Expression of spinal cord Fos protein in response to intrathecal adrenomedullin and CGRP in conscious rats

Adrenomedullin (AM) immunoreactivity and mRNA, in addition to a large number of specific AM-binding sites, exist in the rat spinal cord. However, no phenotype has been reported for AM in the spinal cord. Here, expression of c- fos in response to intrathecal (i.t.) administration of AM, proadrenomedu...

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Bibliographic Details
Published in:Brain research 2004-09, Vol.1020 (1), p.30-36
Main Authors: Takhshid, M.A., Owji, A.A., Vasei, M., Panjehshahin, M.R., Tabei, S.M.B., Tabatabaee, H.R., Ay, J.
Format: Article
Language:English
Subjects:
Adrenomedullin
Analysis of Variance
Animals
Biochemistry and metabolism
Biological and medical sciences
Calcitonin gene-related peptide
Calcitonin Gene-Related Peptide - administration & dosage
Calcitonin Gene-Related Peptide - physiology
Central nervous system
Conscious rat
Dose-Response Relationship, Drug
Enzyme Inhibitors - administration & dosage
Fos
Fundamental and applied biological sciences. Psychology
Injections, Spinal
Male
Neurons - drug effects
Neurons - metabolism
NG-Nitroarginine Methyl Ester - administration & dosage
Nitric Oxide - metabolism
Peptides - administration & dosage
Peptides - physiology
Proto-Oncogene Proteins c-fos - metabolism
Rats
Rats, Sprague-Dawley
Spinal cord
Spinal Cord - cytology
Spinal Cord - drug effects
Spinal Cord - metabolism
Vertebrates: nervous system and sense organs
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Summary:Adrenomedullin (AM) immunoreactivity and mRNA, in addition to a large number of specific AM-binding sites, exist in the rat spinal cord. However, no phenotype has been reported for AM in the spinal cord. Here, expression of c- fos in response to intrathecal (i.t.) administration of AM, proadrenomedullin N-terminal 20 peptide (PAMP) and calcitonin gene-related peptide (CGRP) was examined in the thoracic, lumbar and sacral regions of spinal cord in conscious rats. Two hours after i.t. administration of either CGRP (2.5 and 10 μg) or AM (10 μg), the number of c-Fos immunoreactive nuclei was increased in all the spinal regions examined in this study, with the highest increase observed in the superficial dorsal horn. Few cells with c- fos immunoreactivity were found in the spinal cord of rats 2 h after i.t. injection of either saline or PAMP. Effects of AM (10 μg) and CGRP (2.5 μg) on c- fos expression were blocked when rats were pretreated with 40 μg of intrathecal CGRP8–37 (CGRP1 receptor antagonist). Fos-like immunoreactivity induced by i.t. CGRP and/or AM were also significantly abolished by i.t. administration of the nitric oxide (NO) inhibitor, l-NAME, indicating that endogenous NO is a necessary intermediary in CGRP and AM induced c- fos expression in the rat spinal cord. In conclusion, AM induces c- fos expression in rat spinal cord when administered intrathecally, with the pattern being similar to those produced by i.t. CGRP. Effects of the two peptides are sensitive to CGRP8–37 and l-NAME.
ISSN:0006-8993
1872-6240
DOI:10.1016/j.brainres.2004.05.112