| IntroductionSerotonin and serotonin transporter play an important role in PAH, as reported in patients and animal pathologic models. Recently, it has been suggested that inflammation is one of the major pathogenic changes in some type of pulmonary arterial hypertension (PAH). Nuclear factor kappa B (NF-kB) is a transcription factor that activates gene expression in response to proinflammatory cytokines, and elevated cytokines are associated with PAH, which has a serotonergic component.ICAM-1 is an immunoglobulin-like protein expressed on the surface of several cell types including endothelial cells and cells involved in the immune response. It plays an important role in the adhesion and migration of leukocytes to the sites of inflammation.It can be induced in a cell-specific manner by several cytokines, for example, tumor necrosis factor-alpha, interleukin-1, and interferon-gamma, and inhibited by glucocorticoids. ICAM-1 expression is predominantly transcriptionally regulated. The ICAM-1 promoter contains several enhancer elements, one of the important is a novel kappa B element. Expression regulation is cell specific and depends on the availability of cytokine/hormone receptors, signal transduction pathways, transcription factors, and posttranscriptional modification.Studies have also suggested a protective effect of SSRI use in coronary artery disease. Hypoxia- and monocrotaline-induced pulmonary hypertension in animal models is inhibited by fiuoxetine, a selective serotonin reuptake inhibitor (SSRI) that blocks the SERT. These findings provide a rationale for randomized controlled trials of SSRIs in PAH. We questioned (1) whether NF-κB and ICAM increase in the pulmonary of MCT induced PAH rats (2) whether they are changed by fiuoxetine treatmentMethodsAdult male Wistar rats weighing 140-160g were used in the experiments. Animals were randomly divided into four groups: control group(NS,MCT,FLU2mg and FLU10mg. The MCT and FLU rats were treated with single, intraperitoneal injection of MCT 60mg/kg, while the control rats were treated with an equal volume of saline. Then, FLU rats were treated with FLU (2mg/kg/d and 10mg/kg/d), while the control and MCT rats were treated with an equal volume of saline. 21 days later, all of the rats were anesthetized by intraperitoneal injection of Urethane (5mg/kg); a polyethylene catheter (PE-50) was inserted into the right carotid artery to measure arterial pressure. A PV-1 catheter was inserted through the right jugular vein into the pulmonary artery for measurement of pulmonary arterial pressure. These homodynamic variables were measured with a pressure transducer connected to a polygraph and recorded with a thermal recorder. After completion of the above measurements, the right ventricle (RV), septum and the left ventricle (S+LV) were dissected and weighted separately to evaluate the magnitude of the right ventricular hypertrophy [RV/(S+LV)].Paraffin sections with 5um thick each were obtained from rats' lung and stained with hematoxylin and eosin (HE stains) for examination by light microscopy, the medial wall thickness were measured. Statistical analysis of the medial wall thickness of the pulmonary arteries was performed.Mice anti-NFκB p65 against the N-terminus and Mice anti-ICAM-1 against the N-terminus were used at a dilution of 1/800 in 1% BSA. Goat anti-mice antibody conjugated with HRP and rabbit anti-mice antibody conjugated with HRP were used as second antibodies at a dilution of 1/3000 in 1% BSA. The immunodetected proteins were visualized using a LumiGLO chemiluminescent reagent and exposure to high performance chemiluminescence film.ResultsMCT increased the pulmonary pressure of the rats (MCT25.6±4.4, vs control 15.7±1.9 P<0.05), and right ventricular hypertrophy of rats (MCT 0.4±0.05, vs control 0.2±0.04 P<0.05) after 3 weeks, while fluoxetine alleviated the pulmonary pressure (FLU2 20.5±3.5; FLU10 19.4±3.4 P<0.05 vs MCT) and right ventricular hypertrophy (FLU2 0.34±0.05; FLU10 0.3±0.02 P<0.05 vs MCT) of rats induced by MCT; MCT led to the pulmonary artery smooth muscle hyperplasia (MCT 0.5±0.05, vs control 0.3±0.03 P<0.05) , and fluoxetine alleviated the effect of MCT (FLU2 0.4±0.07 ; FLU10 0.4±0.02 P<0.05 vs MCT) .MCT increased the ICAM-1 and NF-κB (P<0.05) protein expression of pulmonary tissue, and fluoxetine decreased the expression of ICAM-1 and NF-κB (P<0.05) .ConclusionsThese observations are consistent with the notion that inflammatory factor play an important role in PAH and NF-κB is related to it, while fluoxetine can protect against the MCT induced PAH may partly through inhibition of NF-κB.
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