Vascular Actions of Calcitonin Gene-Related Peptide and Adrenomedullin

Nitroxyl (HNO): A Reduced Form of Nitric Oxide with Distinct Chemical, Pharmacological, and Therapeutic Properties

Nitroxyl (HNO), the one-electron reduced form of nitric oxide (NO), shows a distinct chemical and biological profile from that of NO. HNO is currently being viewed as a vasodilator and positive inotropic agent that can be used as a potential treatment for heart failure. The ability of HNO to react with thiols and thiol containing proteins is largely used to explain the possible biological actions of HNO. Herein, we summarize different aspects related to HNO including HNO donors, chemistry, biology, and methods used for its detection.

Isolation of Potent CGRP Neutralizing Antibodies Using Four Simple Assays

Calcitonin gene-related peptide (CGRP) is a small neuropeptide and a potent vasodilator that is widely associated with chronic pain and migraine. An antibody that inhibits CGRP function would be a potential therapeutic for treatment of these disorders. Here we describe the isolation of highly potent antibodies to CGRP from phage and ribosome display libraries and characterization of their epitope, species cross-reactivity, kinetics, and functional activity. Homogenous time-resolved fluorescence (HTRF) binding assays identified antibodies with the desired species cross-reactivity from naïve libraries, and HTRF epitope competition assays were used to characterize and group scFv by epitope. The functional inhibition of CGRP and species cross-reactivity of purified scFv and antibodies were subsequently confirmed using cAMP assays. We show that epitope competition assays could be used as a surrogate for functional cell-based assays during affinity maturation, in combination with scFv off-rate ranking by biolayer interferometry (BLI). This is the first time it has been shown that off-rate ranking can be predictive of functional activity for anti-CGRP antibodies. Here we demonstrate how, by using just four simple assays, diverse panels of antibodies to CGRP can be identified. These assay formats have potential utility in the identification of antibodies to other therapeutic targets.

Involvement of Receptor Activity-Modifying Protein 3 (RAMP3) in the Vascular Actions of Adrenomedullin in Rat Mesenteric Artery Smooth Muscle Cells

CALCB, ADM, and ADM2 are potent vasodilators that share a seven-transmembrane GPCR, calcitonin receptor-like receptor (CALCRL), whose ligand specificity is dictated by the presence of one of the three receptor activity-modifying proteins (RAMPs). We assessed the relative pharmacologic potency of these peptides in mesenteric artery smooth muscle cells (VSMCs) and the specific RAMP that mediates the effect of ADM in VSMCs. VSMCs, with or without RAMP knockdown, were treated with CALCB, ADM, or ADM2 in the presence or absence of their antagonists, CALCB8-37, ADM22-52, and ADM217-47, respectively, to assess the relative effect of peptides on cAMP production and their pharmacologic potency. Proximity ligation assay was used to assess the specific RAMP that associates with CALCRL to mediate the actions of ADM in VSMCs. All three peptides induced cAMP generation in VSMCs and the order of their potency is CALCB > ADM > ADM2. Effects of CALCB were blocked by CALCB8-37, ADM effects were blocked by CALCB8-37 and ADM217-47 but not ADM22-52, and ADM2 effects were blocked by all three antagonists. Knockdown of RAMP2 was ineffective, whereas knockdown of RAMP3 inhibited ADM-induced cAMP production in VSMCs, suggesting involvement of RAMP3 with CALCRL to mediate ADM effects. Absence of both RAMP2 and RAMP3 further increased CALCB-induced cAMP synthesis compared to control (P < 0.05). ADM increased CALCRL and RAMP3 association and RAMP3 knockdown inhibited the interaction of ADM with CALCRL.

Complementary and synergistic therapeutic effects of compounds found in Kampo medicine: analysis of daikenchuto

Herbal medicines have been used in Japan for more than 1500 years and traditional Japanese medicines (Kampo medicines) are now fully integrated into the modern healthcare system. In total, 148 Kampo formulae are officially approved as prescription drugs and covered by the national health insurance system in Japan. However, despite their long track record of clinical use, the multi-targeted, multi-component properties of Kampo medicines, which are fundamentally different from Western medicines, have made it difficult to create a suitable framework for conducting well-designed, large-scale clinical trials. In turn, this has led to misconceptions among western trained physicians concerning the paucity of scientific evidence for the beneficial effects of Kampo medicines. Fortunately, there has been a recent surge in scientifically robust data from basic and clinical studies for some of the Kampo medicines, e.g., daikenchuto (TU-100). Numerous basic and clinical studies on TU-100, including placebo-controlled double-blind studies for various gastrointestinal disorders, and absorption, distribution, metabolism and excretion (ADME) studies, have been conducted or are in the process of being conducted in both Japan and the USA. Clinical studies suggest that TU-100 is beneficial for postoperative complications, especially ileus and abdominal bloating. ADME and basic studies indicate that the effect of TU-100 is a composite of numerous actions mediated by multiple compounds supplied via multiple routes. In addition to known mechanisms of action via enteric/sensory nerve stimulation, novel mechanisms via the TRPA1 channel and two pore domain potassium channels have recently been elucidated. TU-100 compounds target these channels with and without absorption, both before and after metabolic activation by enteric flora, with different timings and possibly with synergism.

Microglia-Induced Maladaptive Plasticity Can Be Modulated by Neuropeptides In Vivo

Microglia-induced maladaptive plasticity is being recognized as a major cause of deleterious self-sustaining pathological processes that occur in neurodegenerative and neuroinflammatory diseases. Microglia, the primary homeostatic guardian of the central nervous system, exert critical functions both during development, in neural circuit reshaping, and during adult life, in the brain physiological and pathological surveillance. This delicate critical role can be disrupted by neural, but also peripheral, noxious stimuli that can prime microglia to become overreactive to a second noxious stimulus or worsen underlying pathological processes. Among regulators of microglia, neuropeptides can play a major role. Their receptors are widely expressed in microglial cells and neuropeptide challenge can potently influence microglial activity in vitro. More relevantly, this regulator activity has been assessed also in vivo, in experimental models of brain diseases. Neuropeptide action in the central nervous system has been associated with beneficial effects in neurodegenerative and neuroinflammatory pathological experimental models. This review describes some of the mechanisms of the microglia maladaptive plasticity in vivo and how neuropeptide activity can represent a useful therapeutical target in a variety of human brain pathologies.

Role of calcitonin gene-related peptide in cardioprotection of short-term and long-term exercise preconditioning

PURPOSE

To examine the role of calcitonin gene-related peptide (CGRP) in cardioprotection of short-term and long-term exercise preconditioning (EP).

