CGRP Research Papers - Academia.edu (original) (raw)

In mice dorsal root ganglia (DRG), some neurons express calcitonin-gene-related peptide (CGRP) without substance P (SP, CGRP(+) SP(-) ). The projections and functions of these neurons are unknown. Therefore, we combined in vitro axonal... more

In mice dorsal root ganglia (DRG), some neurons express calcitonin-gene-related peptide (CGRP) without substance P (SP, CGRP(+) SP(-) ). The projections and functions of these neurons are unknown. Therefore, we combined in vitro axonal tracing with multiple-labelling immunohistochemistry to neurochemically define these neurons and characterise their peripheral and central projections. Cervical spinal cord, DRG and forepaw skin were removed from C57Bl/6 mice and multiple-labelled for CGRP, SP and either marker for sensory neuron subpopulations: TRPV1, NF200 or VGluT1. To determine central projections of CGRP(+) SP(-) neurons Neurobiotin (NB) was applied to the C7 ventral ramus and visualised in DRG and spinal cord sections co-labelled for CGRP and SP. Half (50%) of CGRP-immunoreactive DRG neurons lacked detectable SP and had a mean soma size of 473±14 µm(2) (n = 5). 89% of CGRP(+) SP(-) neurons expressed NF200 (n = 5) but only 32% expressed TRPV1 (n = 5). Cutaneous CGRP(+) SP(-) fibr...

TRPV1 gene disruption results in a loss of capsaicin and proton responsiveness, but has minimal effects on heat-induced nocifensive behavior, suggesting that sensory transduction of heat is independent of TRPV1. TRPV3, another... more

TRPV1 gene disruption results in a loss of capsaicin and proton responsiveness, but has minimal effects on heat-induced nocifensive behavior, suggesting that sensory transduction of heat is independent of TRPV1. TRPV3, another heat-activated ion channel but insensitive to capsaicin, was shown to be expressed in keratinocytes as well as in sensory neurons projecting to the skin. Recently, 2-aminoethoxydiphenyl borate was introduced as a TRPV3 agonist, but its selectivity was questioned by showing that it activated recombinant TRPV1 and TRPV2 as well. We used the isolated mouse skin-saphenous nerve preparation and whole-cell patch-clamping of cultured dorsal root ganglia neurons from TRPV1−/− and wildtype mice. We found no phenotypic differences between the heat responses of polymodal C-fibers, whereas cultured dorsal root ganglia neurons of TRPV1−/− hardly showed any heat-activated currents. Only C-fibers of wildtype but not TRPV1−/− mice were clearly sensitized to heat by 2-aminoethoxydiphenyl borate 10 and 100 μM; heat-activated current in wildtype neurons was only facilitated at 100 μM. Noxious heat-induced calcitonin gene-related peptide release showed clear deficits (<50%) in TRPV1 deficient skin, but the stimulated calcitonin gene-related peptide release from the isolated skull dura was unaffected. In both models, 2-aminoethoxydiphenyl borate was able to potentiate the heat response (46°C, 5 min) in a concentration-dependent manner, again, only in wildtype but not TRPV1−/− mice, suggesting that TRPV2/3 are not involved in this sensitization to heat. The results further suggest that TRPV1 is not responsible for the normal heat response of native nociceptors but plays the essential role in thermal sensitization and a prominent one in controlling dermal calcitonin gene-related peptide release, i.e. neurogenic inflammation.

