research problem that has not been fully investigated. Aims: To explore the possible mechanism underlying vaginal atrophy in rat models. Methods: Following three-week ovariectomy (OVX), Sprague-Dawley female rats were randomly divided into two groups and orally administered estradiol for two weeks in the treated group. In parallel with this, six rats with sham surgery were used as control. Marker-related vaginal atrophy, including calcitonin gene-related protein (CGRP), vascular endothelial growth factor (VEGF), and nerve growth factor (NGF) in the vaginal wall, were compared using immunohistochemistry. Results: OVX as a menopausal model significantly induced vaginal epithelial cell thinning and decreased the expression of CGRP, VEGF, and NGF compared with sham surgery animals (p<0.05). Estrogen replacement in OVX rats reversed the vaginal atrophic by recovering the protein expression CGRP, VEGF, and NGF (p<0.05). Conclusions: Thus, it may be concluded that a possible mechanism underlying the OVX-induced vaginal atrophy may be related to the downregulation expression of CGRP, VEGF, and NGF in vaginal tissue.

Adipose mTORC2 is essential for sensory innervation in white adipose tissue and whole-body energy homeostasis

ObjectiveAdipose tissue, via sympathetic and possibly sensory neurons, communicates with the central nervous system (CNS) to mediate energy homeostasis. In contrast to the sympathetic nervous system, the morphology, role and regulation of the sensory nervous system in adipose tissue are poorly characterized. Methods and resultsTaking advantage of recent progress in whole-mount three-dimensional imaging, we identified a network of calcitonin gene-related protein (CGRP)-positive sensory neurons in murine white adipose tissue (WAT). We found that adipose mammalian target of rapamycin complex 2 (mTORC2), a major component of the insulin signaling pathway, is required for arborization of sensory neurons, but not of sympathetic neurons. Time course experiments revealed that adipose mTORC2 is required for maintenance of sensory neurons. Furthermore, loss of sensory innervation in WAT coincided with systemic insulin resistance. Finally, we established that neuronal protein growth-associated protein 43 (GAP43) is a marker for sensory neurons in adipose tissue. ConclusionOur findings indicate that adipose mTORC2 is necessary for sensory innervation in WAT. In addition, our results suggest that WAT may affect whole-body energy homeostasis via sensory neurons.

Expression and Role of Calcitonin Gene-Related Peptide in Patients With Chronic Rhinosinusitis With Nasal Polyposis

Background and Objectives A recent study revealed that calcitonin gene-related protein (CGRP) plays an important role in inflammatory airway diseases. However, the influence of CGRP on chronic rhinosinusitis (CRS) has not been studied. This study investigated the expression, activity, and potential pathogenic role of CGRP in patients with CRS with nasal polyposis (CRSwNP).Subjects and Method Patients with CRSwNP and control subjects were enrolled. The CRSwNP group was divided according to the presence of eosinophilic polyps and non-eosinophilic polyps. Nasal polyps (NPs) and uncinate tissues (UTs) from patients with CRSwNP and UTs from control subjects were obtained to investigate the expression of α-/β-CGRP and chromogranin A. In addition, the expression patterns of cytokines following exposure to exogenous CGRP were analyzed in dispersed nasal polyp cells (DNPCs) from patients with eosinophilic or non-eosinophilic CRSwNP. The effects of CGRP on lipopolysaccharide (LPS)-induced nuclear factor-kappa light chain enhancer of activated B cells (NF-κB) signaling change were evaluated in THP-1 cells.Results The expression of α-/β-CGRP and number of CGRP-producing cells were significantly higher in NPs from patients with CRSwNP than in UTs from controls. Exogenous CGRP decreased the expression of inflammatory cytokines and increased that of the anti-inflammatory cytokines in DNPCs from patients with eosinophilic nasal polyps (EPs) and also increased the expression of tissue remodeling-related and anti-inflammatory cytokines in DNPCs from patients with non-eosinophilic nasal polyps (N-EPs). CGRP inhibited the nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor (IκB) phosphorylation and NF-κB translocation in LPS-stimulated M1 macrophages.Conclusion CGRP expression in NPs may play a significant role in nasal polypogenesis through inflammatory modulation, and it could be a future target to modulate certain aspects of CRSwNP.

