title: Endomorphin-2 is not released from rat spinal dorsal horn in response to intraplantar formalin.
abstract: Antibody coated microprobes, inserted into the spinal cord at the L4-5 level, were used to detect whether endomorphin-2 (Endo2) was released from spinal dorsal horns in anesthetized rats in response to formalin injected into the hindpaw footpads. Saline injections were used as a control and substance P (SP) was measured to verify activation of nociceptive afferent fibers. SP but not Endo2 was released during pre-stimulation periods. Saline injections did not cause the release of either Endo2 or SP from the spinal cord. Formalin injections caused an increase in Fos expression as well as a release of SP, but not Endo2 from the ipsilateral side dorsal horn in L4-5. We conclude that Endo2 does not play a role in mediating the in vivo responses to acute inflammatory nociceptive signals at the spinal level in the anesthetized rat model.
authors.affiliation: Department of Physiology, College of Medicine, East Tennessee State University, PO Box 70576, Johnson City, TN 37614-1708, USA. williams@etsu.edu
authors.forename: Carole A
authors.initials: CA
authors.lastname: Williams
authors.forename: Brian A
authors.initials: BA
authors.lastname: Ricketts
authors.forename: Fang
authors.initials: F
authors.lastname: Hua
authors.forename: Nae J
authors.initials: NJ
authors.lastname: Dun
mesh_terms: D000818:Animals; D005260:Female; D005557:Formaldehyde / Q000494:pharmacology; D016762:Genes, fos / Q000502:physiology; D006614:Hindlimb / Q000294:innervation; D008297:Male; D009842:Oligopeptides / Q000378:metabolism*; D010146:Pain / Q000503:physiopathology*; D020671:Posterior Horn Cells / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013373:Substance P / Q000378:metabolism
chemical_list: D009842:Oligopeptides; D005557:Formaldehyde; D013373:Substance P; C105294:endomorphin 2