Fluoxetine Protects Against Pulmonary Artery Remodeling And Right Ventricular Hypertrophy In Rats: Potential Roles Of GATA-4 Protein

IntroductionGATA-4 is one of the members of GATA family which contains a highly conserved DNA binding domain consisting of two zinc fingers of the motif Cys-X2-Cys -X17-Cys-X2-Cys that directs binding to the nucleotide sequence element (A/T)GATA(A/G).GATA-4 genes are expressed in various mesoderm- and endoderm-derived tissues such as heart,liver,lung,gonad,and gut where they play critical roles in regulating tissue-specific gene expression,genetic transcription and differentiation,proliferation,survival of cardiac muscle cell.And cardiac myocyte apoptosis is involved with regulation of the GATA-4 transcription factor.It is now well known that 5-HT activates signal transduction pathway,induces mitogenesis and proliferation of PASMCs.This action requires 5-HT uptake through a 5-HT active transport process via 5-HTT and induces the generation of ROS,which in turn activates MEK and ERK Phosphorylation and activation of GATA-4,enhances gene transcription of cell cycle regulators such as cyclin D2 and promotes mitogenesis of PASMCs.It was found that after MCT injection,RVHI were significantly increased by 47%on the 14th day and by 64%on the 28th day,respectively;and followed with elevated expression of GATA4 proteins in a positive correlation manner.In addition, enhancement of anti-apoptotic Bcl-xL gene transcription by chronic hypoxia treatment can be suppressed by targeting the GATA-4 gene transcription.Now it is known that pulmonary artery remodeling and right ventricular hypertrophy is induced by MCT in rats due to increase of 5-HT level in plasma.It is also known that fluoxetine can inhibit pulmonary artery remodeling and right ventricular hypertrophy which was found by us.However,it is not known if fluoxetine produced inhibition on pulmonary artery remodeling and right ventricular hypertrophy by MCT in rats is related with GATA-4 expression.Therefore,the present study was designed by using MCT-induced pulmonary hypertension model,to investigate the expression of GATA-4 in the right ventricle and pulmonary tissues.MethodsMCT is used to establish the model of pulmonary hypertension in rats.Rats were treated with different dose of fluoxetine by garages for three weeks.Then,the weight of left ventricular and intraventricular septum,right ventricular index,lung tissue morphological investigate,elastin and collagen staining were undertaken. GATA-4 expression was detected by Western blot.Statistics were made to compare these indexes in different groups,and investigate the mechanism of GATA-4 of fluoxetine-induced inhibition on pulmonary artery remodeling and right ventricular hypertrophy by MCT-treated rats.Results1.Fluoxetine protects against pulmonary artery Remodeling by MCT in rats and inhibits GATA-4 expression.In MCT group,extensive morphological changes were found,including perivascular and peribronchiolar inflammatory cell infiltration and angiogenesis in lungs.However,after treatment with fluoxetine,it was found that inflammation of lungs was not evident and decreased number of inflammation cells dispersed throughout the lungs dose dependently.It was also found that,in MCT group,the layer of elastin content thickened and collagen deposition in pulmonary arteries and pulmonary tissues.MCT+F10 group decreased the elastin content and collagen deposition compared with MCT group.Protein expression of GATA-4 in right ventricular was measured by Western blot.Compared with control group,the level of GATA-4 in MCT group was significantly increased from 0.81±0.08 to 1.50±0.11(P<0.01,vs Control).Fluoxetine inhibited MCT-induced increase of the protein in a concentration dependent manner.The level was decreased to 0.90±0.16(P<0.01, vs MCT) in MCT+F2 group,while the level was significantly decreased to 0.80±0.04(P<0.01,vs MCT) in MCT + F10 group.2.Fluoxetine protects against right ventricle hypertrophy by MCT in rats and inhibits GATA-4 expression.RVHI was increased by MCT from 0.30±0.03 to 0.56±0.10(P<0.01,vs Control).. MCT-induced RVHI was reduced to 0.44±0.06(P<0.01,vs MCT) and 0.40±0.09 (P<0.01,vs MCT) by fluoxetine,compared with MCT group.The pulmonary artery muscle fibers of right ventricular in MCT groups were increased and MCT+F10 and MCT+F2 groups inhibited it.Protein expression of GATA-4 in right ventricular was measured by Western blot.Compared with control group,the level of GATA-4 in MCT group was significantly increased from 0.91±0.06 to 1.28±0.15(P<0.01,vs Control). Fluoxetine inhibited MCT induced increase of the protein in a concentration dependent manner.In MCT+F2 group,the level was decreased to 0.93±0.13(P<0.01,vs MCT),and in MCT+F10 group,the level was significantly decreased to 0.86±0.08(P<0.01,vs MCT).ConclusionFluoxetine,one of the commonly used SSRIs produced inhibition on pulmonary artery remodeling and right ventricular hypertrophy by MCT in rats,in which the potential role of GATA-4 might be involved.