Comparison of five diarrhea-predominant irritable bowel syndrome (IBS-D) rat models in the brain-gut-microbiota axis

The brain-gut-microbiota (BGM) axis is known to be essential for diarrhea-predominant irritable bowel syndrome (IBS-D). In order to evaluate the effects of IBS-D rat models (the central sensitization model, the peripheral sensitization model and the compound model) on the BGM axis, five models were induced in Wistar rats with 4% acetic acid (AD, dissolved 0.4 ml of AD in 9.6 ml of ultrapure water) + wrap restrain stress (WRS), 4% AD, colorectal distention (CRD), WRS, and neonatal maternal separation (NMS). Abdominal withdrawal reflex (AWR) scale scores and the moisture content of feces (MCF) were evaluated on the day of completing modeling. Body weight was measured every 7 days during modeling. Brain gut peptides, cytokine levels, the activity of spinal cord neurons, intestinal mucosal barrier function, and gut microbiota were determined after induction of IBS-D. We found intervention with 4% AD + WRS, 4% AD, CRD, WRS, and NMS induced a similar course of effects on the BGM axis. Among the five models, AWR scores (60 mmHg, 80 mmHg) were all increased. The levels of 5-hydroxytryptamine, corticotropin-releasing factor, substance P, and calcitonin gene-related protein in serum rapidly increased, whereas that of neuropeptide Y decreased. C-fos in the spinal cord showed increased neuronal activity. The intestinal permeability was increased and the composition and structure of gut microbiota were changed. In conclusion, the five models could cause changes in BGM axis, but the 4% AD + WRS model was closer to the changes BGM axis of post-inflammatory models of IBS-D.

Possible involvement of neuropeptide and neurotransmitter receptors in Adenomyosis

BackgroundAccumulating data indicate that sensory nerve derived neuropeptides such as substance P and calcitonin gene related-protein (CGRP) can accelerate the progression of endometriosis via their respective receptors, so can agonists to their respective receptors receptor 1 (NK1R), receptor activity modifying protein 1 (RAMP-1) and calcitonin receptor-like receptor (CRLR). Adrenergic β2 receptor (ADRB2) agonists also can facilitate lesional progression. In contrast, women with endometriosis appear to have depressed vagal activity, concordant with reduced expression of α7 nicotinic acetylcholine receptor (α7nAChR). The roles of these receptors in adenomyosis are completely unknown.MethodsAdenomyotic tissue samples from 30 women with adenomyosis and control endometrial tissue samples from 24 women without adenomyosis were collected and subjected to immunohistochemistry analysis of RAMP1, CRLR, NK1R, ADRB2 and α7nAChR, along with their demographic and clinical information. The extent of tissue fibrosis was evaluated by Masson trichrome staining.ResultsWe found that the staining levels of NK1R, CRLR, RAMP1 and ADRB2 were all significantly elevated in adenomyotic lesions as compared with control endometrium. In contrast, α7nAChR staining levels were significantly reduced. The severity of dysmenorrhea correlated positively with lesional ADRB2 staining levels.ConclusionsOur results suggest that SP, CGRP and noradrenaline may promote, while acetylcholine may stall, the progression of adenomyosis through their respective receptors on adenomyotic lesions. Additionally, through the activation of the hypothalamic-pituitary-adrenal (HPA)-sympatho-adrenal-medullary (SAM) axes and the lesional overexpression of ADRB2, adenomyosis-associated dysmenorrhea and adenomyotic lesions may be mutually promotional, forming a viscous feed-forward cycle.

