ABSTRACT
AIM: To investigate effects of the cyclin-dependent kinase5 (Cdk5) inhibitor roscovitine on formalin-induced nociceptive responses in rats. METHODS: The flinch response as a methood of pain threshold measurement and intrathecal injection techniques were used. Cdk5 and phosphorylation of its downstream target, DARPP-32 (dopamine- and cAMP-regulated phosphoprotein of M(r) 32 kDa), were investigated by Western blot analysis. RESULTS: Rats demonstrated a typical flinch response after formalin injection. Intrathecal roscovitine injections significantly suppressed the flinch response in a dose-dependent manner. Western blot analysis showed that phosphorylated DARPP-32 at Thr75 increased in concentration after formalin hyperalgesia, with this effect reduced by roscovitine administration. This antinociception was partially attenuated by administration of naloxone before the formalin test. CONCLUSION: DARPP-32 phosphorylation is involved in acute inflammatory pain response. Intrathecal roscovitine administration attenuates formalin-induced nociceptive responses and there is potential for further application.
Subject(s)
Cyclin-Dependent Kinases/metabolism , Hyperalgesia/metabolism , Purines/pharmacology , Animals , Cyclin-Dependent Kinase 5 , Cyclin-Dependent Kinases/antagonists & inhibitors , Dopamine and cAMP-Regulated Phosphoprotein 32 , Formaldehyde/pharmacology , Hyperalgesia/chemically induced , Injections, Spinal , Male , Nerve Tissue Proteins/metabolism , Pain Measurement , Pain Threshold/drug effects , Phosphoproteins/metabolism , Phosphorylation , Purines/administration & dosage , Rats , Rats, Sprague-Dawley , RoscovitineABSTRACT
Oxidative stress has been implicated in the propagation of acute liver injury. The aim of our study was to investigate whether gene transfer of alpha-melanocyte-stimulating hormone (alpha-MSH), a potent anti-inflammatory peptide, could prevent fulminant hepatic failure in mice. Acute liver damage was induced by intraperitoneal administration of thioacetamide. Hydrodynamics-based gene transfection with alpha-MSH expression plasmid via rapid tail vein injection was initiated 1 day prior to intoxication. The mortality in the alpha-MSH-treated mice was significantly lower compared to the vehicle group 3 days after injury. Liver histology significantly improved and TUNEL-positive hepatocytes decreased in the treated mice. The degradation of IkappaBalpha, endogenous inhibitor of nuclear factor kappaB, and upregulation of inducible nitric oxide synthase and tumor necrosis factor-alpha mRNA levels were prevented in the alpha-MSH-treated group, indicating decreased oxidative stress and inflammation. These results suggest alpha-MSH gene therapy might protect against acute hepatic necroinflammatory damage with further potential applications.
