Dynorphin A-induced rat spinal cord injury: Evidence for excitatory amino acid involvement in a pharmacological model of ischemic spinal cord injury

J. B. Long, D. D. Rigamonti, M. A. Oleshansky, C. P. Wingfield, Alberto Martinez-Arizala

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

Dynorphin A reduced lumbosacral blood flow, elevated cerebrospinal fluid lactic acid concentrations and caused flaccid hindlimb paralysis and striking neuropathological changes after its injection into the spinal subarachnoid space in rats. Coadministration of the vasodilator hydralazine substantially eliminated the paralytic, anaerobic metabolic and neuropathological responses to dynorphin A. In contrast, in concentrations up to 1 mM, dynorphin A did not alter the viability of cultured rat spinal cord neurons. Thus, it appears that this peptide lacks direct neurotoxic effects and that neuronal injuries in vivo result primarily from ischemia associated with dynorphin A-induced blood flow reductions. NMDA receptor antagonists significantly improved recovery from dynorphin A-induced hindlimb paralysis, and substantially eliminated neuropathological changes without attenuating the acute blood flow reductions or lactic acid elevations. Additionally, glutamate and aspartate concentrations were increased significantly in spinal cord cerebrospinal fluid samples removed during the time that peptide-induced spinal cord blood flow reductions were observed. In contrast, neither amino acid concentration was elevated in media removed after 1-hr exposure of spinal cord neuronal cell cultures to 100 μM concentrations of dynorphin A. These results indicate that the paralysis and spinal cord injuries produced in rats after spinal subarachnoid injection of dynorphin A result predominantly from spinal cord ischemia, and further identify excitatory amino acids and N-methyl-D- aspartate receptor mechanisms as important mediators in this injury model.

Original languageEnglish
Pages (from-to)358-366
Number of pages9
JournalJournal of Pharmacology and Experimental Therapeutics
Volume269
Issue number1
StatePublished - Jan 1 1994
Externally publishedYes

Fingerprint

Dynorphins
Excitatory Amino Acids
Spinal Cord Injuries
Pharmacology
Spinal Cord
Paralysis
Spinal Injections
Hindlimb
N-Methyl-D-Aspartate Receptors
Cerebrospinal Fluid
Lactic Acid
Spinal Cord Ischemia
Hydralazine
Subarachnoid Space
Peptides
Wounds and Injuries
Vasodilator Agents
Fetal Blood
Aspartic Acid
Glutamic Acid

ASJC Scopus subject areas

  • Pharmacology

Cite this

Dynorphin A-induced rat spinal cord injury : Evidence for excitatory amino acid involvement in a pharmacological model of ischemic spinal cord injury. / Long, J. B.; Rigamonti, D. D.; Oleshansky, M. A.; Wingfield, C. P.; Martinez-Arizala, Alberto.

In: Journal of Pharmacology and Experimental Therapeutics, Vol. 269, No. 1, 01.01.1994, p. 358-366.

Research output: Contribution to journalArticle

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