In utero and lactational PCB exposure drives anatomic changes in the juvenile mouse bladder

Bladder dysfunction, including incontinence, difficulty emptying the bladder, or urgency to urinate is a pervasive health and quality of life concern. However, risk factors for developing these symptoms are not completely understood, and the influence of exposure to environmental chemicals, especially during development, on the formation and function of the bladder is understudied. Environmental contaminants such as polychlorinated biphenyls (PCBs) are known to pose a risk to the developing brain; however, their influence on the development of peripheral target organs, such as bladder, are unknown. To address this data gap, C57Bl/6J mouse dams were exposed to an environmentally-relevant PCB mixture at 0, 0.1, 1 or 6 mg/kg daily beginning two weeks prior to mating and continuing through gestation and lactation. Bladders were collected from offspring at postnatal days (P) 28–31. PCB concentrations were detected in bladders in a dose-dependent manner. PCB effects on the bladder were sex- and dose-dependent. Overall, PCB effects were observed in male, but not female, bladders. PCBs increased bladder volume and suburothelial βIII-tubulin-positive nerve density compared to vehicle control. A subset of these nerves were sensory peptidergic axons indicated by increased calcitonin gene-related protein (CGRP) positive nerve fibers in mice exposed to the highest PCB dose compared to the lowest PCB dose. PCB-induced increased nerve density was also positively correlated with the number of mast cells in the bladder, suggesting inflammation may be involved. There were no detectable changes in epithelial composition or apoptosis as indicated by expression of cleaved caspase 3, suggesting PCBs do not cause overt toxicity. Bladder volume changes were not accompanied by changes in bladder mass or epithelial thickness, indicating that obstruction was not likely involved. Together, these results are the first to suggest that following developmental exposure, PCBs can distribute to the bladder and alter neuroanatomic development and bladder volume in male mice.

The Mechanisms of Action of Botulinum Toxin Type A in Nociceptive and Neuropathic Pathways in Cancer Pain

Botulinum toxin type A (BoNT-A) is widely employed for cosmetic purposes and in the treatment of certain diseases such as strabismus, hemifacial spasm and focal dystonia among others. BoNT-A effect mainly acts at the muscular level by inhibiting the release of acetylcholine at presynaptic levels consequently blocking the action potential in the neuromuscular junction. Despite the great progress in approval and pharmaceutical usage, improvement in displacing BoNT-A to other pathologies has remained very limited. Patients under diagnosis of several types of cancer experience pain in a myriad of ways; it can be experienced as hyperalgesia or allodynia, and the severity of the pain depends, to some degree, on the place where the tumor is located. Pain relief in patients diagnosed with cancer is not always optimal, and as the disease progresses, transition to more aggressive drugs, like opioids is sometimes unavoidable. In recent years BoNT-A employment in cancer has been explored, as well as an antinociceptive drug; experiments in neuropathic, inflammatory and acute pain have been carried out in animal models and humans. Although its mechanism has not been fully known, evidence has shown that BoNT-A inhibits the secretion of pain mediators (substance P, Glutamate, and calcitonin gene related protein) from the nerve endings and dorsal root ganglion, impacting directly on the nociceptive transmission through the anterolateral and trigeminothalamic systems. The study aimed to collect available literature regarding molecular, physiological and neurobiological evidence of BoNT-A in cancer patients suffering from acute, neuropathic and inflammatory pain in order to identify possible mechanisms of action in which the BoNT-A could impact positively in pain treatment. BoNT-A could be an important neo-adjuvant and coadjuvant in the treatment of several types of cancer, to diminish pro-tumor activity and secondary pain.