METHODS

Male Sprague-Dawley rats were, respectively, subjected to continuous intermittent treadmill training 3 days or 3 weeks as short-term or long-term EP protocols. The myocardial injury induced by isoproterenol (ISO) was performed 24 hours after short-term and long-term EP. The myocardial injury was evaluated in terms of the serum cardiac troponin levels and the hematoxylin-basic fuchsin-picric acid staining. Additionally, serum CGRP levels, CGRP expression in the dorsal root ganglion (DRG), and heart were analyzed as possible mechanisms to explain short-term and long-term EP-induced cardioprotection.

RESULTS

Both short-term and long-term EP markedly attenuated the isoproterenol-induced myocardial ischemia with lower serum cardiac troponin levels. Short-term EP does not alter serum CGRP levels and CGRP expression in the DRG and heart. Long-term EP significantly increases serum CGRP levels and CGRP expression in the DRG and heart.

CONCLUSIONS

The results indicate that short-term EP does not increase the synthesis and release of CGRP. Therefore, the cardioprotective effect of short-term EP does not involve CGRP adaptation. Furthermore, long-term EP increases CGRP synthesis in the DRG and promotes CGRP release in the blood and heart. Hence, CGRP may play an important role in the cardioprotective effect of long-term EP.

Sensory nerves contribute to cutaneous vasodilator response to cathodal stimulation in healthy rats

Cutaneous current-induced vasodilation (CIV) in response to galvanic current application is an integrative model of neurovascular interaction that relies on capsaicin-sensitive fiber activation. The upstream and downstream mechanisms related to the activation of the capsaicin-sensitive fibers involved in CIV are not elucidated. In particular, the activation of cutaneous transient receptor potential vanilloid type-1 (TRPV1) channels and/or acid-sensing ion channels (ASIC) (activators mechanisms) and the release of calcitonin gene-related peptide (CGRP) and substance P (SP) (effector mechanisms) have been tested. To assess cathodal CIV, we measured cutaneous blood flow using laser Doppler flowmetry for 20min following cathodal current application (240s, 100μA) on the skin of the thigh in anesthetized healthy rats for 20min. CIV was studied in rats treated with capsazepine and amiloride to inhibit TRPV1 and ASIC channels, respectively; CGRP8-37 and SR140333 to antagonize CGRP and neurokinin-1 (NK1) receptors, respectively; compared to their respective controls. Cathodal CIV was attenuated by capsazepine (12±2% vs 54±6%, P<0.001), amiloride (19±8% vs 61±6%, P<0.01), CGRP8-37 (15±6% vs 61±6%, P<0.001) and SR140333 (9±5% vs 54±6%, P<0.001) without changing local acidification. This is the first integrative study performed in healthy rats showing that cutaneous vasodilation in response to cathodal stimulation is initiated by activation of cutaneous TRPV1 and ASIC channels likely through local acidification. The involvement of CGRP and NK1 receptors suggests that cathodal CIV is the result of CGRP and SP released through activated capsaicin-sensitive fibers. Therefore cathodal CIV could be a valuable method to assess sensory neurovascular function in the skin, which would be particularly relevant to evaluate the presence of small nerve fiber disorders and the effectiveness of treatments.

CGRP as a neuropeptide in migraine: lessons from mice

Migraine is a neurological disorder that is far more than just a bad headache. A hallmark of migraine is altered sensory perception. A likely contributor to this altered perception is the neuropeptide calcitonin gene-related peptide (CGRP). Over the past decade, CGRP has become firmly established as a key player in migraine. Although the mechanisms and sites of action by which CGRP might trigger migraine remain speculative, recent advances with mouse models provide some hints. This brief review focuses on how CGRP might act as both a central and peripheral neuromodulator to contribute to the migraine-like symptom of light aversive behaviour in mice.

Depressed perivascular sensory innervation of mouse mesenteric arteries with advanced age

KEY POINTS

The dilatory role for sensory innervation of mesenteric arteries (MAs) is impaired in Old (∼24 months) versus Young (∼4 months) mice. We investigated the nature of this impairment in isolated pressurized MAs. With perivascular sensory nerve stimulation, dilatation and inhibition of sympathetic vasoconstriction observed in Young MAs were lost in Old MAs along with impaired dilatation to calcitonin gene-related peptide (CGRP). Inhibiting NO and prostaglandin synthesis increased CGRP EC50 in Young and Old MAs. Endothelial denudation attenuated dilatation to CGRP in Old MAs yet enhanced dilatation to CGRP in Young MAs while abolishing all dilatations to ACh. In Old MAs, sensory nerve density was reduced and RAMP1 (CGRP receptor component) associated with nuclear regions of endothelial cells in a manner not seen in Young MAs or in smooth muscle cells of either age. With advanced age, loss of dilatory signalling mediated through perivascular sensory nerves may compromise perfusion of visceral organs.

ABSTRACT

Vascular dysfunction and sympathetic nerve activity increase with advancing age. In the gut, blood flow is governed by perivascular sensory and sympathetic nerves but little is known of how their functional role is affected by advanced age. We tested the hypothesis that functional sensory innervation of mesenteric arteries (MAs) is impaired for Old (24 months) versus Young (4 months) C57BL/6 male mice. In cannulated pressurized MAs preconstricted 50% with noradrenaline and treated with guanethidine (to inhibit sympathetic neurotransmission), perivascular nerve stimulation (PNS) evoked dilatation in Young but not Old MAs while dilatations to ACh were not different between age groups. In Young MAs, capsaicin (to inhibit sensory neurotransmission) blocked dilatation and increased constriction during PNS. With no difference in efficacy, the EC50 of CGRP as a vasodilator was ∼6-fold greater in Old versus Young MAs. Inhibiting nitric oxide (l-NAME) and prostaglandin (indomethacin) synthesis increased CGRP EC50 in both age groups. Endothelial denudation reduced the efficacy of dilatation to CGRP by ∼30% in Old MAs yet increased this efficacy ∼15% in Young MAs while all dilatations to ACh were abolished. Immunolabelling revealed reduced density of sensory (CGRP) but not sympathetic (tyrosine hydroxylase) innervation for Old versus Young MAs. Whereas the distribution of CGRP receptor proteins was similar in SMCs, RAMP1 associated with nuclear regions of endothelial cells of Old but not Young MAs. With advanced age, the loss of sensory nerve function and diminished effectiveness of CGRP as a vasodilator is multifaceted and may adversely affect splanchnic perfusion.

Meningeal blood flow is controlled by H2 S-NO crosstalk activating a HNO-TRPA1-CGRP signalling pathway

BACKGROUND AND PURPOSE

Meningeal blood flow is controlled by CGRP released from trigeminal afferents and NO mainly produced in arterial endothelium. The vasodilator effect of NO may be due to the NO-derived compound, nitroxyl (HNO), generated through reaction with endogenous H2 S. We investigated the involvement of HNO in CGRP release and meningeal blood flow.

