title: Endogenous and exogenous glucocorticoid suppresses up-regulation of preprodynorphin mRNA and hyperalgesia in rats with peripheral inflammation.
abstract: Glucocorticoids (GC) play important roles in response to stressful stimuli, including pain. This study examined the effects of bilateral adrenalectomy (ADX) and dexamethasone (DEX) replacement on the hyperalgesia and spinal preprodynorphin (PPD) mRNA expression induced by injecting complete Freund's adjuvant (CFA) into rats' hind paws. The results demonstrated that CFA induced more intense hyperalgesia and up-expression of spinal PPD mRNA in ADX rats than in control rats, while both of these intensified reactions could be significantly suppressed by subcutaneous pretreatment with DEX. This leads to the conclusion that both exogenous (pharmacological) and endogenous (physiological) GC suppresses the behavioral hyperalgesia and the up-regulation of spinal PPD mRNA induced by sustained peripheral inflammation. The results also suggest that spinal PPD mRNA suppression may partially underlie the inhibition of behavioral hyperalgesia.
authors.affiliation: Center For Integrative Medicine, School of Medicine, University of Maryland, Baltimore, MD 21201, USA. rzhan001@umaryland.edu
authors.forename: Rui-Xin
authors.initials: RX
authors.lastname: Zhang
authors.forename: Lixing
authors.initials: L
authors.lastname: Lao
authors.forename: Jian-Tian
authors.initials: JT
authors.lastname: Qiao
authors.forename: K
authors.initials: K
authors.lastname: Malsnee
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Ruda
mesh_terms: D000818:Animals; D004399:Dynorphins / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D005620:Freund's Adjuvant; D005938:Glucocorticoids / Q000378:metabolism* / Q000494:pharmacology; D006930:Hyperalgesia / Q000139:chemically induced / Q000378:metabolism*; D007249:Inflammation / Q000139:chemically induced / Q000378:metabolism; D008297:Male; D011498:Protein Precursors / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*
chemical_list: D005938:Glucocorticoids; D011498:Protein Precursors; D012333:RNA, Messenger; C036448:pre-prodynorphin; D004399:Dynorphins; D005620:Freund's Adjuvant