The purpose of this study was to identify the effect of sildenafil citrate on IL-1 beta induced nitric oxide (NO) synthesis and iNOS expression in human synovial sarcoma SW982 cells. IL-1 beta stimulated the cells to generate NO in both dose- and time-dependent manners. The IL-1 beta -induced NO synthesis was inhibited by guanylate cyclase (GC) inhibitor, LY83583. When the cells were treated with 8-bromo-cGMP, a hydrolyzable analog of cGMP, NO synthesis was increased upto 5-fold without IL-1 beta treatment suggesting that cGMP is an essential component for increasing the NO synthesis. Synoviocytes and chondrocytes contain strong cGMP phosphodiesterase (PDE) activity, which has biochemical features of PDE5. When SW982 cells were pretreated with sildenafil citrate (Viagra), a PDE5 specific inhibitor, sildenafil citrate significantly inhibited IL-1 beta -induced NO synthesis and iNOS expressions. From this result, we noticed that PDE5 activity is required for IL-1 beta -induced NO synthesis and iNOS expressions in human synovial sarcoma cells, and sildenafil citrate may be able to suppress an inflammatory reaction of synovium through inhibition of NO synthesis and iNOS expression by cytokines.
Anti-Inflammatory Agents/immunology/pharmacology ; Cell Line, Tumor ; Cyclic GMP/analogs & derivatives/immunology/metabolism ; Cyclic Nucleotide Phosphodiesterases, Type 2/antagonists & inhibitors/metabolism ; Humans ; Interleukin-1beta/*metabolism ; Male ; Nitric Oxide/*biosynthesis/genetics/immunology ; Nitric Oxide Synthase Type II/*biosynthesis/genetics/immunology ; Phosphodiesterase Inhibitors/immunology/*pharmacology ; Piperazines/immunology/*pharmacology ; Purines/immunology/pharmacology ; Signal Transduction/drug effects/genetics/immunology ; Sulfones/immunology/*pharmacology ; Synovial Membrane/enzymology/immunology

BACKGROUNDNeuroprotective strategies following cardiopulmonary resuscitation (CPR) are an important focus in emergency and critical care medicine. Matrix metalloproteinases (MMPs), especially MMP9 attracted much attention because of its function in focal brain ischemia/reperfusion injury. In the focal cerebral ischemia model in rats, SB-3CT can suppress the expression of MMP9, relieving brain edema, and there was no studies on global cerebral ischemia-reperfusion injury after CPR.

METHODSOne hundred and twenty rats were randomly assigned to sham-operated (n = 40), resuscitation treatment (n = 40), and resuscitation control (n = 40) groups. Sham-operated group rats were anesthetized only and intubated tracheally, while the resuscitation treatment and resuscitation control groups also received cardiac arrest by asphyxiation. In the resuscitation treatment group, SB-3CT was injected intraperitoneally after restoring spontaneous circulation (ROSC), defined as restoration of supraventricular rhythm and mean arterial pressure (MAP) > or = 60 mm Hg for more than 5 minutes. The resuscitation control group also implemented ROSC without injection of SB-3CT. The rats were executed and samples were taken immediately after death, then at 3, 9, 24, and 48 hours (n = 8). Brain tissue expression of MMP9 protein, MMP9 mRNA, water content, Evans blue content, TNF-alpha, IL-1, and IL-6 was measured, and the brain tissue ultramicrostructure studied with electron microscopy.

RESULTSIn the resuscitation control group, brain tissue expression of MMP9 protein and mRNA, water content, Evans blue content, TNF-alpha, IL-1, and IL-6 were significantly elevated at 3 hours, and peaked at 24 hours after resuscitation, when compared with the sham-operated group (P < 0.05). Tissue ultramicrostructure also changed in the resuscitation control group. By contrast, although all these indexes were increased in the resuscitation treatment group compared with the sham-operated group (P < 0.05), they were lower than in the resuscitation control group (P < 0.05).

CONCLUSIONSExpression of MMP9 protein and mRNA, water content, Evans blue content, TNF-alpha, IL-1, and IL-6 increased in rat brain tissue after CPR, indicating disruption of the blood-brain barrier and excess inflammatory reaction. MMP9 expression was reduced with SB-3CT, resulting in reduced brain injury.

Animals ; Blood-Brain Barrier ; drug effects ; Brain ; immunology ; ultrastructure ; Cardiopulmonary Resuscitation ; Cytokines ; analysis ; Heterocyclic Compounds, 1-Ring ; pharmacology ; Inflammation ; prevention & control ; Male ; Matrix Metalloproteinase 9 ; analysis ; genetics ; Matrix Metalloproteinase Inhibitors ; Neuroprotective Agents ; pharmacology ; RNA, Messenger ; analysis ; Rats ; Rats, Sprague-Dawley ; Sulfones ; pharmacology