Analgesia induced by perineural clonidine is enhanced in persistent neuritis.
Alpha 2-adrenoceptors are concentrated near sites of peripheral nerve injury or inflammation, primarily on immune cells, and their activation reduces inflammation and hypersensitivity to tactile stimuli. These results were obtained during acute inflammation, but the efficacy of alpha2-adrenoceptor stimulation in persistent inflammation has not been tested. Here, we show that perineural injection of the alpha2-adrenoceptor agonist, clonidine, reduces hypersensitivity in persistent sciatic neuritis with an onset more rapid than acute neuritis. Perineural clonidine reduces microglial activation in the spinal cord in persistent, but not acute neuritis, and does not change the number of spinal neurons with phosphorylated transcription factor, cyclic adenosine monophosphate response element binding protein. These data support treatment strategies with alpha2-adrenoceptor agonists in persistent neuritis.
Romero-Sandoval
Alfonso
A
Department of Anesthesiology and Center for Study of Pharmacologic Plasticity in the Presence of Pain, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina 27157-1009, USA.
Bynum
Tanishua
T
Eisenach
James C
JC
D000700:Analgesics / Q000008:administration & dosage*; D000818:Animals; D001522:Behavior, Animal; D002135:Calcium-Binding Proteins / Q000378:metabolism; D003000:Clonidine / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D008840:Microfilament Proteins; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D020426:Sciatic Neuropathy / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D015054:Zymosan / Q000008:administration & dosage
C100745:Aif1 protein, rat; D000700:Analgesics; D002135:Calcium-Binding Proteins; D005904:Glial Fibrillary Acidic Protein; D008840:Microfilament Proteins; D015054:Zymosan; D003000:Clonidine