Characterization and effects on cAMP accumulation of adrenomedullin and calcitonin gene‐related peptide (CGRP) receptors in dissociated rat spinal cord cell culture

1 Adrenomedullin (AM) and calcitonin gene‐related peptide (CGRP) have structural similarities, interact with each others receptors (calcitonin receptor‐like receptor (CLR)/receptor‐activity‐modifying proteins (RAMPs)) and show overlapping biological activities. AM and CGRP receptors are chiefly coup...

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Bibliographic Details
Published in:British journal of pharmacology 2006-06, Vol.148 (4), p.459-468
Main Authors: Takhshid, Mohammad A, Poyner, David R, Chabot, Jean‐Guy, Fournier, Alain, Ma, Weiya, Zheng, Wen‐Hua, Owji, Ali A, Quirion, Remi
Format: Article
Language:English
Subjects:
Adrenomedullin
Animals
BIBN4096BS
Binding Sites
Binding, Competitive
Biological and medical sciences
Calcitonin Gene-Related Peptide
Calcitonin Gene-Related Peptide - pharmacology
calcitonin receptor‐like receptor
cAMP
Cells, Cultured
CGRP
Cyclic AMP
Cyclic AMP - physiology
Female
Immunohistochemistry
Life Sciences
Medical sciences
Peptide Fragments
Peptide Fragments - pharmacology
Pharmacology. Drug treatments
Piperazines
Piperazines - pharmacology
Quinazolines
Quinazolines - pharmacology
Rats
Rats, Sprague-Dawley
receptor binding assays
Receptors, Adrenomedullin
Receptors, Calcitonin Gene-Related Peptide
Receptors, Calcitonin Gene-Related Peptide - metabolism
Receptors, G-Protein-Coupled
Receptors, G-Protein-Coupled - metabolism
receptor‐activity‐modifying protein
Spinal Cord
Spinal Cord - cytology
Spinal Cord - embryology
Spinal Cord - metabolism
Toxicology
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Summary:1 Adrenomedullin (AM) and calcitonin gene‐related peptide (CGRP) have structural similarities, interact with each others receptors (calcitonin receptor‐like receptor (CLR)/receptor‐activity‐modifying proteins (RAMPs)) and show overlapping biological activities. AM and CGRP receptors are chiefly coupled to cAMP production. In this study, a method of primary dissociated cell culture was used to investigate the presence of AM and CGRP receptors and their effects on cAMP production in embryonic spinal cord cells. 2 Both neuronal and non‐neuronal CLR immunopositive cells were present in our model. 3 High affinity, specific [125I]‐AM binding sites (Kd 79±9 pM and Bmax 571±34 fmol mg−1 protein) were more abundant than specific [125I]‐CGRP binding sites (Kd 12±0.7 pM and Bmax 32±2 fmol mg−1 protein) in embryonic spinal cord cells. 4 Specific [125I]‐AM binding was competed by related molecules with a ligand selectivity profile of rAM>hAM22–52>rCGRPα>CGRP8–37≫[r‐(r*,s*)]‐N‐[2‐[[5‐amino‐1‐[[4‐(4‐pyridinyl)‐1‐piperazinyl]carbonyl]pentyl]amino]‐1‐[(3,5‐dibromo‐4‐hydroxyphenyl)methyl]‐2‐oxoethyl]‐4‐(1,4‐dihydro‐2‐oxo‐3(2H)‐quinazolinyl)‐,1‐piperidinecarboxamide (BIBN4096BS). 5 Specific [125I]‐CGRP binding was competed by rCGRPα>rAMCGRP8–37BIBN4096BS>hAM22–52. 6 Cellular levels of cAMP were increased by AM (pEC50 10.2±0.2) and less potently by rCGRPα (pEC50 8.9±0.4). rCGRPα‐induced cAMP accumulation was effectively inhibited by CGRP8–37 (pA2 7.63±0.44) and hAM22–52 (pA2 6.18±0.21) while AM‐stimulation of cAMP levels was inhibited by CGRP8–37 (pA2 7.41±0.15) and AM22–52 (pA2 7.26±0.18). BIBN4096BS only antagonized the effects of CGRP (pA2 8.40±0.30) on cAMP accumulation. 7 These pharmacological profiles suggest that effects of CGRP are mediated by the CGRP1 (CLR/RAMP1) receptor in our model while those of AM are related to the activation of the AM1 (CLR/RAMP2) receptor subtype. British Journal of Pharmacology (2006) 148, 459–468. doi:10.1038/sj.bjp.0706750
ISSN:0007-1188
1476-5381
DOI:10.1038/sj.bjp.0706750