EXPERIMENTAL APPROACH

Blood flow in exposed dura mater of rats was recorded by laser Doppler flowmetry. CGRP release from the dura mater in the hemisected rat head was quantified using an elisa. NO and H2 S were localized histochemically with specific sensors.

KEY RESULTS

Topical administration of the NO donor diethylamine-NONOate increased meningeal blood flow by 30%. Pretreatment with oxamic acid, an inhibitor of H2 S synthesis, reduced this effect. Administration of Na2 S increased blood flow by 20%, an effect abolished by the CGRP receptor antagonist CGRP8-37 or the TRPA1 channel antagonist HC030031 and reduced when endogenous NO synthesis was blocked. Na2 S dose-dependently increased CGRP release two- to threefold. Co-administration of diethylamine-NONOate facilitated CGRP release, while inhibition of endogenous NO or H2 S synthesis lowered basal CGRP release. NO and H2 S were mainly localized in arterial vessels, HNO additionally in nerve fibre bundles. HNO staining was lost after treatment with L-NMMA and oxamic acid.

CONCLUSIONS AND IMPLICATIONS

NO and H2 S cooperatively increased meningeal blood flow by forming HNO, which activated TRPA1 cation channels in trigeminal fibres, inducing CGRP release. This HNO-TRPA1-CGRP signalling pathway may be relevant to the pathophysiology of headaches.

Therapeutic use of botulinum toxin in migraine: mechanisms of action

Migraine pain represents sensations arising from the activation of trigeminal afferents, which innervate the meningeal vasculature and project to the trigeminal nucleus caudalis (TNC). Pain secondary to meningeal input is referred to extracranial regions innervated by somatic afferents that project to homologous regions in the TNC. Such viscerosomatic convergence accounts for referral of migraine pain arising from meningeal afferents to particular extracranial dermatomes. Botulinum toxins (BoNTs) delivered into extracranial dermatomes are effective in and approved for treating chronic migraine pain. Aside from their well-described effect upon motor endplates, BoNTs are also taken up in local afferent nerve terminals where they cleave soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins, and prevent local terminal release. However, a local extracranial effect of BoNT cannot account for allthe effects of BoNT upon migraine. We now know that peripherally delivered BoNTs are taken up in sensory afferents and transported to cleave SNARE proteins in the ganglion and TNC, prevent evoked afferent release and downstream activation. Such effects upon somatic input (as from the face) likewise would not alone account for block of input from converging meningeal afferents. This current work suggests that BoNTs may undergo transcytosis to cleave SNAREs in second-order neurons or in adjacent afferent terminals. Finally, while SNAREs mediate exocytotic release, they are also involved in transport of channels and receptors involved in facilitated pain states. The role of such post-synaptic effects of BoNT action in migraine remains to be determined.

Calcitonin gene-related peptide and vascular endothelial growth factor are expressed in lesional but not uninvolved skin in chronic spontaneous urticaria

BACKGROUND

The mechanisms for producing weals in chronic spontaneous (idiopathic) urticaria (CSU) are incompletely understood. Leucocyte infiltration with vascular leakage and expression of the potent vasoactive agents' calcitonin gene-related peptide (CGRP) and vascular endothelial growth factor (VEGF) are features of late-phase allergic skin reactions, previously proposed as a model of CSU.

OBJECTIVE

To measure CGRP and VEGF expression in lesional and non-lesional skin from CSU patients and to compare results with a control group.

METHODS

Eight paired biopsies (one from 4-8 h spontaneous weals and one from uninvolved skin) were taken from eight patients with CSU and nine control subjects and studied by immunohistochemistry and confocal microscopy.

RESULTS

Lesional skin in CSU contained significantly more CGRP+ and VEGF+ cells than non-lesional skin. No significant differences were observed in CGRP and VEGF expression between non-lesional skin and controls. In lesional skin, VEGF and CGRP co-localised to UEA-1+ blood vessels. CGRP was also expressed by neutrophils and eosinophils and to a lesser extent by CD90(+) fibroblasts, mast cells, CD3(+) and CD68(+) cells. CGRP and VEGF expression was not related to the duration of disease.

CONCLUSION AND CLINICAL RELEVANCE

Increased expression of CGRP and VEGF in lesional, but not uninvolved, skin indicates that these potent vasoactive agents may play a role in wealing and tissue oedema in CSU so representing novel targets in therapy.

Calcitonin gene-related peptide regulates mitogen-activated protein kinase pathway to decrease transforming growth factor β1-induced hepatic plasminogen activator inhibitor-1 mRNA expression in HepG2 cells

Transforming growth factor (TGF) β1-induced plasminogen activator inhibitor (PAI)-1 is one of factors associated with the development of hepatic fibrosis. Calcitonin gene-related peptide (CGRP) shows hepatoprotective effect during hepatic injuries, including fibrosis. However, the effects of CGRP on PAI-1 expression induced by TGFβ1 are unknown. In this study, we investigated the effect of CGRP on TGFβ1-induced PAI-1 expression and its regulatory mechanisms in HepG2 cells. CGRP inhibited TGFβ1-induced PAI-1 expression. H89, a protein kinase A inhibitor, abolished the inhibition of TGFβ1-induced PAI-1 expression by CGRP. TGFβ1 activated mitogen-activated protein kinase (MAPK), including extracellular signal-regulated kinase, c-jun NH2-terminal kinase, and p38, and this activation was abolished by CGRP. These results show that the CGRP-induced cAMP/PKA activation suppresses activation of MAPK induced by TGFβ1, leading to decreased PAI-1 expression in HepG2 cells.

Neuropeptide receptors as potential drug targets in the treatment of inflammatory conditions

Cross-talk between the nervous, endocrine and immune systems exists via regulator molecules, such as neuropeptides, hormones and cytokines. A number of neuropeptides have been implicated in the genesis of inflammation, such as tachykinins and calcitonin gene-related peptide. Development of their receptor antagonists could be a promising approach to anti-inflammatory pharmacotherapy. Anti-inflammatory neuropeptides, such as vasoactive intestinal peptide, pituitary adenylate cyclase-activating polypeptide, α-melanocyte-stimulating hormone, urocortin, adrenomedullin, somatostatin, cortistatin, ghrelin, galanin and opioid peptides, are also released and act on their own receptors on the neurons as well as on different inflammatory and immune cells. The aim of the present review is to summarize the most prominent data of preclinical animal studies concerning the main pharmacological effects of ligands acting on the neuropeptide receptors. Promising therapeutic impacts of these compounds as potential candidates for the development of novel types of anti-inflammatory drugs are also discussed.