Reg-2 is a secreted protein that is expressed de novo in motoneurons, sympathetic neurons, and dorsal root ganglion (DRG) neurons after nerve injury and which can act as a Schwann cell mitogen. We now show that Reg-2 is also upregulated... more

Reg-2 is a secreted protein that is expressed de novo in motoneurons, sympathetic neurons, and dorsal root ganglion (DRG) neurons after nerve injury and which can act as a Schwann cell mitogen. We now show that Reg-2 is also upregulated by DRG neurons in inflammation with a very unusual expression pattern. In a rat model of monoarthritis, Reg-2 immunoreactivity was detected in DRG neurons at 1 day, peaked at 3 days (in 11.6% of DRG neurons), and was still present at 10 days (in 5%). Expression was almost exclusively in the population of DRG neurons that expresses the purinoceptor P2X3 and binding sites for the lectin Griffonia simplicifolia IB4, and which is known to respond to glial cell line–derived neurotrophic factor (GDNF). Immunoreactivity was present in DRG cell bodies and central terminals in the dorsal horn of the spinal cord. In contrast, very little expression was seen in the nerve growth factor (NGF) responsive and substance P expressing population. However intrathecal delivery of GDNF did not induce Reg-2 expression, but leukemia inhibitory factor (LIF) had a dramatic effect, inducing Reg-2 immunoreactivity in 39% of DRG neurons and 62% of P2X3 cells.Changes in inflammation have previously been observed predominantly in the neuropeptide expressing, NGF responsive, DRG neurons. Our results show that changes also take place in the IB4 population, possibly driven by members of the LIF family of neuropoietic cytokines. In addition, the presence of Reg-2 in central axon terminals implicates Reg-2 as a possible modulator of second order dorsal horn cells.

Objective: The trigeminovascular system plays a central role in migraine, a condition in need of new treatments. The neuropeptide calcitonin gene-related peptide (CGRP) is proposed as causative in migraine and is the subject of intensive... more

Objective: The trigeminovascular system plays a central role in migraine, a condition in need of new treatments. The neuropeptide calcitonin gene-related peptide (CGRP) is proposed as causative in migraine and is the subject of intensive drug discovery efforts. This study explores the expression and functionality of two CGRP receptor candidates in the sensory trigeminal system.
Methods: Receptor expression was determined using Taqman G protein-coupled receptor (GPCR) arrays and immunohistochemistry in trigeminal ganglia (TG) and the spinal trigeminal complex of the brainstem in rat and human. Receptor pharmacology was quantified using sensitive signaling assays in primary rat TG neurons.
Results: mRNA and histological expression analysis in rat and human samples revealed the presence of two CGRP-responsive receptors (AMY1: calcitonin receptor/receptor activity-modifying protein 1 [RAMP1] and the CGRP receptor (calcitonin receptor-like receptor/RAMP1). In support of this finding, quantification of agonist and antagonist potencies revealed a dual population of functional CGRP-responsive receptors in primary rat TG neurons.
Interpretation: The unexpected presence of a functional non-canonical CGRP receptor (AMY1) at neural sites important for craniofacial pain has important implications for targeting the CGRP axis in migraine.

Members of the transient receptor potential (TRP) family of nonselective cation channels are involved in several pathological and physiological conditions. The search for the molecular targets for naturally occurring substances,... more

Members of the transient receptor potential (TRP) family of nonselective cation channels are involved in several pathological and physiological conditions. The search for the molecular targets for naturally occurring substances, especially from plants, allowed the characterization of ...

CGRP receptor antagonists are effective acute migraine treatments. A capsaicin-induced dermal vasodilatation (CIDV) model has been developed to provide target-engagement information in healthy volunteers. In the model, CGRP release is... more

CGRP receptor antagonists are effective acute migraine treatments. A capsaicin-induced dermal vasodilatation (CIDV) model has been developed to provide target-engagement information in healthy volunteers. In the model, CGRP release is provoked after dermal capsaicin application, by activating transient receptor potential vanilloid-type-1 (TRPV1) receptors at peripheral sensory nerves. Laser Doppler imaging is used to quantify CIDV and subsequent inhibition by CGRP receptor antagonists. We sought to evaluate a CGRP receptor antagonist, MK-3207, in the biomarker model and to assess the predictability of the CIDV response to migraine clinical efficacy. An integrated population pharmacokinetic/pharmacodynamic (PK/PD) model was developed to describe the exposure-response relationship for CIDV inhibition by CGRP and TRPV1 receptor antagonists. MK-3207 dose-response predictions were made based on estimated potency from the PK/PD model and mean plasma concentrations observed at the doses investigated. The results suggested that a 20 mg dose of MK-3207 (EC50 of 1.59 nM) would be required to attain the peripheral CIDV response at a target level that was shown previously to correlate with 2-hour clinical efficacy based on Phase-3 telcagepant clinical data, and that a plateau of the dose-response would be reached around 40-100mg. These predictions provided a quantitative rationale for dose selection in a Phase-2 clinical trial of MK-3207 and helped with interpretation of the efficacy results from the trial. The integrated CIDV PK/PD model provides a useful platform for characterization of PK/PD relationships and predictions of dose-response relationships to aid in future development of CGRP and TRPV1 receptor antagonists.

