title: Atrial natriuretic peptide reduces ischemia/reperfusion-induced spinal cord injury in rats by enhancing sensory neuron activation.
abstract: We recently demonstrated that calcitonin gene-related peptide (CGRP) released from sensory neurons reduces spinal cord injury (SCI) by inhibiting neutrophil activation through an increase in the endothelial production of prostacyclin (PGI(2)). Carperitide, a synthetic alpha-human atrial natriuretic peptide (ANP), reduces ischemia/reperfusion (I/R)-induced tissue injury. However, its precise therapeutic mechanism(s) remains to be elucidated. In the present study, we examined whether ANP reduces I/R-induced spinal cord injury by enhancing sensory neuron activation using rats. ANP increased CGRP release and cellular cAMP levels in dorsal root ganglion neurons isolated from rats in vitro. The increase in CGRP release induced by ANP was reversed by pretreatment with capsazepine, an inhibitor of vanilloid receptor-1 activation, or with (9S, 10S, 12R)-2,3,9,10,11,12-hexahydro-10-hydroxy-9-methyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i][1,6]-benzodiazocine-10-carboxylic acid hexyl ester (KT5720), an inhibitor of protein kinase A (PKA), suggesting that ANP might increase CGRP release from sensory neurons by activating PKA through an increase in the cellular cAMP level. Spinal cord ischemia was induced in rats using a balloon catheter placed in the aorta. ANP reduced mortality and motor disturbances by inhibiting reduction of the number of motor neurons in animals subjected to SCI. ANP significantly enhanced I/R-induced increases in spinal cord tissue levels of CGRP and 6-keto-prostaglandin F(1alpha). a stable metabolite of PGI(2). ANP inhibited I/R-induced increases in spinal cord tissue levels of tumor necrosis factor and myeloperoxidase. Pretreatment with 4'-chloro-3-methoxycinnamanilide (SB366791), a specific vanilloid receptor-1 antagonist, and indomethacin reversed the effects of ANP. These results strongly suggest that ANP might reduce I/R-induced SCI in rats by inhibiting neutrophil activation through enhancement of sensory neuron activation.
authors.affiliation: Departments of Cardiovascular Surgery, Nagoya City University Graduate School of Medical Sciences, Mizuho-cho, Mizuho-ku, Nagoya, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Nakayama
authors.forename: Naoaki
authors.initials: N
authors.lastname: Harada
authors.forename: Miki
authors.initials: M
authors.lastname: Asano
authors.forename: Norikazu
authors.initials: N
authors.lastname: Nomura
authors.forename: Takayuki
authors.initials: T
authors.lastname: Saito
authors.forename: Akira
authors.initials: A
authors.lastname: Mishima
authors.forename: Kenji
authors.initials: K
authors.lastname: Okajima
mesh_terms: D015121:6-Ketoprostaglandin F1 alpha / Q000378:metabolism; D000813:Anilides / Q000494:pharmacology; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002211:Capsaicin / Q000031:analogs & derivatives / Q000494:pharmacology; D002227:Carbazoles / Q000494:pharmacology; D002478:Cells, Cultured; D002934:Cinnamates / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D009475:Neurons, Afferent / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D009195:Peroxidase / Q000378:metabolism; D011597:Psychomotor Performance / Q000187:drug effects; D011758:Pyrroles / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000150:complications*; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D013118:Spinal Cord Diseases / Q000188:drug therapy* / Q000209:etiology / Q000378:metabolism; D050916:TRPV Cation Channels / Q000037:antagonists & inhibitors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000813:Anilides; D002227:Carbazoles; D002934:Cinnamates; D004791:Enzyme Inhibitors; D007211:Indoles; C477659:N-(3-methoxyphenyl)-4-chlorocinnamanilide; C472955:NPPA protein, human; D011758:Pyrroles; D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; D014409:Tumor Necrosis Factor-alpha; D015121:6-Ketoprostaglandin F1 alpha; C057416:KT 5720; D009320:Atrial Natriuretic Factor; D000242:Cyclic AMP; D009195:Peroxidase; D015740:Calcitonin Gene-Related Peptide; C071423:capsazepine; D002211:Capsaicin; D007213:Indomethacin