Effect and mechanism of the CACNA2D1-CGRP pathway in osteoarthritis-induced ongoing pain

This study built an OA model in rats by monosodium iodoacetate (MIA) injection to determine the effects and mechanism of the voltage-dependent calcium channel subunit alpha-2/delta-1 (CACNA2D1)-calcitonin gene-related protein (CGRP) pathway in osteoarthritis (OA)-induced ongoing pain. CACNA2D1 expression was measured by qPCR assay, western blotting assay, and immunofluorescence. Pain behaviors in rats were assessed with the measurement of thermal paw withdrawal latency (PWL) and mechanical paw withdrawal threshold (PWT). The expression of CACNA2D1, neuropeptide Y (NPY), activating transcription factor 3 (ATF3), CGRP, protein kinase A (PKA), phosphorylated (p)-PKA, adenylyl cyclase (AC), protein kinase C (PKC), p-PKC, phospholipase C (PLC), and mitogen-activated protein kinase (MAPK) signaling pathway proteins were measured, OA rats had higher CACNA2D1 expression than normal rats. Knockdown of CACNA2D1 led to the elevation of the pain threshold of OA rats, and CACNA2D1 over-expression decreased the pain threshold of normal rats. Moreover, CACNA2D1 over-expression inhibited the expression of CGRP, up-regulated the expressions of NPY, ATF3, p-PKA, AC, p-PKC, PLC, p-Jun N-terminal kinase (JNK), and p-p38, and had no significant effect on phosphorylated extracellular signal-regulated kinase (p-ERK) expression in vivo and in vitro. Using this model of MIA-induced OA, we demonstrated that CACNA2D1 might be involved in the process of pain by modulating the CGRP and AC-PKA/PKC/MAPK signaling pathways in the dorsal root ganglion.

Oxytocin as a regulatory neuropeptide in the trigeminovascular system: Localization, expression and function of oxytocin and oxytocin receptors.

Recent clinical findings suggest that oxytocin could be a novel treatment for migraine. However, little is known about the role of this neuropeptide/hormone and its receptor in the trigeminovascular pathway. Here we determine expression, localization, and function of oxytocin and oxytocin receptors in rat trigeminal ganglia and targets of peripheral (dura mater and cranial arteries) and central (trigeminal nucleus caudalis) afferents. The methods include immunohistochemistry, messenger RNA measurements, quantitative PCR, release of calcitonin gene-related peptide and myography of arterial segments. Oxytocin receptor mRNA was expressed in rat trigeminal ganglia and the receptor protein was localized in numerous small to medium-sized neurons and thick axons characteristic of A∂ sensory fibers. Double immunohistochemistry revealed only a small number of neurons expressing both oxytocin receptors and calcitonin gene-related peptide. In contrast, double immunostaining showed expression of the calcitonin gene-related peptide receptor component receptor activity-modifying protein 1 and oxytocin receptors in 23% of the small cells and in 47% of the medium-sized cells. Oxytocin immunofluorescence was observed only in trigeminal ganglia satellite glial cells. Oxytocin mRNA was below detection limit in the trigeminal ganglia. The trigeminal nucleus caudalis expressed mRNA for both oxytocin and its receptor. K+-evoked calcitonin gene-related peptide release from either isolated trigeminal ganglia or dura mater and it was not significantly affected by oxytocin (10 µM). Oxytocin directly constricted cranial arteries ex vivo (pEC50 ∼ 7); however, these effects were inhibited by the vasopressin V1A antagonist SR49059. Oxytocin receptors are extensively expressed throughout the rat trigeminovascular system and in particular in trigeminal ganglia A∂ neurons and fibers, but no functional oxytocin receptors were demonstrated in the dura and cranial arteries. Thus, circulating oxytocin may act on oxytocin receptors in the trigeminal ganglia to affect nociception transmission. These effects may help explain hormonal influences in migraine and offer a novel way for treatment.