Pharmacological evidence that histamine H3 receptors inhibit the vasodepressor responses by selective stimulation of the rat perivascular sensory CGRPergic outflow

This study has investigated whether pharmacological activation of Gi/o coupled histamine H3/H4 receptors inhibits the rat vasodepressor sensory outflow. For this purpose, 100 male Wistar rats were pithed, artificially ventilated and pretreated (i.v.) with: 25mg/kg gallamine, 2mg/kg/min hexamethonium and 20μg/kg/min methoxamine, followed by i.v. continuous infusions of physiological saline (0.02ml/min) or immepip (3.1, 10 or 31μg/kg/min; a histamine H3/H4 receptor agonist). Under these conditions, electrical stimulation (0.56-5.6Hz; 50V and 2ms) of the spinal cord (T9-T12) resulted in frequency-dependent vasodepressor responses, which were: (i) unchanged during the infusions of saline or immepip (3.1μg/kg/min); and (ii) significantly but, surprisingly, not dose-dependently inhibited by 10 and 31μg/kg/min immepip. Moreover, the sensory-inhibition by 10μg/kg/min immepip (which failed to inhibit the vasodepressor responses by i.v. bolus injections of α-CGRP; 0.1-1µg/kg) was: (i) essentially unaltered after i.v. administration of saline (1ml/kg) or blocking doses of the antagonists ketotifen (100μg/kg; H1), ranitidine (1000μg/kg; H2) or JNJ7777120 (310μg/kg; H4); and (ii) abolished after i.v. thioperamide (310µg/kg; H3). In conclusion, our results suggest that immepip-induced inhibition of the vasodepressor sensory outflow is mainly mediated by prejunctional activation of histamine H3 receptors.

Calcitonin gene-related peptide inhibits human immunodeficiency type 1 transmission by Langerhans cells via an autocrine/paracrine feedback mechanism

AIM

Peripheral neurones innervating mucosal epithelia are in direct contact with resident immune cells, including Langerhans cells (LCs). Such neurones secrete the neuropeptide calcitonin gene-related peptide (CGRP) that modulates LCs function. We recently found that CGRP strongly inhibits human immunodeficiency virus type 1 (HIV-1) transmission, by interfering with multiple steps of mucosal LC-mediated HIV-1 transfer, including increased expression of the LC-specific lectin langerin. Herein, we investigated the anti-HIV-1 mechanism of CGRP.

METHODS

In the presence of CGRP, HIV-1 transfer from LCs to CD4+ T cells was tested with viral clones using either the HIV-1 co-receptor CCR5 (R5) or CXCR4 (X4). Surface expression of CCR5, CXCR4 and langerin was evaluated by flow cytometry. CGRP secretion by LCs was measured with an enzyme immunoassay. Expression of the multimeric CGRP receptor was examined by quantitative real-time RT-PCR and immuno-fluorescent microscopy.

RESULTS

Calcitonin gene-related peptide decreased transfer of HIV-1 R5, but increased that of X4. These opposing effects correlated with decreased CCR5 vs. increased CXCR4 surface expression in LCs. Inhibition of HIV-1 R5 transfer by CGRP involved signal transducer and activator of transcription 4 (STAT4) activation. Both αCGRP and βCGRP were similarly efficient in decreasing HIV-1 R5 transfer and increasing langerin expression. LCs secreted low basal levels of endogenous CGRP, which increased markedly following CGRP treatment. CGRP also increased expression of its cognate receptor in LCs.

CONCLUSION

CGRP engages a positive feedback mechanism that would further enhance its anti-HIV-1 activity. This information might be relevant for the therapeutic use of CGRP as a prophylactic agent against HIV-1.

Fasting serum CGRP levels are related to calcium concentrations, but cannot be elevated by short-term calcium/vitamin D supplementation

Calcitonin gene-related peptide (CGRP) is an important cardioprotective neuropeptide. Few studies have shown that calcium supplementation may increase CGRP levels transiently. However, the relationship between CGRP and calcium is poorly known. This study was to explore the correlation between serum calcium and CGRP in coronary artery disease (CAD), and observe whether short-term calcium/vitamin D supplementation would increase fasting serum CGRP. A randomized, placebo-controlled and double-blind clinical trial, and a supplementary study for further analysis of the correlations were conducted. The results showed that the correlation between serum calcium and CGRP was positive in CAD without myocardial infarction (MI) (r = 0.487, P = 0.029), but negative in acute and healing MI (r = -0.382, P = 0.003). Moreover, we found a positive correlation between lg (amino-terminal pro-B-type natriuretic peptide, NT-proBNP) and CGRP (r = 0.312, P = 0.027), but a negative correlation between lg (NT-proBNP) and serum calcium (r = -0.316, P = 0.025) in acute and healing MI. As to the clinical trial, participants subjected to CAD but without evolving or acute MI, together with blood calcium ≤ 2.4 mmol/L, were randomized into three groups. Among the groups of placebo, caltrate (600 mg elemental calcium; 125 IU vitamin D3, per tablet) 1 tablet/d and caltrate 2 tablets/d, there were no significant differences in baseline characteristics. After short-term (5 days) treatments, the results indicated that the effect of grouping was not statistically significant (P = 0.915). In conclusion, the correlations between serum calcium and CGRP in different types of CAD are inconsistent, and the main reason may be associated with elevated natriuretic peptides after acute MI. Further, our study shows that short-term calcium/vitamin D supplementation cannot significantly increase fasting serum CGRP levels.

Neurotrophins and neuropeptides as inflammatory mediators in case of chronic dermatosis

This literature review examines the role of neurotrophins and neuropeptides for the development of skin inflammatory reactions in case of chronic inflammatory dermatoses. The article describes inflammatory effects of neurotrophin, a nerve growth factor, neuropeptide substance P and calcitonin gene-related peptide. Factors affecting the condition of skin innervation and development of inflammation - neurotrophin, a nerve growth factor, amphiregulin, an epidermal growth factor, and semaphorin 3A, a nerve repulsion factor - were examined. Searching for and administering antagonists of proinflammatory effects of neuropeptides, neurotrophins and epidermal growth factor can become new approaches to the treatment of chronic inflammatory dermatoses.