Dental pulp has neural fibers that produce neuropeptides like Substance P (SP) and calcitonin gene-related peptide (CGRP). The inflammation of dental pulp can lead to an increase amount of SP and CGRP release, especially in symptomatic... more

Dental pulp has neural fibers that produce neuropeptides like Substance P (SP) and calcitonin gene-related peptide (CGRP). The inflammation of dental pulp can lead to an increase amount of SP and CGRP release, especially in symptomatic irreversible pulpitis. Therefore, it can be assumed that neuropeptides have some role in the progression of inflammation of the dental pulp. The aim of this study was to determine the relation between the presence and concentration of neuropeptides in dental pulps of carious teeth caries. For this purpose, pulpal tissues were collected from 40 teeth (20 carious and 20 intact). Pulpal samples were cultured for 72 hours. ELISA reader was used for the detection of SP and CGRP in supernatant fluids. Statistical analysis was made by Mann-Whitney U and Chi square tests. SP and CGRP were present in 65% and 20% of inflamed pulpal samples, respectively and 40% and 5% of normal pulpal samples, respectively. Level of SP was significantly higher in inflamed pulp ...

By means of immunoperoxidase and immune-alkaline phosphatase methods the immunoreactivities to neuropeptides: neuropeptide Y (NPY), calcitonin gene related peptide (CGRP) and a pan-neuronal marker, the protein gene product 9.5 (PGP 9.5),... more

By means of immunoperoxidase and immune-alkaline phosphatase methods the immunoreactivities to neuropeptides: neuropeptide Y (NPY), calcitonin gene related peptide (CGRP) and a pan-neuronal marker, the protein gene product 9.5 (PGP 9.5), were evaluated in guinea pig deep dorsal skin specimens. CGRP immunoreactive (CGRP-IR) and NPY-immunoreactive (NPY-IR) nerve fibres were dispersed in the papillary dermis and sometimes inside the hair roots and among the sebaceous gland cells. Such localized nerve fibres have not so far been described. In the subcutaneous layer nerve trunks were found composed of CGRP-IR and NPY-IR nerve fibres. Some of these indicated vestigial or negative immunoreactivity to PGP 9.5.

High-throughput screening of the Merck sample collection identified benzodiazepinone tetralin-spirohydantoin 1 as a CGRP receptor antagonist with micromolar activity. Comparing the structure of 1 with those of earlier peptide-based... more

High-throughput screening of the Merck sample collection identified benzodiazepinone tetralin-spirohydantoin 1 as a CGRP receptor antagonist with micromolar activity. Comparing the structure of 1 with those of earlier peptide-based antagonists such as BIBN 4096 BS, a key hydrogen bond donor–acceptor pharmacophore was hypothesized. Subsequent structure activity studies supported this hypothesis and led to benzodiazepinone piperidinyldihydroquinazolinone 7, CGRP receptor Ki = 44 nM and IC50 = 38 nM. Compound 7 was orally bioavailabile in rats and is a lead in the development of orally bioavailable CGRP antagonists for the treatment of migraine.Structure activity studies led to the non-peptide CGRP antagonist, 7 (Ki = 44 nM, IC50 = 38 nM), which was orally bioavailable in rats. Benzodiazepinone 7 is a promising new lead in the development of orally bioavailable CGRP antagonists for the treatment of migraine.