The role of CGRP receptor antagonist (CGRP8-37) and Endomorphin-1 combination therapy on neuropathic pain alleviation and expression of Sigma-1 receptors and antioxidants in rats

BackgroundSpinal cord injury is one of the most common causes of neuropathic pain which is not responsive to common treatments. Owing to the adverse effects of drugs, it seems that the use of Calcitonin Gene-Related Protein (CGRP) receptor antagonist or Morphine and their combination could be an appropriate strategy for pain alleviation. MethodTo achieve the objective, fifty six male Wistar rats were divided into seven groups. CGRP8-37 and Endomorphin-1 alone, and in combinated administration, as bolus and continues dose. Both mechanical and cold allodynia, and mechanical hyperalgesia were evaluated before and also15 and 60 min after injection to indicate the efficacy of the therapies in the acute and chronic circumstances on pain induced by spinal cord compression injury. Sigma-1 receptor experssion, oxidant and antioxidant activity after the seven days of the drug adminestration were evaluated. ResultThe results showed that Endomorphin-1and CGRP8-37 injections were able to reduce neuropathic pain after spinal cord compression injury. Compared to Endomorphin-1, or CGRP8-37 monotherapy, combination therapy did not show more attenuating effects on the pain threshold. Compared to the continous administration of Endomorphin-1 alone, and CGRP8-37 alone, the continous combination therapy did not reduce the pain further. Molecular studies disclosed the increased expression of the Sigma1 receptor, in the spinal cord after administration of Endomorphin-1, and CGRP8-37 alone, as well as combination therapy. Although, an increase in GPx and SOD activity, and decrease in MDA activity was observed in the combination therapy. ConclusionOur results demonstrate that either Endomorphin-1 or CGRP receptor antagonist is able to decrease the neuropathic pain after SCI but combination therapy by a CGRP receptor antagonist and Endomorphin-1 did not make any further reduction in pain sensation.

Serum Calcitonin Gene-Related Peptide and Receptor Protein Levels in Patients With Fibromyalgia Syndrome: A Cross-Sectional Study.

Objectives This study aims to compare the serum calcitonin gene-related peptide (CGRP) and CGRP receptor protein levels between patients with fibromyalgia syndrome (FM) and healthy control subjects.Patients and methods The study included 88 patients (7 males, 81 females; mean age 44.5±9.1 years; range, 20 to 72 years) newly-diagnosed with FM according to the 2010 American College of Rheumatology criteria and 88 healthy volunteers (6 males, 82 females; mean age 43.0±6.1 years; range, 20 to 57 years). Venous blood samples were collected from both groups for the measurement of the levels of serum CGRP and CGRP receptor proteins (receptor component protein [RCP], receptor activity modifying protein 1 [RAMP 1] and calcitonin receptor-like receptor [CLR]).Results A comparison of the serum CGRP, CLR and RCP levels of the FM and control groups revealed a statistically significant difference (p=0.001, p=0.005, p=0.001, respectively). The difference between the groups in respect of the serum RAMP 1 levels was not statistically significant (p=0.107). Conclusion The serum CGRP, CLR and RCP levels were found to be higher in the FM patients, but no difference was determined between the FM patients and the healthy control group in respect of the RAMP 1 level. These results can be of guidance for further clinical studies of the etiopathogenesis and treatment of FM.

Identifying spinal afferent (sensory) nerve endings that innervate the marrow cavity and periosteum using anterograde tracing.

While sensory and sympathetic neurons are known to innervate bone, previous studies have found it difficult to unequivocally identify and characterize only those that are of sensory origin. In this study, we have utilized an in vivo anterograde tracing technique to selectively label spinal afferent (sensory) nerve endings that innervate the periosteum and marrow cavity of murine long bones. Unilateral injections of dextran-biotin (anterograde tracer; 20% in saline, 50-100 nl) were made into L3-L5 dorsal root ganglia. After a 10-day recovery period to allow sufficient time for selective anterograde transport of the tracer to nerve terminal endings in bone, the periosteum (whole-mount) and underlying bone were collected, processed to reveal anterograde labeling, and immuno-labeled with antibodies directed against protein gene product (pan-neuronal marker; PGP9.5), tyrosine hydroxylase (sympathetic neuron marker; TH), calcitonin gene-related protein (peptidergic nociceptor marker; CGRP), and/or neurofilament 200 (myelinated axon marker; NF200). Anterograde-labeled nerve endings were dispersed throughout the periosteum and marrow cavity and could be identified in close apposition to blood vessels and at sites distant from them. The periosteum and the marrow cavity were each innervated by myelinated (NF200+) sensory neurons, and unmyelinated (NF200-) sensory neurons that were either peptidergic (CGRP+) or nonpeptidergic (CGRP-). Spinal afferent nerve endings did not express TH, and lacked the cylindrical morphology around blood vessels characteristic of sympathetic innervation. This approach to selective labeling of sensory nerve terminal endings will help to better identify how different sub-populations of sensory neurons, and their peripheral nerve terminal endings, interact with bone.