Sensory nerves and pancreatitis

Sensory nerves are a kind of nerve that conduct afferent impulses from the periphery receptors to the central nervous system (CNS) and are able to release neuromediators from the activated peripheral endings. Sensory nerves are particularly important for microcirculatory response, and stimulation of pancreatic sensory nerves releases a variety of neuropeptides such as substance P (SP), calcitonin gene-related peptide (CGRP), etc., leading to neurogenic inflammation characterized as the local vasodilatation and plasma extravasation. Deactivation of sensory nerves often leads to the disturbances of pancreatic microcirculation. Pancreatitis is a common digestive disease that can lead to severe complications and even death if it goes untreated. Experimental studies in animals and tissue analysis in patients with pancreatitis have shown significant changes in sensory nerves supplying the pancreatic gland. Thus making clear the whole mechanism of pancreatitis is essential to treat and cure it. Sensory nerves may have a close correlation with the development of pancreatitis, and knowing more about the role of sensory nerve in pancreatitis is important for the treatment for pancreatitis. This review is aimed to summarize the relationship between sensory nerves and pancreatitis.

Effects of stellate ganglion block on the peri-operative vasomotor cytokine content and intrapulmonary shunt in patients with esophagus cancer

OBJECTIVE

To investigate the effects of stellate ganglion block (SGB) on the peri-operative vasomotor cytokine content and intrapulmonary shunt in patients with esophagus cancer who underwent thoracotomy.

MATERIALS AND METHODS

Forty patients undergoing elective resection of esophageal cancer patients who had I~II American Society of Anesthesiologist (ASA) were randomly divided into total intravenous anesthesia group (group N, n=20) and total intravenous anesthesia combined with SGB group (group S, n=20, 0.12 mL/kg 1% lidocaine was used for SGB 10 min before induction). Heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP), mean pulmonary arterial pressure (MPAP) and continuous cardiac output (CCO) were continuously monitored. The blood from internal jugular vein was drawn respectively before induction (T0), and 30 min (T1), 60 min (T2) and 120 min (T3) after one-lung ventilation (OLV), and 30 min (T4) after two-lung ventilation. The contents of plasma endothelin (ET), nitric oxide (NO) and calcitonin gene-related peptide (CGRP) were detected with enzyme linked immunosorbent assay (ELISA). Meanwhile, arterial and mixed venous blood samples were collected for determination of blood gas and calculation of intrapulmonary shunt fraction (Qs/Qt).

RESULTS

During OLV, ET contents were increased significantly in two groups (P<0.05), and no significant difference was presented (P>0.05). NO content in group S was obviously higher than in group N at T3 (P<0.05), whereas CGRP content in group N was markedly lower than in group S at each time point (P<0.05). Qs/Qt was significantly increased in both groups after OLV, but there was no statistical significant regarding the Qs/Qt at each time point between two groups.

CONCLUSIONS

Total intravenous anesthesia combined with SGB is conducive to regulation of perioperative vasomotor cytokines in thoracotomy, and has little effect on intrapulmonary shunt at the time of OLV.

Calcitonin gene-related peptide (CGRP): a new target for migraine

Migraine is a neurological disorder that manifests as a debilitating headache associated with altered sensory perception. The neuropeptide calcitonin gene-related peptide (CGRP) is now firmly established as a key player in migraine. Clinical trials carried out during the past decade have proved that CGRP receptor antagonists are effective for treating migraine, and antibodies to the receptor and CGRP are currently under investigation. Despite this progress in the clinical arena, the mechanisms by which CGRP triggers migraine remain uncertain. This review discusses mechanisms whereby CGRP enhances sensitivity to sensory input at multiple levels in both the periphery and central nervous system. Future studies on epistatic and epigenetic regulators of CGRP actions are expected to shed further light on CGRP actions in migraine. In conclusion, targeting CGRP represents an approachable therapeutic strategy for migraine.

Progression and reversal of coronary and mesenteric vascular dysfunction associated with obesity

OBJECTIVE

The purpose of this study was to examine progression and reversal of microvascular complications when rats were fed a high fat diet.

METHODS

Sprague-Dawley rats 10 weeks of age were fed a diet containing 45% kcal fat for up to 32 weeks. Blood pressure and heart rate was measured by telemetry. Vascular reactivity of aorta and small coronary and mesenteric vessels was determined after 8, 16, 24, and 32 weeks on diet.

RESULTS

There was a modest increase in weight and blood pressure in high fat fed rats. Sodium nitroprusside (SNP)-induced relaxation of coronary arteries was potentiated after 8 weeks on high fat diet, however, this enhanced response was not observed after 16, 24, or 32 weeks of diet. Acetylcholine (Ach) mediated relaxation was attenuated after 16, 24, and 32 weeks of high fat diet in coronary arteries; however, in aorta and mesenteric arteries, Ach-mediated response was not altered until 32 weeks on high fat diet. Reversing the high fat diet for 8 weeks resulted in partial recovery of metabolic parameters; however endothelial function in coronary arteries remained impaired.

CONCLUSIONS

These studies indicate that high fat diet promotes progressive impairment of coronary vascular function that is difficult to reverse.

Calcitonin gene-related peptide: physiology and pathophysiology

Calcitonin gene-related peptide (CGRP) is a 37-amino acid neuropeptide. Discovered 30 years ago, it is produced as a consequence of alternative RNA processing of the calcitonin gene. CGRP has two major forms (α and β). It belongs to a group of peptides that all act on an unusual receptor family. These receptors consist of calcitonin receptor-like receptor (CLR) linked to an essential receptor activity modifying protein (RAMP) that is necessary for full functionality. CGRP is a highly potent vasodilator and, partly as a consequence, possesses protective mechanisms that are important for physiological and pathological conditions involving the cardiovascular system and wound healing. CGRP is primarily released from sensory nerves and thus is implicated in pain pathways. The proven ability of CGRP antagonists to alleviate migraine has been of most interest in terms of drug development, and knowledge to date concerning this potential therapeutic area is discussed. Other areas covered, where there is less information known on CGRP, include arthritis, skin conditions, diabetes, and obesity. It is concluded that CGRP is an important peptide in mammalian biology, but it is too early at present to know if new medicines for disease treatment will emerge from our knowledge concerning this molecule.

The effect of high-fat diet and streptozotocin-induced diabetes and endurance training on plasma levels of calcitonin gene-related peptide and lactate in rats

OBJECTIVE

The aim of this study was to investigate the effect of type 2 diabetes induced by high-fat diet and streptozotocin, and the effect of endurance training on basal circulating levels of calcitonin gene-related peptide (CGRP) and lactate.

METHODS

Male Wistar rats were randomly divided into 4 groups: 1) control (n=8); 2) trained (n=8); 3) diabetic (n=8) and 4) trained diabetic (n=8). At the age of 7 weeks, diabetes was induced by feeding the animals a high-fat diet and injecting them with a low dose of streptozotocin (35 mg/kg). The animals at 10 weeks of age underwent an endurance training protocol on a treadmill for 7 weeks. Plasma lactate concentrations were measured by a lactate assay kit, and an enzyme immunoassay kit was used to measure CGRP.

RESULTS

The diabetic rats showed significant increases in plasma CGRP (3.0±1 ng/mL vs. 0.5±0.3 ng/mL, p<0.001) and plasma lactate levels (3.6±0.5 mmol/L vs. 1.3±0.5 mmol/L, p<0.001). Further, significant decrease in basal plasma lactate (2.6±0.5 mmol/L vs. 3.6±0.5 mmol/L, p<0.025) but not plasma CGRP levels (2.5±1.2 ng/mL vs. 3.0±1.3 ng/mL) were found in the diabetic subjects after the endurance training.

CONCLUSIONS

The results showed that endurance training could modify the basal circulating levels of lactate but not CGRP, which were elevated in this model of type 2 diabetic rats, indicating the lack of correspondence between the endurance training-induced changes of lactate and CGRP in this model of diabetes.

Upregulation of pronociceptive mediators and downregulation of opioid peptide by adrenomedullin following chronic exposure to morphine in rats

Adrenomedullin (AM) belongs to a calcitonin gene-related peptide (CGRP) family and has been demonstrated to recruit CGRP following chronic use of morphine and neuronal nitric oxide synthase (nNOS) in inflammation. The present study investigated the possibility that AM initiates the changes of other molecules contributing to the development of morphine tolerance in its chronic use. Intrathecal (i.t.) co-administration of the AM receptor antagonist AM22-52 (35.8 μg) inhibited tolerance to morphine-induced analgesia while a daily injection of the AM receptor agonist AM1-50 (8 μg, i.t., bolus) for 9 days induced a decrease in the potency of morphine analgesia and thermal hyperalgesia. Persistent exposure of cultured dorsal root ganglion (DRG) explants to morphine (3.3 μM) for 4 days resulted in an increase in AM and CGRP mRNA levels. However, morphine failed to produce these effects in the presence of AM22-52 (2 μM). The i.t. administration of morphine for 6 days increased the expression of nNOS in the spinal dorsal horn and DRG neurons but decreased expression of the endogenous opioid peptide bovine adrenal medulla 22 (BAM22) in small- and medium-sized neurons in DRG. Particularly, the co-administration of AM22-52 (35.8 μg) inhibited the morphine-induced alterations in nNOS and BAM22. These results indicated that the increase in nNOS and CGRP expressions and the decrease in BAM22 were attributed to the increased AM receptor signaling induced by chronic morphine. The present study supports the hypothesis that the enhancement of AM bioactivity triggered upregulation of pronociceptive mediators and downregulation of pain-inhibiting molecule in a cascade contributing to the development of morphine tolerance.

Induction of adrenomedullin 2/intermedin expression by thyroid stimulating hormone in thyroid

TSH is the important regulator of thyroid function but detailed molecular mechanisms have not been clarified. We first generated the iodine deficient (ID) rat in which goiter is induced by accelerated endogenous TSH secretion. The result of microarray analysis demonstrated markedly increased levels of adrenomedullin 2/intermedin (AM2/IMD) expression in the ID rat thyroid. AM2/IMD is a potent vasodilator. AM2/IMD mRNA expression was induced by TSH in a rat thyroid follicular cell line FRTL-5. Immunohistochemical analysis in human normal and Graves' disease thyroid revealed that AM2/IMD immunoreactivity was detected in follicular cells and more pronounced in Graves' disease. These results indicated that TSH induced AM2/IMD expression in the rat thyroid gland and it could locally work as a potent vasodilator, resulting in the expansion of thyroid inter-follicular capillaries. AM2/IMD could also contribute to facilitate thyroid hormone synthesis possibly via vasodilation effects and/or cAMP stimulating effects in the human thyroid gland.

H2S and NO cooperatively regulate vascular tone by activating a neuroendocrine HNO-TRPA1-CGRP signalling pathway

Nitroxyl (HNO) is a redox sibling of nitric oxide (NO) that targets distinct signalling pathways with pharmacological endpoints of high significance in the treatment of heart failure. Beneficial HNO effects depend, in part, on its ability to release calcitonin gene-related peptide (CGRP) through an unidentified mechanism. Here we propose that HNO is generated as a result of the reaction of the two gasotransmitters NO and H₂S. We show that H₂S and NO production colocalizes with transient receptor potential channel A1 (TRPA1), and that HNO activates the sensory chemoreceptor channel TRPA1 via formation of amino-terminal disulphide bonds, which results in sustained calcium influx. As a consequence, CGRP is released, which induces local and systemic vasodilation. H₂S-evoked vasodilatatory effects largely depend on NO production and activation of HNO–TRPA1–CGRP pathway. We propose that this neuroendocrine HNO–TRPA1–CGRP signalling pathway constitutes an essential element for the control of vascular tone throughout the cardiovascular system.

Nitric oxide (NO) and hydrogen sulphide (H₂S) are two gaseous signalling molecules produced in tissues. Here the authors propose that NO and H₂S react with each other to form nitroxyl (HNO), which activates the TRPA1 channel in nerve cells and triggers the release of the vasoactive peptide CGRP.

Relations between metabolic homeostasis, diet, and peripheral afferent neuron biology

It is well established that food intake behavior and energy balance are regulated by crosstalk between peripheral organ systems and the central nervous system (CNS), for instance, through the actions of peripherally derived leptin on hindbrain and hypothalamic loci. Diet- or obesity-associated disturbances in metabolic and hormonal signals to the CNS can perturb metabolic homeostasis bodywide. Although interrelations between metabolic status and diet with CNS biology are well characterized, afferent networks (those sending information to the CNS from the periphery) have received far less attention. It is increasingly appreciated that afferent neurons in adipose tissue, the intestines, liver, and other tissues are important controllers of energy balance and feeding behavior. Disruption in their signaling may have consequences for cardiovascular, pancreatic, adipose, and immune function. This review discusses the diverse ways that afferent neurons participate in metabolic homeostasis and highlights how changes in their function associate with dysmetabolic states, such as obesity and insulin resistance.