Structural and molecular characteristics of axons in the long head of the biceps tendon

The innervation of the long head of the biceps tendon (LHBT) is not sufficiently documented. This is a drawback since pathologies of the LHBT are a major source of shoulder pain. Thus, the study aimed to characterize structurally and molecularly nervous elements of the LHBT. The proximal part of 11 LHBTs was harvested intraoperatively. There were 8 female and 3 male specimens. Age ranged from 66 to 86 years. For structural analyses, nervous elements were viewed in the transmission electron microscope. For molecular characterization, we used general neuronal markers including antibodies against neurofilament and protein gene product 9.5 (PGP9.5) as well as specific neuronal markers including antibodies against myelin basic protein (MBP), calcitonin gene-related product (CGRP), substance P (SP), tyrosine hydroxylase (TH), and growth-associated protein 43 (GAP43). Anti-neurofilament and anti-PGP9.5 visualized the overall innervation. Anti-MBP visualized myelination, anti-CGRP and anti-SP nociceptive fibers, anti-TH sympathetic nerve fibers, and anti-GAP43 nerve fibers during development and regeneration. Immunolabeled sections were analyzed in the confocal laser scanning microscope. We show that the LHBT contains unmyelinated as well as myelinated nerve fibers which group in nerve fascicles and follow blood vessels. Manny myelinated and unmyelinated axons exhibit molecular features of nociceptive nerve fibers. Another subpopulation of unmyelinated axons exhibits molecular characteristics of sympathetic nerve fibers. Unmyelinated sympathetic fibers and unmyelinated nociceptive fibers express proteins that are found during development and regeneration. Present findings support the hypothesis that ingrowth of nociceptive fibers are the source of chronic tendon pain.

An orally administered magnoloside A ameliorates functional dyspepsia by modulating brain-gut peptides and gut microbiota

AimsFunctional dyspepsia (FD) is very common worldwide with a high prevalence of 10%–30%, and it becomes a heavy burden to patients because of its hard to be cured. In our previous study, phenylethanoid glycosides were found to exist in Houpo, a traditional Chinese medicine commonly used for the treatment of abdominal distention, pain and dyspepsia. In the present study, the effect of magnoloside A (MA), a main phenylethanoid glycoside in Houpo, on FD was firstly evaluated and its potential mechanism was concluded. Materials and methodsMA was orally administered consequently for 3 weeks, and its effect on a FD rat model established through transient neonatal gastric irritation and mature alternate-day fasting was tested. Levels of brain-gut peptides and inflammatory factors in blood or tissues were determined by ELISA methods. Meanwhile, the gut microbiota was analyzed by 16S rRNA gene sequencing and short chain fat acids were determined by GC/MS. Key findingsMA exhibited anti-FD activities by fastening the delayed gut emptying rate of FD rat and increasing the levels of gastrin, motilin, and calcitonin gene related protein; and decreasing the levels of 5-hydroxytryptamine, nitric oxide synthase, and vasoactive intestinal peptide. On the other hand, MA can modulate the composition of gut microbiota, resulting in the variation of the short chain fat acids. SignificanceMA ameliorated FD rats by modulating of the secretion of related brain-gut peptides and altering the composition of intestinal microbiota.