A novel oral dual amylin and calcitonin receptor agonist (KBP-042) exerts antiobesity and antidiabetic effects in rats

The present study investigated a novel oral dual amylin and calcitonin receptor agonist (DACRA), KBP-042, in head-to-head comparison with salmon calcitonin (sCT) with regard to in vitro receptor pharmacology, ex vivo pancreatic islet studies, and in vivo proof of concept studies in diet-induced obese (DIO) and Zucker diabetic fatty (ZDF) rats. In vitro, KBP-042 demonstrated superior binding affinity and activation of amylin and calcitonin receptors, and ex vivo, KBP-042 exerted inhibitory action on stimulated insulin and glucagon release from isolated islets. In vivo, KBP-042 induced a superior and pronounced reduction in food intake in conjunction with a sustained pair-fed corrected weight loss in DIO rats. Concomitantly, KBP-042 improved glucose homeostasis and reduced hyperinsulinemia and hyperleptinemia in conjunction with enhanced insulin sensitivity. In ZDF rats, KBP-042 induced a superior attenuation of diabetic hyperglycemia and alleviated impaired glucose and insulin tolerance. Concomitantly, KBP-042 preserved insulinotropic and induced glucagonostatic action, ultimately preserving pancreatic insulin and glucagon content. In conclusion, oral KBP-042 is a novel DACRA, which exerts antiobesity and antidiabetic efficacy by dual modulation of insulin sensitivity and directly decelerating stress on the pancreatic α- and β-cells. These results could provide the basis for oral KBP-042 as a novel therapeutic agent in type 2 diabetes.

Corticosteroids alter CGRP and melatonin release in cluster headache episodes

BACKGROUND

Calcitonin gene-related peptide (CGRP) is a marker of trigeminal activation in acute cluster headache (CH). Melatonin production is altered in CH patients and may reflect hypothalamic dysfunction. We assessed the effects of short-term CH prevention with corticosteroids on CGRP and melatonin release in a prospective observational cohort study hypothesizing that corticosteroids influence the interictal activity of both systems indicated by the change of these biomarkers.

METHODS

Episodic CH subjects (n = 9) in the bout and controls with multiple sclerosis (n = 6) received 1000 mg/d methylprednisolone (MPD) i.v. for three days followed by oral tapering with prednisone. We determined CGRP plasma levels in external jugular vein blood outside an attack and 6-sulfatoxymelatonin (aMT6s) - the stable metabolite of melatonin - in 12-hour day- and nighttime urine collection prior to and several times after MPD therapy and again when CH subjects were outside the bout in complete remission. CH patients recorded the frequency of attacks.

RESULTS

In parallel to the reduction of headache frequency, administration of corticosteroids resulted in significantly decreased CGRP plasma levels and increased nocturnal aMT6s urine excretion in CH subjects. No significant changes were observed in controls.

CONCLUSION

Corticosteroids alter CGRP plasma and aMT6s urine levels in a cluster bout. These changes may indicate an effect of corticosteroids on trigeminal activation and hypothalamic dysfunction.

Ultraviolet B irradiation reduces the expression of adiponectin in ovarial adipose tissues through endocrine actions of calcitonin gene-related peptide-induced serum amyloid A

Ultraviolet (UV) B irradiation decreases blood adiponectin levels, but the mechanism is not well understood. This study investigated how UVB irradiation reduces adiponectin expression in ovarial adipose tissues. Female Hos:HR-1 hairless mice were exposed to UVB (1.6 J/cm²) irradiation and were killed 24 h later. UVB irradiation decreased the adiponectin protein level in the serum and the adiponectin mRNA level in ovarial adipose tissues. UVB irradiation also decreased the mRNA levels of peroxisome proliferator-activated receptor (PPAR) γ, CCAAT/enhancer binding protein (C/EBP) α, C/EBPβ, and fatty acid binding protein 4 (aP2) in ovarial adipose tissues. In contrast, UVB irradiation increased the mRNA levels of interleukin (IL)-6 and monocyte chemoattractant protein (MCP)-1 in ovarial adipose tissues. In the serum and liver, the levels of serum amyloid A (SAA), involved in PPARγ, C/EBPα, C/EBPβ, aP2, IL-6, and MCP-1 regulation, increased after UVB irradiation. The SAA gene is regulated by IL-1β, IL-6, and tumor necrosis factor-α, but only IL-6 expression increased in the liver after UVB irradiation. Additionally, in the liver, hypothalamus, and epidermis, UVB irradiation increased the expression of calcitonin gene-related peptide (CGRP), which upregulates SAA in the liver. Collectively, our results suggest that the CGRP signal induced by skin exposure to UVB transfers to the liver, possibly through the brain, and increases SAA production via IL-6 in the liver. In turn, serum SAA acts in an endocrine manner to decreases the serum adiponectin level by downregulating factors that regulate adiponectin expression in adipose tissues.

Calcitonin gene-related peptide receptor antagonists: beyond migraine pain--a possible analgesic strategy for osteoarthritis?

Osteoarthritis (OA) pain is poorly understood and managed, as current analgesics have only limited efficacy and unwanted side effect profiles. A broader understanding of the pathological mechanisms driving OA joint pain is vital for the development of improved analgesics. Both clinical and preclinical data suggest an association between joint levels of the sensory neuropeptide calcitonin gene-related peptide (CGRP) and pain during OA. Whether a direct causative link exists remains an important unanswered question. Given the recent development of small molecule CGRP receptor antagonists with clinical efficacy against migraine pain, the interrogation of the role of CGRP in OA pain mechanisms is extremely timely. In this article, we provide the background to the importance of CGRP in pain mechanisms and review the emerging clinical and preclinical evidence implicating a role for CGRP in OA pain. We suggest that the CGRP receptor antagonists developed for migraine pain warrant further investigation in OA.

The TRPA1 channel in migraine mechanism and treatment

Migraine remains an elusive and poorly understood disease. The uncertainty is reflected by the currently unsatisfactory acute and prophylactic treatments for this disease. Genetic and pharmacological information points to the involvement of some transient receptor potential (TRP) channels in pain mechanisms. In particular, the TRP vanilloid 1 (TRPV1) and TRP ankyrin 1 (TRPA1) channels seem to play a major role in different models of pain diseases. Recent findings have underscored the possibility that TRP channels expressed in the nerve terminals of peptidergic nociceptors contribute to the migraine mechanism. Among this channel subset, TRPA1, a sensor of oxidative, nitrative and electrophilic stress, is activated by an unprecedented series of irritant and pain-provoking exogenous and endogenous agents, which release the pro-migraine peptide, calcitonin gene-related peptide, through this neuronal pathway. Some of the recently identified TRPA1 activators have long been known as migraine triggers. Furthermore, specific analgesic and antimigraine medicines have been shown to inhibit or desensitize TRPA1 channels. Thus, TRPA1 is emerging as a major contributing pathway in migraine and as a novel target for the development of drugs for pain and migraine treatment.

End o' the line revisited: moving on from nitric oxide to CGRP

When endothelin-1(ET-1) was discovered it was hailed as the prototypical endothelium-derived contracting factor (EDCF). However, over the years little evidence emerged convincingly demonstrating that the peptide actually contributes to moment-to-moment changes in vascular tone elicited by endothelial cells. This has been attributed to the profound inhibitory effect of nitric oxide (NO) on both the production (by the endothelium) and the action (on vascular smooth muscle) of ET-1. Hence, the peptide is likely to initiate acute changes in vascular diameter only under extreme conditions of endothelial dysfunction when the NO bioavailability is considerably reduced if not absent. The present essay discusses whether or not this concept should be revised, in particular in view of the potent inhibitory effect exerted by calcitonin gene related peptide (CGRP) released from sensorimotor nerves on vasoconstrictor responses to ET-1.

Involvement of adrenomedullin in the attenuation of acute morphine-induced analgesia in rats

Adrenomedullin (AM) is a member of calcitonin gene-related peptide (CGRP) family and a pain-related peptide. We have shown that chronic administration of morphine (20 μg) upregulates AM activity contributing to morphine tolerance. The present study investigated if AM is involved in acute morphine-induced analgesia. Single intrathecal (i.t.) injection of morphine at a dose of 5 μg increased the tail-flick latency (TFL). This analgesic effect was potentiated by the co-administration of the AM receptor antagonist AM22-52 (5 and 10 nmol). Exposure of sensory ganglion culture to morphine increased AM content in the ganglia in concentration (0.33-10 μM)- and time (10-240 min)-dependent manners. However, treatment with morphine (3.3 μM) for 30-240 min did not alter AM mRNA levels in the cultured ganglia. Furthermore, exposure of ganglion cultures to morphine (3.3 μM) for 30-240, but not 10 min induced an increase in AM content in the culture medium. These results reveal that a single morphine treatment potentiates post-translational change and the release of AM in sensory ganglia masking morphine-induced analgesia. Thus, targeting AM and its receptors should be considered as a novel approach to improve the analgesic potency of opiates during their acute use.

Development of a novel antibody to calcitonin gene-related peptide for the treatment of osteoarthritis-related pain

OBJECTIVE

Investigate a role for calcitonin gene-related peptide (CGRP) in osteoarthritis (OA)-related pain.

DESIGN

Neutralizing antibodies to CGRP were generated de novo. One of these antibodies, LY2951742, was characterized in vitro and tested in pre-clinical in vivo models of OA pain.

RESULTS

LY2951742 exhibited high affinity to both human and rat CGRP (KD of 31 and 246 pM, respectively). The antibody neutralized CGRP-mediated induction of cAMP in SK-N-MC cells in vitro and capsaicin-induced dermal blood flow in the rat. Neutralization of CGRP significantly reduced pain behavior as measured by weight bearing differential in the rat monoiodoacetate model of OA pain in a dose-dependent manner. Moreover, pain reduction with neutralization of CGRP occurred independently of prostaglandins, since LY2951742 and NSAIDs worked additively in the NSAID-responsive version of the model and CGRP neutralization remained effective in the NSAID non-responsive version of the model. Neutralization of CGRP also provided dose-dependent and prolonged (>60 days) pain reduction in the rat meniscal tear model of OA after only a single injection of LY2951742.

CONCLUSIONS

LY2951742 is a high affinity, neutralizing antibody to CGRP. Neutralization of CGRP is efficacious in several OA pain models and works independently of NSAID mechanisms of action. LY2951742 holds promise for the treatment of pain in OA patients.

Involvement of adrenomedullin in spinal glial activation following chronic administration of morphine in rats

BACKGROUND

Adrenomedullin (AM) belongs to the calcitonin gene-related peptide (CGRP) family. Our previous studies show that chronic exposure to morphine increases spinal AM bioactivity, contributing to the development and maintenance of morphine tolerance. This study investigated the possible involvement of AM in morphine-evoked gliosis.

METHODS

Real-time polymerase chain reaction was performed to determine interleukin-1β (IL-1β), IL-6 and tumour necrosis factor-α (TNF-α) mRNAs in the spinal dorsal horn and cultured sensory ganglion explants. Immunohistochemistry was performed to identify spinal microglia and astrocytes.

RESULTS

Repetitive intrathecal (i.t.) injection of morphine (20 μg) increased the expression of IL-1β, IL-6 and TNF-α mRNAs in the spinal dorsal horn. The co-administration of the selective AM receptor antagonist AM22-52 (36 μg) markedly attenuated chronic morphine-evoked increase in IL-1β and IL-6, but not TNF-α, mRNA levels. Exposure of cultured dorsal root ganglion (DRG) explants to morphine (3.3 μmol/L) for 6 days up-regulated IL-1β and IL-6 mRNA expressions. The depletion of AM gene using small interfering RNA (siRNA) approach abolished morphine-evoked increase in IL-1β and IL-6 syntheses in the cultured DRG. The blockade of AM receptors by i.t. AM22-52 also inhibited chronic morphine-evoked cell hypertrophy of microglia and astrocytes as well as an increase in OX-42 and GFAP (glial fibrillary acidic protein) immunoreactivities. Furthermore, the 6-day treatment with AM (10 μg, i.t.) induced morphological changes of microglia and astrocytes as well as an increase in IL-1β, IL-6 and TNF-α mRNA levels in the spinal dorsal horn.

CONCLUSION

The present study supports the idea that up-regulation of the pronociceptive mediator AM can recruit spinal glial cells, resulting in an increase in cytokines during chronic use of morphine.

Cardiovascular and hemodynamic parameters in women following prolonged CGRP inhibition using LBR-101, a monoclonal antibody against CGRP

BACKGROUND

The vascular effects of acute calcitonin gene-related peptide (CGRP) inhibition are well described, but the effects of sustained inhibition warrant further exploration in humans.

OBJECTIVES

The objective of this article is to assess the effects of sustained CGRP inhibition on blood pressure, heart rate, and ECGs in healthy women ≥ 40 years of age.

METHODS

In this double-blind, placebo-controlled study, 31 women (mean age = 56) were randomized to receive placebo or an anti-CGRP monoclonal antibody at doses up to 2000 mg. Participants were confined for seven days and followed for 168 days. Cardiac telemetry was conducted for eight hours after infusion completion. Hemodynamic assessments and ECGs were conducted six times during Day 1 and periodically for three months.

RESULTS

No clinically relevant changes in systolic or diastolic blood pressure, heart rate, or ECG parameters (RR, PR, QRS, or QTcF) were observed when comparing baseline vs. post-dose time-points or in-between groups. No significant changes were seen for adjusted QTcF (baseline subtracted and placebo and baseline subtracted). No significant differences or relevant abnormalities were seen when comparing parameters obtained at Tmax vs. any other time-point.

CONCLUSION

Sustained CGRP inhibition was not associated with hemodynamic or ECG changes in a population at an increased age risk for cardiovascular events.